The Descent of Man, and Selection in Relation to Sex
The Descent of Man, and Selection in Relation to Sex is a book by English naturalist Charles Darwin, first published in 1871, which applies evolutionary theory to human evolution, and details his theory of sexual selection, a form of biological adaptation distinct from, yet interconnected with, natural selection. Darwin used the word "descent" to mean lineal descendant of ancestors. The book discusses many related issues, including evolutionary psychology, evolutionary ethics, evolutionary musicology, differences between human races, differences between sexes, the dominant role of women in mate choice, and the relevance of the evolutionary theory to society.
Publication
As Darwin wrote, he sent chapters to his daughter Henrietta for editing to ensure that damaging inferences could not be drawn, and also took advice from his wife Emma. The zoological illustrator T. W. Wood,, drew many of the figures in this book. The corrected proofs were sent off on 15 January 1871 to the publisher John Murray and published on 24 February 1871 as two 450-page volumes, which Darwin insisted was one complete, coherent work, and were priced at £1/4/–.Within three weeks of publication a reprint had been ordered, and 4,500 copies were in print by the end of March 1871, netting Darwin almost £1,500. Darwin's name created demand for the book, but the ideas were old news. "Everybody is talking about it without being shocked," which he found "proof of the increasing liberality of England".
Editions and reprints
Darwin and some of his children edited many of the large number of revised editions, some extensively. In late 1873, Darwin tackled a new edition of the Descent of Man. Initially, he offered Wallace the work of assisting him, but, when Emma found out, she had the task given to their son George, so Darwin had to write apologetically to Wallace. Huxley assisted with an update on ape-brain inheritance, which Huxley thought "pounds the enemy into a jelly... though none but anatomists" would know it. The manuscript was completed in April 1874 and published on 13 November that year. This has been the edition most commonly reprinted after Darwin's death and to the present day.Content
Part I: The evolution of man
Evolution of physical traits
In the introduction to Descent, Darwin lays out the purpose of his text:Darwin's approach to arguing for the evolution of human beings is to outline how similar human beings are to other animals. He begins by using anatomical similarities, focusing on body structure, embryology, and "rudimentary organs" that presumably were useful in one of man's "pre-existing" forms. He then moves on to argue for the similarity of mental characteristics.
Evolution of mental traits
Based on the work of his cousin, Francis Galton, Darwin asserts that human character traits and mental characteristics are inherited in the same way as physical characteristics, and argues against the mind/body distinction for the purposes of evolutionary theory. From this Darwin then provides evidence for similar mental powers and characteristics in certain animals, focusing especially on apes, monkeys, and dogs for his analogies for love, cleverness, religion, kindness, and altruism. He concludes on this point that "Nevertheless the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind." He additionally turns to the behaviour of "savages" to show how many aspects of Victorian England's society can be seen in more primitive forms.In particular, Darwin argues that even moral and social instincts are evolved, comparing religion in man to fetishism in "savages" and his dog's inability to tell whether a wind-blown parasol was alive or not. Darwin also argues that all civilisations had risen out of barbarism, and that he did not think that barbarism is a "fall from grace" as many commentators of his time had asserted.
File:Olive baboon1.jpg|right|thumb|Darwin's primary rhetorical strategy was to argue by analogy. Baboons, dogs, and "savages" provided his chief evidence for human evolution.
Natural selection and civilised society
In this section of the book, Darwin also turns to the questions of what after his death would be known as social Darwinism and eugenics. Darwin notes that, as had been discussed by Alfred Russel Wallace and Galton, natural selection seemed to no longer act upon civilised communities in the way it did upon other animals:Darwin felt that these urges towards helping the "weak members" was part of our evolved instinct of sympathy, and concluded that "nor could we check our sympathy, even at the urging of hard reason, without deterioration in the noblest part of our nature". As such, '"we must therefore bear the undoubtedly bad effects of the weak surviving and propagating their kind". Darwin did feel that the "savage races" of man would be subverted by the "civilised races" at some point in the near future, as stated in the human races section below. He did show a certain disdain for "savages", professing that he felt more akin to certain altruistic tendencies in monkeys than he did to "a savage who delights to torture his enemies". However, Darwin is not advocating genocide, but clinically predicting, by analogy to the ways that "more fit" varieties in a species displace other varieties, the likelihood that indigenous peoples will eventually die out from their contact with "civilization", or become absorbed into it completely.
His political opinions were strongly inclined against the coercive, authoritarian forms of eugenics that became so prominent in the 20th century. Note that even Galton's ideas about eugenics were not the compulsory sterilisation which became part of eugenics in the United States, or the later genocidal programs of Nazi Germany, but rather further education on the genetic aspects of reproduction, encouraging couples to make better choices for their wellbeing.
For each tendency of society to produce negative selections, Darwin also saw the possibility of society to itself check these problems, but also noted that with his theory "progress is no invariable rule." Towards the end of Descent of Man, Darwin said that he believed man would "sink into indolence" if severe struggle was not continuous, and thought that "there should be open competition for all men; and the most able should not be prevented by laws or customs from succeeding best and rearing the largest number of offspring", but also noted that he thought that the moral qualities of man were advanced much more by habit, reason, learning, and religion than by natural selection. The question plagued him until the end of his life, and he never concluded fully one way or the other about it.
On the Races of Man
In the first chapters of the book, Darwin argued that there is no fundamental gap between humans and other animals in intellectual and moral faculties as well as anatomy. Retreating from his egalitarian ideas of the 1830s, he ranked life on a hierarchic scale which he extended to human races on the basis of anthropology published since 1860: human prehistory outlined by John Lubbock and Edward Burnett Tylor combined archaeology and studies of modern indigenous peoples to show progressive evolution from Stone Age to steam age; the human mind as the same in all cultures but with modern "primitive" peoples giving insight into prehistoric ways of life. Darwin did not support their view that progress was inevitable, but he shared their belief in human unity and held the common attitude that male European liberalism and civilisation had progressed further in morality and intellect than "savage" peoples.He attributed the "great break in the organic chain between man and his nearest allies" to extinction, and as spreading civilisation wiped out wildlife and native human cultures, the gap would widen to somewhere "between man in a more civilised state, as we may hope, than the Caucasian, and some ape as low as a baboon, instead of as at present between the negro or Australian and the gorilla." While there "can be no doubt that the difference between the mind of the lowest man and that of the highest animal is immense", the "difference in mind between man and the higher animals, great as it is, is certainly one of degree and not of kind." At the same time, all human races had many mental similarities, and early artefacts showing shared culture were evidence of evolution through common descent from an ancestral species which was likely to have been fully human.
Introducing Chapter 7, Darwin wrote: "It is not my intention here to describe the several so-called races of men; but to inquire what is the value of the differences between them under a classificatory point of view, and how they have originated." In answering the question of whether the races should rank as varieties of the same species or count as different species, Darwin discussed arguments which could support the idea that human races were distinct species. This included the geographical distribution of mammal groups which was correlated with the distribution of human races, and the finding of Henry Denny that different species of lice affected different races differently.
Darwin then presented the stronger evidence that human races are all the same species, noting that when races mixed together, they intercrossed beyond the "usual test of specific distinctness" and that characteristics identifying races were highly variable. He put great weight on the point that races graduate into each other, writing "But the most weighty of all the arguments against treating the races of man as distinct species, is that they graduate into each other, independently in many cases, as far as we can judge, of their having intercrossed", and concluded that the stronger evidence was that they were not different species.
This conclusion on human unity was supported by monogenism, including John Bachman's evidence that intercrossed human races were fully fertile. Proponents of polygenism opposed unity, but the gradual transition from one race to another confused them when they tried to decide how many human races should count as species: Louis Agassiz said eight, but Morton said twenty-two. Darwin commented that the "question whether mankind consists of one or several species has of late years been much agitated by anthropologists, who are divided into two schools of monogenists and polygenists." The latter had to "look at species either as separate creations or as in some manner distinct entities" but those accepting evolution "will feel no doubt that all the races of man are descended from a single primitive stock". Although races differed considerably, they also shared so many features "that it is extremely improbable that they should have been independently acquired by aboriginally distinct species or races." He drew on his memories of Jemmy Button and John Edmonstone to emphasise "the numerous points of mental similarity between the most distinct races of man. The American aborigines, Negroes and Europeans differ as much from each other in mind as any three races that can be named; yet I was incessantly struck, whilst living with the Fuegians on board the Beagle, with the many little traits of character, shewing how similar their minds were to ours; and so it was with a full-blooded negro with whom I happened once to be intimate." Darwin concluded that "when the principles of evolution are generally accepted, as they surely will be before long, the dispute between the monogenists and the polygenists will die a silent and unobserved death."
Darwin rejected both the idea that races had been separately created, and also the concept that races had evolved in parallel from separate ancestral species of apes. He reviewed possible explanations of divergence into racial differences such as adaptations to different climates and habitats, but found inadequate evidence to support them, and proposed that the most likely cause was sexual selection, a subject to which he devoted the greater part of the book, as described in the following section.