A continuation of Charles Darwin’s earlier On the Origin of Species, The Descent of Man argued that humans evolved from lower animals and that all of the features typically used to distinguish humans from animals originated through natural evolutionary processes. The work provided an impetus to the growth of materialist analyses of humanity and of scientific investigations into the origins of human nature.

Charles Darwin’s On the Origin of Species (Darwin)
Darwin, Charles
[p]Darwin, Charles;On the Origin of Species
On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for Life (1859; commonly known as On the Origin of Species) postulated that all life on Earth evolved from a common ancestor by means of natural selection Darwin, Charles
[p]Darwin, Charles;on natural selection[Natural selection] . This theory provoked a flood of controversy because it implied that humanity also arose from lower animals by purely naturalistic mechanisms, rather than through supernatural means. Even though Darwin scrupulously avoided the question of human origins in that book, the issue of human evolution generated most of the controversy over his theory. Darwin was nevertheless eager to apply his theory to humans. From 1859 to 1871, he gathered valuable information by corresponding with scientists around the world and conducting his own experiments. What he learned during this time provided material for The Descent of Man and Selection in Relation to Sex (1871; commonly known as The Descent of Man). Darwin, Charles
[p]Darwin, Charles;The Descent of Man[Descent of Man]
Descent of Man, The (Darwin)
Evolution;and Charles Darwin[Darwin]
[kw]Darwin Publishes The Descent of Man (1871)
[kw]Publishes The Descent of Man, Darwin (1871)
[kw]Descent of Man, Darwin Publishes The (1871)
[kw]Man, Darwin Publishes The Descent of (1871)
Darwin, Charles
[p]Darwin, Charles;The Descent of Man[Descent of Man]
Descent of Man, The (Darwin)
Evolution;and Charles Darwin[Darwin]
[g]Great Britain;1871: Darwin Publishes The Descent of Man[4470]
[c]Biology;1871: Darwin Publishes The Descent of Man[4470]
[c]Science and technology;1871: Darwin Publishes The Descent of Man[4470]
Huxley, Thomas Henry
Lubbock, John
Tylor, Edward B.
Lyell, Sir Charles
Haeckel, Ernst

The Descent of Man begins by asserting that there are no fundamental qualitative differences between the anatomies and development of humans and higher mammals. Comparative anatomical work on humans and nonhuman primates by Thomas Henry Huxley, Huxley, Thomas Henry Darwin’s friend and most loyal defender, tended to support a common ancestry for these two groups. Darwin depended on Huxley’s Evidence as to Man’s Place in Nature
Evidence as to Man’s Place in Nature (Huxley) (1863) for the first section of his own book. He also used Huxley’s Huxley, Thomas Henry extensive anatomical data to show that there are no distinctly human structures and to argue that humans are even more closely related to apes than apes are to monkeys. This assertion shrank the physical gulf between humans and nonhuman primates. Darwin also argued that human populations possessed great variability and that natural selection could operate upon these differences.

Charles Darwin.

(Courtesy of University of Texas at Austin)

In his book’s next few chapters, Darwin argues that human mental capacities differ only in degree, not in essence, from those of animals. He provides several admittedly anthropomorphic anecdotal examples from animal behavior to support this claim. He believed that the origin and development of characteristics thought to distinguish humans from the animals, such as religion, language, and morality, can be reasonably explained by evolutionary mechanisms. Some found Darwin’s line of argumentation convincing because by the late 1850’s, many people were beginning to believe that humanity was more ancient than previously presumed. To establish the ancient age of humanity firmly, Darwin relied upon the research of three English scientists: archaeologist John Lubbock Lubbock, John , anthropologist Edward B. Tylor Tylor, Edward B. , and geologist Sir Charles Lyell Lyell, Sir Charles .

Another friend and defender of Darwin, Lubbock subdivided the Stone Age into the Neolithic and Paleolithic periods, based on progressive improvements in toolmaking, with the oldest remains of human activity displaying the most primitive levels of technology. Darwin also corresponded regularly with Edward Tylor, whose anthropological Anthropology;and evolution[Evolution] studies suggested that cultural differences between Europeans and non-European societies were well explained by an evolutionary model of inheritance, diffusion, and independent innovation. Drawing on Tylor’s work, Tylor, Edward B. Darwin hypothesized that religious belief in humans originated from a primitive need to find a cause for things that evade simple explanation.

Yet another friend and sometime defender of Darwin, Charles Lyell Lyell, Sir Charles , the author of The Geological Evidences of the Antiquity of Man with Remarks on the Theories of the Origin of Species by Variation (1863), cataloged, in great detail and with tremendous clarity for any educated Victorian, the accumulated evidence for the antiquity of humankind. His book was the first work after On the Origin of Species to cause a reevaluation of what it meant to be human. All these discoveries made degenerationism—the popular belief of the time that human culture had originated at a relatively high level of social organization and sophistication, after which some cultures degenerated to simpler states while others advanced to more complex states—untenable. They also made evolutionary accounts of the rise of modern humans from more primitive ones seem much more plausible.

In the matter of language, Darwin referenced the evolutionary genealogy of Indo-European languages constructed by August Schleicher. Schleicher’s analyses intimated that all modern languages had evolved from earlier ones. Darwin postulated that human language originated from social sounds—similar to those produced by apes—that gradually developed when primitive humans began to imitate natural sounds. To explain the origin of morality, Darwin argued that right and wrong are relative and are learned by children when they are young, and that there is no innate sense of morality in humans. He used many examples from so-called uncivilized peoples and their practices to corroborate his claims.

Darwin was unsure of the identity of the actual biological Fossils;human ancestor of humanity, as he knew almost nothing about fossil primates. He suspected that the Old World monkeys gave rise to humans, but he had little evidence other than anatomical similarities to support that contention. He referred to the embryological work of Ernst Haeckel Haeckel, Ernst , the most enthusiastic promoter of Darwinism in Germany, to unite the evolutionary ancestors of primates with those of marsupials, monotremes (egg-laying mammals such as the duckbill platypus), reptiles, amphibians, and fishes. Darwin suggested that the ancestor of the vertebrates was the lowly tunicate (ascidian), whose larval stage possesses a notochord, the dorsally located cartilage rod, found in the embryos of all vertebrates, that serves as the embryological precursor to the backbone that is lost upon metamorphosis to the adult form in tunicates.

Darwin also devoted the latter part of The Descent of Man to the concept of sexual selection. Original to Darwin, sexual selection postulates that the evolution of particular traits is driven by competition for mates between individuals of the same sex. Darwin theorized that human beings, like the animals, possess a variety of superfluous traits that exist because they aid reproductive success. With sexual selection, Darwin attempted to explain most of the geographical and behavioral distinctions among human societies. He saw differences in physical appearance, such as skin color, hair texture, and body size, and divergent behavioral traits, such as bravery, social cohesion, maternal feelings, work ethic, obedience, and altruism, as explainable by means of applying sexual selection to humans. Like most Europeans of his day, Darwin believed that men were intellectually superior to women and that European society, whose set the evolutionary direction for humanity, was the most advanced kind of society.

By the time of Darwin’s death in 1882, his theory of common descent, which included humans, enjoyed almost universal acceptance among scientists. However, natural selection Darwin, Charles
[p]Darwin, Charles;on natural selection[Natural selection] , his proposed mechanism of evolutionary change, was heavily disputed and widely disbelieved. In 1891, Dutch anthropologist Anthropology;physical Eugene Dubois discovered a skull cap near Trinil, in central Java. This fossil seemed to belong to a species possessing anatomical features that were intermediate between those of apes and modern humans and was named Pithecanthropus erectus by Dubois. Its modern designation is Homo erectus, and it is commonly known as Java Man. Although disputed at first, Dubois’s find was eventually viewed as vindicating Darwin’s theories and initiated other efforts to find fossil human ancestors.

The Descent of Man deals with questions regarding humanity’s origins that had never been asked before Darwin’s time. In this regard, the book was truly pioneering, even if some of its arguments were less than convincing. Darwin’s book also spurred scientific investigation into the origin of humanity, particularly in areas that were formerly thought to be outside the purview of science. Biological investigations of human reasoning, consciousness, and moral motivations had their inauguration with The Descent of Man. Darwin’s ideas also generated great controversy, since many people were appalled by the thought that they had descended from apelike creatures. In the United States, this controversy culminated in the 1925 Scopes “Monkey” Trial. The application of Darwin’s theories to other fields, such as the social sciences and humanities, stimulated new avenues of research but also dehumanized them to some extent, which caused much of the controversy that surrounds Darwin’s theories—a controversy that rages in the twenty-first century and shows no signs of abating.

• Adler, Jerry. “Charles Darwin: Evolution of a Scientist.” Newsweek, November 29, 2005, 50-58. Well-illustrated examination of Darwin’s personal struggle to reconcile his developing theories on evolution with his Christian beliefs, with attention to modern challenges to Darwinism.
• Bowler, Peter J. Charles Darwin: The Man and His Influence. Cambridge, England: Cambridge University Press, 1996. Brief but important biography of Charles Darwin that focuses on the lasting influence of his ideas.
• Browne, Janet. Charles Darwin: The Power of Place. New York: Alfred A. Knopf, 2002. Authoritative and exhaustive biography of the later years of the life of Charles Darwin by a distinguished Darwin scholar.
• Darwin, Charles. From So Simple a Beginning: The Four Great Books of Charles Darwin. Edited by Edward O. Wilson. New York: W. W. Norton, 2006. First one-volume edition of Darwin’s most important books. Includes an introductory essay by Pulitzer Prize-winning author Edward O. Wilson, who also contributes a new introduction for each book and an afterword discussing evolutionary theory in the context of modern religious conservatism. Other features include a comprehensive index, reproductions of the original illustrations in Darwin’s books, and a map.
• Desmond, Adrian. Huxley: From Devil’s Disciple to Evolution’s High Priest. Reading, Mass.: Perseus Books, 1997. Nearly definitive biography of Thomas Henry Huxley and his role in the human origins debates.
• Hodge, Jonathan, and Gregory Radick, eds. The Cambridge Companion to Darwin. New York: Cambridge University Press, 2003. Collection of original essays that examine Darwin’s major theories, the development of his thinking, and how his thought has influenced philosophical, religious, and social debate.
• Ruse, Michael. The Darwinian Revolution: Science Red in Tooth and Claw. 2d ed. Chicago: University of Chicago Press, 1999. Lively description and analysis of the scientific history of the inception of biological evolution.

Lamarck Publishes Zoological Philosophy

Lyell Publishes Principles of Geology

Clausius Formulates the Second Law of Thermodynamics

Wallace’s Expeditions Give Rise to Biogeography

Neanderthal Skull Is Found in Germany

Darwin Publishes On the Origin of Species

Archaeopteryx Lithographica Is Discovered

Spencer Introduces Principles of Social Darwinism

Mendel Proposes Laws of Heredity

Lartet Discovers the First Cro-Magnon Remains

Rediscovery of Mendel’s Hereditary Theory

Charles Darwin; Ernst Haeckel; Thomas Henry Huxley. Darwin, Charles
[p]Darwin, Charles;The Descent of Man[Descent of Man]
Descent of Man, The (Darwin)
Evolution;and Charles Darwin[Darwin]