No field of biology has been more deeply influenced by Darwin's notion of evolution than has the science of human origins. Yet while Charles Darwin himself was happy to speculate in the abstract upon the qualities of hypothetical human ancestors, he remained curiously reluctant to engage directly with its tangible fossil record. There appear to have been several reasons for this, including Darwin's desire to avoid confrontation; the scandal-ridden nature of antiquarianism in the mid-nineteenth century; Darwin's own abiding qualms about the reliability of the fossil record; and his close colleague Thomas Henry Huxley's dismissal of the Neanderthal skeleton, the most distinctive hominid fossil known at the time, as merely representing a "barbaric" variety of Homo sapiens. There can be no doubt that human evolution and its implications had been very much on Darwin's mind in the years leading up to the publication of On the origin of species; but in the end he seems to have made a conscious decision to stay clear of this social and intellectual minefield. Even his vast treatise on The descent of man is more plausibly read as an anti-polygenist, anti-slavery tract, and as an exegesis of sexual selection, than as a serious examination of the actual tangible evidence for the origins of humankind. Nonetheless, while staying safely in the realm of abstract speculation, in this great work Darwin managed to establish many of the themes that still dominate paleoanthropology today, including human descent from a single species of ape-like progenitor, the primacy of upright locomotion in human evolution, the birth of our family in the continent of Africa, and, for better or for worse, "the necessary acquirement of each mental power and capacity by gradation", the founding mantra of today's evolutionary psychology.
