ABSTRACT
The last ten years have seen remarkable advances in our understanding of the origin of Homo sapiens (used here in the restricted sense of Stringer & Andrews 1988a, to represent living and fossil humans displaying specific morphological synapomorphies). Five of these advances are summarised below:
Neanderthals were present in western Europe at a surprisingly young date (‘Wurm III’ of the old usage, probably less than 35 000 radiocarbon years BP). These Neanderthals are apparently associated with the Upper Palaeolithic Châtelperronian industry, and other Neanderthals may well have been responsible for comparable industries elsewhere in Europe, such as the Szeletian and Uluzzian. The chronological implications are that there was, broadly speaking, contemporaneity between these late Neanderthals and early H. sapiens (assumed to be responsible for the Aurignacian) in various parts of Europe after 40 000 radiocarbon years ago (see various papers in Mellars & Stringer 1989). Documentation of the full extent of the inferred period of coexistence is hampered at present by practical limits on radiocarbon dating.
The hominids from Skhûl and Qafzeh (Israel) represent a somewhat archaic H. sapiens (sensu stricto), rather than a transitional or hybrid form between Neanderthals and H. sapiens. Just as significantly, there are growing indications of an early (oxygen isotope stage 5 equivalent) date for these specimens (Valladas et al. 1988, Schwarcz et al. 1989, Stringer et al. 1989). They may thus lie chronologically between the earlier, poorly-known, but apparently archaic hominids from sites such as Gesher Benot Ya’acov and Zuttiyeh, and Neanderthals from sites such as Tabun C-D and Kebara. However, uncertainty will remain about the sequence of populations in the area until a better absolute dating framework can be established for all the important sites. If the Skhûl and Qafzeh hominids are now correctly dated, they seem too ancient to serve as the direct and exclusive ancestors for the earliest H. sapiens of Europe implied by their colloquial name ‘Proto-Cro-Magnons’. It is unclear whether their presence in south west Asia represents a brief incursion into the area from elsewhere (north Africa?) which was part of an episodic first appearance of H. sapiens in Eurasia, without wider consequences. Alternatively, their appearance might presage a major dispersal of H. sapiens across Asia and into the Far East. In either case, these specimens provide us with our best samples of early H. sapiens, at perhaps three times the age of European examples, and an age comparable to that inferred for less complete African specimens from sites such as Klasies River Mouth Caves, Orno-Kibish and, less certainly, Border Cave and ‘Guomde’ (Bräuer, this volume). They also 10seem to confirm that Neanderthals sensu stricto were not ancestral to the earliest H. sapiens (Stringer 1988).
H. sapiens was present in Africa during the time span of oxygen isotope stage 5 (prior to 70 kyr BP). Each part of the morphological, archaeological, stratigraphie or chronological evidence from the African sites mentioned in 2 is subject to some degree of uncertainty, and it is right that the evidence should be scrutinised carefully. However, it would be wrong to be especially sceptical of the African evidence simply because it does not fit with particular models developed elsewhere (Wolpoff 1989). Otherwise there will seem to be double standards operating when comparing evidence from these African sites with some in Europe and elsewhere (see Mellars & Stringer 1989, Bräuer, this volume, Bräuer et al., this volume, Morris, this volume).
The geographic spread of humans across Australia had occurred by about 30 kyr BP, and the first arrival of humans in Sahul must have been at least 10 kyr before this. The early Australians already displayed considerable morphological variation, and the significance of this remains in dispute (Brown 1987, Wolpoff 1989).
The significance of new genetic evidence on present human variation to interpretations of the origin of H. sapiens has been much debated (see, for example, Saitou & Omoto 1987, Moritz et al. 1987, Darlu & Tassy 1987, Cann et al. 1987, Excoffier et al. 1987, Bowcock et al. 1987, Sanchez-Mazas & Langaney 1988, Pamilo & Nei 1988, Cann 1988, Spuhler 1988, Stoneking & Cann 1989). Although the peculiar features of mitochondrial DNA (mtDNA) make it especially useful for intraspecific phylogeographic studies (Avise et al. 1987), it also requires evidence from the many different genetic polymorphism and nuclear DNA data to build up a realistic overall picture of the genetic history of H. sapiens. The different bodies of evidence are now complementing each other to show the fundamental patterns of relationship between major geographical populations of humans, and the probability of an African origin for H. sapiens (Cann et al. 1987, Cann 1988, Cavalli-Sforza et al. 1988, various papers in Mellars … Stringer 1989). The pattern which is emerging is not simple (cf. the relationships of Ethiopian and San populations discussed in Cavalli-Sforza et al. 1988), but it cannot easily be reconciled with the global fossil record from the middle Pleistocene, suggesting that recent human population relationships do not have a long Pleistocene history (see below). This is so even if direct calibration of past events remains problematic from the genetic evidence alone (Stringer & Andrews 1988a, Wolpoff 1989).
