This idea links the origin of humans directly with the succession in time of mammalian species, and it would be seen today as implicitly evolutionary. However, Lyell (1863, p. 499) proposed withholding final judgement regarding human evolution until a great many fossils confirming modern humanity’s link with
Still, Lyell clearly felt we should not let the lack of such evidence prejudice us against the idea of evolution. “The opponents of the theory of transmutation sometimes argue,” he wrote, “that, if there had been a passage by variation from the lower Primates to Man, the geologist ought ere to this have detected some fossil remains of the intermediate links of the chain” (Lyell 1863, p. 435). But Lyell went on to suggest that “what we have said respecting the absence of gradational forms between the recent and Pliocene mammalia . . . may serve to show the weakness in the present state of science of any argument based on such negative evidence, especially in the case of man, since we have not yet searched those pages of the great book of nature, in which alone we have any right to expect to find records of the missing links alluded to” (1863, pp. 435–436). He believed the proper paleontological pages were to be found in Africa and the East Indies. It is there, he felt that “the discovery, in a fossil state, of extinct forms allied to the human, could be looked for” (Lyell 1863, p. 498).
Lyell’s approach was reasonable, since he advocated withholding judgement until enough evidence was gathered. However, while rejecting arguments based on a lack of evidence, he was perhaps implicitly assuming that the discovery of semihuman forms would confirm modern humanity’s descent from those forms. This is an error (and a perennial one), for the presence of a semihuman form does not preclude the contemporary or prior existence of fully human forms.
1.5 Darwin speaks
We have now seen that Huxley, Haeckel, and Lyell all wrote major works dealing with the question of human origins and that they did so before Darwin, who had deliberately held back from treating the question in
In
The absence of evidence of possible transitional forms may not provide a proper disproof of evolution, but one can argue that such forms are required in order to positively prove the theory. Yet aside from the Neanderthal skulls and a few other little-reported finds of modern morphology, there were no discoveries of hominid fossil remains. This fact soon became ammunition to those who were revolted by Darwin’s suggestion that humans had apelike ancestors. Where, they asked, were the fossils to prove it?
1.6 The Incompleteness of the Fossil Record