In 1871, Darwin had almost no fossil evidence to support his theory of the Descent of Man from "simian" ancestors. He relied instead on structural similarities with Primata, including information supplied by Julian Huxley. The first human fossil had been discovered in 1856 in the Neanderthal valley near Dusseldorf, Germany. The heavy brow ridges in this frontal view gave rise to the popular picture of early humans as heavy-set, massively built forms, with low foreheads (and by implication, low intelligence). "Neanderthal Man" is now  considered a subspecies of Homo sapiens: H. s. neanderthalensis. Genetic evidence shows that though Neanderthals were a separate evolutionary lineage from modern humans, they coexisted in time and space, and could and did interbreed. Many modern Homo sapiens have considerable Neanderthal ancestry, as shown by DNA tests.

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