从中国晚期智人颅牙特征看中国现代人起源

ORIGIN OF MODERN HUMANS OF CHINA VIEWED FROM CRANIO DENTAL CHARACTERISTICS OF LATE HOMO SAPIENS IN CHINA

本文提供或援引了中国晚期智人头骨的额骨鳞部最突出点位置、颊部骨骼下缘的形状、头骨最宽处位置等特征和铲形门齿等牙齿特征的出现率等的有关数据，并探讨了这些特征系来源于非洲“夏娃”的后裔，还是中国当地更早的人群。所得结论更倾向于后者而不利于前者。中国旧石器时代中期和晚期的文化之间缺乏显然的反差，没有中断的迹象，也是不利于中国现代人起源的替代说的有力佐证。

In 1993 Bruer and I reported several cranial features that existed both in the broad spectrum of African archaic Homo sapiens and the narrow spectrum of archaic Chinese variation.For instance:the most prominent point on the frontal squama is lower in Chinese specimens,while some are in a similarly lower position and others are higher in African crania;the inferior margin of the cheek bones forms a curve in Chinese specimens,but varies from a curved to a straight form in the Africans;the broadest point on the neurocranium as seen in superior view is found in the middle third in the Chinese,but its position varies from the middle to the posterior thirds in the Africans;the meeting of the inferior margin of the zygomatic process of the maxilla and the alveolar wall is well above the alveolar margin in the Chinese,while it varies from a low to a high position in the African specimens.We explained the narrow spectrum of genetic variation in China by genetic drift. In the present paper I find that in later Chinese crania,the condition of the above mentioned features is the same as in the earlier archaic crania.Chinese populations continuously present a narrow spectrum of variation that occupies the same part of a broad spectrum (Tables 1,2). According to the Eve theory,the late Homo sapiens populations of China described above were derived from the earlier archaic Homo sapiens in Africa via the early modern humans who evolved there.How can we explain the same narrow spectrum of features in these earlier and later Chinese samples if the earlier did not evolve into the later?One possibility is common selection,presumably the same evolutionary response to the East Asian environment.If this seems improbable for the above mentioned features,genetic drift might be the most reasonable alternative explanation.It is certainly possible that drift at a later time could limit the broad spectrum of variation for a feature in a later East Asian population evolving from a late African ancestor in the same way drift limited its variation an earlier East Asian population evolving independently from an earlier African ancestor.But this is a very convoluted and improbable explanation for all four of the above mentioned traits,which I found to occupy the same narrow part of the broad African spectrum in the archaic and later Chinese samples.Therefore,the Eve theory is an unlikely explanation for the origin of modern East Asian populations.To the contrary,the similarity of the narrow spectrum of variation in archaic and more recent East Asians is best explained by descent. Dental evidence suggests the same explanation.Turner (1987,1990) and Irish (1997) have shown that many dental features strongly contrast Africans and east Asians.For instance,the frequency of shovel shaped incisors is much higher in East Asians.If the Eve theory is correct,the rapid increase in shoveling frequency poses a serious problem,while the continuation of high frequencies from earlier archaic East Asian samples to modern ones is more reasonably explained by continuous evolution in the region.In fact,all maxillary incisors dated to the Pleistocene found thus far in East Asia are shoveled. Finally,if the Eve theory was correct it should be reflected in the Paleolithic archaeology .I would expect that early modern invaders from Western Asia would bring Mousterian culture to China,since the earliest moderns in Near East are associated with this distinctive culture.However,there is only one site with Mousterian artifacts in the Chinese Paleolithic.This is Shuidonggou,in the northwestern part of the country.There is no sharp contrast between earlier and later Paleolithic cultures in China,which should exist if replacement of human populations had taken place. In short,continuous evolution of human populations in China from at least the Middle Pleistocene on is strongly supported by cranial,dental,and archaeological data. Meanwhile it is necessary to indicate also that in the orgin of modern humans of China there was gene flow between China and other areas which