In 1871, Charles Darwin published Descent of Man and Selection in Relation to Sex, a text that extended, elaborated and completed his On the Origin of Species (1859). When he had published Origin, Darwin sought, albeit unsuccessfully, to skirt controversy; in Descent he waded into the fray on near-innumerable issues. Readers could find explicit the claim that humans had descended from apes, in addition to explorations of the similarities and apparent gulfs between ‘man’ and other animals. They also found Darwin's opinions on issues ranging from the origin and hierarchy of races to the question of women's education, from the source of altruistic bravery to the biological importance of aesthetic judgement, from his views on what his cousin would term ‘eugenics’ to the history of monogamy. In the last 150 years these ideas have been variously contested, rejected and recovered, so that the shadow of Descent extended into debates over the development of languages, the evolution of human sexualities, the ongoing possibilities of eugenics and the question of women's equality. In this volume, appearing during the sesquicentennial of the text's first appearance, one finds papers dedicated to all of these themes and more, laying out the roots and fruits of Darwin's Descent.

Charles Darwin's theory of sexual selection, as described in The Descent of Man, and Selection in Relation to Sex (1871), should be viewed as a significant transitional point in the modern expression of race. Unlike earlier race theorists, Darwin proposed that sexual reproduction was not merely a testing ground of racial character, but was itself a causal force that could create new races. His account of race was distinctly modern – viewing race not in terms of blood but as a collection of population-level characteristics. Recognizing this feature of Darwin's sexual-selection theory allows us to situate Darwin's work not solely within the history of evolutionary science, but also within the structures of racism that became the governing principles of modern nation states. In other words, sexual selection is an expression of Michel Foucault's biopolitics, in which political power is exercised by states not through the contracts of liberal governance but through the management of population-level phenomena. Furthermore, by contextualizing sexual selection in this theoretical framework, it becomes possible to more clearly emphasize the importance of race in the rise of modern biopolitics.

In the course of his discussion of the origin of variations in skin colour among humans in the Descent of Man, Charles Darwin suggested that darker skin might be correlated with immunity to certain diseases. To make that suggestion, he drew upon a claim that seemed self-evidently correct in 1871, although it had seemed almost certainly incorrect in the late eighteenth century: that immunity to disease could be understood as a hereditary racial trait. This paper aims to show how fundamental was the idea of ‘constitutions selection’, as Darwin would call it, for his thinking about human races, tracking his (ultimately unsuccessful) attempts to find proof of its operation over a period of more than thirty years. At the same time and more broadly, following Darwin's conceptual resources on this question helps explicate relationships between conceptions of disease and conceptions of race in the nineteenth century. That period saw the birth of a modern, fixist, biologically determinist racism, which increasingly manifested itself in medical writings. The reverse was also true: medicine was a crucial site in which race was forged. The history of what has been called ‘race-science’, it is argued, cannot and should not be written independent of the history of ‘race-medicine’.

This paper engages with a specific image: Darwin's tree of the primates. Although this diagram was sketched in ink on paper in 1868, it did not make it into the publication of The Descent of Man (1871). This may seem all the more in need of an explanation because, as Adrian Desmond and James Moore have shown, Darwin strongly relied on the notion of familial genealogy in the development of his theory of organismic evolution, or rather descent. However, Darwin expressed scepticism towards visualizations of phylogenies in correspondence with Ernst Haeckel and in fact also in Descent, considering such representations at once too speculative and too concrete. An abstraction such as a tree diagram left little room to ponder possibilities or demarcate hypotheses from evidence. I thus bring Darwin's primate tree into communication with his view on primate and human phylogeny as formulated in Descent, including his rejection of polygenism. I argue that considering the tree's inherent teleology, as well as its power to suggest species status of human populations and to reify ‘racial’ hierarchies, the absence of the diagram in The Descent of Man may be a significant statement.

The article explores the extent and nature of the relationship between Darwinian science and the British Empire. It does so by unpicking Darwin's British Indian examples of avian combat in constructing his ‘law of battle’. The article shows how Darwin's interpretation of these reports was simultaneously enabled, shaped and limited by the imperial context within which the reports were generated. Particularly important was Darwin's inability to see the enormous investment of human labour and complex knowledge in sculpting and curating these avian fights through a culture of shauq. Partly this oversight followed from the South Asian birds having already been saturated by Romantic poetic associations, even before Darwin began considering them. Somewhat surprisingly, I note, Clifford Geertz shared Darwin's blindness towards the ‘cultural’ sculpting of ‘nature’ during avian combat.

Charles Darwin never doubted the common ancestry of the human races. But he was open-minded about whether the races might nevertheless be so different from each other that they ought to be classified not as varieties of one species but as distinct species. He pondered this varieties-or-species question on and off for decades, from his time aboard the Beagle through to the publication of the Descent of Man. A constant throughout was his concern with something that he first learned on the Beagle voyage and that, on the face of it, seemed to favour the species ranking: the different races, he was told, play host to distinct species of lice. This paper reconstructs the long run of Darwin's reflections and interactions on race, lice and history, using his extended correspondence with Henry Denny – curator of the scientific collections of the Leeds Philosophical and Literary Society, and Britain's leading expert in the natural history of lice – as a window onto the social world whose imprint is everywhere in the pages of the Descent.

The origin of human language has been a perennial – and perennially controversial – topic in linguistics since the nineteenth century. Much of this work has engaged themes Charles Darwin set out in The Descent of Man, though few authors acknowledge the text directly. How might we interpret such neglect? This essay contends that Darwin's reflections on language challenged foundational commitments in linguistics about the barrier between the history and prehistory of human communication. These commitments are thrown into relief through a detailed study of the dissenting symbolic and gestural theory of language origin put forth by Mary LeCron Foster, who rejected doctrines of linguistic arbitrariness and transformational-generative grammar. Her work on the frontier between animal and human communication is presented through a description of her ‘phememic’ account of the language origins. The paper also emphasizes the rhythm of Foster's career, which provides a significant counterpoint to standard accounts of the development and institutionalization of American linguistics during the twentieth century.

Most studies of the American reception of Darwin have focused on the Origin. The Descent of Man, however, was even more widely read and discussed, especially by those outside the emerging scientific establishment. This essay maps the varied, popular and radical responses to the Descent and suggests that these unauthorized readers helped shape the formation of American scientific institutions (by encouraging scientists to close ranks), as well as ordinary Americans’ perceptions of gender and sex. I argue that the radical – freethinkers, socialists and feminists – embrace of sexual selection theory provides one explanation for naturalists’ scepticism of the theory.

Charles Darwin's Descent of Man was suffused with questions of courtship, mating and sex. Following in his footsteps, biologists throughout the twentieth century interrogated the sexual behaviour of humans and animals. This paper charts the fate of evolutionary theories of sexuality to argue that – despite legal and social gains of the past century – when biologists used sexual selection as a tool for theorizing the evolution of homosexual behaviour (which happened only rarely), the effect of their theories was to continuously reinscribe normative heterosexuality. If, at the end of the nineteenth century, certain sex theorists viewed homosexuality as a marker of intermediate sex, by the late twentieth a new generation of evolutionary theorists idealized gay men as hyper-masculine biological males whose sexual behaviours were uncompromised by the necessity of accommodating women's sexual preferences. In both cases, normative assumptions about gender were interwoven with those about sexuality. By the twenty-first century, animal exemplars were again mobilized alongside data gathered about human sexual practices in defence of gay rights, but this time by creating the opportunity for naturalization without recourse to biological determinism.

Although many read Charles Darwin's Origin of Species as an endorsement, rather than merely a description, of individualism and competition, in Descent of Man (1871) Darwin intended to show that natural selection could account for the most noble aspects of human morality and conscience. He did so in response to Alfred Russel Wallace's 1869 statement to the contrary. In doing so, Darwin appealed to the natural selection of groups rather than individuals, and to the maternal, parental and filial instincts, as the origin of truly other-regarding moral sentiments. Further, the inheritance of acquired characters and sexual selection had important implications for Darwin's understanding of how other-regarding ethics might prevail in an evolutionary framework that seemed to reward self-interest. In a short addendum to this essay I highlight just three of a number of Darwin's contemporaries who were impressed by this aspect of his work: the science popularizer Arabella Buckley, the Scottish Presbyterian scholar Henry Drummond and the anarchist geographer and naturalist Peter Kropotkin. In closing, I point to an extensive network of others who framed their concerns about both the ‘labour question’ and the ‘woman question’ in evolutionary terms, as a fruitful area for future research in this direction.

Darwin in The Descent of Man deliberates over the question of progress in relation to three categories of traits – aesthetic, moral and intellectual – attending to their interplay. The later formulations of Thomas Henry Huxley and Alfred Russel Wallace shift and reframe the terms for weighing together progress and the relationship across these traits, downplaying the role of aesthetic assessments. Huxley and Wallace invoke ‘antagonisms’ countering, respectively, ‘ethical progress’ and ‘cosmic process’, ‘humanity – the essentially human emotion’ and ‘physical and even intellectual race-improvement’. Thereafter, evolutionary antagonisms reappear – whether to endorse, dismiss or overcome them – and they remain relevant in evolutionary arguments, whether made explicit or left implicit. Following a thread of ongoing appeals to this interplay of traits and corresponding antagonisms invoking Huxley's 1893 lecture ‘Evolution and ethics’, implicit differences appear in the treatment of aesthetic, moral and intellectual development. These treatments maintain the progress that their own ethical systems represented, even while granting moral variation and conceding independent/alternative notions of the beautiful. They generally took as granted the uniformity of intellectual judgements, where evolutionary progress was both ethical and intellectual/scientific, even when speculating on the development of different types of mind. As characteristic of future-oriented visions of progress by the first decades of the twentieth century, sexual selection was subsumed under natural selection.

Darwin's ideas held sway among Chinese intellectuals by the early twentieth century. Yet the usual emphasis was a Spencerism instead of Darwin's original ideas. As a result, translations of The Descent of Man in the early twentieth century quickly fell into oblivion. When the embryologist Zhu Xi (1900–62) eventually decided to give all evolutionary theories a comprehensive examination, he nevertheless found the idea of sexual evolution inadequate, as expressed in his volume Biological Evolution (1958). Only in the 1950s did serious efforts to translate Descent gather momentum, thanks to eugenicist and sociologist Pan Guangdan (1899–1967). Such efforts were not only responses to a renewed interest in Darwinism under the socialist regime, but also expressions that synthesized both scholars’ earlier paths in wrestling with schemes of human evolution and the roles of women in China's survival and renewal. Trained in different scientific and cultural milieus and holding almost oppositional views, the two scholars nevertheless converged in finding new meanings in Darwin's Descent.