 The dual publication of the Descent of Man, and Selection in Relation to Sex (1871) and the Expression of the Emotions (1872) created a watershed in the public reception of Darwin’s views (Radick 2013). Although Darwin had first worked out many of his views on human evolution in the early “M” and “N” Notebooks of 1838–40, public knowledge of Darwin’s own conclusions on human evolution rested on the one vague sentence on the issue in the Origin itself. The Descent, however, made public his more radical conclusions, and seemed to many of his readers, even those previously sympathetic to the Origin, to throw Darwin’s weight behind materialist and anti-religious forces spearheaded by such individuals as German physiologist Friederich Ludwig Büchner (1824–1899), Dutch physiologist Jacob Moleschott (1822–93), English socialist and Darwin popularizer Edward Aveling (1849–98), and German zoologist Ernst Haeckel. Although the question of human evolution had already been dealt with in part by Thomas Huxley in the Man’s Place in Nature of 1863, by Charles Lyell in the same year in his Geological Evidences of the Antiquity of Man, by Alfred Russel Wallace in articles in 1864 and 1870 (Wallace 1864, 1870 and online), and by Haeckel in his Natürliche Schöpfungsgeschichte of 1868, these authors had either not dealt with the full range of questions presented by the inclusion of human beings in the evolutionary process (Huxley), or they had emphasized the moral and mental discontinuity between humans and animals (Lyell, Wallace). Only Haeckel had drawn out a more general reductive conception of humanity from evolutionary theory and he had not ventured into the specific issues of ethics, social organization, the origins of human races, and the relation of human mental properties to those of animals, all of which are dealt with in the Descent. Darwin’s two-volume treatise presented, as one commentator has put it, “a closer resemblance to Darwin’s early naturalistic vision than anything else he ever published” (Durant 1985: 294).