Darwin and the recent African origin of modern humans.

Abstract

On this 200th anniversary of Charles Darwin's birth and the 150th anniversary of the publication of his monumental The Origin of Species (1859) (1), it seems fitting to summarize Darwin's views on human evolution and to show how far we have come since. Darwin famously neglected the subject in The Origin , except near the end where he noted only that “light would be thrown on the origin of man and his history” by the massive evidence he had compiled for evolution by means of natural selection. In The Descent of Man (1871) (2), he said that addressing human evolution in 1859 would “only add to the prejudices against my views.” Satisfied now that those prejudices had significantly receded, he deployed an array of comparative anatomical, embryological, and behavioral observations to argue that people had evolved in the same manner as other species. He emphasized the comparative anatomical details in Thomas Huxley's monograph Evidence as to Man's Place in Nature (1863) (3) to substantiate the particularly close evolutionary relationship between people and the “anthropomorphous” apes. He also reiterated Huxley's prescient inference, grounded in the distribution of the especially humanlike African apes, that the last shared ancestor of people and apes lived in tropical Africa. The fossil record now confirms that Darwin and Huxley were right to place human origins in Africa, but when they were writing, fossil support for human evolution was almost absent. The most meaningful exception was the Neanderthal skullcap and associated limb bones recovered by quarry workers from a limestone cave near Dusseldorf, Germany in 1856. Unfortunately, the antiquity of the bones was unclear and there seemed to be a reasonable possibility that the skull came from a pathological modern human. Similar skulls and limb bones from other sites, excavated from layers with ancient stone tools and … 1E-mail: rklein{at}stanford.edu