On the publication of ‘The Descent of Man’ 150 years ago

«I have given the evidence to the best of my ability; and we must acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system—with all these exalted powers—Man still bears in his bodily frame the indelible stamp of his lowly origin.»

(Charles Darwin, The Descent of Man, and Selection in Relation to Sex)

2021 marks 150 years since the publication of Charles Darwin’s (1809-1882) The Descent of Man, and Selection in Relation to Sex. The first edition of this work appeared in 1871, when Darwin was 62 years old, and 12 years after the publication of On the Origin of Species. Many years before, in a letter dated 22nd December 1857, Darwin explains to Alfred Russel Wallace that he will avoid touching on the subject of the origin of our species in the work which would become On the Origin of Species «as so surrounded with prejudices», although he accepted that it «is the highest & most interesting problem for the naturalist».

Darwin published his Origin of Species in 1859, and, effectively, the work does not touch on this subject. Following this publication, Darwin wrote about pollination by insects, climbing plants, and the domestication of animals and plants. Janet Browne’s biography of Darwin believes that the publication over those years of several works by prestigious colleagues finally encouraged Darwin to tackle the subject of our origins, overcoming his misgivings about the controversy and confrontation this delicate subject might bring about in Victorian society. In 1863 Charles Lyell had published Antiquity of Man, a work in which he assigned geological time to our evolutionary history. The same year, Thomas Henry Huxley (Darwin’s bulldog) published Evidence as to Man’s Place in Nature, a short and extraordinary work in which he showed the anatomical proximity of our species to the primates which we now consider to be our closest relatives, chimpanzees, gorillas, and orang-utans. The following year Wallace published The Origin of Human Races and the Antiquity of Man Deduced from the Theory of “Natural Selection”, where he argued that the mechanism for natural selection also allowed us to explain the emergence of our species from primate ancestors, and which Darwin praised in a letter sent to him in May 1864, in which he admitted that he had hardly touched on the subject, but had drawn up some notes which he put at his friend’s disposal.

Darwin finally began this task in early 1868, recovering reflections he had accumulated over three decades, since his voyage on the Beagle, between 1831 and 1836. While Darwin worked on his manuscript, Wallace published in 1869 a review of the new editions of Lyell’s works called Sir Charles Lyell on geological climates and the origin of species. At the end of his article, Wallace expresses for the first time the idea that natural selection cannot explain the development of the distinctive cognitive faculties of our species —language or our maximum intelligence— and defers to a supernatural power for their appearance, «a Power which has guided the action of those laws [of organic development] in definite directions and for special ends». Wallace’s theological and idealist regression (which he would set out expressly in his Darwinism of 1889) was an unexpected blow for Darwin. After reading the review, in a letter dated 14 April Darwin writes to Wallace that he does not recognise him as the author of such a text:  

«As you expected I differ grievously from you, & I am very sorry for it. I can see no necessity for calling in an additional & proximate cause in regard to Man.»

Despite such a profound discrepancy, their Today, reading The Descent of Man continues to surprise us with the prescience Darwin shows when he anticipates what we now know about human evolution. and mutual recognition lasted until Darwin’s death. Wallace was the most quoted writer in The Descent of Man.

Given the length of his work, Darwin had to publish it in two separate books. 1871 saw the publication of the two beautifully illustrated volumes of The Descent of Man, and Selection in Relation to Sex, the second of which is dedicated to sexual selection to which Darwin attributes population differences in our species (such as —wrongly— skin pigmentation) as well as cognitive and social skills. The following year he published On the Expression of the Emotions in Man and Animals, a work in which he pioneeringly uses photographs to support his idea of the universal character of human emotions. Both books sold well and were the first to give Darwin financial profits. Darwin asserted that the qualities highlighted by the critics in the Descent of Man —his vigorous style, his clarity— were thanks to the suggestions made by his daughter Henrietta, Etty (1843-1927). Henrietta Darwin not only helped her father with the editing of the manuscript but was also his closest interlocutor, his intellectual confidante for the preparation of the texts.

Both works follow Darwin’s intention of showing that, like any other living being, we human beings are the product of biological evolution and that even those characteristics which we consider distinctive for our species gradually developed from qualities already sketched out in our primate ancestors: our differences are «of degree, not of class», Darwin asserts. Darwin thus considers whether the origin of human morality is based on the evolution of the social instincts of our ancestor species, this bold idea then inspiring Piotr Kropotkin (1842-1921) to propose intra-species cooperation («mutual aid») as an additional mechanism of biological evolution which he formulated during his exile in Britain as from 1886. 

Some passages from these two works may shock our anti-colonial or feminist commitment (as happened when they were published), but as a whole, they still keep the powerful force of Darwin’s radical determination to dismantle —in a discreet and reasonable way, in his own style— anthropocentric or theological creationism. They are also a passionate assertion of the universality of the human condition and of our intimate link to all other living things, which he puts on an equal footing with our species, like the branches of the coral in his earlier evolutionary scheme of 1837. 

Today, reading The Descent of Man, and Selection in Relation to Sex continues to surprise us with the prescience Darwin shows when he anticipates what we now know about human evolution. continues to surprise us with the prescience Darwin shows when he anticipates what we now know about human evolution. With hardly any human fossil evidence (Darwin had, a few years before, examined the Neanderthal skull discovered in Forbes’s Quarry in Gibraltar, though he does not mention it), but thanks to his powerful deductive capability and his intellectual courage, Darwin describes our primate ancestors, identifies the probable location of our origin, establishes the sequence of our evolutionary history and highlights the biocultural relevance of using tools. Darwin argues that what made us human was becoming bipedal and that our portentous intelligence is only a later, derived consequence of our change in locomotion. This was a definite depth charge launched against our anthropocentric pride which the scientific community was loath to accept for 80 years until the definitive denunciation of the Piltdown hoax. 

Darwin shows how the visionary strength of Science lies in its ability to knock down our assumptions and prejudices, revealing new horizons. This happened once again 150 years ago with The Descent of Man.

Carlos Varea is a biological anthropologist, member of the Biology Department at the Universidad Autónoma de Madrid (Spain), president of the Association for the Study of Human Ecology, and co-director of the Virtual Museum of Human Ecology.