The Original Out of Africa

The earliest fossil hominins so far found outside of the African continent are from Dmanisi, in Georgia. Archaeologists digging a medieval site found the first specimen, a mandible, in association with Oldowan-like tools; it was dated to between 1.96 and 1.77 Ma and allocated to H. erectus (Gabunia & Vekua, 1995). Recently three skulls have been discovered from the same locality, and most now consider them to represent members of a European deme of H. ergaster (Gabunia et al., 2000a; Vekua et al., 2002); revised dates indicate an age of around 1.7 Ma (Gabunia et al., 2000a).

Gabunia et al. (2000a) suggest that the Dmanisi hominins share most of their features with H. ergaster, including similar supraorbital torus and frontal bone morphology, reduced postorbital constriction, moderate height of the cranial vault, substantial increase in mastoid development, and similar proportions of the facial skeleton. Comparisons of the mandibles, however, including a remarkably large and robust one discovered in 2002, persuaded Gabunia et al. (2002) to allocate the Dmanisi sample to a new species, Homo georgicus (Figure 6.4). The phylogenetic analyses of Cameron et al. (in press) of hominin crania support this, for they do not share a sister-group relationship with either the African H. ergaster or Asian H. erectus. The Dmanisi hominins have a rather small cranial capacity, with a mean of just 675 ml, which is closer to H. habilis at 610 ml than to H. ergaster at 851 ml, let alone H. erectus at 1151 ml. And, unlike either the African H. ergaster or Asian H. erectus, they lack frontal keeling.

Figure 6.4 ► Homo georgicus (or H. ergaster?) specimen D2282 from Dmanisi, Georgia.

Vekua et al. (2002) suggested that the Dmanisi hominins may share a closer relationship to H. habilis. We cannot support this assessment. The recent description of a metatarsal from Dmanisi shows that Homo georgi-cus clearly fits within the more derived H. ergaster body plan, not with the australopithecine body plan retained in H. habilis (Gabunia et al., 2000b).

Regardless of their eventual taxonomic status, the Dmanisi hominins indicate that early Homo had migrated into Eastern Europe by 1.7 Ma. They do not show any features foreshadowing the later hominins that were to occupy western Europe almost 1 million years later — H. antecessor, H. heidelbergensis, H neanderthalensis, which have origins from a later migration into Europe from Africa.

This scenario also helps explain a longstanding archaeological "dilemma" concerning the presence of two "geographical toolkits" by 1.5 Ma. As we have discussed, the simple Oldowan chopper toolkit (Mode 1 technology) has a long prehistory, established around 2.5 Ma. But by 1.5 Ma a new tool type appears in Africa — the Acheulean tradition (Mode 2 technology). The new tool type represents a major reconfiguration in tool production — the "biface hand ax culture." While the Acheulean tradition is found throughout Africa, Europe, and the Levantine corridor after 1.5 Ma, with few exceptions it does not appear in eastern Asia, where the Oldowan tradition continues to dominate, though Torre et al. (2003) have recently suggested that an incipient form of a Mode 2 technology was being developed in Pakistan.

Given that until recently most accepted that hominins first appeared in Asia around 1.0 Ma, it has been difficult to explain the absence of this culture in Asia, for surely the later immigrants would have brought their Acheulean stone tool tradition with them. Gabunia et al. (2000a) suggested that the early appearance of hominins in Dmanisi associated with Oldowan tools indicates that the original migration into Asia occurred before the Acheulean tool tradition was developed. Even were this not the case, the Acheulean does not appear in Africa before the ancestors of H. erectus have left, so the dispersal from Africa was driven not by technological innovation but from biological and ecological considerations, including greater reliance on animal protein. A further implication is that there had been only a few early migrations into eastern Asia, and after the initial occupation by these Oldowan tool-manufacturing hominins, the migrations ceased and there was no cultural diffusion between the Acheulean and Oldowan tool cultures (see Larick & Ciochon, 1996; Tattersall & Schwartz, 2000).

There appears to have been a short-term migration into China around 250,000 years ago of an H. heidelbergensis-like form, as represented by the Dali and Jinniushan crania and perhaps the Maba cranium (see also Stringer, 1985; Groves, 1989a; Etler & Li, 1994; Tattersall, 1995; Wu & Poirier, 1995; Tattersall & Schwartz, 2000). This may help explain the suggestion that some Acheulean-like artifacts have occasionally been identified from some localities in China and South Korea (Yi & Clarke, 1983; Foley & Lahr, 1997). But H. erectus and H. pekinensis left no extant descendants; their long-unchallenged occupation of southeastern and eastern Asia ended in extinction.

It is now widely accepted that the earliest appearance of H. erectus in Java is around 1.8-1.7 Ma, before 1.5 Ma anyway (Larick & Ciochon, 1996; Swisher et al., 1994, 2000). The earliest appearance of Homo (H. erectus?) in China is the Gongwangling (Lantian) cranium, dated to around 1.2-1.0 Ma (Wu & Poirier, 1995; Klein, 1999) (Figure 6.5). It has also been suggested that an H. ergaster-like hominin is present in Longgupo Cave in southern China (Larick & Ciohon, 1996), though the specimen is simply a fragmentary piece of jaw with a premolar and first molar, and Wu Xinzhi has shown, in a very decisive analysis, that it is

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