TAXONOMY AND HUMAN EVOLUTION*

Summary . I. A species can usually be diagnosed for purposes of classification on the basis of a few characters. An assessment of its phyletic relations entails a consideration of as many characters as can usefully be defined. 2. Owing to a confusion of taxonomy with phylogeny, the uneven classification of fossil anthropoid and human remains has helped to distort views about the course of human evolution. 3. The human and ape fossil remains that have been found up to the present are relatively few in number, and with one or two exceptions, unrelated to each other in known sequence of age within one homogeneous set of deposits. They do not lend themselves to the determination of lineages within the Hominoidea. 4. Biometric and modern statistical methods have, in general, not been used in the description of fossil primate material. 5. During the past fifteen years information about fossil man from south‐east Asia and about fossil anthropoids from South and East Africa has increased considerably. The fossil men of south‐east Asia are typical of the groups of fossils usually referred to as Palaeanthropidae. The fossil anthropoids of South and East Africa are predominantly apes. In some of their features they resemble orang‐utans as well as the African apes, and in a few they appear to resemble man more than do existing apes. 6. On what appear to be mainly arbitrary grounds, the African fossils have been divided into five different genera: (a) the family Australopithecinae comprising the genera Australopithecus, Plesianthropus, Paranthropus, (b) the genus Telanthropus , and (c) the genus Proconsul. The Australopithecinae have been stated on the basis of qualitative description to be ‘hominids’. 7. The south‐east Asian fossil men have been arranged in a lineage which leads from giant hominids to modern man. 8. Current descriptions of the South African fossils minimize the difficulties that exist in associating and attributing different fragments to different species, as well as the problem of diagnosing age and sex. 9. A critical biometric analysis of the dimensions of the teeth of these fossils has failed to substantiate various claims that have been made, on the basis of superficial comparisons, about their hominid proportions. For example, neither the teeth of Plesianthropus nor Paranthropus differ significantly in proportions from the orangutan or gorilla. The proportions of the teeth of Proconsul do not differ significantly from the chimpanzee. 10.A further comparison showed that the dimensions of these fossil teeth correspond to the dimensions of existing apes far more than they do to man, and that in their dimensions the teeth of existing apes are at least as hominid as those of the fossil anthropoids. In view of this finding, it is misleading to emphasize, as has been repeatedly done, that the size and proportions of the teeth of the Australopithecinae are a major consideration in the claim that these creatures were hominids. 11. A biometric analysis of the humeral fragments of Paranthropus and of the femoral fragments of Plesianthropus has failed to corroborate strongly expressed claims that these bones are specifically hominid in character. 12. Estimates of the cranial capacity of the Australopithecinae show that they do not exceed the range for existing apes. 13. Because of the results of the biometric analyses referred to in the preceding paragraphs, it is suggested that whatever morphological resemblances they may have to the human condition, a thorough biometric study be made of the South African fossils before currently stated views about their phyletic significance are accepted. 14. The horizon of the south‐east Asian human fossils is believed to be the Günz‐Mindel Inter‐glacial period and early Middle Pleistocene. That of the South African fossils is uncertain, but in the light of recent studies it is unlikely to be earlier than the Pleistocene. 15. The view that man evolved from giant ancestors is not specifically supported by the available evidence. Further, whatever validity they may have on a morphological level, the hominid resemblances of the Australopithecinae which have been emphasized as indicating descent may, for all that is known, have no phylogenetic significance whatever.