PALAEONTOLOGICAL EVIDENCE BEARING ON HUMAN EVOLUTION

Summary Palaeontological evidence bearing on the evolutionary origin of the Hominidae is provided by dryopithecine fossils of Miocene and Pliocene date. These fossils consist almost entirely of jaws and teeth. They indicate that, while the dentition of Dyropithecus was essentially simian in its general characters, in certain features, notably the cusp‐pattern and proportions of the molars, it showed some significant approach to a human type of dentition. In certain allied genera, this approach is still further emphasized by the conformation of the dental arcade. The fact that in some species of these fossil apes the characteristic specializations of modem anthropoid apes were already evident in incipient form suggests that the divergence of the evolutionary line leading to the Hominidae from that which culminated in the modem genera of anthropoid apes must probably be referred to the beginning of Miocene times. More recent fossil apes from South Africa, even though they themselves may not bear any ancestral relation to man, emphasize the evolutionary potentialities of the Dryopithecinae for development in the direction of the Hominidae. However, a considerable gap still exists between the dryopithecine apes and the earliest known representatives of the Hominidae, a gap which can only be filled by further palaeon‐tological discoveries, with particular reference to the skull and limb characters of the former. The accession of new palaeontological material of the Pithecanthropus group (including those fossils which have been referred to the genus Sinanthropus ) has served to emphasize its hominid status. It is important to note that, despite many primitive features of the skull, brain and dentition, the limb bones of the Pithecanthropus group are closely comparable with those of modem man. It becomes clear that if the modem characters of the human limbs had already been acquired so early as the beginning of Pleistocene times, the point of divergence of the Hominidae from the Simiidae must have been correspondingly more remote. The Pithecanthropus group almost certainly provided the basis for the develop‐nent of later types of man. Of these, one is represented by the rather specialized Neanderthal type of later Mousterian date. That this is to be regarded as an aberrant line is indicated by the fact that fossil human remains of early Mousterian and pre‐Mousterian date were less distinctively “Neanderthaloid”, and more akin in their anatomical features to Homo sapiens . There seems little doubt that these fossils represent, as a group, the direct ancestors of modem man.