Modern human origins in China

I have been reading Wu's "On the origin of modern humans in China" (Quaternary International 117, 2004) where he argues for a "Continuity with hybridization" model. This model treats Homo erectus as a sub-species of Homo sapiens, i.e. Homo sapiens erectus, and modern humans as Homo sapiens sapiens. There is no room for Homo heidelbergensis who appears to be subsumed within the two respective sub-species.

The forementioned effect of creating two sub-species is that fossils such as Dali, Jinniushan and Maba, dated at 109kya, 280kya and 135kya respectively, are allocated to Homo sapiens sapiens.

He starts off my mentioning the 12 morphological features proposed by Weidenreich to be representative of a straight line of evolution from Peking Man to modern Chinese, and points out that some of these characteristics are rather "primitive characteristics shared by members of
the genus Homo".

He moves on to cite common features from the existing known remains such as the shovel-shaped teeth, the large nasomalar angle, et al. While recognising that at least some of the features are found elsewhere in the world, nowhere else do they form a morphological complex. Therefore, he concludes, this mosaic of features "indicates a gradual transition between these sub-species".

There are morphological commonalities between Maba's skull-cap in terms of constriction in the post-orbital region when compared to the H. sapiens erectus remains. Also, "the angular torus has been described as one of the unique features of H. s. erectus; however, it is shown also in H. s. sapiens skulls from Dali and Ziyang." Ziyang is missing from the site chronology table, Table 1. Thus, considering the lack of a clear demarcation in features, Wu considers it to be prudent to regard "erectus" and "sapiens" to be sub-species of the same chronological species.

The polytypic species viewpoint of Wolpoff et al. (1984) is endorsed and a strict Out-of-Africa replacement model is rejected on morphological, archaeological and genetic grounds. Rather, "the most reasonable explanation for the fortuitous occurrence of these features in Pleistocene
China is that they are attributable to small amounts of intermittent gene flow from the West" with "gene flow [becoming] a more potent force in later periods such as the Late Pleistocene and Holocene, thus diminishing the differences between the human populations of China and those westward".

The artifacts from China belong, until after 40kya, to lithic Mode I. While the occasional biface (Gongwangling) and handaxes (Dingcum, Baise Basin) have been found, there remains no evidence of a massive change from Mode I to Mode III as would be expected if immigrants from Africa entered China around or prior to 60kya. Instead the scattered data is claimed to be supportive of limited hybridization.

The genetic data is examined, from the Neanderthal mtDNA to studies such as B-globin. The latter, published by Harding et al. (1998), yielded a date of around 800kya for the most recent common ancestor of modern humans. Problems with genetic analyses are pointed out: gene loss, irregularity of the clock, and the irregular evolution within and inter-loci. He concludes by stating that "the different dates of the MRCA [most recent common ancestor] represent only "locus-specific conclusion(s)" instead of a "genome-wide conclusion" and may imply different times of migration from Africa".