who is charles darwin essay

ENCYCLOPEDIC ENTRY

Charles darwin.

Charles Darwin and his observations while aboard the HMS Beagle , changed the understanding of evolution on Earth.

Biology, Earth Science, Geography, Physical Geography

Historic photograph of Charles Darwin in profile.

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Charles Darwin was born in 1809 in Shrewsbury, England. His father, a doctor, had high hopes that his son would earn a medical degree at Edinburgh University in Scotland, where he enrolled at the age of sixteen. It turned out that Darwin was more interested in natural history than medicine—it was said that the sight of blood made him sick to his stomach. While he continued his studies in theology at Cambridge, it was his focus on natural history that became his passion.

In 1831, Darwin embarked on a voyage aboard a ship of the British Royal Navy, the HMS Beagle, employed as a naturalist . The main purpose of the trip was to survey the coastline of South America and chart its harbors to make better maps of the region. The work that Darwin did was just an added bonus.

Darwin spent much of the trip on land collecting samples of plants, animals, rocks, and fossils . He explored regions in Brazil, Argentina, Chile, and remote islands such as the Galápagos. He packed all of his specimens into crates and sent them back to England aboard other vessels.

Upon his return to England in 1836, Darwin’s work continued. Studies of his samples and notes from the trip led to groundbreaking scientific discoveries. Fossils he collected were shared with paleontologists and geologists, leading to advances in the understanding of the processes that shape the Earth’s surface. Darwin’s analysis of the plants and animals he gathered led him to question how species form and change over time. This work convinced him of the insight that he is most famous for— natural selection . The theory of natural selection says that individuals of a species are more likely to survive in their environment and pass on their genes to the next generation when they inherit traits from their parents that are best suited for that specific environment. In this way, such traits become more widespread in the species and can lead eventually to the development of a new species .

In 1859, Darwin published his thoughts about evolution and natural selection in On the Origin of Species . It was as popular as it was controversial. The book convinced many people that species change over time—a lot of time—suggesting that the planet was much older than what was commonly believed at the time: six thousand years.

Charles Darwin died in 1882 at the age of seventy-three. He is buried in Westminster Abbey in London, England.

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Charles Darwin

(1809-1882)

Who Was Charles Darwin?

Charles Robert Darwin was a British naturalist and biologist known for his theory of evolution and his understanding of the process of natural selection. In 1831, he embarked on a five-year voyage around the world on the HMS Beagle , during which time his studies of various plants and an led him to formulate his theories. In 1859, he published his landmark book, On the Origin of Species .

Darwin was born on February 12, 1809, in the tiny merchant town of Shrewsbury, England. A child of wealth and privilege who loved to explore nature, Darwin was the second youngest of six kids.

Darwin came from a long line of scientists: His father, Dr. R.W. Darwin, was a medical doctor, and his grandfather, Dr. Erasmus Darwin, was a renowned botanist. Darwin’s mother, Susanna, died when he was only eight years old.

His father hoped he would follow in his footsteps and become a medical doctor, but the sight of blood made Darwin queasy. His father suggested he study to become a parson instead, but Darwin was far more inclined to study natural history.

While Darwin was at Christ's College, botany professor John Stevens Henslow became his mentor. After Darwin graduated Christ's College with a bachelor of arts degree in 1831, Henslow recommended him for a naturalist’s position aboard the HMS Beagle .

The ship, commanded by Captain Robert FitzRoy, was to take a five-year survey trip around the world. The voyage would prove the opportunity of a lifetime for the budding young naturalist.

On December 27, 1831, the HMS Beagle launched its voyage around the world with Darwin aboard. Over the course of the trip, Darwin collected a variety of natural specimens, including birds, plants and fossils.

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Darwin in the Galapagos

Through hands-on research and experimentation, he had the unique opportunity to closely observe principles of botany, geology and zoology. The Pacific Islands and Galapagos Archipelago were of particular interest to Darwin, as was South America.

Upon his return to England in 1836, Darwin began to write up his findings in the Journal of Researches , published as part of Captain FitzRoy's larger narrative and later edited into the Zoology of the Voyage of the Beagle .

The trip had a monumental effect on Darwin’s view of natural history. He began to develop a revolutionary theory about the origin of living beings that ran contrary to the popular view of other naturalists at the time.

Theory of Evolution

Darwin’s theory of evolution declared that species survived through a process called "natural selection," where those that successfully adapted or evolved to meet the changing requirements of their natural habitat thrived and reproduced, while those species that failed to evolve and reproduce died off.

Through his observations and studies of birds, plants and fossils, Darwin noticed similarities among species all over the globe, along with variations based on specific locations, leading him to believe that the species we know today had gradually evolved from common ancestors.

Darwin’s theory of evolution and the process of natural selection later became known simply as “Darwinism.”

At the time, other naturalists believed that all species either came into being at the start of the world or were created over the course of natural history. In either case, they believed species remained much the same throughout time.

'Origin of Species'

In 1858, after years of scientific investigation, Darwin publicly introduced his revolutionary theory of evolution in a letter read at a meeting of the Linnean Society . On November 24, 1859, he published a detailed explanation of his theory in his best-known work, On the Origin of Species by Means of Natural Selection.

In the next century, DNA studies provided scientific evidence for Darwin’s theory of evolution. However, controversy surrounding its conflict with Creationism — the religious view that all of nature was born of God — is still found among some people today.

Social Darwinism

Social Darwinism is a collection of ideas that emerged in the late 1800s that adopted Darwin’s theory of evolution to explain social and economic issues.

Darwin himself rarely commented on any connections between his theories and human society. But while attempting to explain his ideas to the public, Darwin borrowed widely understood concepts, such as “survival of the fittest” from sociologist Herbert Spencer.

Over time, as the Industrial Revolution and laissez faire capitalism swept across the world, social Darwinism has been used as a justification for imperialism, labor abuses, poverty, racism, eugenics and social inequality.

Following a lifetime of devout research, Charles Darwin died at his family home, Down House, in London, on April 19, 1882. He was buried at Westminster Abbey .

More than a century later, Yale ornithologist Richard Brum sought to revive Darwin's lesser-known theory on sexual selection in The Evolution of Beauty .

While Darwin's original attempts to cite female aesthetic mating choices as a driving force of evolution was criticized, Brum delivered an effective argument via his expertise in birds, earning selection to The New York Times ' list of 10 best books of 2017.

QUICK FACTS

• Name: Charles Darwin
• Birth Year: 1809
• Birth date: February 12, 1809
• Birth City: Shrewsbury
• Birth Country: England
• Gender: Male
• Best Known For: Charles Darwin was a British naturalist who developed a theory of evolution based on natural selection. His views and “social Darwinism” remain controversial.
• Science and Medicine
• Astrological Sign: Aquarius
• University of Edinburgh
• Interesting Facts
• Although Charles Darwin originally went to college to be a physician, he changed career paths when he realized that he couldn't stomach the sight of blood.
• Charles Darwin had a mountain named after him, Mount Darwin, in Tierra del Fuego for his 25th birthday. The monumental gift was given by Captain FitzRoy.
• Death Year: 1882
• Death date: April 19, 1882
• Death City: Downe
• Death Country: England

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CITATION INFORMATION

• Article Title: Charles Darwin Biography
• Author: Biography.com Editors
• Website Name: The Biography.com website
• Url: https://www.biography.com/scientists/charles-darwin
• Access Date:
• Publisher: A&E; Television Networks
• Last Updated: March 29, 2021
• Original Published Date: April 3, 2014
• A man who dares to waste one hour of time has not discovered the value of life.
• [How great the] difference between savage and civilized man is—it is greater than between a wild and [a] domesticated animal.
• If all men were dead, then monkeys make men. Men make angels.
• I am a complete millionaire in odd and curious little facts.
• Multiply, vary, let the strongest live and the weakest die.
• For the shield may be as important for victory, as the sword or spear.
• I see no good reason why the views given in this volume should shock the religious feelings of anyone."[In 'Origin of the Species']
• A grain in the balance may determine which individuals shall live and which shall die—which variety or species shall increase in number, and which shall decrease, or finally become extinct.
• If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case.
• The extinction of species and of whole groups of species, which has played so conspicuous a part in the history of the organic world, almost inevitably follows from the principle of natural selection.
• There is grandeur in this view of life...from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

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Charles Darwin: Biography, Theories, Contributions

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.

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Biography of Charles Darwin

• Best Known For

Natural Selection and Evolution

• Controversies
• Research on Emotions
• Views on Women
• Contributions

Charles Darwin was a renowned British naturalist and biologist best known for his theory of evolution through natural selection. His theory that all life evolved from a common ancestor is now a cornerstone of modern science, making Darwin one of the most influential individuals in history. It is difficult to overstate the monumental influence his work has had on our scientific understanding of the world.

This article discusses Charles Darwin's life and work, including his famous theory of natural selection as well as some of his lesser-known research on human emotion.

Charles Darwin was born in Shrewsbury, England, on February 12, 1809. His father was a wealthy doctor, and his grandfather on his mother's side was the noted potter Josiah Wedgwood. After his mother’s death when he was eight, Darwin began attending boarding school with his older brother. 

Darwin originally began his studies at the University of Edinburgh Medical School, but later developed an interest in ministry and botany, eventually receiving his degree from Cambridge in 1831.

His famed voyage to the Galapagos Islands led to the observations that served as the basis for Darwin's groundbreaking theory of natural selection.

In 1839, Darwin married his cousin Emma Wedgwood. They had 10 children together, with seven surviving to adulthood. In 1859, he published his observations and ideas in his book "On the Origin of Species By Means of Natural Selection."

Darwin's ideas were heavily debated in his own time and continue to spark controversy today. In contrast to this, Darwin himself lived a secluded life at his home in England, where he continued to work as a highly regarded scientist.

Darwin died on April 19, 1882, and is buried at Westminster Abbey in London, England.

Darwin's Illness

For much of his adult life, Darwin had an undiagnosed chronic illness that limited his activities. Symptoms included physical complaints such as stomach pain and dizziness, as well as signs of panic attacks such as shortness of breath and heart palpitations.

One theory suggests that he may have had panic disorder with agoraphobia . This diagnosis would also explain his secluded lifestyle, difficulty with public speaking, and struggles when meeting with colleagues.

Other proposed diagnoses include mercury poisoning, allergies, Crohn's disease, and irritable bowel syndrome. However, many researchers now believe that he had an adult-onset mitochondrial disorder.

What Was Charles Darwin Most Famous For?

Charles Darwin is most famous for his theory of evolution through the process of natural selection. Since introducing his ideas in “On the Origin of the Species,” his work has revolutionized the scientific understanding of how species evolve over time. This helped lay the foundation for modern biological sciences .

His Studies on the Galapagos Islands

During a voyage on a ship called the HMS Beagle, Darwin traveled to the Galapagos Islands, a journey that had a profound influence on his thinking and ideas. During this trip, he noticed interesting variations in the different species of finches that lived on the islands.

The beaks of these birds appeared to vary depending on the native food sources where the birds lived. Darwin hypothesized that the variations he observed resulted from natural selection that favored birds with beaks suited to the local food sources.  

There are 14 species of finches found on the Galapagos Islands, which are now collectively referred to as "Darwin's finches."

In “On the Origin of the Species,” Darwin suggested that all species on Earth, including humans, evolved from common ancestors. The diversity found in all species, he explained, results from changes that occur gradually over very long periods of time, a process he referred to as “descent with modification.” This happens through natural selection, where certain traits that benefit an organism's survival are more likely to be passed down. 

Because these organisms are more likely to survive and reproduce, those beneficial traits are more likely to be handed down. This leads to the adaptation and evolution of species.

Charles Darwin's concept of evolution through natural selection suggested that species change slowly over time as a response to their environment. This theory changed our scientific understanding of the diversity of life on Earth and laid the groundwork for the development of modern biology.

How Does Natural Selection Work?

According to Darwin, the individuals within a population possess variations, some of which are better suited to the environment in which they live. As a result, those with these adaptations are more likely to survive, reproduce, and thus pass these advantageous characteristics down to their offspring.

Over time, this process gradually leads the adaptive traits to become more prominent and can eventually lead to the emergence of new species.

The Five Principles of Natural Selection

The five principles of natural selection described by Charles Darwin can be remembered using the acronym VISTA, standing for variation, inheritance, selection, time, and adaptation.

• Variation : In all populations of any species, there are individual variations in different traits. The species' members can vary in appearance, size, abilities, immunity, and numerous other characteristics. Many of these variations result from genetic inheritance but can also occur due to random mutations.
• Inheritance : The various traits organisms possess can be inherited through genetic inheritance. In other words, when members of a species reproduce, their offspring are more likely to also possess those same traits.
• Selection : Environmental resources are limited, so organisms with advantageous characteristics that make it easier for them to survive are more likely to thrive in their environment and reproduce. This increased chance of reproduction means that their children are more likely to have the same traits that helped their ancestors survive.
• Time : As time passes, each generation continues to produce more offspring with advantageous characteristics. With the passage of time, the beneficial traits continue to accumulate, resulting in significant changes in the characteristics of the entire population.
• Adaptation : Such traits eventually become more common in the population, making the entire species better suited to survive in their environment.

What Does ‘Survival of the Fittest’ Mean?

An important part of natural selection is the idea of ‘survival of the fittest.’ The phrase was first introduced in 1854 by Herbert Spencer in his book "The Principles of Biology."

The idea suggests that when it comes to each organism's struggle to survive and reproduce, those with traits that make them the best suited to their environment are the most likely to survive and pass down their genes to the next generation.

In this context, "fitness" refers to an organism's ability to survive in its environment and reproduce. It is the traits that help the individual survive that are considered most advantageous. 

Fitness does not refer to physical strength. Instead, it means the individual has traits that make them better suited for life in a specific environment. For example, an organism with coloring that camouflages it from predators would be considered a better fit, from an evolutionary perspective, than coloring that makes it more susceptible to becoming prey.

Fitness can refer to a wide variety of characteristics. This might include physical attributes such as camouflage, speed, strength, or agility. It might also refer to behavioral adaptations that confer a greater chance of survival. Migration, hibernation, and courtship behaviors are a few examples of behavioral adaptations influenced by evolution.

Controversies Surrounding Darwin’s Theory of Evolution

Darwin's theory was considered shocking and controversial after its introduction. While the theory is accepted by nearly all scientists today, Darwin's ideas are still disputed or rejected by some people.

Darwin and his work have remained controversial in the more than 140 years since his death. One survey found that a third of U.S. adults reject the idea that humans evolved through natural selection, views that correspond with rates of religious belief.

One critic during Darwin's time was the English comparative anatomist and paleontologist Richard Owen. While Owen agreed that evolution occurred, he was a vocal critic of Darwin's idea of natural selection. Instead, he proposed the existence of predetermined "archetypes" that guide the evolutionary changes that species experience. 

During Darwin's time, some critics suggested that the lack of transitional fossils (demonstrating the gradual progression of a species over time) was evidence that Darwin’s evolutionary theory was wrong. In the subsequent years, however, many of these so-called "missing links" have been added to the fossil record, providing paleontological support for these evolutionary transitions.

Other critics focus on their belief that all life results from divine creation. However, it is important to note that Darwin's theory of evolution does not focus on how life originated. Instead, Darwin's theory of natural selection explains how life evolved over time and how this explains the diversity of life on Earth.

While there have been debates and criticisms from various sources, it is important to note that Darwin was highly regarded in his own time. Support from the scientific community continued to build over the years, and more evidence supporting Darwin's theory accumulated from various fields.

Charles Darwin’s Research on Human Emotions

While Darwin is best known for his theory of evolution, he also studied and wrote about a wide range of topics, from plants to sea life. Beyond his work as a naturalist, he also conducted one lesser-known experiment on the study of human emotions , making him one of the earliest experimental psychology researchers. 

In archival research looking at Darwin's letters and other writings, researchers found references to a small experiment that Darwin had conducted at home. Darwin had corresponded with the French physician Guillaume Duchenne de Boulogne, who had used electrical impulses to stimulate facial muscles into specific expressions, which were then recorded on photographic plates. Using this method, Duchenne suggested that the human face is capable of expressing at least 60 distinct emotions.

Darwin disagreed. Using Duchenne's plates, Darwin devised his own experiment, a single-blind study in which he randomized the order of the plates and then presented them to over 20 participants (i.e., Darwin's guests). He then asked his guests to identify the emotions represented in the photographic slides. 

In studying Darwin's notes, researchers discovered that the participants agreed when it came to the basic emotions , such as happiness , surprise, and fear. For more ambiguous photographs, responses were much more mixed.

In Darwin's view, only those emotions that were readily identifiable and agreed upon by observers represented universal emotions.

Darwin's observations and conclusions in this and other studies he conducted helped inform his 1872 book "The Expression of the Emotions in Man and Animals." In this book, Darwin emphasized the importance of emotional expression in both humans and animals, suggesting that:

• Some emotional expressions are universal
• Some emotions have a biological, evolutionary basis
• These universal expressions evolved through natural selection because they aid in survival, reproduction, and communication
• Humans and animals display similar emotions, suggesting they have a common evolutionary origin

Darwin's work offered insights into the importance of emotions, their evolutionary roots, and their universality across cultures and species . His observations also helped lay the groundwork for future research on the psychology of human emotions.

However, Darwin's ideas about emotion were eclipsed by his more famous theory of natural selection. It wasn't until the 1960s that psychologist Paul Ekman returned to Darwin's findings and, using methods similar to those originally pioneered by Darwin, found additional evidence for the existence of basic, universal human emotions.

Try the emotion experiment yourself!

The Darwin Correspondence Project allows viewers to see the original photographic plates Duchenne and Darwin used this in their experiments. You can also give your own response and see how your interpretation compares to those of Darwin's guests.

What Were Charles Darwin’s Views on Women?

While Darwin revolutionized the field of science, his views on women were far from progressive. His attitudes reflected the prevailing sexist, misogynistic ideas of his time. In his published writings, he echoed the societal and cultural beliefs that women were inferior to men, viewing them as less intelligent.

In his book "The Descent of Man," Darwin wrote, "Woman seems to differ from man in her mental disposition, chiefly in her greater tenderness and less selfishness."

Darwin suggested that the purported superiority of men stemmed from sexual selection, a mode of natural selection in which men compete for mates, leading to the evolution of characteristics that improve their reproductive fitness, including intelligence, physical strength, and competitiveness.

He believed that women's roles were primarily as domestic caretakers and nurturers, which, in his view, did not require strong intellectual capabilities.

There is evidence that Darwin's ideas changed somewhat over time, often influenced by the women in his life, including his wife, daughters, and women intellectuals. While he could not be regarded as a feminist thinker, research on his private correspondence suggests that his views on women were more complex than what appears in his published writing.

Who Did Charles Darwin Influence?

In addition to his profound influence on the biological sciences, Darwin inspired a number of other scientists and researchers in their own work.

Some of these thinkers included:

• Alfred Russel Wallace : A contemporary of Darwin, Wallace was an English naturalist and explorer who independently introduced the idea of evolution through natural selection. His own ideas were published in 1858 along with some of Darwin's earlier writings, prompting Darwin to publish "On the Origin of the Species" the next year.
• William James : The founder of the functionalist school of thought in psychology was heavily influenced by the work of Charles Darwin. This school of thought suggests that the functions of the mind exist because they serve a purpose in survival and adaptation. This idea has its roots in Darwin's theory of natural selection. James was also heavily influenced by Darwin's writings on the topic of emotions. According to the James-Lange theory of emotions , emotions stems from the physiological reactions people experience in response to environmental stimuli.
• Ronald A. Fisher : A British mathematician and biologist, Fisher is considered a founder of modern statistical science. He also played an important role in what is known as modern synthesis, which involved integrating Darwin's natural selection with Mendelian genetics in order to explain how genetic variations within a group can be affected by natural selection.

How Does Charles Darwin’s Work Affect Modern Science Today?

It is difficult to overstate the enormous impact of Darwin's work on modern science. Some of the ways that science continues to be impacted by Darwin's theory of evolution include:

• Evolutionary sciences : The theory of evolution plays an essential role in biology as well as other fields that explain how life has adapted and changed over time, including genetics and evolutionary psychology .
• Medicine : Researchers continue to use their understanding of evolutionary science to study how diseases originate, spread, and mutate.
• Scientific education : While Darwin's ideas remain controversial for some, his work has helped advance scientific literacy and understanding among the general public.

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By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

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AP®︎/College Biology

Course: ap®︎/college biology   >   unit 7.

• Introduction to evolution and natural selection
• Natural selection and the owl butterfly
• Biodiversity and natural selection
• Variation in a species

Darwin, evolution, & natural selection

Natural selection.

Key points:

• Charles Darwin was a British naturalist who proposed the theory of biological evolution by natural selection.
• Darwin defined evolution as "descent with modification," the idea that species change over time, give rise to new species, and share a common ancestor.
• The mechanism that Darwin proposed for evolution is natural selection . Because resources are limited in nature, organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers, causing the traits to increase in frequency over generations.
• Natural selection causes populations to become adapted , or increasingly well-suited, to their environments over time. Natural selection depends on the environment and requires existing heritable variation in a group.

What is evolution?

Early ideas about evolution, influences on darwin, darwin and the voyage of the beagle.

• Traits are often heritable. In living organisms, many characteristics are inherited, or passed from parent to offspring. (Darwin knew this was the case, even though he did not know that traits were inherited via genes.)
• More offspring are produced than can survive. Organisms are capable of producing more offspring than their environments can support. Thus, there is competition for limited resources in each generation.
• Offspring vary in their heritable traits. The offspring in any generation will be slightly different from one another in their traits (color, size, shape, etc.), and many of these features will be heritable.
• In a population, some individuals will have inherited traits that help them survive and reproduce (given the conditions of the environment, such as the predators and food sources present). The individuals with the helpful traits will leave more offspring in the next generation than their peers, since the traits make them more effective at surviving and reproducing.
• Because the helpful traits are heritable, and because organisms with these traits leave more offspring, the traits will tend to become more common (present in a larger fraction of the population) in the next generation.
• Over generations, the population will become adapted to its environment (as individuals with traits helpful in that environment have consistently greater reproductive success than their peers).

Example: How natural selection can work

Key points about natural selection, natural selection depends on the environment, natural selection acts on existing heritable variation, heritable variation comes from random mutations, natural selection and the evolution of species, attribution:, works cited:.

• Wilkin, D. and Akre, B. (2016, March 23). Influences on Darwin - Advanced. In CK-12 biology advanced concepts . Retrieved from http://www.ck12.org/book/CK-12-Biology-Advanced-Concepts/section/10.18/ .
• Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., and Jackson, R. B. (2011). The voyage of the Beagle . In Campbell Biology (10th ed., p. 466). San Francisco, CA: Pearson.
• Darwin's finches. (2016, April 25). Retrieved March 16, 2016 from Wikipedia: https://en.wikipedia.org/wiki/Darwin%27s_finches .
• Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., and Jackson, R. B. (2011). Figure 1.18. Natural selection. In Campbell biology (10th ed., p. 14). San Francisco, CA: Pearson.

Additional references:

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Darwin in letters, 1844–1846: Building a scientific network

Darwin correspondence project.

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• Be envious of ripe oranges: To W. D. Fox, May 1832
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• Our poor dear dear child: To Emma Darwin, [23 April 1851]
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• Prize possessions: To Henry Denny, 17 January [1865]
• How to manage it: To J. D. Hooker, [17 June 1865]
• A fly on the flower: From Hermann Müller, 23 October 1867
• Reading my roommate’s illustrious ancestor: To T. H. Huxley, 10 June 1868
• A beginning, & that is something: To J. D. Hooker, [22 January 1869]
• Perfect copper-plate hand: From Adolf Reuter, 30 May 1869
• Darwin’s favourite photographer: From O. G. Rejlander, 30 April 1871
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• Lost in translation: From Auguste Forel, 12 November 1874
• I never trusted Drosera: From E. F. Lubbock, [after 2 July] 1875
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• Terms of engagement: To Julius Wiesner, 25 October 1881
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Natural selection

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Hooker-j-d-02-02357.jpg.

The scientific results of the  Beagle  voyage still dominated Darwin's working life, but throughout these years he broadened his continuing investigations into the nature and origin of species and varieties. In contrast to the received image of Darwin as a recluse in Down, the letters show him to be an established and confident naturalist at the heart of British scientific society, travelling often to London and elsewhere to attend meetings and confer with colleagues, and involved in the social and political activities of the community of savants as well as in its philosophical and scientific pursuits. At home, time was filled with copious natural history work, writing, and gathering information from an ever-expanding network of correspondents. Down House was altered and extended to accommodate Darwin’s growing family and the many relatives and friends who came to stay; and, with his father’s advice, Darwin began a series of judicious financial investments to ensure a comfortable future for all those under his care.

The geological publications

In these years, Darwin published two books on geology,  Volcanic islands  (1844) and  Geological observations on South America  (1846), which completed his trilogy on the geological results of the  Beagle  voyage, and extensively revised his  Journal of researches  for a second edition in 1845, having already provided corrections in 1844 for a German translation of the first edition. He continued as an officer of the Geological Society of London, acting as one of four vice-presidents in 1844 and remaining on the council from 1845 onwards; he was a conscientious member of the Royal Geographical Society and the Royal Society; he regularly attended meetings and refereed papers for all these organisations. Between 1844 and 1846 Darwin himself wrote ten papers, six of which related to the  Beagle  collections. Among these were some studies of invertebrates that at first had been intended for publication in  The zoology of the voyage of H.M.S. Beagle  (1838–43) but were deferred when the Government grant was exhausted ( Correspondence  vol. 2, letter to A. Y. Spearman, 9 October 1843, n. 1).

Darwin's inner circle: first discussions of species change

In addition, Darwin threw himself into analysing the results emerging from the examination of  Beagle  plant specimens by the young botanist and traveller, Joseph Dalton Hooker. More than 1200 letters between the two men survive, fully documenting a life-long friendship.

species are not (it is like confessing a murder) immutable

Darwin’s earlier scientific friendships were not neglected either, as the correspondence with Charles Lyell, George Robert Waterhouse, John Stevens Henslow, Leonard Horner, Leonard Jenyns, Edward Forbes, and Richard Owen shows. These friends, with the addition of Hooker, were important to Darwin for—among other things—they were the first people he turned to when he wished to discuss the problems and various scientific issues that arose out of his work on species. Darwin discussed his ideas on species mutability with Hooker, Horner, Jenyns, Lyell, Owen, and Charles James Fox Bunbury; he may well have broached the subject with others. Only two months after their first exchange, early in 1844, Darwin told Hooker that he was engaged in a ‘very presumptuous work’ which had led to the conviction that ‘species are not (it is like confessing a murder) immutable’ ( letter to J. D. Hooker, [11 January 1844] ). Nine months later, in his letter of 12 October [1844], he explained to Jenyns: 'I have continued steadily reading & collecting facts on variation of domestic animals & plants & on the question of what are species; I have a grand body of facts & I think I can draw some sound conclusions. The general conclusion at which I have slowly been driven from a directly opposite conviction is that species are mutable & that allied species are co-descendants of common stocks. I know how much I open myself, to reproach, for such a conclusion, but I have at least honestly & deliberately come to it.'

It is clear from the correspondence that his close friends were not outraged by Darwin’s heterodox opinions and later in the year both Jenyns and Hooker were invited to read a manuscript essay on his species theory (DAR 113;  Foundations , pp. 57–255), an expanded version, completed on 5 July 1844, of a pencil sketch he had drawn up some two years earlier. But although eager for the views of informed colleagues, Darwin was naturally protective of his untried theory and seems to have shied away from the risk of pushing it too early into the open. In the event, it was not until the beginning of 1847 that Hooker was given a fair copy of the essay of 1844 to read (see  Correspondence  vol. 4, letter to J. D. Hooker, 8 [February 1847]). Darwin can be seen as a cautious strategist, sometimes confident, but often uneasy about his work, and always attempting to gauge the kind of response that his theory of transmutation would generate. In particular, he anxiously watched the controversy seething around an evolutionary book,  Vestiges of the natural history of creation , published anonymously in 1844. His old friend Adam Sedgwick attacked the work vehemently in the  Edinburgh Review  (1845), while other colleagues like Edward Forbes ridiculed the theories employed there, caring only to join in the popular guessing-game about the identity of the author. One candidate, known to be working on species and varieties, was Darwin himself: as he told his cousin William Darwin Fox in a letter of [24 April 1845] , he felt he ought to be both ‘flattered & unflattered’ to hear that other naturalists attributed the book to him. But, as his letters to Hooker show, Darwin carefully considered and then rejected almost all of the contents of  Vestiges , and he feared that the reaction to his own work would be prejudiced by the arguments aroused by its skilful but scientifically unsound reasoning.

Perhaps the most interesting letter relating to Darwin’s species theory, which also bears on his concern for the future, is that addressed to his wife Emma, dated 5 July 1844 , just after Darwin had completed the final draft of his essay on the subject. He asked her to ensure that the essay would be published in the event of his death and stipulated a sum of money to be bequeathed, together with his extensive library and portfolios of notes on species, to an editor who would undertake to see the work through the press. Darwin also listed possible editors: at first he proposed any one of Lyell, Henslow, Edward Forbes, William Lonsdale, Hugh Edwin Strickland, or Owen—the last with the caveat that he would probably not wish to take on the work. But the list was subsequently altered after Darwin’s second, and possibly third, thoughts on the choice of the right person. The names of Lonsdale, Forbes, and Owen were deleted, Henslow’s was queried, and J. D. Hooker’s was added. Much later, by the autumn of 1854 when Darwin began sorting out his notes in preparation for writing up his ‘big book’ on species ( Natural selection ), he had decided that Hooker was by far the best man for the task and added a note on the cover to that effect.

The full consideration that Darwin gave to the future editing and publication of his essay, and the way in which he wrote to colleagues and friends about his work, show clearly his intention to publish his theory. His instructions to Emma may, perhaps, as some scholars have thought, indicate a reluctance to take the responsibility for publishing upon himself, but, more plausibly, they portray a man faced with the task of establishing a theory and its consequences, and fearful lest both the energy and time necessary to achieve this end should be denied him. After prolonged illnesses in 1841 and 1842, years poorly represented in the  Correspondence  because he was for much of the time too ill even to write letters, Darwin felt that his life was only too likely to be cut short. Moreover, even when at his best, Darwin could never work as intensively as he felt he ought to, or needed to, for fear of inducing another breakdown in his health.

Volcanoes, rocks, and fossils

Darwin’s published work during this period secured his position as one of Britain’s foremost naturalists. His study of the volcanic islands visited during the  Beagle  voyage was based on a wide range of rock and mineral specimens, including his own, and considerable research into contemporary theories of volcanic activity, mountain formation, and the elevation of extensive tracts of land relative to the sea. Darwin put forward a new explanation of the origin of so-called ‘craters of elevation’, which formed the basis of discussions with Charles Lyell and Leonard Horner in letters in this volume. His observations on the lamination of volcanic rocks prompted an exchange with James David Forbes on the analogous structure of glacier-ice. In South America he proposed that the tension generated in molten rock before final consolidation, which he believed gave rise to this lamination, could also explain and link the widespread phenomena of cleavage and foliation, observable in some metamorphic rocks. His description and explanation of cleavage and foliation in the clay-slates and schists of South America benefitted from the mathematical expertise of William Hopkins and aroused the interest of Daniel Sharpe, whose subsequent work led to the general acceptance of Darwin’s views.  South America  drew together all the geological and palaeontological results of Darwin’s travels through that area and, like  Volcanic islands , demonstrated how the structure of the land could best be explained by elevation. Darwin presented a wholeheartedly Lyellian picture of the geology of this vast area, reflecting the influence of Lyell’s  Principles of geology  (1830–3) and a commitment to Lyell’s idea of gradual geological change taking place overimmensely long periods of time; a commitment that transcended Darwin’s purely geological thought and influenced his speculations in all fields of natural history. But despite this clear and acknowledged debt, Darwin’s independence of mind was never in doubt and is well evidenced by the skilled and determined defence of his theories he invariably made against rivals of whatever standing. Through the pages of South America Darwin pursued an argument against the French palaeontologist Alcide d’Orbigny, insisting that the vast pampas formation could not have been laid down at a single moment through the action of a great  débâcle , as Orbigny proposed. Darwin not only used his personal notes and records but, by letter, marshalled the resources of experts such as palaeontologists Edward Forbes and George Brettingham Sowerby, and the German naturalist Christian Gottfried Ehrenberg, to support his own opinion that the pampas formations had been deposited successively under mostly brackish or estuarine conditions.

Journal of researches : Darwin's story of the Beagle voyage

In addition to writing up his geology, Darwin undertook the revision of his  Journal of researches  for a second edition in 1845. At Lyell’s recommendation, arrangements were made for the rights of the work to be transferred from Henry Colburn, the original publisher, to John Murray, and throughout 1845 Darwin worked hard to provide manuscript copy to be published in three parts during the year. Though the text was reduced in volume, Darwin went to considerable trouble to add the latest descriptions of the  Beagle  collections, to alter and expand some of his previous suggestions about the causes of extinction, and to supplement the original account of the three Fuegians carried on board the Beagle  back to Tierra del Fuego. By 1845, Darwin was in full command of a sophisticated theory of species transmutation and there is much interplay between the information supplied in letters to Darwin, the contents of the new edition of the  Journal of researches , and his species work.

Joseph Hooker and the Beagle plant collections

The botany of the  Beagle  voyage was a topic still relatively unexplored by Darwin, even though he had collected plants extensively. Henslow, who had undertaken to describe the collection, was overwhelmed by ever-increasing parish and local concerns in Cambridge and Hitcham and apparently relieved to handover Darwin’s plants to Hooker, who had just returned from accompanying James Clark Ross’s Antarctic surveying expedition and who hoped to publish a detailed account of the flora of the Southern Hemisphere. Darwin was quick to spot in Hooker a man he judged could become the ‘first authority in Europe on that grand subject, that almost key-stone of the laws of creation, Geographical Distribution’ ( letter to J. D. Hooker, [10 February 1845] ) and quick to make use of the young man’s already large fund of botanical knowledge and his extensive connections with other British and European botanists. Darwin’s questions challenged Hooker to apply his particular knowledge to more general problems, always relating, directly or indirectly, to the question of the origin and nature of species. There is little in contemporary botany and botanical systematics that is not touched upon in their correspondence. Hooker’s observations on classification provided Darwin with a professional judgment on the plant world to place beside that of Waterhouse with respect to the animal kingdom. Hooker was also ready to discuss contemporary ideas on transformism in Britain and France and was a constant source of useful references and books. Some indication of the intellectual value that both men placed on their correspondence is found in the fact that they independently kept practically all the letters received from each other. The letters also document aspects of Hooker’s life: his search for a paid position, involving an unsuccessful campaign for the chair of botany at Edinburgh University and a period of half-hearted work with the Geological Survey of Great Britain. Like Darwin, he obtained Government aid to publish the results of his own four-year voyage and struggled to keep up to the time-table. And like Darwin, he was deeply committed to philosophical natural history.

Mr Arthrobalanus - Darwin's work on barnacles

It was also Hooker who helped Darwin in the first stages of his barnacle work, a study commenced towards the end of 1846. Hooker, ready with advice on microscopes and microscopic technique, assisted Darwin with drawings of his first dissection. The barnacle—‘M r  Arthrobalanus’ in Hooker’s and Darwin’s letters—was a minute, aberrant species collected by Darwin in the Chonos Archipelago, off southern Chile, which lived inside the shell of the mollusc,  Concholepas . Unusual sexual dimorphism, with the male virtually a parasite on the female, a complex life-cycle, and difficult taxonomic considerations, combined to intrigue Darwin, and he launched himself into a survey of related species to elucidate some of the problems presented by the animal. The cirripedes were to remain central to Darwin’s working life for the next eight years.

In this section:

• 1837-43: The London years to 'natural selection'
• 1856-1857: The 'Big Book'

Related people

Forbes, edward, forbes, j. d., henslow, j. s., hooker, j. d., horner, leonard, jenyns, leonardblomefield, leonard, lyell, charles, murray, john (b), owen, richard, waterhouse, g. r., about this article.

Based on the introduction to The correspondence of Charles Darwin , volume 3: 1844-1846

Edited by Frederick Burkhardt, Sydney Smith. (Cambridge University Press 1987)

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UC MUSEUM OF PALEONTOLOGY

Understanding Evolution

Your one-stop source for information on evolution

The History of Evolutionary Thought

Natural selection: charles darwin & alfred russel wallace.

Pre-Darwinian ideas about evolution

It was Darwin’s genius both to show how all this evidence favored the evolution of species from a common ancestor and to offer a plausible mechanism by which life might evolve. Lamarck and others had promoted evolutionary theories, but in order to explain just how life changed, they depended on speculation. Typically, they claimed that evolution was guided by some long-term trend. Lamarck, for example, thought that life strove over time to rise from simple single-celled forms to complex ones. Many German biologists conceived of life evolving according to predetermined rules, in the same way an embryo develops in the womb. But in the mid-1800s, Darwin and the British biologist Alfred Russel Wallace independently conceived of a natural, even observable, way for life to change: a process Darwin called  natural selection.

The pressure of population growth

Interestingly, Darwin and Wallace found their inspiration in economics. An English parson named  Thomas Malthus  published a book in 1797 called  Essay on the Principle of Population  in which he warned his fellow Englishmen that most policies designed to help the poor were doomed because of the relentless pressure of population growth. A nation could easily double its population in a few decades, leading to famine and misery for all.

When Darwin and Wallace read Malthus, it occurred to both of them that animals and plants should also be experiencing the same population pressure. It should take very little time for the world to be knee-deep in beetles or earthworms. But the world is not overrun with them, or any other species, because they cannot reproduce to their full potential. Many die before they become adults. They are vulnerable to droughts and cold winters and other environmental assaults. And their food supply, like that of a nation, is not infinite. Individuals must compete, albeit unconsciously, for what little food there is.

Selection of traits

In this struggle for existence, survival and reproduction do not come down to pure chance. Darwin and Wallace both realized that if an animal has some trait that helps it to withstand the elements or to breed more successfully, it may leave more offspring behind than others. On average, the trait will become more common in the following generation, and the generation after that.

As Darwin wrestled with  natural selection  he spent a great deal of time with pigeon breeders, learning their methods. He found their work to be an analogy for evolution. A pigeon breeder selected individual birds to reproduce in order to produce a neck ruffle. Similarly, nature unconsciously “selects” individuals better suited to surviving their local conditions. Given enough time, Darwin and Wallace argued, natural selection might produce new types of body parts, from wings to eyes.

Darwin and Wallace develop similar theory

Darwin began formulating his theory of natural selection in the late 1830s but he went on working quietly on it for twenty years. He wanted to amass a wealth of evidence before publicly presenting his idea. During those years he corresponded briefly with Wallace (right), who was exploring the wildlife of South America and Asia. Wallace supplied Darwin with birds for his studies and decided to seek Darwin’s help in publishing his own ideas on evolution. He sent Darwin his theory in 1858, which, to Darwin’s shock, nearly replicated Darwin’s own.

Charles Lyell  and Joseph Dalton Hooker arranged for both Darwin’s and Wallace’s theories to be presented to a meeting of the Linnaean Society in 1858. Darwin had been working on a major book on evolution and used that to develop  On the Origins of Species , which was published in 1859. Wallace, on the other hand, continued his travels and focused his study on the importance of biogeography.

The book was not only a best seller but also one of the most influential scientific books of all time. Yet it took time for its full argument to take hold. Within a few decades, most scientists accepted that evolution and the descent of species from common ancestors were real. But natural selection had a harder time finding acceptance. In the late 1800s many scientists who called themselves Darwinists actually preferred a Lamarckian explanation for the way life changed over time. It would take the discovery of  genes  and  mutations  in the twentieth century to make natural selection not just attractive as an explanation, but unavoidable.

• More Details
• Read more about  the process of natural selection  in Evolution 101.
• Go right to the source and read Darwin's  On the Origin of Species by Means of Natural Selection .
• Explore the  American Museum of Natural History's Darwin exhibit  to learn more about his life and how his ideas transformed our understanding of the living world.

Discrete Genes Are Inherited: Gregor Mendel

Early Evolution and Development: Ernst Haeckel

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Darwinism designates a distinctive form of evolutionary explanation for the history and diversity of life on earth. Its original formulation is provided in the first edition of On the Origin of Species in 1859. This entry first formulates ‘Darwin’s Darwinism’ in terms of six philosophically distinctive themes: (i) probability and chance, (ii) the nature, power and scope of selection, (iii) adaptation and teleology, (iv) the interpretation of the concept of ‘species’, (v) the tempo and mode of evolutionary change, and (vi) the role of altruism and group selection in the explanation of morality. Both Darwin and his critics recognized that his approach to evolution was distinctive on each of these topics, and it remains true that, though Darwinism has developed in many ways unforeseen by Darwin, its proponents and critics continue to differentiate it from other approaches in evolutionary biology by focusing on these themes. This point is illustrated in the second half of the entry by looking at current debates in the philosophy of evolutionary biology on these six themes.

1. Introduction

2.1 darwin’s life, 2.2 darwin’s darwinism, 2.3 philosophical problems with darwin’s darwinism, 3.1 the roles of chance in evolutionary theory, 3.2 the nature, power and scope of selection, 3.3 selection, adaptation and teleology, 3.4 species and the concept of ‘species’, 3.5 tempo and mode of evolutionary change, 3.6 evolutionary ethics, altruism, and group selection, 4. conclusion, further reading, other internet resources, related entries.

Scientific theories are historical entities. Often you can identify key individuals and documents that are the sources of new theories—Einstein’s 1905 papers, Copernicus’ 1539 De Revolutionibus , Darwin’s On the Origin of Species . Sometimes, but not always, the theory tends in popular parlance to be named after the author of these seminal documents, as is the case with Darwinism.

But like every historical entity, theories undergo change through time. Indeed a scientific theory might undergo such significant changes that the only point of continuing to name it after its source is to identify its lineage and ancestry. This is decidedly not the case with Darwinism. As Jean Gayon has put it:

The Darwin-Darwinism relation is in certain respects a causal relation, in the sense that Darwin influenced the debates that followed him. But there is also something more: a kind of isomorphism between Darwin’s Darwinism and historical Darwinism. It is as though Darwin’s own contribution has constrained the conceptual and empirical development of evolutionary biology ever after. (Gayon 2003, 241)

Darwinism identifies a core set of concepts, principles and methodological maxims that were first articulated and defended by Charles Darwin and which continue to be identified with a certain approach to evolutionary questions. [ 1 ] We will thus need to begin with Darwin’s Darwinism as articulated in On the Origin of Species in 1859. We will then examine these same themes as they have been discussed by evolutionary biologists and philosophers of biology from the beginnings of the Neo-Darwinian Synthesis to the present.

Charles Darwin was not, as we use the term today, a philosopher, though he was often so described during his lifetime. [ 2 ] Nevertheless, for an encyclopedia of philosophy what is needed is a discussion of the impact of philosophy on Darwin’s Darwinism, and the impact of Darwin’s Darwinism on topics that both he, and we, would consider philosophical. We focus here on the impact of philosophical discussions about the nature of science during Darwin’s lifetime on Darwin’s scientific research, thinking and writing; and on the impact of that research, thinking and writing on philosophy. Taking the time to do such philosophical archaeology stems from a conviction that if the concept of Darwinism has legitimate application today, it is due to a set of principles, both scientific and philosophical, that were articulated by Darwin and that are still widely shared by those who call themselves ‘Darwinians’ or ‘neo-Darwinians’.

2. Darwin and Darwinism

Charles Darwin was born February 12, 1809 and died April 18, 1882. It was a time of radical changes in British culture, and his family background put him in the midst of those changes. His grandfather, Erasmus Darwin, was a prosperous and highly respected physician living in Western England, south of Birmingham. He was also a philosophical radical, advocating Enlightenment ideas about human equality and liberty, including the liberty to think freely about the existence of God and about natural origins for the earth’s creatures. He wrote a number of very popular works of natural history, some in verse, in which he defended views about progress that included evolutionary speculations about the upward progress of living things from primordial beginnings.

Erasmus Darwin was an early member of an informal group of free thinkers self-styled the Lunar Society, [ 3 ] that met regularly in Birmingham to discuss everything from the latest philosophical and scientific ideas to the latest advances in technology and industry. The Society included James Watt, Joseph Priestley and Charles Darwin’s other grandfather, Josiah Wedgwood. Wedgwood, like Erasmus Darwin, lived in Staffordshire and was in the process of developing a family pottery works into a major industrial concern by applying new scientific and technological ideas to the production of ‘china’. The religious inclinations of the group were ‘non-conforming’ and included a number of Unitarians, a sect Erasmus Darwin referred to as ‘a featherbed to catch a falling Christian’. Looked upon with suspicion by High Church conservatives, they actively promoted in Great Britain the revolutionary philosophical, scientific and political ideas sweeping across Europe and the Americas. Most had spent considerable time absorbing Enlightenment ideas in Edinburgh, Scotland.

Under the circumstances, it is not surprising that Robert Darwin, Charles’ father, should follow in his father’s footsteps and become a doctor, nor that he should end up marrying Susannah Wedgwood, by all reports Josiah’s favorite offspring. Politically and philosophically engaged, Susannah worked to organize her children’s education in the town of Shrewsbury, where she and Robert took up residence. She sent her children to a day school operated by Unitarian minister Rev. George Case and this is where Charles began his education. Unfortunately, Susannah died in 1817 when Charles was only 8, and his father then transferred him to the Shrewsbury School, operated by Dr. Samuel Butler, grandfather of the novelist (and sometime satirist of Darwin’s work) of the same name. “Nothing could have been worse for the development of my mind than Dr. Butler’s school” Charles proclaimed in the autobiography he wrote for his family, and he escaped down the street to his home whenever he could.

His older siblings took good care of him, under the Doctor’s watchful eye. Early letters indicate that he and his brother Erasmus were enthusiastic amateur chemists, and after his brother went up to Cambridge their letters were often full of possible experiments, orders to purchase chemicals and equipment for their ‘laboratory’, and discussions of the latest discoveries. This was an obvious enough passion that his classmates nicknamed him ‘Gas’. During summers he helped his father on his rounds to his patients, and when only 16 his father sent him and his brother to Edinburgh for the best medical education Great Britain had to offer. Erasmus needed to move from Cambridge to a proper medical school to complete his medical education, and young Charles was taken out of Shrewsbury School early to accompany his brother to Edinburgh, apparently being prepared to follow in his father’s and grandfather’s footsteps in medicine. The two brothers arrived in Edinburgh in October of 1825. Erasmus left after the first year, leaving his brother on his own during his second year at Edinburgh.

Privately, Darwin early on decided he could not practice medicine. But his already serious inclination toward science was considerably strengthened at Edinburgh both by some fine scientific lectures in chemistry, geology and anatomy and by the mentoring of Dr. Robert Grant. Grant certainly knew that young Charles was Erasmus Darwin’s grandson; Grant expounded evolutionary ideas derived from Jean-Baptiste Lamarck and Charles’ grandfather. But his primary gift to Charles was introducing him to marine invertebrate anatomy and the use of the microscope as a scientific tool and as an aid to dissecting extremely small creatures dredged out of the Firth of Forth. Darwin joined an Edinburgh scientific society, the Plinean society, of which Grant was a prominent member, and presented two lectures that reported discoveries he had made while working with Grant. This interest in marine invertebrates was to be a life long obsession, climaxing in his massive four-volume contribution to the comparative anatomy and systematics of fossil and living Cirripedia or ‘barnacles’ (Barrett & Freeman 1988, vols. 11–13).

When he finally broke the news of his distaste for medicine to his father, he enrolled to take a degree in Divinity at Christ College, Cambridge University, from which he graduated in January of 1831. As with the Shrewsbury School and Edinburgh, his official course of study had very little impact on him, but while in Cambridge he befriended two young men attempting to institute serious reforms in the natural science curriculum at Cambridge, Rev. John Henslow, trained in botany and mineralogy, and Rev. Adam Sedgwick, a leading member of the rapidly expanding community of geologists. Henslow and his wife treated Darwin almost as a son, and through Henslow Darwin was introduced to the men whose ideas were currently being debated in geology and natural history, as well as to men whom we look back on as among the very first to take up the historical and philosophical foundations of science as a distinct discipline, Sir John Herschel and Rev. William Whewell. As he wrote in his autobiography:

During my last year at Cambridge, I read with care and profound interest Humboldt’s Personal Narrative . This work, and Sir J. Herschel’s Introduction to the Study of Natural Philosophy , [ 4 ] stirred up in me a burning zeal to add even the most humble contribution to the noble structure of Natural Science. No one or a dozen other books influenced me nearly so much as these two.

In the next section we will discuss the influence of the philosophical ideals of Herschel and Lyell on Darwin.

Furthering his scientific training, Adam Sedgwick on two occasions took Darwin on extended geological tours of England and Wales. In addition Darwin and a cousin, William Darwin Fox, a year ahead of him at Cambridge, developed what began as an amateur passion for bug collecting into serious entomology.

His Edinburgh and Cambridge mentors were to shape Darwin’s philosophical attitudes and scientific career decisively. It was Henslow who was the final link to Darwin in a chain connected to Captain Robert Fitzroy of H. M. S. Beagle. Fitzroy sought a gentleman companion who could also collect information on geology and natural history during a proposed circumnavigation of the globe. Henslow’s note to Darwin, asking if he would be interested in being recommended for this post, arrived at the Darwin home, ‘the Mount’, while Charles Darwin was on a geological survey of Northern Wales with Adam Sedgwick. After resistance from his father had been overcome, Darwin was offered the post and accepted it.

The combination of meticulous field observation, collection and experimentation, note taking, reading and thinking during what turned into the Beagle’s five year journey through a very wide cross-section of the earth’s environments was to set the course for the rest of his life. During the voyage he read and reread Charles Lyell’s newly published Principles of Geology , a three-volume work that articulated a philosophical vision of rigorously empirical historical science, oriented around five key ideas:

• The geologist investigates both the animate and inanimate changes that have taken place during the earth’s history.
• His principal tasks are to develop an accurate and comprehensive record of those changes, to encapsulate that knowledge in general laws, and to search for their causes.
• This search must be limited to causes that can be studied empirically—those ‘now in operation’, as Lyell puts it in the sub-title of his Principles , on the assumption that they have always operated, into the deep past, at the same intensity at which they now operate.
• The records or ‘monuments’ of the earth’s past indicate a constant process of the ‘introduction’ and ‘extinction’ of species, and it is the geologist’s task to search for the causes of these introductions and extinctions, according to the strictures note in 3., above.
• The only serious attempt to do so according to the idea that species are capable of ‘indefinite modification’, that of Jean Baptiste Lamarck, is a failure on methodological grounds. All the evidence supports the view that species variability is limited, and that one species cannot be transformed into another.

This vision influenced Darwin profoundly, as he freely admitted. While he became convinced by his observations and reading that the fossil record and current distribution of species could only be due to the gradual transformation of one species into another, he was determined to articulate a theory that measured up to Lyell’s principles. The crucial event in convincing him that this was to be his life’s work was likely a visit to Cape Town, South Africa during the Beagle’s return trip to England. John F. W. Herschel was in Cape Town on a mission to do for the Southern Hemisphere what his father William had done for the Northern, namely to develop a comprehensive star map with the new powerful telescopes developed by his father and aunt. As noted earlier, Darwin had been deeply impressed by Herschel’s Preliminary Discourse on the Study of Natural Philosophy when it first appeared a year before the Beagle set sail, and in his private journal he referred to his meetings with Herschel during a week long stop in Cape Town in June of 1836 as among the most profound events of the entire voyage. Just five months before meeting Darwin, Herschel had finished reading the 2 nd edition of Lyell’s Principles . He sent Lyell a long letter filled with detailed constructive commentary. The letter opens by praising Lyell for facing the issue of the ‘introduction of new species’—which Herschel calls ‘that mystery of mysteries’—scientifically, and for advocating that we search for ‘intermediate causes’ to explain these ‘introductions’—code for natural, as opposed to ‘miraculous’, causes. [ 5 ] This part of the letter was quoted in Charles Babbage’s Bridgewater Treatise , published in 1837 while Darwin was struggling to develop just such a theory. Upon reading the Herschel quotation in Babbage, Darwin wrote in his private ‘species’ notebooks:

Babbage 2d Edit, p. 226.—Herschel calls the appearance of new species. the mystery of mysteries. & has grand passage upon problem.! Hurrah.—“intermediate causes”. (Barrett et al., 1987, 413; original punctuation)

He clearly recognizes that Herschel is here providing a philosophical justification for the project upon which Darwin was secretly working. And, in the very first paragraph of On the Origin of Species , Darwin looks back to this ‘Hurrah’, attributing the idea that the origin of species is ‘that mystery of mysteries’ to ‘one of our greatest philosophers’, without mentioning Herschel by name. The first mention of the possibility of an evolutionary solution to this problem is in his Ornithological Notebooks , in a note written shortly after departing Cape Town. [ 6 ]

Darwin’s theoretical task was, by the time he opened his species notebooks, tolerably clear: the only process that could produce the systematic patterns in the fossil record and the otherwise strange biogeographic distribution of species he now understood so widely and deeply was a process of slow, gradual transformation of species. He needed to come up with a natural, causal theory that would account for such transformations, and every element of that theory had to identify ‘causes now in operation’, causes that could be investigated empirically. The problem, and the methodological constraints, had been advocated by his geological hero, and now close friend, Charles Lyell; and they had been defended philosophically by his philosophical hero, Sir John Herschel.

Darwin, of course, expected, and got, outraged reactions from religiously conservative colleagues, such as his old geology teacher Sedgwick, who in a review expressed his “deep aversion to the theory; because of its unflinching materialism;–because it has deserted the inductive track,–the only track that leads to physical truth;–because it utterly repudiates final causes, and therby [sic] indicates a demoralized understanding on the part of its advocates.” What he had not expected was Lyell’s refusal to openly endorse his theory and Herschel’s decisive (if polite) rejection of its key elements. After we set out the theory in its Darwinian form, we can consider these reactions from those who apparently shared Darwin’s philosophical norms about scientific theory, explanation and confirmation.

The theory can be set out as a series of causal elements that, working together, will produce the needed transformations.

• Species are comprised of individuals that vary ever so slightly from each other with respect to their many traits.
• Species have a tendency to increase in numbers over generations at a geometric rate.
• This tendency is checked, to use the language of Thomas Malthus’ On the Principle of Population , by limited resources, disease, predation, and so on, creating a struggle for existence among the members of a species.
• Some individuals will have variations that give them a slight advantage in this struggle, variations that allow more efficient or better access to resources, greater resistance to disease, greater success at avoiding predation, and so on.
• These individuals will tend to survive better and leave more offspring.
• Offspring tend to inherit the variations of their parents.
• Therefore favorable variations will tend to be passed on more frequently than others and thus be preserved, a tendency Darwin labeled ‘Natural Selection’.
• Over time, especially in a slowly changing environment, this process will cause the character of species to change.
• Given a long enough period of time, the descendant populations of an ancestor species will differ enough both from it and each other to be classified as different species, a process capable of indefinite iteration. There are, in addition, forces that encourage divergence among descendant populations, and the elimination of intermediate varieties.

It will be noticed that there is no element of this theory that is incapable of empirical investigation—indeed by now the published confirmatory studies of this process would fill a small library. [ 7 ] One can understand why devout and orthodox Christians would have problems; but why Darwin’s philosophical and scientific mentors? It would seem to be the model of Herschelian/Lyellian orthodoxy.

The answer lies in six philosophically problematic elements of the theory.

2.3.1 Probability and Chance

First, notice the use of the language of ‘tendencies’ and ‘frequencies’ in the above principles. Privately, Darwin learned, Herschel had referred to his theory as ‘the Law of higgledy-piggledy’, presumably a reference to the large element played in its key principles by chance and probability. Darwin’s theory is, as we would say today, a ‘statistical’ theory. One cannot say that every individual with favorable variation v will survive or will leave more offspring than individuals without it; one cannot say that no environment will ever support all of the offspring produced in a given generation, and thus that there must always be a competitive struggle. These are things that tend to happen due to clearly articulated causes, and this allows us to make accurate predictions about trends , at the level of populations, but not to make absolute claims about what must happen in each and every case. Only well after Herschel’s time did philosophers of science become comfortable with the idea of a theory of this sort, and the proper philosophical understanding of such explanations is still debated.

2.3.2 The Nature, Power and Scope of Selection

The core of Darwin’s theory is the concept of natural selection. Perhaps because of his use of the term selection, this core element of his theory apparently baffled nearly everyone. Could it be, as Lyell, Herschel and Darwin’s great American defender Asa Gray would ask, an ‘intermediate cause’, i.e. a causal principle instituted and sustained by God? Or is it, in its very nature, the antithesis of such a principle, as his old geology teacher Sedgwick believed? Could it possibly create species, or is it, by its nature, a negative force, eliminating what has already been created by other means? In one of his copies of On the Origin of Species , Alfred Russell Wallace crosses out ‘natural selection’ and writes ‘survival of the fittest’ next to it. Wallace always felt that ‘selection’ inappropriately imported anthropomorphic notions of Nature choosing purposefully between variants into natural history. And, in a devastating review, Fleeming Jenkin happily accepted the principle of natural selection but challenged its power to modify an ancestral species into descendent species, and thus limited its scope to the production of varieties. A number of reviewers, even some sympathetic ones, questioned the possibility of extending the theory to account for the evolution of those characteristics that differentiate humans from their nearest relatives.

2.3.3 Selection, Adaptation and Teleology

Moreover, because Darwin was very fond of describing natural selection as a process that worked for the good of each species, Darwin’s followers seemed to have diametrically opposed views as to whether his theory eliminated final causes from natural science or breathed new life into them. In either case, there was also serious disagreement on whether this was a good thing or a bad thing. [ 8 ]

2.3.4 Species and the Concept of ‘Species’

There is a fundamental philosophical problem with the idea that a species can undergo a series of changes that will cause it to become one or more other species. To illustrate it, look carefully at the first question that Charles Lyell wishes to address in the second volume of the Principles of Geology :

…first, whether species have a real and permanent existence in nature; or whether they are capable, as some naturalists pretend, of being indefinitely modified in the course of a long series of generations. (Lyell 1831, II. 1)

Lyell pretty clearly assumes that to allow for evolution is to deny the reality of species. For a species to be ‘real’, it must have ‘permanent existence in nature’, or as he puts it elsewhere , “…fixed limits beyond which the descendants from common parents can never deviate from a certain type…”. (Lyell 1831, II. 23) To accept evolutionary change, on this view, you must become comfortable with a variety of nominalism about species. And Darwin seems to have become so. [ 9 ]

Hence I look at individual differences, though of small interest to the systematist, as of high importance for us, as being the first step towards such slight varieties as are barely thought worth recording in works on natural history. And I look at varieties which are in any degree more distinct and permanent, as steps leading to more strongly marked and more permanent varieties; and at these latter, as leading to sub-species, and to species. (Darwin 1859, 52)

Permanence, as applied to species, is for Darwin a relative concept, and there are no fixed limits to variability within a species. Given enough time the individual differences found in all populations can give rise to more permanent and stable varieties, these to sub-species, and these to populations that systematists will want to class as distinct species. Moreover, he concludes the Origin with very strong words on this topic, words bound to alarm his philosophical readers:

Systematists will be able to pursue their labours as at present; but they will not be incessantly haunted by the shadowy doubt whether this or that form be in essence a species. …In short, we will have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial combinations made for convenience. This may not be a cheering prospect; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species. (Darwin 1859, 485)

Lyell, Herschel, Whewell, Sedgwick and many of Darwin’s contemporaries certainly would not find this a cheering prospect, since they were unrepentant realists about species. [ 10 ] Members of a species possess a ‘type’ established in the original parents, and this type provides ‘fixed limits’ to variability. Lyell clearly feels this is an empirically verifiable fact—most of chapters 2–4 of Principles Vol. II is devoted to presenting the evidence that such ‘fixed limits’ exist; and after the Origin’s publication this evidence was canvassed again in Fleeming Jenkin’s review. If this is so, then species extinction is easy to account for—there are fixed limits to a species’ ability to track environmental change. But a naturalistic account of species origination is more difficult, since there will need to be, in sexually reproducing species, a natural production of a new pair of parents with a new type. On the other hand, to adopt the sort of nominalism that Darwin seems to be advocating in the above quotations has undesirable consequences as well. [ 11 ] How are we to formulate objective principles of classification? What sort of a science of animals and plants will be possible if there are no fixed laws relating their natures to their characteristics and behaviors? A good deal of chapter 2 of Darwin’s Origin is devoted to convincing the reader that current best practice among botanists and zoologists accepts a natural world organized as he is insisting rather than as his opponents claim:

It must be admitted that many forms, considered by highly competent judges as varieties, have so perfectly the character of species that they are ranked by other highly competent judges as good and true species. (Darwin 1859, 49)

From a Darwinian perspective, this is a predictable consequence of the fact that the organisms we today wish to classify as species are merely the most recent stage of a slow, gradual evolutionary process. Organisms within a genus have common ancestors, perhaps relatively recent common ancestors; some naturalists may see ten species with a few varieties in each; others may rank some of the varieties as species and divide the same genus into twenty species. Both classifications may be done with the utmost objectivity and care by skilled observers. As systematists like to say, some of us are ‘lumpers’, some of us are ‘splitters’. Reality is neither.

2.3.5 Tempo and Mode of Evolutionary Change

The question of nominalism versus realism regarding species points toward a final aspect of Darwin’s theory with which many of those otherwise sympathetic to him disagreed, his gradualism. For apart from the question of whether his views entailed ‘nominalism’ about natural kinds, they do seem to reflect a belief that the evolutionary process must be a slow and gradual one. It is perhaps here that we see the most lasting impact of Darwin’s careful study of Charles Lyell’s Principles of Geology while on H.M.S. Beagle. We stress slow and gradual, for it is clear that one could have a slow but non-gradual evolutionary process (perhaps the long periods of evolutionary stasis punctuated by geologically rapid periods of speciation postulated by Eldridge and Gould’s ‘punctuated equilibrium model’ is such); and one could have a rapid but gradual one (for example the process George Gaylord Simpson labeled ‘adaptive radiation’, where a population migrates to a location with a variety of unexploited niches, and rapidly evolves to exploit them). Darwin stresses over and over again that he conceives of natural selection ‘adding up infinitely small variations’, and that he imagines the process of speciation to take place over a very long period of time.

2.3.6 Evolutionary Ethics, Altruism, and Group Selection

Despite Darwin’s effort to eschew discussion of human beings in the Origin (famously writing only that “light will be thrown on the origin of man and his history”; Darwin 1859, 488), he clearly believed that an evolutionary account of the human “moral sense”—as Darwin described it, borrowing from James Mackintosh—could be offered. This account, as a sub-species of what we now would call (though Darwin did not use these terms) altruistic behavior in general (see the entry for biological altruism ), quickly brought Darwin into contact with a host of difficult problems.

In the Descent of Man , he flirted with an explanation of the moral sense in terms of the characteristics not of moral individuals, who would seem to fare less well in the struggle for existence than their egoistic compatriots, but in terms of the characteristics of groups exhibiting moral virtues. In a case of struggle between two tribes of “primeval man,” he writes, the one with “a greater number of courageous, sympathetic, and faithful members, who were always ready to warn each other of danger, to aid and defend each other, this tribe would without doubt succeed best and conquer the other” (Darwin 1871, 1:162). Whether this involves a genuine appeal to what contemporary scholars would call “group selection” (see the entry on units and levels of selection ), or whether this can be described solely in terms of individuals desiring to help themselves and their relatives (i.e., in terms of kin selection) remains the subject of much discussion.

One of the strongest arguments for insisting that ‘Darwinism’ as it is used today is isomorphic to Darwin’s Darwinism, as Gayon puts it, is that each of these questions is still hotly debated, and has been throughout the theory’s history. With all of the amazing changes that have been wrought by the genetic, biochemical, and molecular revolutions, with the development of mathematical models of population genetics and ecology, of sophisticated techniques for both field and laboratory investigation of evolutionary processes, and of cladistic analysis in systematics, it nevertheless remains true that one can find evolutionary biologists who adhere to Darwin’s Darwinism, and are recognized as doing so by both themselves and their critics. In the next section of this article, we will develop a portrait of contemporary Darwinism around each of these contested features.

By the same token, however, Darwinism has evolved. As one example of this truth, think for a moment of contemporary debates about the nature of selection. The problems people had with natural selection in the 19 th century continue to be problematic, but there are a variety of problems that were either not discussed, or discussed very differently, in the 19 th century. Can, and does, natural selection work at levels other than the level of Darwin’s focus, individual organisms; is there a non-vacuous way to formulate the theory abstractly; how are we to understand the relationships between the concepts of fitness, selection and adaptation? How strong are the constraints on the selection process, and what sorts of constraints are there? Are there other motors of evolutionary change besides selection, and if so, how important are they?

3. The Six Core Philosophical Problems Today

Theories need both essences and histories. Stephen Jay Gould (2002, 1)

So reads the heading of the very first section of the first chapter of Gould’s monumental The Structure of Evolutionary Theory . Opening with a subtle reading of an exchange of letters in 1863 between paleontologist Hugh Falconer and Charles Darwin, Gould eventually explains what he has in mind by this section heading:

In short, “The structure of evolutionary theory” combines enough stability for coherence with enough change to keep any keen mind in a perpetual mode of search and challenge. (Gould 2002, 6)

Gould, of course, was both an unabashed admirer of Charles Darwin and one of the most outspoken critics of the ‘neo-Darwinian synthesis’. We will be using both his account of ‘the Essence of Darwinism’ in Part I of this magnum opus and his arguments for a ‘Revised and Expanded Evolutionary Theory’ in its Part II as touchstones and targets.

In the preceding section of this essay, we organized our discussion of the problems that Darwin’s allies had with Darwin’s Darwinism around six issues: [i] the role of chance as a factor in evolutionary theory and the theory’s apparently probabilistic nature; [ii] the nature of selection; [iii] the question of whether selection/adaptation explanations are teleological; [iv] the ontological status of species and the epistemological status of species concepts; [v] the implications of Darwin’s insistence on the slow and gradual nature of evolutionary change; and [vi] the impact of natural selection on ethics and altruistic behavior. We claimed that one very good reason for continuing to characterize one dominant approach to evolutionary biology, that represented by the so-called ‘Neo-Darwinian Synthesis’, as ‘Darwinism’ is that its proponents side with Darwin on these issues, to the extent that Darwin had a clear position on them (and on many less fundamental ones besides). That in itself is remarkable, but it is the more so because the Darwinian position on each of these issues is under as much pressure from non-Darwinian evolutionary biologists today as it was in the wake of the Origin . It is not surprising, given the situation as we have just characterized it, that historians and philosophers of biology have made significant contributions to the discussion, especially in pointing out the underlying philosophical issues and conceptual confusions and ambiguities that stand in the way of resolving the issues at hand, and their historical origins.

It is our conviction that a full understanding of the underlying philosophical disagreements on these questions will only come from a patient historical study of how the ‘Synthesis’ positions on these various issues, and those of their critics, arose. That we cannot do here. Rather, in what follows we will simply be presupposing certain answers to these questions of historical origins. The list of references at the end of this essay includes a number of excellent pieces of work on this subject for those who share our convictions about its importance.

Let us begin with the language Darwin uses when he first sketches his theory at the beginning of the fourth chapter of the Origin :

Can it, then, be thought improbable , seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life, should sometimes occur in the course of thousands of generations? If such do occur, can we doubt (remembering that many more individuals are born than can possibly survive) that individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind? (Darwin 1859, 80–81, emphasis added)

Unlike Darwin’s contemporaries, and despite Darwin’s own apparent hesitation, the founders of the synthesis of Mendelian genetics and Darwinian selection theory, Sewall Wright, Ronald Fisher and J. B. S. Haldane, were entirely comfortable with a selection theory formulated in such terms. This was a substantial shift in the presentation of evolution, from a reluctantly probabilistic picture to a thoroughly mathematized, statistical, and probabilistic theory, which occurred in the first several decades after the publication of the Origin (Gayon 1998; Pence 2022).

On this issue, contemporary Darwinism has adopted an approach every bit as ‘chancy’ as that of Darwin. Note one clear statement of the Principle of Natural Selection from the philosophical literature:

If a is better adapted than b to their mutual environment E , then (probably) a will have greater reproductive success than b in E . (Brandon 1990, 11).

The theory trades pervasively in probabilities. Given the fact that evolutionary biologists, especially in so far as they take their cues from population genetics, deal with large populations conceived as ‘gene pools’, and think of evolution as long run changes in the frequencies of different combinations of genes from generation to generation, it is clear that, in the sense of making use of probabilistic or statistical reasoning, chance permeates contemporary Darwinism. The models of population biology provide a means of assigning probabilities to various outcomes, given information about population size, rates of mutation and migration (themselves given as averages and estimates). That is, as Darwin notes, being relatively better adapted increases an organism’s ‘chances’, i.e. increases its probability, of leaving viable offspring. It does not guarantee it. Since natural selection is a stochastic process, Darwinians from Darwin to the present rightly characterize it in terms of influencing the ‘chances’ of a given outcome, given variables such as selection pressure, population size or mutation rates.

Conceptual confusion arises, however, from the fact that ‘chance’ and ‘randomness’ are often contrasted, not with ‘deterministic’ or ’non-probabilistic’ outcomes, but with ‘selected’ outcomes. The evolutionary process, as Darwin understood it, involves both the generation of variation and a process producing a differential perpetuation of variation. One way to think about chance in Darwinism is in relation to a logical space of alternatives, by means of the following variation grid :

On this second sense of chance, what seems to make a theory ‘chancy’ is the fact that generation of variation and perpetuation of variation have both been, for some of these theorists, independent of future utility or fitness. As we see from the grid, a contrast on both scores is found in the evolutionary philosophy of Jean-Baptiste Lamarck. Lamarck’s is a materialistic argument against the variation in nature being a matter of chance. On the Lamarckian view, variations arise in an organism as a direct response to environmental stress or demand, giving rise to a stimulus, which in turn elicits a physiological response, which finally can be passed on via reproduction to offspring. Variations are not chance or random, since they are an appropriate response to an environmental stress. Here ‘chance’ signals a lack of relation or connection to adaptive needs .

The concept of ‘random variation’ is today often used as a synonym for ‘chance variation’ in precisely this latter sense. Here are two examples of this notion of chance or randomness as used by contemporary Darwinians.

…mutation is a random process with respect to the adaptive needs of the species. Therefore, mutation alone, uncontrolled by natural selection, would result in the breakdown and eventual extinction of life, not in adaptive or progressive evolution. (Dobzhansky 1970, 65)

Thus the production of variations may be a ‘chance’ process in that there are a number of possible outcomes with assignable probabilities, but it is also a ‘chance’ process in the sense that the probability assignments are not biased by ‘adaptive needs’ or ‘fitness’.

Referring now to perpetuation rather than generation of variation, when John Beatty describes ‘random drift’ as ‘changes in frequencies of variations due to chance’ in the following passage, he presumably has something like a contrast with changes in frequencies due to selection in mind.

In Darwin’s scheme of things, recall, chance events and natural selection were consecutive rather than alternative stages of the evolutionary process. There was no question as to which was more important at a particular stage. But now that we have the concept of random drift taking over where random variation leaves off, we are faced with just such a question. That is, given chance variations, are further changes in the frequencies of those variations more a matter of chance or more a matter of natural selection? (Beatty 1984, 196)

Notice that in the above quote we first get a substitution of ‘random’ for ‘chance’ in the phrases ‘random variation’ and ‘chance variation’, and then at least the suggestion that the concept of ‘random drift’ can be characterized as ‘changes in frequencies of variations due to chance’, where the contrast class consists of similar changes due to natural selection.

With respect to the generation of variation, chapter 5 of On the Origin of Species opens with the following apology:

I have hitherto sometimes spoken as if the variations—so common and multiform in organic beings under domestication, and in a lesser degree in those in a state of nature—had been due to chance. This, of course, is a wholly incorrect expression, but it serves to acknowledge plainly our ignorance of the cause of each particular variation. (Darwin 1859, 131)

Here Darwin is noting that, though to speak of ‘chance variations’ may seem to be citing chance as the cause of the variations, in fact it is simply acknowledging that they ‘appear to have no assignable cause’. But it is important to keep historical context in mind here. Whether Darwin himself ever flirted with the idea of ‘directed’ variation or not, he was acutely aware of two views from which his needed to be distinguished, very different from each other, but both holding to the view that variations arose for a purpose. [ 12 ] The most widely shared alternative was that found in natural theology. To quote the Reverend William Paley’s Natural Theology , regarding a beautiful instance of adaptation: “A conformation so happy was not the gift of chance”. Likewise, among Darwin’s followers, the American botanist Asa Gray, in an essay entitled ‘Natural Selection and Natural Theology’, uses the same contrast to advise Darwin against the notion of ‘chance variation’: “…we should advise Mr. Darwin to assume, in the philosophy of his hypothesis, that variation has been led along certain beneficial lines.”

Gray is here insisting that, since Darwin admits that using the term ‘chance’ merely signals ignorance of the true cause, and since the pervasive adaptations in nature suggest design, Darwin should avoid the suggestion that variations are due to chance in the sense of ‘absence of design’ . This introduces yet a third sense of ‘chance’ that has been instrumental in the interpretation of evolutionary theory (Shanahan 1991, 264).

Darwin, in fact never refers to ‘chance variations’ in the Origin , though occasionally he will note that if a beneficial variation ‘chances [i.e. happens] to appear’, it will be favored by selection (see pp. 37, 82) What Darwin has in mind, however, is clear from his concluding remarks in his chapter on Laws of Variation :

Whatever the cause may be of each slight difference in the offspring from their parents—and a cause of each must exist—it is the steady accumulation, through natural selection, of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure… (Darwin 1859, 170)

Whatever the cause of the generation of a variation may be, the role of selection is to accumulate those already present variations that happen to be beneficial, a process that, while probabilistic, is not at all independent of fitness (and hence not ‘chancy’ in our second sense). As Beatty put it, the generation of variations and their selection are ‘consecutive’ processes. But to call the generation of variation a ‘chance’ process is to use ‘chance’ in either the second or the third sense, meaning either that such generation is independent of the future utility of variations for the organism, or that it is not by design, not for some end.

There are, therefore, at least three forms of ‘chance’ at play in contemporary evolutionary theory: an invocation of probabilistic or statistical inferences, an invocation of processes that act independently of current or future fitness, and an invocation of the absence of design. To these we might add, as mentioned above, chance as ignorance of causes, and chance as historical contingency, though we lack the space to discuss either of those notions further here, bringing the total to five (see, e.g., Shanahan 1991, 263–267). Eble (1999, 76) drops the notion of probabilistic or statistical inference and adds the idea, less relevant in evolutionary contexts, that ‘chance’ can refer to uncaused events (see analysis in Millstein 2000, 609–613).

One further example can illustrate how all this interacts in the broader context of contemporary evolutionary theory (for more such examples, see the contributions to Ramsey and Pence 2016). Here, a champion of the neutral theory of molecular evolution characterizes his position:

…the great majority of evolutionary changes at the molecular (DNA) level do not result from Darwinian natural selection acting on advantageous mutants but, rather, from random fixation of selectively neutral or very nearly neutral mutants through random genetic drift, which is caused by random sampling of gametes in finite populations. (Kimura 1992, 225)

Here, it will be noticed, the focus is not on the generation of variations but on the perpetuation of variations. The contrast is between a random sampling of gametes that leads to the fixation of selectively neutral alleles and natural selection favoring advantageous variations. That is, the contrast between ‘chance’ and ‘fitness biased’ processes is now being used to distinguish different means of perpetuating certain variations . We are contrasting two sampling processes. Drift samples without concern for adaptation; selection samples discriminately on the basis of differences in fitness. Both samplings are ‘probabilistic’, of course, but that in no way obviates the above contrast.

However, as Beatty has pointed out, it was quite common until fairly recently to characterize natural selection in such a way as to make it almost indistinguishable from random drift (cf. Lennox 1992, Lennox and Wilson 1994). Numerous accounts of fitness characterized the fitness of a genotype as defined by its relative contribution to the gene pool of future generations—the genotype contributing the larger percentage being the fitter. But of course that could easily be the result of a ‘random’—non-fitness biased—sampling process; which organisms would be declared ‘fitter’ by this method might have nothing to do with natural selection. In order to provide a proper characterization of the role of chance in evolutionary change, then, it is critical to provide a more robust and sophisticated account of fitness. (For further information, see the entry on fitness .) This, in turn, requires that we discuss the conceptual network that includes the notions of adaptation and natural selection, to which we will turn shortly.

For now, let us assume that there is a way of characterizing fitness such that there is a substantial empirical question of what role indiscriminate sampling of genotypes (or phenotypes) plays in evolutionary change. This issue was first placed squarely before evolutionary biologists by Sewall Wright in the early 1930s. As Wright pointed out, genes that are neutral with respect to fitness can, due to the stochastic nature of any process of sampling from a population, increase their representation from one generation to the next. The likelihood of this happening goes up as effective population size goes down. Since Wright imagined that a quite typical scenario in evolutionary change was for species to be broken up into relatively small, relatively isolated, populations (or ‘demes’), with significantly more breeding within than between demes, the likelihood that such ‘neutral genotypes’ could become fixed at relatively high levels was significant. Though he gradually toned down this aspect of his work, a significant school of mathematical population geneticists in the 1960s and 70s took these ideas and ran with them, developing a ‘Neutralist’ approach to evolutionary change. This is the position characterized by Kimura (one of its most eloquent defenders) in the passage quoted above. Whether or not such a process plays a significant role in evolution is not a philosophical issue, but it is highly relevant to whether evolutionary biology should be seen as predominantly Darwinian. For if any view is central to Darwinism, it is that the evolutionary process is predominantly guided by the fitness-biasing force of natural selection, acting on variations that arise by chance. It is to natural selection and related concepts that we now turn.

The greatest number of females will, of course, fall to the share of the most vigorous males; and the strongest individuals of both sexes, by driving away the weakest, will enjoy the best food, and the most favourable situations, for themselves and for their offspring. A severe winter, or a scarcity of food, by destroying the weak and the unhealthy, has had all the good effects of the most skilful selection.

The words of Charles Darwin? No; these are the words of John Sebright, penned in The Art of Improving the Breeds of Domestic Animals in 1809, the year of Charles Darwin’s birth and fifty years before On the Origin of Species was published. Darwin refers to this passage in Notebook C of his Species Notebooks. [ 13 ] It will be noticed that Sebright is not discussing domestic selection, but is quite clearly saying that processes leading to differential survival and reproduction in nature will have ‘all the good effects of the most skilful selection’. Darwin, then, did not need to read Malthus to see what is here so plainly and clearly stated—namely, that the struggle for survival in nature will have the same ‘selective’ effects as the actions of the domestic breeder of plants and animals.

As this passage, and the argument of the Origin , shows, ‘natural selection’ began life as the product of analogical reasoning. Sebright sees clearly that the natural processes he is describing will have the same effects as the breeder’s selection, but he is not about to describe those processes as selection processes. Darwin took that step, and Darwinism has followed.

Darwin himself consistently refers to natural selection as a power of preserving advantageous, and eliminating harmful, variations. As noted in the last section, whether a particular variation is advantageous or harmful is, in once sense of that term, a matter of chance; and whether an advantageous variation is actually preserved by selection is, in another sense of the term, also a matter of chance. For Darwinism, selection is the force or power that biases survival and reproduction in favor of advantageous variations, or to look ahead to the next section, of adaptations. It is this that distinguishes selection from drift.

Recent years have seen significant challenges to the idea that this framework is sufficient to explain all evolutionary phenomena, or even to explain an important fraction of evolutionary phenomena of interest. On one side we find partisans of the so-called “extended evolutionary synthesis” (EES), who argue that features like niche construction, developmental bias, phenotypic plasticity, and non-genetic inheritance entail the existence of a theory that at least radically supplements, if not transcends entirely, the Darwinian perspective (for an introduction, see Laland et al. 2014; further references include Pigliucci and Müller 2010; Uller and Laland 2019). On the other side we could put scholars like George C. Williams, who has vigorously defended the explanatory sufficiency of Darwinian selection theory (Williams 1992), or a number of proposals arguing that sufficiently reformulated concepts from “traditional” evolutionary theory can allow it to take on the challenge of the EES without radical changes (e.g., the gene for Lu and Bourrat 2017, or adaptationism for Welch 2017; see also the entries on the gene , adaptationism , and population genetics ).

We can distinguish two broad categories into which we might sort these non-Darwinian amendments: [i] proposed limitations on natural selection as an evolutionary force; and [ii] expansions of the scope of natural selection to include new ‘targets’, ‘processes’ or ‘mechanisms’, and ‘levels’. It will be noted that in neither case is it obvious that the theory itself requires modification in the face of such challenges—in principle these might be nothing more than challenges to the theory’s range of application . However, if it turned out that most evolutionary change could be explained without recourse to natural selection, this would be grounds for arguing that evolutionary biology was no longer Darwinian. And if it turned out that the theory of natural selection could only be integrated with our new understanding of the processes of inheritance and development by a wholesale modification of its foundations, it might be best to see the new theory as a modified descendent of Darwinism, rather than Darwinism itself. Theories may need essences, as Gould claims; but if what is fundamental to the theory has changed, then so has its essence. To borrow a phrase from Paul Griffiths, perhaps it is not that theories need histories and essences—perhaps what they need are historical essences .

Alfred Russell Wallace regularly urged Darwin to jettison the term ‘selection’ as misleadingly anthropomorphic, and substitute Herbert Spencer’s ‘survival of the fittest’. Darwin went halfway—in later editions he added ‘or Survival of the Fittest’ to ‘Natural Selection’ in the title of chapter 4. As the theory developed in the mid-20 th century, the expression ‘survival of the fittest’ was gradually eliminated from any serious presentation of Darwinian selection theory. On the other hand, the concept of ‘fitness’ has played a prominent, and problematic, role. In the mathematical models used in population genetics, ‘fitness’ refers either to the abilities of the different genotypes in a population to leave descendants, or to the measures of those abilities, represented by the variable W . Here is a rather standard textbook presentation of the relevant concepts:

In the neo-Darwinian approach to natural selection that incorporates consideration of genetics, fitness is attributed to particular genotypes. The genotype that leaves the most descendants is ascribed the fitness value W =1, and all other genotypes have fitnesses, relative to this, that are less than 1. … Fitness measures the relative evolutionary advantage of one genotype over another, but it is often important also to measure the relative penalties incurred by different genotypes subject to natural selection. This relative penalty is the corollary of fitness and is referred to by the term selection coefficient . It is given the symbol s and is simply calculated by subtracting the fitness from 1, so that: s = 1 − W . (Skelton 1993, 164)

The problem lies in the fact that the concept of fitness plays dual roles that are instructively conflated in this quotation. For when fitnesses are viewed as measures of differential abilities of organisms with different genotypes to leave different numbers of offspring, the language of fitness encourages us to suppose that ‘fitness’ refers to the relative selective advantages of genotypes. On the other hand, if ‘fitness’ simply refers to the measure of reproductive success, it is a quantitative representation of small scale evolutionary change in a population, and leaves entirely open the question of the causes of the change. But then the assumed connections among the concepts of fitness, adaptation and natural selection are severed. ‘Selection coefficients’ may have nothing to do with selection; what W represents may have nothing to do with selective advantage.

There is, however, a way of formulating the theory in its modern guise which maintains an essentially Darwinian character. Since there are a number of confirmed ways in which natural populations can evolve in the absence of natural selection, and since balancing selection, i.e. countervailing selection forces, may prevent a population from evolving in its presence, it is clear that establishing, by measuring different reproductive rates among its members, that the genetic make-up of a population has changed does not establish that natural selection was the source of that change; nor does the fact that no change has been measured establish that natural selection is not operative. Population genetics and its associated models should be treated as the ‘kinematics’, not the ‘dynamics’ of evolutionary processes (on this distinction, see also Pence 2021). That is, it is a way of establishing that a population either is or is not in equilibrium, and it provides sophisticated tools for measuring rates of change in a population across generations. Moreover, like the kinematics of any physical theory, if it establishes cross-generational change, it also tells us that there are causes to be found—the detailed contours of those measures may even provide suggestions as to where to look for those causes. What it cannot do on its own is provide knowledge of the forces at work. To use language introduced by Elliott Sober, fitness, unlike natural selection, is causally inert . (For further information, see the entry on population genetics .)

That means that, as valuable as population genetics is, it should not be equated with the theory of natural selection. Too often in both biological presentations of the theory and philosophical discussions of it, this is forgotten. For example:

Most people are familiar with the basic theory of natural selection. Organisms vary in a heritable fashion. Some variants leave more offspring than others; their characteristics, therefore, are represented at a greater frequency in the next generation. (Wilson 1984, 273)

This is a presentation of ‘the basic theory of natural selection’ that makes no reference to natural selection at all!

Natural selection, if it is to resemble the Darwinian concept that bears that name, must be reserved for reference to an interaction between a variable, heritable feature of an organic system and the environment of that system . That interaction may or may not change the proportions of those features across generations, and those proportions may change for reasons other than those interactions. But a plausible natural selection hypothesis must posit some such interaction. (Whether this interaction is accurately described as causal is another much-debated topic in recent years; see Pence 2021 for a high-level summary.) On this issue we will give the last word to Stephen Jay Gould:

…when we consider natural selection as a causal process, we can only wonder why so many people confused a need for measuring the results of natural selection by counting the differential increase of some hereditary attribute (bookkeeping) with the mechanism that produces relative reproductive success (causality). (Gould 2003, 619)

The concept of natural selection has to this point been presented broadly because of the other two critical questions surrounding the contemporary Darwinian concept of natural selection that we mentioned earlier—questions having to do with possible limiting constraints on natural selection and about the sorts of objects that can be viewed as appropriate organismic/environmental ‘interactors’ in the selection process.

If we suppose that for Darwin natural selection was almost exclusively thought of as an interaction between individual organisms and their organic and inorganic environments, then we can see two challenges to Darwinism today with respect to levels of selection. There are those, such as G. C. Williams, Richard Dawkins (1976) and, more recently, J. Arvid Ågren (2021), who argue that selection is always and only of genes. Here is a clear statement:

These complications [those introduced by organism/environment interactions] are best handled by regarding individual [organismic] selection, not as a level of selection in addition to that of the gene, but as the primary mechanism of selection at the genic level. (Williams 1993, 16)

Dawkins’ preferred mode for making the same point is to refer to organisms—or interactors—as the vehicles of their genes, in fact vehicles constructed by the genome for its own perpetuation.

The original impulse for this approach, especially clear in Williams’ classic Adaptation and Natural Selection (1966), was philosophical—it was to use a sort of Ockham’s razor strategy against group selection hypotheses, showing that alleged group selection effects could be explained by explanations operating at the level of the genome (an approach more recently taken by the controversial Nowak et al. 2010). Throughout that book, selection is always said to be of individual alleles, regardless of the role environments at various levels may play in the process.

This view has been extensively challenged by philosophers of biology on both methodological and conceptual grounds, though there are, among philosophers, enthusiastic supporters (cf. Dennett 1995). In all the give and take, it is seldom noticed that defenders of this view claim to be carrying the Darwinian flag (Gayon 1998 and Gould 2003 are exceptions). Yet it is certainly not a position that Darwin would recognize—and not merely because he lacked a coherent theory of the units of inheritance. It is not a Darwinian view because for Darwin it was differences in the abilities of organisms at various stages of development to respond to the challenges of life that had causal primacy in the explanation of evolutionary change. Among evolutionary biologists from the ‘neo-Darwinian synthesis’ on, it is those who stress the role of organisms in populations interacting differentially to ever-variable ecological conditions in causing changes in the gene pools of those populations who are the card-carrying Darwinians. Such a “return of the organism” (Nicholson 2014) in evolutionary explanations marks a profound link between proponents of an extended evolutionary synthesis (e.g., Walsh 2015) and Darwin himself.

Darwinism also has challenges from the opposite direction. In the 1970s a number of biologists working in the fields of paleontology and systematics challenged the Neo-Darwinian dogma that you could account for ‘macro-evolution’ by means of long term extrapolation from micro-evolution. Gould, in particular, opens Part II of The Structure of Evolutionary Theory ( Towards a Revised and Expanded Evolutionary Theory ), with a chapter entitled ‘Species as Individuals in the Hierarchical Theory of Selection’. That chapter title combines two conceptually distinct theses that connect debates about the fundamentals of natural selection to patterns in macroevolution: first, the thesis defended by Michael Ghiselin (Ghiselin 1997) and championed and refined by David Hull (Hull 2001), that species are, in a robust sense of the term, ‘individuals’; and second, that there may well be selection among groups of organisms, qua groups (see section 3.6 ). These debates over the importance of selective and non-selective processes and the relationship between these mechanisms of biological change and broader patterns of diversification and adaptation comprise some of the most important and heated discussions currently underway in evolutionary theory.

Early in the Introduction to On the Origin of Species , Darwin observes that the conclusion that each species had descended from others “even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified so as to acquire that perfection of structure and co-adaptation which most justly excites our admiration” (Darwin 1859, 3). One might say this was the central promise of Darwinism—to account for both phylogenic continuity and adaptive differentiation by means of the same principles; or as Darwin puts it, to integrate in one theory the supposed opposition between Unity of Type and Conditions of Existence.

But it is here that even the most sympathetic of Darwin’s theistic supporters were forced to qualify their support for the theory of descent with modification by means of natural selection. In Darwin’s day the reactions of Asa Gray and John Herschel are perhaps the most interesting in this respect. Both men saw in Darwin’s theory a way to account for ‘that mystery of mysteries,’ the regular appearance of new species by means of natural, or as they might say, ‘intermediate’ causes. However both instinctively recoiled from the irreducible and central role of ‘chance’ in the theory. They did not, but easily could have, said ‘God does not play dice with the universe.’ But as Darwin stated repeatedly, if gently, to Gray—if God ordained that variations should be along beneficial lines, natural selection would be redundant. Moreover, the evidence from the study of variation in domestic and natural populations put the lie to any claim that God directs all or most variation along beneficial lines. Darwinian selection theory is a two-step process—the production of variation unrelated to the adaptive requirements of the organism, and differential perpetuation of those variations that serve adaptive needs. Again, a theory of evolution that could not be so described would not be a Darwinian theory.

The nature of ‘selection explanations’ is a topic to which much philosophical attention has been devoted in recent years. Here we want to focus on only one important question—to what extent is the teleological appearance of such explanations simply that, an appearance masking a causal process in which goals play no role?

The appearance of teleology is certainly present in Darwinian explanations, and has been since Darwin spoke of natural selection working solely for the good of each being. The appearance of teleology stems from the ease with which both evolutionary biology and common sense take it for granted that animals and plants have the adaptations they do because of some benefit or advantage to the organism provided by those adaptations.

This is a hotly contested question, and we will here simply sketch a case that selective explanations of adaptations are robustly teleological. The interested reader may want to refer to the literature on this question referred to in the discussion and listed in the list of readings provided at the end of this entry. The serious philosophical issue can be put simply and directly: in selection explanations of adaptations, are the functions served by adaptations a central and irreducible feature of the explanans in such explanations? If the answer is yes, the explanations are teleological. [ 14 ]

A good place to begin is with a simple, yet realistic, example. In research carried out over many years and combining painstaking field work and laboratory experimentation, John Endler was able to demonstrate that the color patterns of males in the guppy populations he was studying in rivers feeding into the southern Caribbean were a consequence of a balance between mate selection and predator selection. To take one startling example, he was able to test and confirm a hypothesis that a group of males, with a color pattern that matched that of the pebbles on the bottoms of the streams and ponds they populated except for bright red spots, have that pattern because a common predator in those populations, a prawn, is color blind for red. Red spots did not put their possessors at a selective disadvantage, and were attractors for mates (Endler 1983, 173–190). We may refer to this pattern of coloration as a complex adaptation that serves the functions of predator avoidance and mate attraction. But what role do those functions play in explaining why it is that the males in this population have the coloration they do?

This color pattern is an adaptation, as that term is used in Darwinism, only if it is a product of natural selection (Williams 1966, 261; Brandon 1985; Burian 1983). In order for this to be true, there must be an array of color variation available in the genetic/developmental resources of the species wider than this particular pattern but including this pattern. Which factors are critical, then, in producing differential survival and reproduction of guppies with this particular pattern? The answer would seem to be the value-consequences this pattern has compared to others available in promoting viability and reproduction. In popular parlance (and the parlance favored by Darwin), this color pattern is good for the male guppies that have it, and for their male offspring, and that is why they have it (Binswanger 1990; Brandon 1985; Lennox 2002). This answer strengthens the ‘selected effects’ or ‘consequence etiology’ accounts of selection explanations by stressing that selection ranges over value differences. The reason for one among a number of color patterns having a higher fitness value has to do with the value of that pattern relative to the survival and reproductive success of its possessors.

Selection explanations are, then, a particular kind of teleological explanation, an explanation in which that for the sake of which a trait is possessed, its valuable consequence , accounts for the trait’s differential perpetuation and maintenance in the population.

In listing the topics we would discuss under the heading of neo-Darwinism, we distinguished the question of the ontological status of species from the epistemological status of the species concept . Though they are closely related questions, it is important to keep them distinct. As will become clear as we proceed, this distinction is rarely honored. Moreover, it is equally important to distinguish the species concept from the categories of features that belong in a definition of species (Rheins 2011). Advances in our theoretical understanding may lead us to reconsider the sorts of attributes that are most important for determining whether a group of organisms is a species, and thus whether it deserves to be assigned a name at that taxonomic level. It should not be assumed that such changes constitute a change in the species concept, though at least some such changes may lead us to restrict or expand the range of taxa that are designated as species. In his contribution to the Neo-Darwinian Synthesis, Systematics and the Origin of Species , Ernst Mayr titled chapter five ‘The Systematic Categories and the New Species Concept’. Recall that Darwin made a point of treating the species category as continuous with ‘well-marked variety’ and ‘sub-species’, and made the radical suggestion that its boundaries would be just as fluid. Without explicitly acknowledging Darwin, Mayr takes the same tack, discussing ‘individual variants’ and ‘sub-species’ as a preliminary to discussing the species concept. Mayr notes that for someone studying the evolutionary process, speciation is a critical juncture; “…his interpretation of the speciation process depends largely on what he considers to be the final stage of this process, the species.” (Mayr 1942/1982, 113) With this in mind, he offers the following definition, the so-called ‘biological species concept’ (BSC):

Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups (Mayr 1942/1982, 120; 1976, 518)

Mayr was well aware of the limitations of this definition, and treated it somewhat as a ‘regulative ideal’. Dobzhansky in 1937 gave what he claimed to be a definition of species, but which seems, as Mayr noted (Mayr 1976, 481), much more a definition of speciation :

…that stage of evolutionary process, “at which the once actually or potentially interbreeding array of forms becomes segregated in two or more separate arrays which are physiologically incapable of interbreeding.” (312)

Simpson (1943) and others built even more historicity into the concept. These are all, of course, intended as definitions of the species category , and they attempt to provide a test (or a ‘yardstick’: Mayr 1976, 479) that in principle will permit a researcher to decide whether a group of individuals should all be identified by a single species-level concept such as ‘homo sapiens’. The test for species membership is the capacity to interbreed; the test distinguishing two species is incapacity to interbreed. Dobzhansky makes the importance of this test transparent—the transition from a single interbreeding population to two reproductively isolated ones is the process of speciation.

Now in each of these definitions, little attention is paid to the actual methods used by taxonomists and systematists in differentiating between varieties of a species and distinct species, something to which Darwin gave a great deal of attention. Darwin’s apparent nominalism regarding the species concept likely stemmed from his close attention to his own taxonomic practices and those of other specialists.

Mayr, on the contrary, relates different approaches to the species concept to the philosophical distinction between essentialism and nominalism (for the history of this argumentative move, see Witteveen 2015; 2016). He associates what he calls essentialism (and what we called above “realism” about species) with the view that a species concept refers to a universal or type. This view of the referent of the concept leads to the Typological Species Concept, which he traces from Linnaeus back to Plato and Aristotle, and which he claims ‘is now universally abandoned’ (1976, 516). It is worth noting that serious doubt has been cast both on the historical and the philosophical credentials of Mayr’s ‘Typological Species Concept’ (see, e.g. Lennox, 1987; repr. in Lennox 2001b; Winsor 2001, 2006; Walsh 2006; Wilkins 2009). At the opposite extreme is nominalism, which combines the view that only individuals exist in nature and that species are concepts invented for the purpose of grouping these individuals collectively.

Mayr claims that his Biological Species Concept (BSC) is an advance on both; individual species members are objectively related to one another not by a shared relation to a type but by causal and historical relationships to one another. He can thus be understood as arguing for a new, objective way of understanding the epistemological grounds for grouping individuals into species. This new way of grouping stresses historical, genetic and various ecological relationships among the individuals as the grounds for determining species membership. His claim is that this is more reliable and objective than similarities of phenotypic characteristics. This makes sense of the importance he eventually places on the fact the BSC defines species relationally:

…species are relationally defined. The word species corresponds very closely to other relational terms such as, for instance, the word brother . … To be a different species is not a matter of degree of difference but of relational distinctness. (Mayr 1976, 518)

Mayr has in mind that brothers may or may not look alike; the question of whether two people are brothers is determined by their historical and genetic ties to a common ancestry. Notice, however, that this is a claim about which characteristics, among the many that they have, should be taken most seriously in determining the applicability to them of the concept ‘brother’. That is, it is a defense of a sort of essentialism.

A number of critics have pointed out that essentialism need not be committed to ‘types’ understood as universalia in re ; and on certain accounts of essences any species taxon that meets the standards of BSC does so in virtue of certain essential (though relational and historical) properties. At one extreme, Michael Ghiselin and David Hull have argued that this causal/historical structure of species provides grounds, at least within evolutionary biology, for considering species to be individuals. [ 15 ] Organisms are not members of a class or set, but ‘parts’ of a phylogenetic unit. Taking a very different tack, Denis Walsh has recently argued that a form of ‘evolutionary essentialism,’ bearing a striking resemblance to the essentialism of Aristotle’s zoological work, is implicit in the work of a number of evolutionary developmental theorists (Walsh, 2006).

A critical issue in this debate over the account of the species concept most appropriate for Darwinism is the extent to which the process of biological classification—taxonomy—should be informed by advances in biological theory. Besides those already discussed, the moderate pluralism associated with Robert Brandon and Brent Mischler or the more radical pluralism defended by Philip Kitcher, argues that different explanatory aims within the biological sciences will require different criteria for determining whether a group constitutes a species (perhaps, controversially, including non-epistemic value commitments; see Garnett and Christidis 2017; Conix 2019). Cladists, on the other hand, employ strictly defined phylogenetic tests to determine species rank (see Rheins 2011).

Unlike many of the other topics that define the history of Darwinism, there is no clear-cut position on this question that can be identified as ‘Darwinian’ or ‘neo-Darwinian’. In a recent collection of papers defending most of the alternatives currently being advanced (Ereshefsky 1992), our suspicion is that virtually every author in that collection would identify himself as Darwinian. This may be because, as different as they are, a number of positions currently being defended have their roots in Darwin’s own theory and practice (see Beatty 1985; reprinted in Ereshefsky 1992).

Contemporary debates over the tempo and mode of evolutionary change often travel with those concerning the role of “non-Darwinian” processes in evolutionary biology, as discussed in section 3.2 . As was argued above, the classical Darwinist position on questions of tempo and mode is usually taken to be a strict gradualism, with natural selection slowly pushing populations toward adaptive peaks (see the entry on adaptationism ). From Darwin’s day to our own, a number of processes other than natural selection that significantly impact the speed and direction of population change have been increasingly emphasized. The oldest among them was genetic drift , which draws our attention toward selectively neutral (sometimes, as we saw above, described as “random”) change in populations. If one emphasizes processes of this sort, evolution might still be gradual, but it would not necessarily, or even not usually, be adaptively directed.

The same is true for the increasing interaction between evolution and developmental biology , or evo-devo. If processes like phenotypic plasticity, in which an organism with a static genotype may exhibit radically different phenotypes as a developmental response to environmental influences, are extremely prevalent, then the kind of gradual walk toward an adaptive peak which it is clear Darwin had in mind would be regularly punctuated by fits and starts of various kinds, as new portions of evolutionary space became available as a result of developmental novelty. In turn, this could lead to the non-gradual (potentially even non-Darwinian) pattern of punctuated equilibrium , Stephen Jay Gould’s term for this oscillation between periods of stasis and rapid change across the history of the tree of life (see the entry on macroevolution ). Examples of this sort could be multiplied (e.g., biased mutation, epigenetics), though we lack the space to do so here.

To be sure, it is not clear that Darwin himself would have considered any of these to be “anti-Darwinian” approaches. As counter-examples to Darwin’s gradualism accumulated in his own day, especially those driven by (misplaced, we now know) concerns about the age of the earth like those raised by William Thomson, Lord Kelvin, Darwin began to increase the importance of “sports” in later revisions of his works, large variations that could cause brief periods of rapid phenotypic change. That said, when a reference is made in contemporary work to the “Darwinian” position on tempo and mode, it is clearly his early, extreme gradualism that authors have in mind.

In-depth discussions of the contemporary state of the field on evolutionary ethics and biological altruism would take us too far afield for our purposes here, and each is the subject of a separate article in this encyclopedia (see morality and evolutionary biology ; biological altruism ). In short, ethical behavior seems to pose at least two prima facie challenges for evolutionary explanations. First, how could genuinely altruistic behavior, which seems to involve organisms making sacrifices for others, evolve under the strict optimizing regime of natural selection? And second, what is the relationship between evolutionary explanations of our mental and perceptual capacities and our understanding of moral knowledge? Must evolutionary theory undermine or “debunk” any claims to true moral beliefs (see the entry on moral epistemology )?

It is worth underlining here, however, that debate around Darwin’s own position on these issues has turned on whether or not Darwin was genuinely offering us a “group-selection” explanation for moral traits in human beings (e.g., Ruse and Richards 2016). This question, in addition to testing the limits of our ability to interpret precious little source material found in Darwin’s own writings, is difficult also because of the host of issues that might be implicated in the effort to explicate just what we mean by “a group-selection explanation” of a particular phenomenon.

As we mentioned in section 3.2 above, in linking the question of species’ metaphysical individuality to the hierarchy of natural selection, Stephen Jay Gould offers us a window onto the conceptual complexity to which this debate can lead. His title exemplifies one approach to group selection—the unit of selection is always the individual, but there are individuals other than individual organisms that are subject to selection. A very different result emerges if one assumes that groups of organisms such as demes, kin-groups, or species, though not individuals, are nevertheless subject to selection. Adding to the conceptual complexity, some researchers propose that the term ‘group selection’ be restricted to the process whereby group-level traits provide advantages to one group over another, in which case there are strict conditions delimiting cases of group selection. Others define group selection primarily in terms of group level effects . Thus a debate analogous to that earlier discussed regarding the definitions of ‘fitness’ emerges here—by group selection do we mean a distinct type of causal process that needs to be conceptually distinguished from selection at the level of individual organism or gene, or do we merely mean a tendency within certain populations for some well-defined groups to displace others over time? (For further discussion, see Sterelny and Griffiths 1999, 151–179; Hull 2001, 49–90; and see the entry on levels and units of selection .)

We hope that this survey has demonstrated, first and foremost, the rich past and present of philosophical reflections both about and inspired by Darwin’s theory of evolution by natural selection. Furthermore, as we have seen, Darwin’s own positions and works remain touchstones for such reflections, not only because he was the theory’s first proponent, but also because his positions still offer us a useful frame of reference as well as a host of sophisticated insights. To be sure, the philosophy and practice of biology have advanced significantly in the intervening nearly two hundred years since Darwin’s first notebooks on natural selection. But if history is any guide, considering whether and how these innovations depart from Darwin’s own views on the subject will be a fruitful enterprise well into the theory’s next century.

• Ågren, J. A., 2021, The Gene’s-Eye View of Evolution , Oxford: Oxford University Press.
• Amundson, R., and Lauder, G. 1994, “Function without Purpose: The Uses of Causal Role Function in Evolutionary Biology”, Biology and Philosophy , 9: 443–469.
• Babbage, C., 1837, The Ninth Bridgewater Treatise , London: Murray.
• Barrett, P. H., and Freeman R. B. (eds.), 1988, The Works of Charles Darwin , Vols. 1–29, New York: New York University Press.
• Barrett, P. H. et al. (eds.), 1987, Charles Darwin’s Notebooks, 1836–1844: Geology, Transmutation of Species, Metaphysical Enquiries , Ithaca NY: Cornell University Press.
• Beatty, J., 1984, “Chance and Natural Selection”, Philosophy of Science , 51: 183–211.
• –––, 1992, “Teleology and the Relationship Between Biology and the Physical Sciences in the Nineteenth and Twentieth Centuries”, in Durham and Purrington, pp. 113–144.
• Binswanger H., 1990, The Biological Basis of Teleological Concepts , Los Angeles: ARI Press.
• Brandon, Robert, 1981, “Biological Teleology: Questions and Explanations”, Studies in History and Philosophy of Science , 12: 91–105.
• –––, 1985, “Adaptation Explanations: Are Adaptations for the Good of Replicators or Interactors?”, in Weber and Depew, pp. 81–96.
• –––, 1990, Adaptation and Environment , Princeton: Princeton University Press.
• Brandon, R. and Burian, R. (eds.), 1984, Genes, Organisms, Populations: Controversies over the Units of Selection , Cambridge MA: Harvard University Press.
• Burian, R., 1983, “Adaptation”, in Grene, pp. 287–314.
• Conix, S., 2019, “Taxonomy and Conservation Science: Interdependent and Value-Laden”, History and Philosophy of the Life Sciences 41:15.
• Darwin, C., 1859 , On the Origin of Species , London: John Murray.
• –––, 1871, The Descent of Man and Selection in Relation to Sex , London: John Murray, 2 vols.
• Dawkins, R., 1976, The Selfish Gene , Oxford: Oxford University Press.
• Dennett, D., 1995, Darwin’s Dangerous Idea: Evolution and the Meanings of Life , New York: Simon and Shuster.
• Dobzhansky, T., 1937, Genetics and the Origin of Species , New York: Columbia University Press.
• –––, 1970, Genetics of the Evolutionary Process , New York: Columbia University Press.
• Durham, F. and Purrington R. (eds.), 1992, Some Truer Method: Reflections on the Heritage of Newton , New York: Columbia University Press.
• Eble, G., 1999, “On the Dual Nature of Chance in Evolutionary Biology and Paleobiology”, Paleobiology , 25: 75–87.
• Endler, J. 1983, “Natural and Sexual Selection on Color Patterns in Poeciliid Fishes”, Environmental Biology of Fishes 9: 173–190.
• Ereshefsky, M. (ed.), 1992, The Units of Evolution: Essays on the Nature of Species , Cambridge, MA: Harvard University Press.
• –––, 2010, “Darwin’s Solution to the Species Problem”, Synthese 175: 405–425.
• Garnett , S. T. and Christidis, L., 2017, “Taxonomy Anarchy Hampers Conservation”, Nature 417:17–19.
• Gayon, J., 1998, Darwinism’s Struggle for Survival: Heredity and the Hypothesis of Natural Selection , Cambridge: Cambridge University Press.
• –––, 2003, “From Darwin to Today in Evolutionary Biology”, in Hodge and Radick, pp. 240–264.
• Gotthelf, A. and Lennox, J. G. (eds.), 1987, Philosophical Issues in Aristotle’s Biology , Cambridge: Cambridge University Press.
• Grene, M. (ed.), 1983, Dimensions of Darwinism , Cambridge: Cambridge University Press.
• Gould, S. J., 2002, The Structure of Evolutionary Theory , Cambridge, MA: Harvard University Press.
• Herbert, S. (ed.), 1980, The Red Notebook of Charles Darwin , Ithaca: Cornell University Press.
• Herschel, J., 1830/1987, A Preliminary Discourse on the Study of Natural Philosophy , Chicago: Chicago University Press.
• Hodge, J. and Radick, G. (eds.), 2003, The Cambridge Companion to Darwin , Cambridge: Cambridge University Press.
• Horowitz, T. and Massey, G. (eds.), 1991, Thought Experiments in Science and Philosophy , Savage, MD: Rowman and Littlefield.
• Hull, D., 2001, Science and Selection: Essays on Biological Evolution and the Philosophy of Science , Cambridge: Cambridge University Press.
• Huxley, L. (ed.), 1901, Life and Letters of Thomas H. Huxley, Vols. I-II , New York: D. Appleton & Co.
• Keller, E. Fox and Lloyd, E. (eds.), 1992, Keywords in Evolutionary Biology , Cambridge, MA: Harvard University Press.
• Kimura, M., 1992, “Neutralism”, in Fox Keller and Lloyd, pp. 225–230.
• Kitcher, P., 1993, The Advancement of Science: Science without Legend, Objectivity without Illusions , Oxford: Oxford University Press.
• Laland, K. et al., 2014, “Does Evolutionary Theory Need a Rethink?”, Nature 514: 161–164.
• Lamarck, J-B., 1809/1984, Zoological Philosophy , Chicago: University of Chicago Press.
• Laudan, L., 1976, Progress and its Problems , Berkeley: University of California Press.
• Lennox, James G. 1987, “Kinds, Forms of Kinds, and the More and the Less in Aristotle’s Biology”, in Gotthelf and Lennox, pp. 339–359.
• –––, 1991, “Darwinian Thought Experiments: A Function for Just-so Stories”, in Horowitz and Massey, pp. 223-246.
• –––, 1992, “Philosophy of Biology”, in Salmon et al., pp. 269–309.
• –––, 1993, “Darwin was a Teleologist”, Biology and Philosophy 8: 409–422.
• –––, 2000, Aristotle’s Philosophy of Biology: Essays on the Origins of Life Science , Cambridge: Cambridge University Press.
• Lennox, J. and Wilson, B., 1994, “Natural Selection and the Struggle for Existence”, Studies in History and Philosophy of Science , 25: 65–80.
• Lu, Q. and Bourrat, P., 2017, “The Evolutionary Gene and the Extended Synthesis”, British Journal for the Philosophy of Science , 69: 775–800.
• Lyell, C., 1831–3/1991, Principles of Geology, First Edition, Vol. I-III , Chicago: University of Chicago Press.
• Millstein, R., 2000, “Chance and Macroevolution”, Philosophy of Science 67: 603–624.
• Nicholson, D. J., 2014, “The Return of the Organism as a Fundamental Explanatory Concept in Biology”, Philosophy Compass 9: 347–359.
• Nowak, M. A., Tarnita, C. E., and Wilson, E. O., 2010, “The Evolution of Eusociality”, Nature 466: 1057–1062.
• Ospovat, D., 1980, The Development of Darwin’s Theory: Natural History, Natural Theology, and Natural Selection, 1838–1859 , Cambridge: Cambridge University Press.
• Pence, C. H., 2021, The Causal Structure of Natural Selection , Cambridge: Cambridge University Press.
• –––, 2022, The Rise of Chance in Evolutionary Theory: A Pompous Parade of Arithmetic , London: Academic Press.
• Pigliucci, M. and Müller, G. B., 2011, Evolution: The Extended Synthesis , Cambridge, MA: MIT Press.
• Ramsey, G. and Pence, C. H. (eds.), 2016, Chance in Evolution , Chicago: University of Chicago Press.
• Rheins, J., 2011, “Similarity and Species Concepts”, in J. Campbell, M. O’Rourke, and M. Slater (eds.), Carving Nature at its Joints: Natural Kinds in Metaphysics and Science , Cambridge, MA: MIT Press, pp. 253–288.
• Robson, G. C. and Richards, O. W., 1936, The Variation of Animals in Natur e, London: Longmans.
• Ruse, M. and Richards, R. J., 2016, Debating Darwin , Chicago: University of Chicago Press.
• Salmon, M. et al., 1992, Introduction to Philosophy of Science , Indianapolis: Hackett.
• Shanahan, T., 1991, “Chance as an Explanatory Factor in Evolutionary Biology”, History and Philosophy of the Life Sciences 13: 249–269.
• Skelton, P. (ed.), 1993, Evolution: A Biological and Palaeontological Approach , London: Pearson.
• Sterelny, K. and Griffiths, P., 1999, Sex and Death: An Introduction to Philosophy of Biology , Chicago: Chicago University Press.
• Uller, T. and Laland, K. N., 2019, Evolutionary Causation: Biological and Philosophical Reflections , Cambridge, MA: MIT Press.
• Uglow, J., 2002, The Lunar Men: Five Friends Whose Curiosity Changed the World , New York: Farrar, Strauss and Giroux.
• Walsh, D. M., 2006, “Evolutionary Essentialism”, British Journal for Philosophy of Science , 57: 425–448.
• –––, 2015, Organisms, Agency, and Evolution , Cambridge: Cambridge University Press.
• Weber, B. and Depew, D. (eds.), 1985, Evolution at a Crossroads: The New Biology and the New Philosophy of Science , Cambridge MA: MIT Press.
• Welch, J. J., 2017, “What’s Wrong with Evolutionary Biology?”, Biology & Philosophy , 32: 263–279.
• Williams, G. C., 1966, Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought , Princeton: Princeton University Press.
• –––, 1992, Natural Selection: Domains, Levels, and Challenges , Oxford: Oxford University Press.
• Wilkins, J. S., 2009, Species: A History of the Idea , Berkeley: University of California Press.
• Wilson, D. S., 1984, “Individual Selection and the Concept of Structured Demes”, in Brandon and Burian, pp. 272–291.
• Winsor, M. P., 2001, “Cain on Linnaeus: The Scientist-Historian as Unanalysed Entity”, Studies in History and Philosophy of Biological and Biomedical Sciences 32 (2): 239–25.
• –––, 2006, “Linnaeus’s Biology was not Essentialist”, Annals of the Missouri Botanical Gardens , 93: 2–7.
• Witteveen, J., 2015, “‘A Temporary Oversimplification’: Mayr, Simpson, Dobzhansky, and the Origins of the Typology/Population Dichotomy (Part 1 of 2)”, Studies in History and Philosophy of Biological and Biomedical Sciences 54: 20–33.
• –––, 2016, “‘A Temporary Oversimplification’: Mayr, Simpson, Dobzhansky, and the Origins of the Typology/Population Dichotomy (Part 2 of 2)”, Studies in History and Philosophy of Biological and Biomedical Sciences 57: 96–105.

Charles Darwin’s Life

• Browne, E. J. 1995, Charles Darwin: A Biography. Vol. 1: Voyaging , Princeton: Princeton University Press.
• –––, 2000, Charles Darwin: A Biography. Vol. 2: The Power of Place , Princeton: Princeton University Press.
• Desmond, A. and Moore, J., 1992, Darwin: The Life of a Tormented Evolutionist , New York: Norton.
• Herbert, S., 2005, Charles Darwin, Geologist , Ithaca: Cornell University Press.

Charles Darwin: Primary Sources

• Barrett, P. H. (ed.), 1977, The Collected Papers of Charles Darwin , 2 Vols., Chicago: University of Chicago Press.
• Burkhardt, F. (ed.), 1985–2023, The Correspondence of Charles Darwin , Volumes 1–30, Cambridge: Cambridge University Press.
• Chancellor, G. and John van Wyhe (eds.), 2009, Charles Darwin’s Notebooks from the Voyage of the Beagle , Cambridge: Cambridge University Press.
• Keynes, R. (ed.), 2000, Charles Darwin’s Zoology Notes & Specimen Lists from H.M.S. Beagle , Cambridge: Cambridge University Press.
• Peckham, M. (ed.), 1959, The Origin of Species by Charles Darwin: A Variorum Text , Philadelphia: University of Pennsylvania Press. [1st Paperback edition, 2006]
• Weinshank, D. et al. (eds.), 1990, A Concordance to Charles Darwin’s Notebooks, 1836–1844 , Ithaca: Cornell University Press.

Charles Darwin’s Context

• Owen, R., 1837/1992, The Hunterian Lectures in Comparative Anatomy, May and June 1837 (Edited and with an Introductory Essay and Commentary by Phillip Reid Sloan), Chicago: Chicago University Press.
• Rudwick, M., 1997, George Cuvier, Fossil Bones and Geological Catastrophes , Chicago: University of Chicago Press.
• Ruse, M., 1999, The Darwinian Revolution: Science Red in Tooth and Claw (Revised edition), Cambridge: Cambridge University Press.
• Ruse, M. and Richards, R. J. (eds.), 2009, The Cambridge Companion to the Origin of Species, Cambridge: Cambridge University Press.
• Snyder, L., 2010, The Philosophical Breakfast Club , New York: Broadway Books.

The Evolution of Darwinism

• Amundson, R., 2005, The Changing Role of the Embryo in Evolutionary Thought: Roots of Evo-Devo , Cambridge: Cambridge University Press.
• Depew, D. and Weber, B., 1995, Darwinism Evolving: Systems Dynamics and the Genealogy of Natural Selection , Cambridge MA: MIT Press.
• Kohn, D. (ed.), 1995, The Darwinian Heritage , Princeton: Princeton University Press.
• Mayr, E., 1976, Evolution and the Diversity of Life , Cambridge MA: Harvard University Press.
• Ruse, M. (ed.), 2013, The Cambridge Encyclopedia of Darwin and Evolutionary Thought , Cambridge: Cambridge University Press.

Philosophy and Evolutionary Theory

• Brandon, R. N., 1996, Concepts and Methods in Evolutionary Biology , Cambridge: Cambridge University Press.
• Burian, R. M., 2005, The Epistemology of Development, Evolution, and Genetics , Cambridge: Cambridge University Press.
• Godfrey-Smith, P., 2009, Darwinian Populations and Natural Selection , Oxford: Oxford University Press.
• –––, 2014, The Philosophy of Biology , Princeton: Princeton University Press.
• Hull, D. and Ruse, M. (eds.), 1998, The Philosophy of Biology , Oxford: Oxford University Press.
• Lloyd, E., 1994, The Structure and Confirmation of Evolutionary Theory , 2 nd edition Princeton: Princeton University Press.
• Okasha, S., 2006, Evolution and the Levels of Selection , Oxford: Clarendon Press.
• –––, 2019, Philosophy of Biology: A Very Short Introduction , Oxford: Oxford University Press.
• Sober, E., 1984, The Nature of Selection: Evolutionary Theory in Philosophical Focus , Cambridge MA: MIT Press.
• ––– (ed.), 1994, Conceptual Issues in Evolutionary Biology , 2 nd edition, Cambridge MA: MIT Press.
• –––, 2008, Evidence and Evolution: The Logic Behind the Science , Cambridge: Cambridge University Press.
• –––, 2024, The Philosophy of Evolutionary Theory: Concepts, Inferences & Probabilities , Cambridge: Cambridge University Press.
• Smith, David Livingstone (ed.), 2017, How Biology Shapes Philosophy: New Foundations for Naturalism , Cambridge: Cambridge University Press.

How to cite this entry . Preview the PDF version of this entry at the Friends of the SEP Society . Look up topics and thinkers related to this entry at the Internet Philosophy Ontology Project (InPhO). Enhanced bibliography for this entry at PhilPapers , with links to its database.

Though there are an abundance of web sites on Darwinism, the three most useful sites meeting the highest of academic standards are listed below. The first is the official site for the publication of material in the extensive Darwin Archives at Cambridge University, but has grown to become the default site for Darwin texts and related literature as well. The second is the official site for on-line publication of Darwin’s extensive correspondence. The third site is a very good starting point amd links to sites related to Charles Darwin’s historical context.

• Complete World of Charles Darwin Online
• Darwin Correspondence Project
• Victorian Science: An Overview , The Victorian Web (funded by the University Scholars Program, National University of Singapore)

adaptationism | biology: philosophy of | creationism | developmental biology: evolution and development | essential vs. accidental properties | evolution | fitness | -->individuals and individuation --> | laws of nature | natural selection | natural selection: units and levels of | scientific explanation | Scottish Philosophy: in the 18th Century | Scottish Philosophy: in the 19th century | species | teleology: teleological notions in biology | Whewell, William

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Darwin and His Theory of Evolution

At first glance, Charles Darwin seems an unlikely revolutionary. Growing up a shy and unassuming member of a wealthy British family, he appeared, at least to his father, to be idle and directionless. But even as a child, Darwin expressed an interest in nature. Later, while studying botany at Cambridge University, he was offered a chance to work as an unpaid naturalist on the HMS Beagle , a naval vessel embarking on an exploratory voyage around the world. In the course of nearly five years at sea – during which time the Beagle surveyed the coast of South America and stopped in such places as Australia and, most famously, the Galapagos Islands – Darwin took advantage of countless opportunities to observe plant and animal life and to collect both living and fossilized specimens for later study.

After the Beagle returned to England in October 1836, Darwin began reflecting on his observations and experiences, and over the next two years developed the basic outline of his groundbreaking theory of evolution through natural selection. But beyond sharing his ideas with a close circle of scientist friends, Darwin told no one of his views on the origin and development of life. Indeed, he did not publish his now-famous volume, On the Origin of Species by Means of Natural Selection , until 1859, more than 20 years after he had first formulated his theory.

On the Origin of Species may never have been written, let alone published, if it had not been for Alfred Russel Wallace, another British naturalist who independently proposed a strikingly similar theory in 1858. Wallace’s announcement prompted Darwin to publicly reveal that his own research had led him to the same conclusion decades earlier. This being the age of Victorian gentlemen, it was agreed that the two scientists would jointly publish their writings on the subject. Their work – comprising a collection of Darwin’s earlier notes and an essay by Wallace – was read to the Linnean Society, an association of naturalists, in London on July 1, 1858. The following year, Darwin published On the Origin of Species , a lengthy, fleshed-out treatment of his ideas on evolutionary theory. The book was an immediate bestseller and quickly set off a firestorm of controversy.

Darwin had expected no less – fear of a backlash from Britain’s religious and even scientific establishment had been the primary reason he had delayed publicizing his ideas. Yet the concept of species adaptation was not so radical at the time. Scientists had been debating whether animals evolved decades before Darwin put forth his theory. The idea of “transmutation of species” had been rejected by many prominent naturalists, among them French scientist Georges Cuvier, who believed that species had been created much as they appeared in his day. But transmutation also had early champions, including Darwin’s grandfather, the famed Birmingham physician Erasmus Darwin.

The younger Darwin’s achievement was to offer a plausible and compelling explanation for how species evolve and to use this explanation to trace the history of life’s development. All existing creatures, he argued, descended from a small number of original or progenitor species. Darwin compared the history of life to a great tree, its trunk representing these few common ancestors and an extensive system of branches and twigs symbolizing the great variety of life that has evolved from them.

This evolution, Darwin wrote, is due to two factors. The first factor, Darwin argued, is that each individual animal is marked by subtle differences that distinguish it from its parents. Darwin, who called these differences “variations,” understood their effect but not their cause; the idea of genetic mutation, and indeed the scientific study of genetics, would not arise fully until the early 20th century. The second factor, Darwin argued, is that although variations are random, some of them convey distinct advantages – superior camouflage, a heartier constitution or greater speed, for example – that better equip a creature to survive in its environment. A greater chance of survival allows for more opportunity to breed and pass on advantageous traits to a greater number of offspring. Over time, an advantage spreads throughout a species; in turn, the species is more likely to endure and reproduce. Thus, over the course of many generations, subtle changes occur and accumulate, eventually morphing into bigger changes and, possibly, even a new species.

While Darwin’s ideas initially challenged long-held scientific and religious belief systems, opposition to much of Darwin’s thinking among the scientific communities of the English-speaking world largely collapsed in the decades following the publication of On the Origin of Species . Yet evolution continued to be vigorously rejected by British and American churches because, religious leaders argued, the theory directly contradicted many of the core teachings of the Christian faith.

Darwin’s notion that existing species, including man, had developed over time due to constant and random change seemed to be in clear opposition to the idea that all creatures had been created “according to their kind” by God, as described in the first chapter of the biblical book of Genesis. Before Darwin, the prevailing scientific theory of life’s origins and development had held that species were fixed and that they never changed. This theory, known as “special creationism,” comported well with the biblical account of God creating the fish, fowl and mammals without mention of subsequent alteration.

Darwinian thinking also appeared to contradict the notion, central to Christianity and many other faiths, that man had a special, God-given place in the natural order. Instead, proponents of evolution pointed to signs in human anatomy – remnants of a tailbone, for instance – showing common ancestry with other mammals.

Finally, the idea of a benevolent God who cared for his creation was seemingly challenged by Darwin’s depiction of the natural world as a savage and cruel place – “red in tooth and claw,” as Darwin’s contemporary, Alfred Lord Tennyson, wrote just a few years before On the Origin of Species was published. Darwin’s theory challenged the idea that the natural world existed in benevolent harmony.

Darwin fully understood, and at times agonized over, the threat that his work might pose to traditional religious belief, explaining in an 1860 letter to American botanist Asa Gray that he “had no intention to write atheistically.” But, he went on, “I cannot see as plainly as others do … evidence of design and beneficence on all sides of us. There seems to be too much misery in the world.”

Regardless of his intentions, Darwin’s ideas provoked a harsh and immediate response from religious leaders in Britain. For instance, England’s highest-ranking Catholic official, Henry Cardinal Manning, denounced Darwin’s views as “a brutal philosophy – to wit, there is no God, and the ape is our Adam.” Samuel Wilberforce, the Anglican Archbishop of Oxford and one of the most highly respected religious leaders in 19th-century England, also condemned natural selection in a now-famous speech on what he deemed the theory’s scientific deficiencies at an 1860 meeting of the British Association for the Advancement of Science. At one point during the meeting, Wilberforce reportedly asked biologist Thomas Henry Huxley whether he was related to an ape on his grandmother’s or grandfather’s side. Huxley, whose vigorous defense of evolutionary theory would earn him the nickname “Darwin’s bulldog,” allegedly replied that he would rather be the ancestor of a monkey than an advanced and intelligent human being who employed his “knowledge and eloquence in misrepresenting those who are wearing out their lives in the search for truth.”

Some scholars now contend that Huxley’s rebuke of Wilberforce never occurred. Regardless, it was around this time that the British scientific establishment gained the upper hand in the debate over evolution. And while the public disagreement between ecclesiastical and scientific authorities did not end in the 1860s, religious thinkers became more wary of directly challenging evolution on scientific grounds. In the late 19th and early 20th centuries, churches instead focused much of their energy on resisting the idea that man had evolved from lower animal orders and hence had no special place in creation or, for that matter, a soul. Indeed, while some churches, including the Catholic Church, eventually accepted evolution as a God-directed mechanism of biological development, none questioned the role of God as the sole creator of man.

By the time of his death, in 1882, Darwin was considered the greatest scientist of his age. Moreover, the very church his theory had challenged accorded him a full state funeral and burial in Westminster Abbey, near the grave of Sir Isaac Newton. Darwin’s idea was still provocative, but by the time of his death it had gained general acceptance in Britain, even among many in the Anglican clergy. Indeed, his interment in the abbey was seen by some contemporaries as symbolic of an uneasy truce between science and religion in Britain.

This report was written by David Masci, a senior researcher at the Pew Research Center’s Religion & Public Life Project.

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• Darwinian Essays
• Open access
• Published: 06 December 2008

Charles Darwin and Human Evolution

• Ian Tattersall 1  

Evolution: Education and Outreach volume  2 ,  pages 28–34 ( 2009 ) Cite this article

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Along with his younger colleague Alfred Russel Wallace, Charles Darwin provided the initial theoretical underpinnings of human evolutionary science as it is practiced today. Clearly, nobody seeking to understand human origins, any more than any other student of the history of life, can ignore our debt to these two men. As a result, in this bicentennial year when Darwin’s influence in every field of biology is being celebrated, it seems reasonable to look back at his relationship to paleoanthropology, a field that was beginning to take form out of a more generalized antiquarian interest just as Darwin was publishing On the Origin of Species in 1859. Yet there is a problem. Charles Darwin was curiously unforthcoming on the subject of human evolution as viewed through the fossil record, to the point of being virtually silent. He was, of course, most famously reticent on the matter in On The Origin of Species , noting himself in 1871 that his only mention of human origins had been one single throwaway comment, in his concluding section:

“light will be thrown on the origin of man and his history” (Darwin 1859 , p. 488).

This has, of course, to rank among the most epic understatements ever. And of course, it begged the question, “what light?” But in the event, Darwin proved highly resistant to following up on this question. This is true even of his 1871 book The Descent of Man, and Selection in Relation to Sex in which Darwin finally forced himself to confront the implications of his theory for the origin of humankind, and the main title of which is in many ways something of a teaser.

There were undoubtedly multiple reasons for this neglect of the issue that was naturally enough in the back of everyone’s mind when reading The Origin , let alone The Descent of Man . First, and most famously, there was the intellectual and social milieu in which Darwin lived. During the second quarter of the nineteenth century, during which Darwin’s most formative experiences all occurred, England was at one level a place of intense political and social ferment. The Reform Act of 1832 had witnessed significant changes in the way Parliament was elected; the New Poor Law of 1834 had at least recognized problems in the system of poverty relief; and the founding of London University in 1826 had provided, at last, a secular alternative to the fusty Anglican Universities of Cambridge and Oxford. But despite all this, early Victorian England remained a strait-laced Anglican society whose upper classes, well remembering events in France not so long before, had little taste for radical ideas in any field.

In such an unreceptive milieu, the retiring Darwin had little relish for stirring things up with radical ideas on human emergence. He had originally planned to include mankind in the “Big Book” he was working on when spurred by Wallace into writing and publishing its “abstract” in the form of On the Origin of Species (Moore and Desmond, 2004 ). But despite having then made the conscious decision to avoid the vexatious and contentious issue of human evolution in On the Origin of Species , he still saw his book widely condemned as intellectual heresy, even as a recipe for the ruin of established society. As a result, while contemplating the publication of The Descent of Man a decade later, Darwin was still able to write to a colleague that:

“When I publish my book, I can see that I shall meet with universal disapprobation, if not execution” (in a letter to St. George Mivart, April 23, [probably] 1869).

As the least combative of men, Darwin dreaded the response he knew that any attempt to stake out a position on human origins would receive. And to be quite frank, given all his hesitations, it is not at all clear to me exactly why Darwin felt so strongly impelled to publish The Descent of Man or at least to have given it the provocative if not quite accurately descriptive title he did.

One possibility is merely that, during the 1860s, such luminaries as Alfred Russel Wallace, Ernst Haeckel, and Thomas Henry Huxley had all publicly tackled the matter of human origins and not invariably to Darwin’s satisfaction. As a result, Darwin may simply have felt it necessary to make his own statement on the matter, come hell or high water, in a decade that was already significantly more receptive to evolutionary notions than the 1850s had been. As to why it was so important to him to see it written, the Darwin historians James Moore and Adrian Desmond have pointed to an agenda that did not translate directly from Darwin’s stated desire simply:

“to see how far the general conclusions arrived at in my former works were applicable to man… all the more desirable as I had never applied these views to a species taken singly” (Darwin 1871 , ii, p. 2).

There was clearly more to it than that, and Moore and Desmond emphasize that Darwin came from a family of free-thinkers. He was the grandson both of the libertarian poet and physician Erasmus Darwin and of the Unitarian Josiah Wedgwood who had, in 1787, produced the famous “am I not a man and a brother?” cameo that became the emblem of the movement to abolish slavery. What is more, at a very impressionable age, Charles had attended the more or less secularist Edinburgh University in Scotland. There he had studied under the anatomist Robert Grant who quoted Lamarck with approval; and there also he was taught taxidermy by John Edmondston, a freed slave from British Guiana for whom he developed very considerable respect.

From the very beginning, then, Darwin abhorred slavery; and he was already a convinced abolitionist by the time he boarded the Beagle in 1831 for his formative round-the-world voyage. His subsequent experiences in Brazil, where he witnessed hideous cruelties being inflicted on slaves, and in Argentina, where he saw the pampas Indians being slaughtered to make way for Spanish ranchers, only confirmed him in his egalitarian beliefs. This concern linked in with Darwin’s strong views on the unity of mankind. In the early and middle nineteenth century, this was a very hot topic in the English-speaking world, even “the question of the day,” as the blurb to a book by the Presbyterian abolitionist Thomas Smyth ( 1850 ) put it.

The precise question at issue was of course whether the races of mankind had been separately created (or even, after The Origin of Species was published, descended from different species of apes), as the proslavery polygenists proposed; or whether they were simply varieties of one single species, as proclaimed by the antislavery monogenists.

In this matter, there was little hope that science could ever be disentangled from politics; and it was this, above anything else, it seems, that had dissuaded Darwin from including humans in On the Origin of Species . By 1871, however, the world had changed enough to allow Darwin to contemplate entering the fray; and there is substantial reason for viewing The Descent of Man as Darwin’s contribution on the monogenist side to the monogenism versus polygenism debate—although Moore and Desmond ( 2004 ) make a strong argument that, in the end, it became at least as important to Darwin as a showcase for his notion of sexual selection.

Indeed, these two aspects could hardly be separated, since sexual selection—in other words, mate choice—was Darwin’s chosen mechanism to explain:

“the divergence of each race from the other races, and all from a common stock” (Darwin 1871 , ii, p. 371).

And most of the book is, in true Darwinian style, taken up with hugely detailed documentation of sexual selection among organisms, in support of the proposition that humankind was simply yet another product of Nature, albeit with many of its peculiar features governed by mate choice rather than by adaptiveness.

Still, Darwin had chosen to title his book The Descent of Man . And “descent” was a word that he had long used as equivalent to “ancestry.”

Given which, it seems at the least a bit odd that in the entire two volumes of the first edition of the work only passing consideration at best is given to those fossils that might have given a historical embodiment to the notion of human emergence. Even when Darwin wrote the Origin in 1858–1859, a handful of “antediluvian” human fossils was already known. The most famous of these was the skullcap and associated bones discovered in 1856 in the “Little Feldhofer Grotto,” a limestone cave in the Neander Valley, near Dusseldorf in Germany. This fossil, associated with the bones of mammal species now extinct, was destined in 1863 to become the type specimen of Homo neanderthalensis , now known to be an extinct cousin of our own species, Homo sapiens . But it was not published until 1858, barely a year before the Origin appeared; and even then, it was described in German, in a rather obscure local scientific journal, making it highly unlikely that the Neanderthal fossil came to Darwin’s attention before Hermann Schaaffhausen’s work on it was translated into English by the London anatomist George Busk in 1861. Still, this was an entire decade before The Descent of Man first appeared, which makes it a little odd that the detail-obsessed Darwin made virtually no reference to the Feldhofer fossil in a book which one might have expected to find it at front and center or at least introduced as a phenomenon to be explained. Only in passing did he mention it at all.

The neglect of the Neanderthal fossil is all the more remarkable in light of the fact that, in 1863, George Busk had already described another individual, of similarly distinctive appearance, from the British possession of Gibraltar. Taken together, these two specimens had demonstrated pretty conclusively by the mid-1860s that here was not simply a pathological form of Homo sapiens , as many influential biologists had claimed, but at the very least a highly distinctive human “variety” that needed explanation of some kind. In sharp contrast to any modern human fossils then known from anywhere in the world, the Neanderthal skull was very long and low. What’s more, it terminated in front in prominent brow ridges that arced individually above each eye and at the rear in a curious bulge that became known as a “chignon” or “bun.” On the other side of the balance, this skull had evidently contained a brain that was equal in size to the brain that resided in the heads of modern people. Either way, it was obviously an important fossil.

Yet the only reference that the astonishingly erudite Darwin made to this fossil, in almost 800 pages of dense text, was in the context of a throwaway admission that:

“some skulls of very high antiquity, such as the famous one of Neanderthal, are well developed and capacious.” (Darwin 1871 , i, p. 140).

It is hard not to conclude that, in limiting his reference to the Feldhofer in this way, Darwin was grasping at the politically congenial notion that the Neanderthaler, ancient as it was, was simply a bizarre kind of modern human. For perhaps more remarkably yet, nowhere in The Descent of Man did Darwin directly confront the idea that the human species might even in principle have possessed extinct relatives—despite the fact that the entire Origin of Species is suffused with the notion that having extinct relatives must be a general property of all living forms.

In his introduction to The Descent , Darwin partially excused himself for only passing reference to human antiquity by deferring to the work of Jacques Boucher de Perthes, Charles Lyell, his protégé Sir John Lubbock, and others. But there was very likely another key to Darwin’s reluctance to embroil himself too closely with the actual tangible evidence for human ancientness and ancestry. For the 1860s, the years leading up to the publication of the Decent of Man , were a period of rampant fraud and fakery in the antiquities business—and a business it certainly was. By the time Darwin published the Descent , it was widely accepted that, at the very least, the human past far antedated Biblical accounts. And an energetic search was on for evidence of that ancient past, with wealthy dilettantes pouring money into excavations all across Europe. Today, we honor the French antiquarian and customs-collector, Boucher de Perthes, as the first man to recognize the Ice Age stone handaxes found in the terraces of the Somme River as the products of truly ancient humans. But in the 1840s and 1850s, Boucher de Perthes was widely ridiculed as the gullible victim of hoaxers; and indeed, it is true that he was entirely undiscriminating in what he was prepared to consider ancient. Many of his prize artifacts turned out later to have been knapped by his quarrymen, who were only too happy to con their employer out of a few francs. Indeed, there is a charming story of a lady who asked a local peasant what he was doing chipping away at a piece of flint and was told: “Why, I am making Celtic handaxes for Monsieur Boucher de Perthes.” “Celtic” was then the current term for anything prehistoric.

Of course, Boucher de Perthes was not alone. For profitable deception of the gentry, by clever tricksters from the underclasses, was a rather sporting component of class warfare all across Europe in the mid—nineteenth century. But Boucher de Perthes had, in particular, been embroiled in a famous hoax involving a supposedly antediluvian human fossil (Trinkaus and Shipman 1993 ). In early 1863, he offered a reward of 200 francs to any workman who could find the remains of the maker of his ancient stone tools. And on March 28 of that year, a supposedly ancient human jawbone duly showed up, along with handaxes, at a site called Moulin-Quignon. A scandal almost immediately blew up over the authenticity of this object and the stone tools supposedly associated with it; and eventually, an international commission was convened to settle the matter. This committee of savants consisted of various French luminaries, plus several English scientists including George Busk. Eventually, the commission exonerated Boucher de Perthes himself as a fraudster, but remained deadlocked over the authenticity of the fossil and tools. The French intelligentsia mostly accepted them for political reasons, while the English remained opposed. And the whole affair added up to the sort of unseemly squabble that Darwin most detested and always did his best to avoid.

What’s more, there were similar and equally embarrassing scandals closer to home. In England, the so-called “Prince of Counterfeiters” was one Edward Simpson, alias “Flint Jack” (Milner 2008 ). During several years of assisting a local physician who dug for antiquities in his spare time, Flint Jack taught himself the art of stoneworking. Soon, this gifted flintknapper was producing supposedly Stone Age tools that would fool even the most expert eye. And he sold his forgeries to collectors and museums all over the country. Finally, he brazenly peddled them as his own work, before the sheer quantity of real Stone Age artifacts coming on to the market put him out of business. There can be little doubt that Darwin found all this fraud and scandal in the antiquarian marketplace very distasteful. And it must surely have been at least one more contributory factor in his reluctance to dabble in the human fossil record.

Still, it is nonetheless necessary to ask why Darwin gave even the idea of an actual fossil ancestry for humans such a wide berth in his great work on human descent. In this connection, it is quite possibly enough to conclude with Moore and Desmond ( 2004 ) that Darwin considered it simply too provocative, both politically and socially, to tie human ancestry in with any tangible evidence. For it is well known that even the contemplation of doing so caused this complex and delicate man extreme physical and mental distress; and it certainly seems plausible that Darwin felt that limiting himself to the comparative method, contrasting humans with apes, and merely conjecturing about possible transitional forms, was somehow the safest route to take. After all, those speculative intermediates remained hypothetical, unenshrined in any material object that his opponents might take exception to.

However, it is possible that another contributing factor may well have been Darwin’s rather suspicious attitude toward the fossil record itself—which in the nature of things is the only direct archive we have of the origins and evolution of the human family or any other. Of course, by its very nature, the fossil record is and always will be incomplete. And in Darwin’s time, 150 years ago, it was vastly more incomplete than it is now, and conspicuously lacked many of the intermediate forms predicted by Darwin’s theory. But while under such circumstances it is completely understandable that Darwin would not have wished to embrace the fossil record as a key element bolstering his notion, he seems to have deliberately shied away from it. Thus, under the rubric of “Objections to the Theory,” he devoted an entire chapter in the Origin of Species to the “Imperfection of the Geological Record,” enumerating reason after reason not only why this record was not adequate, but why it could not be adequate.

“Geology assuredly does not reveal any such finely graduated chain [as evolution requires]; and this, perhaps is the gravest objection which can be urged against my theory. The explanation lies, as I believe, in the extreme imperfection of the geological record.” (Darwin 1859 , p. 280).

Even in the remarkably brief chapter of the Origin in which he recruited the fossil record to his cause, Darwin was dubious:

“[numerous causes] must have tended to make the fossil record extremely imperfect, and will to a large extent explain why we do not find interminable varieties, connecting together all the extinct and existing forms of life by the finest graduated steps.” (Darwin 1859 , p. 342).

Darwin’s general wariness of the fossil record may seem a bit odd in a person who not only considered himself first and foremost a geologist, but whose nascent ideas about the history of life had been so clearly nourished by the fossils he had encountered during his voyage on the Beagle . For Darwin was always ready to acknowledge what a seminal event his discovery during the Beagle voyage of the amazing South American fossil glyptodonts had been for him. The glyptodonts are large extinct armored xenarthrans, relatives of today’s armadillos and sloths, which are found quite abundantly in Ice Age geological deposits of southern South America. And finding these extinct beasts in the very same place as surviving members of their family—something that implied the replacement of faunas by related ones—was a revelation to Darwin:

“[I was] deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that of the existing armadillos” (C. Darwin in F. Darwin 1950 , p. 52).

Indeed, as Eldredge ( 2005 ) points out, Darwin’s encounter with the glyptodonts constituted one of the three key observations that first led him toward the explicit realization that species were not immutable.

This realization was a truly formative one because, for Darwin, the adoption of the corollary belief in the “transmutation of species” was fundamental to everything that was to follow, and it was emotionally as well as intellectually a difficult transition for him to make. In an 1844 letter to Joseph Hooker, Darwin famously described how admitting his new belief was “like confessing a murder,” and it was as formidable a psychological hurdle as he faced in his entire career. Still, although his geological observations had made Darwin acutely aware of the transitory nature of everything he saw around him, he clearly felt very acutely the inadequacies of the fossil record for determining specific events. And although the notion that fossil “missing links” were out there to be discovered was soon to become a governing principle of the quest for human origins, Darwin himself seems to have remained rather dubious that such links would ever be found.

Of course, the whole notion of links, missing or otherwise, came from the medieval concept of the Great Chain of Being with which Darwin was philosophically in contention—indeed, in a marginal note in one of the Notebooks , he specifically warned himself against ever using the terms “higher” or “lower” in relation to living beings. But the Great Chain of Being, the idea that all living things were ranged in graded series, was nonetheless part of the ethos that suffused English society, and it was a notion from which Darwin found it difficult to disengage himself entirely. For it was not only a religious concept with a succession of forms leading from the most lowly pond scum, through mankind, the highest Earthly form, on up to the Angels and God above. It had political and social dimensions as well. On one hand, the Great Chain ranked the races of mankind from “lower” to “higher;” and on the other, within English society, it carried through the social order with peasants and servants at the bottom, then tradesmen and the gentry, then the nobility, and on up to royalty at the top who served to link earthly and heavenly existences. Correspondingly, the designations of “lower” and “higher,” stemming directly from the Great Chain notion, proved irresistible to zoologists: lemurs, for example, were and still are “lower” primates, while apes and humans are “higher primates.”

It is well-established that, long before he published On the Origin of Species , Darwin was fully aware that his theory firmly placed our species Homo sapiens as simply another product of the evolutionary process, among literally millions of others. So, while the effective absence of a hominid fossil record before he published the Origin may have meant that Darwin could not have made extensive reference to it there if he had wanted to, we still need to ask if there are reasons beyond the admittedly powerful sociopolitical ones why he more or less ignored it in the post-Neanderthal times of The Descent of Man . One reason for such neglect is, of course, the very specific monogenist agenda that Darwin was pursuing in that work. But another reason may be that his colleague Thomas Henry Huxley, who is often, if misleadingly, referred to as “Darwin’s Bulldog,” had already tackled the matter head-on in his 1863 book of essays, Evidence as to Man’s Place in Nature .

The last chapter in Huxley’s book was explicitly titled On Some Fossil Remains of Man , and it dealt exclusively with the best-preserved and best-documented fossil humans known at the time: the Neanderthal skullcap already mentioned, and two partial crania from Engis, in Belgium, that had been published by Philippe-Charles Schmerling in the early 1830s. By the time Huxley wrote, the Engis fossils had been certified as contemporaneous with the extinct Ice Age wooly mammoth and wooly rhinoceros by no less an authority than Darwin’s close colleague the geologist Charles Lyell, who had also pronounced the Neanderthaler to be of “great but uncertain antiquity.” We now know that one of the Engis crania, a juvenile braincase, had belonged to a Neanderthal. However, since many of the osteological differences between Homo neanderthalensis and Homo sapiens only emerge later in development, it is fully understandable that Huxley (like everyone else at the time) did not recognize it as such. And in any event, Huxley basically ignored it. The other Engis cranium was adult, and it was on a plaster cast of this specimen that Huxley based his analysis. The Engis adult clearly is a Homo sapiens and it is now known to represent a later burial into the Neanderthal deposits at the site—which means it is younger than those deposits.

Huxley’s ignorance of this fact may not in fact have mattered much, in light of his rather perfunctory and dismissive analysis of the adult Engis specimen. He recognized this cranium as that of a fully modern person, concluding that it:

“has belonged to a person of limited intellectual faculties, and we conclude thence that it belonged to a man of a low degree of civilization” (Huxley 1863 , pp. 114–115).

He then continued to the Neanderthal skull, an altogether more interesting specimen, and to which he devoted much greater space. Initially, he quoted extensively from Schaaffhausen who had declared that the bones:

“exceed all the rest in those peculiarities of conformation which lead to the conclusion of their belonging to a barbarous and savage race.” (Schaaffhausen 1861 , translated by Busk).

Huxley finally proceeded to a detailed examination of the Neanderthal skullcap, again based on a plaster cast. He was amazed by the differences between the cranial contours of the Neanderthal and Engis crania, but he noted that:

“…the posterior cerebral lobes [of the Neanderthaler] must have projected considerably beyond the cerebellum, and… [this] constitutes one among several points of similarity between [it] and certain Australian skulls” (Huxley 1863 , p. 134).

As Schwartz ( 2006 ) has pointed out, the comparison with “certain Australian skulls” comes straight out of the Great Chain of Being. For in nineteenth-century European scientific mythology, the Australian aborigines belonged, along with the South African Bushmen, to the “lowest” of races. Having established this philosophical baseline, Huxley proceeded to a long dissertation about variation in human skulls, eventually concluding that the key to comparison among them was provided by the basicranial axis, a line between certain points on the internal base of the skull:

“I have arrived at the conviction that no comparison of crania is worth very much, that is not founded upon the establishment of a relatively fixed base line… the basicranial axis.” (Huxley 1863 , pp. 138–40).

He then showed, to his own satisfaction, that relative to this axis, the basicranium became shorter “in ascending from the lower animals up to man” and that this trend was continued up from the “lower” human races to the “higher” ones. In which case:

“Now comes the important question, can we discern, between the lowest and highest forms of the human cranium, anything answering, in however slight a degree, to this revolution of the side and roof bones of the skull upon the basicranial axis observed upon so great a scale in the mammalian series? Numerous observations lead me to believe that we must answer this question in the affirmative.” (Huxley 1863 , pp 140–142).

One might object at this point that the basicranial axis had no relevance whatever to the Feldhofer Neanderthal, a specimen that totally lacked a skull base. The important thing here, though, was that Huxley had managed to establish a graded series. And by superimposing the profile of the Neanderthaler onto an Australian skull, he contrived to convince himself that:

“A small additional amount of flattening, and lengthening, with a corresponding increase of the supraciliary ridge, would convert the Australian brain case into a form identical with the aberrant [Neanderthal] fossil.” (Huxley 1863 , p. 146).

Nonetheless, whereas:

“[The Engis skull] is… a fair average human skull, which might have belonged to a philosopher, or might have contained the thoughtless brains of a savage… The case of the Neanderthal skull is very different. Under whatever aspect… we meet with ape-like characters, stamping it as the most pithecoid of human crania yet discovered” (Huxley 1863 , p. 147).

Yet, at the same time, the Neanderthal skullcap had held a large brain—larger, indeed, than the modern average. Furthermore, although the preserved bones of the individual’s skeleton were robustly built, Huxley felt that such stoutness was to be “expected in savages” (Huxley 1863 , p. 148). As a result, he concluded that:

“In no sense… can the Neanderthal bones be regarded as the remains of a human being intermediate between men and apes. At most, they demonstrate the existence of a man… somewhat toward the pithecoid type… the Neanderthal cranium… forms… the extreme term of a series leading gradually from it to the highest and best developed of human crania” (Huxley 1863 , p. 149).

By this intellectual sleight of hand, Huxley dismissed the Neanderthal find as a mere savage Homo sapiens , essentially robbing the slender human fossil record then known of any potential human precursor. Instead, in a move that was as radical in its own way as the alternative would have been, Huxley pushed the antiquity of the species Homo sapiens back into the remotest past and was moved to ask:

“Where, then, must we look for primaeval Man? Was the oldest Homo sapiens pliocene or miocene, or yet more ancient? In still older strata do the fossilized bones of an ape more anthropoid, or a Man more pithecoid, than any yet known await the researches of some unborn palaeontologist?” (Huxley 1863 , p. 150).

Taken overall, this rather startling conclusion was not just a major shift away from the demonstrable morphology of the Neanderthal specimen—which in the same year had been branded a distinct species, Homo neanderthalensis , by the Dublin anatomist William King. It was also a considerable reversal of perspective for one who had been a convinced saltationist. After all, when reviewing On the Origin of Species , Huxley had been moved to observe that:

“Mr Darwin’s position might, we think, have been even stronger than it is if he had not embarrassed himself with the aphorism ‘ natura non facit saltum ,’ which turns up so often in his pages. We believe… that Nature does make jumps now and again, and a recognition of that fact is of no small importance in disposing of many minor objections to the doctrine of transmutation” (Huxley 1860 , p. 77).

Famously combative though Huxley was, with none of Darwin’s reluctance to hash out in public the implications of evolution for human origins, he too had thus caved when it came to the contemplation of the human fossil record.

What Huxley’s motives may have been in this, it is hard to judge. But I am pretty sure that Jeffrey Schwartz ( 2006 ) was correct to suggest that, if Huxley had been writing in Man’s Place in Nature about any other mammal than a hominid, he would have reached a very different conclusion. Almost certainly, he would have discerned one of Nature’s jumps between the Neanderthaler and the avowedly “higher” type from Engis. As it was, however, Huxley elected to reject the idea that the Feldhofer Neanderthal specimen had belonged to “a human being intermediate between men and apes” in favor of viewing it as a member of Homo sapiens , via an extension into the past of the widely assumed “racial hierarchy” that expressed itself in terms not only of morphology, but of technology, society, and presumed intelligence. In a very real sense, then, it is to Huxley that we can trace the exceptionalism that has dogged paleoanthropology ever since.

Historically, however, the significance of Huxley’s contribution goes beyond this. For by employing anti-Darwinian reasoning in support of the conclusion that the Feldhofer fossil was merely a brutish Homo sapiens , Huxley had provided Darwin with just the excuse he needed not to broach the fossil evidence seriously in The Descent of Man . Darwin could brush the crucial Neanderthal fossil off in passing because Huxley, in however non-Darwinian a spirit and however much in contradiction of his own principles, had given him license to.

There were, then, many reasons why Darwin should have been disposed in The Descent of Man to shrink from any substantive discussion of whether extinct human relatives might actually be represented in fossil form. The fossil and antiquarian records were awash with fakes; any discussion of human ancestry was rife with social and political pitfalls; and anyway, by his own close colleague’s testimony, the record contained nothing that could have any relevance to ancient and now-extinct human precursors. Add to that Darwin’s innate suspicion of the distorting effects of incompleteness in the fossil record, and he may have felt that a large degree of discretion on the matter was mandatory.

None of this means, of course, that The Descent of Man has not exerted an immense influence on the sciences of human origins over the last century and a half. Just as it is easy for English speakers to forget how much they owe to William Shakespeare for the language they use daily, we tend to lose sight of the fact that much received wisdom in paleoanthropology has come down to us direct from Darwin. Darwin it was who proposed a mechanism for the structural continuity of human beings with the rest of the living world and who gave a detailed argument for human descent from an “ape-like progenitor” (1871, i, p. 59). It was Darwin who documented beyond doubt, in The Descent of Man , that all living humans belong to a unitary species with a single origin—which we now know, on the basis of evidence of which Darwin could never have dreamed, to have been around 200,000 years ago.

He also had the inspired hunch that our species originated in the continent of Africa—and again, this guess has been amply substantiated by later science. Darwin’s perceptions on the behaviors of other primates and how they relate to the way humans behave were remarkably astute, particularly given the highly anecdotal nature of what was then known.

And, for better or for worse, a single comment in The Origin is proclaimed as founding Scripture by practitioners of today’s evolutionary psychology industry:

“In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history” (Darwin, 1859 , p. 488; emphasis added).

Virtually every section in the first part of the Descent of Man foreshadows an area of anthropology or biology that has independently flowered since; and in this way, Darwin wrote much of the agenda that was to be followed by paleoanthropology and primatology over the next century and a half.

I just wish I knew what he really thought about the Neanderthal fossil!

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Acknowledgments

I would like to thank Niles Eldredge for inviting me to contribute this piece and Richard Milner for the valuable discussion.

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Tattersall, I. Charles Darwin and Human Evolution. Evo Edu Outreach 2 , 28–34 (2009). https://doi.org/10.1007/s12052-008-0098-8

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• Charles Darwin

Charles Darwin did not formally publish on the topic of evolution until 1858, when excerpts from an essay he had privately written in 1844 and a portion of a letter to the American botanist Asa Gray were published along with Alfred Russel Wallace's formal manuscript on the mechanism of natural selection (click  here  to read all three pieces) in the  J ournal of the Linnean Society of London , Zoology . Nevertheless, Darwin wrote extensively about evolution in his private notebooks beginning shortly after his return from the voyage of the Beagle in 1836. In 1842, he we wrote his first formal essay on evolution and this was expanded in 1844. These two essays were first published in 1909 (click  here  to read). Between 1855 and 1858, Darwin worked on what became known as his "Big Species Book" which was subsequently abandoned when he learned that Alfred Russel Wallace had independently elucidated the principle of natural selection and there was a need for expeditious publication of his views. What came next, was the remarkable flurry of writing activity that resulted in  On the Origin of Species , published in November of 1859 (click  here  to read).

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Charles Darwin's Papers Online

For decades available only to scholars at Cambridge University Library, the private papers of Charles Darwin, one of the most influential scientists in history, can now be seen by anyone online and free of charge. This is the largest ever publication of Darwin papers and manuscripts, totalling about 20,000 items in over 100,000 electronic images.

This vast and varied collection of papers includes the first draft of his theory of evolution, notes from the voyage of the Beagle and Emma Darwin's recipe book .

We are extremely grateful for the kind permission of Cambridge University Library to reproduce these online. (See the Cambridge University Library Order Form for Digital Images .) They are presented in the same sequence as the original catalogue, which was divided mostly into bound volumes, each with a library classmark.

History of the material: The Darwin family and the Pilgrim Trust presented a magnificent collection of Darwin's papers to Cambridge University Library in 1942; they were delivered after the war. As the 1960 Handlist describes:

They were in parcels each containing small packets of manuscript wrapped in tissue paper on which the subjects had been noted in Darwin's hand. They were presumably just as Darwin left them, and accordingly this arrangement was preserved when they were bound, the volumes now representing as closely as possible Charles Darwin's papers in the order in which he left them. Beside the original papers there were copies of a large number of letters to Darwin, collections of press-cuttings, etc.

The immense value of this vast collection of material far exceeds the disadvantages of the occasional unreadable image and the lack of full colour. Several million pounds and years of production would be needed to produce colour digital images of the Darwin Archive. Hopefully this will eventually be achieved. In the meantime, most of the world's finest collection of Darwin's original manuscripts is now available for all to read, study and explore online and free of charge.

For an overview of Darwin's papers click here .

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1. Browse through whole volumes of Darwin's papers . Click here . 2. Search the catalogue for specific items, people, dates etc . Click here .

Darwin's first recorded doubt in 'the stability of species', from his Galapagos bird notes from the voyage of the Beagle , 1836 First sketch of the theory of evolution, 1842     Theoretical notebooks.     Drafts of Descent of Man Review of Origin of Species , 1859 Emma Darwin's recipe book. Darwin family photos

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•  The first drafts of Darwin's theory of evolution: the 1842 sketch and 1844 essay. •   Darwin's papers from the Beagle voyage. Click here . •   Darwin's religious views: Emma Darwin's 1839 memo , and an entire volume on the subject. Click here . •   Drafts of Darwin's unpublished 'big book', Natural selection. Click here . •   Notes & drafts for his book Descent of Man . Click here . •   Unpublished photos collected for Expression of the Emotions . Click here . •   Reviews of Darwin's works. Click here . •   Darwin and experimentation on animals. Click here . •   Caricatures, cartoons & sketches of Darwin. Click here and here . •   Darwin's accounts with his publisher John Murray for 1881. Click here . •   Obituaries of Charles Darwin, Click here , here and here . •   Items in French , German , Spanish or Italian .

See a list of all available online images of Darwin's papers. Click here .

See Darwin's handwriting beside a typed version:

[ Beagle animal notes (1832-33)]. Text & images 'Chiloe Jan r . 1835' [ Beagle notes]. Text & images 'The position of the bones of Mastodon (?) at Port St Julian is of interest'. Text & images [Darwin's personal 'Journal' (1809-1881)]. Text & images [An autobiographical fragment] (08.1838). Text & images 'Our poor child, Annie' [Darwin's reminiscence of Anne Elizabeth Darwin] (30.04.1851). Text & images Part of Darwin's 'autobiography', 1876

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Read about the reception of the launch of Darwin's papers here .

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8 People Who Influenced and Inspired Charles Darwin

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Charles Darwin may be known for his originality and genius, but he was influenced heavily by many people throughout his life. Some were personal collaborators, some were influential geologists or economists, and one was even his very own grandfather. Together, their influence helped Darwin develop his theory of evolution and his ideas about natural selection.

Jean Baptiste Lamarck

Jean Baptiste Lamarck was a botanist and zoologist who was one of the first to propose that humans evolved from a lower species through adaptations over time. His work inspired Darwin's ideas of natural selection.

Lamarck also came up with an explanation for vestigial structures. His evolutionary theory was rooted in the idea that life started out very simple and developed over time into the complex human form. Adaptations occurred as new structures that would spontaneously appear, and if they weren't used they would shrivel up and go away.

• Thomas Malthus

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Thomas Malthus was arguably the person who was most influential to Darwin. Even though Malthus was not a scientist, he was an economist and understood populations and how they grow. Darwin was fascinated by the idea that the human population was growing faster than food production could sustain. This would lead to many deaths from starvation, Malthus believed, and force the population to eventually level out.

Darwin applied these ideas to populations of all species and came up with the idea of "survival of the fittest". Malthus's ideas seemed to support all of the studying Darwin had done on the Galapagos finches and their beak adaptations. Only individuals that had favorable adaptations would survive long enough to pass down those traits to their offspring. This is the cornerstone of natural selection.

Comte de Buffon

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Georges Louis Leclerc Comte de Buffon was first and foremost a mathematician who helped invent calculus. While most of his works focused on statistics and probability, he did influence Charles Darwin with his thoughts on how life on Earth originated and changed over time. He was also the first to assert that biogeography was evidence for evolution.

Throughout his travels, Comte de Buffon noticed that even though geographic areas were nearly the same, each place had unique wildlife that was similar to wildlife in other areas. He hypothesized that they were all related in some way and that their environments were what made them change.

Once again, these ideas were used by Darwin to help come up with the idea of natural selection. It was very similar to the evidence he found when traveling on the HMS Beagle collecting his specimens and studying nature. The Comte de Buffon's writings were used as evidence for Darwin while he wrote about his findings and presented them to other scientists and the public.

Alfred Russel Wallace

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Alfred Russel Wallace did not exactly influence Charles Darwin, but rather was his contemporary and collaborated with Darwin on the theory of evolution. In fact, Wallace actually came up with the idea of natural selection independently, but at the same time as Darwin. The two pooled their data to present the idea jointly to the Linnaean Society of London.

It wasn't until after this joint venture that Darwin went ahead and published the ideas in his book "The Origin of Species." Even though both men contributed equally, Darwin gets most of the credit today. Wallace has been relegated to a footnote in the history of the theory of evolution.

Erasmus Darwin

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Many times, the most influential people in life are found within the bloodline. This is the case for Charles Darwin. His grandfather, Erasmus Darwin, was a very early influence on him. Erasmus had his own thoughts about how species changed over time that he shared with his grandson. Instead of publishing his ideas in a traditional book, Erasmus originally put his thoughts about evolution into poetry form. This kept his contemporaries from attacking his ideas for the most part. Eventually, he did publish a book about how adaptations result in speciation. These ideas, passed down to his grandson, helped shape Charles's views on evolution and natural selection.

Charles Lyell

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Charles Lyell was one of the most influential geologists in history. His theory of uniformitarianism was a great influence on Charles Darwin. Lyell theorized that geologic processes that were around at the beginning of time were the same ones that were happening in the present as well and that they worked the same way.

Lyell believed the Earth developed through a series of slow changes that built up over time. Darwin thought this was the way that life on Earth also changed. He theorized that small adaptations accumulated over long periods of time to change a species and give it more favorable adaptations for natural selection to work on.

Lyell was actually a good friend of Captain Robert FitzRoy who piloted the HMS Beagle when Darwin sailed to the Galapagos Islands and South America. FitzRoy introduced Darwin to Lyell's ideas and Darwin studied the geological theories as they sailed.

James Hutton

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James Hutton  was another very famous geologist who influenced Charles Darwin. In fact, many of Charles Lyell's ideas were actually first put forth by Hutton. Hutton was the first to publish the idea that the same processes that formed the Earth at the very beginning of time were the same that were happening in the present day. These "ancient" processes changed the Earth, but the mechanism never changed.

Even though Darwin saw these ideas for the first time while reading Lyell's book, it was Hutton's ideas that indirectly influenced Charles Darwin as he came up with the idea of natural selection. Darwin said the mechanism for change over time within species was natural selection and it was this mechanism that had been working on species ever since the first species appeared on Earth.

Georges Cuvier

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While it is odd to think that a person who rejected the idea of evolution would be an influence on Darwin, that was exactly the case for Georges Cuvier . He was a very religious man during his life and sided with the Church against the idea of evolution. However, he inadvertently laid some of the groundwork for Darwin's idea of natural selection.

Cuvier was the most vocal opponent of Jean Baptiste Lamarck during their time in history. Cuvier realized there was no way to have a linear system of classification that put all species on a spectrum from very simple to the most complex humans. In fact, Cuvier proposed that new species formed after catastrophic floods wiped out other species. While the scientific community did not accept these ideas, they were very well received in religious circles. His idea that there was more than one lineage for species helped shape Darwin's views of natural selection.

• What Is Evolution?
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Home — Essay Samples — Science — Evolution — Natural Selection in Littorina Littorea: A Darwinian Perspective

Natural Selection in Littorina Littorea: a Darwinian Perspective

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Genetic variation: the raw material of evolution, environmental pressures and adaptations, the role of predation, implications and future directions.

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