现代中国人群形成与分化的形态证据——中国与非洲和欧洲人群头骨非测量特征分析

现代人群形成与分化导致生活在世界不同地区的人类形成了具有明显体质特征差别的人群(或种族)。对更新世末期及全新世以来不同地理区域近代和现代人群体质特征差别、相互亲缘关系的分析是现代人群形成与分化研究的重要组成部分。本文通过对21项头骨非测量特征在近代和现代中国人群, 以及现代非洲和欧洲人群共330例标本的出现率和表现特点的观察和数据分析, 发现绝大多数特征的出现率或表现特点在三个人群间都具有不同程度的差异, 有些特征在人群间的差异甚至非常明显。与非洲及欧洲人群相比, 现代中国人头骨总体显得纤细, 眉弓、角圆枕、颧三角、颧结节等反映头骨粗壮程度的特征在现代中国人群的发育明显弱于非洲和欧洲人群。此外, 现代中国人群还具有一些明显不同于非洲和欧洲人群的头骨非测量特征, 包括锐利的眶外下缘、相对平坦的眉间鼻根点、较圆隆的颅侧壁、平坦的顶孔人字区、深弧形的上颌颧突下缘, 梯形和左右不一的鼻额-额颌缝走向等。采用判别分析可以将67.0%—79.5%的标本正确地判别归入其原来所属的组群。其中对中国人群的正确判别率分别达到70.4%和82.9%。个体标本分布显示非洲人群表现较大的分散性, 而中国和欧洲人群样本的分布明显密集集中, 提示中国和欧洲人群似乎具有更多的衍生性特征。本研究还发现多数在人群间差别显著的头骨非测量特征与头骨粗壮程度有关, 作者对相关的问题进行了分析探讨。

Morphological Evidence of the Formation and Diversification of Modern Chinese: Analysis of Cranial Non-metric Traits in Chinese, African and European Populations

The formation and diversification of modern human populations brought about the emergence of current human populations ( or races ) living in various geographical regions. Physical differences and biological affinities are an important component of studying the formation and diversification of modern human populations. In the present study, the frequency and expression patterns of 21 cranial non-metric traits were analyzed in 330 crania from three main human groups of recent-modern Chinese, modern African and European populations. Our result and some impressions are as follow:
1. Crania of modern Chinese were characterized by gracile morphology with features of robusticity ( e.g., supraorbital structure, angular torus, zygomatic trigone and zygomaxillary tuberosity) much less developed compared to African and European populations. Modern Chinese crania differed from African and European populations in terms of their sharp infero-lateral margin, flat intraglabellar notch, round cranial later profile, flat obelionic and lambdoid region, deeply arc-shaped lower zygomaxillary margin and different frontonasal and frontomaxillary sutures.
2. In terms of non-metric cranial features and population affinities, our results showed different frequency and patterns in most of the features among the three populations with some anatomical traits having significant inter-populational differences. The value of differentiating populations with only one feature is very limited, so in order to explore populational relationships of these non-metric cranial features, discriminant analysis was used to distinguish the three main population groups. Using this approach, between 67 and 79.5 percent of the specimens could be correctly classified (70.4% -82.9% of the Chinese specimens were correctly classified). In the discrimination plots of individual specimens, the African crania were scattered widely, while Chinese and European crania were closely concentrated, suggesting that Chinese and European populations were more derived.
3. Recent studies of non-metric cranial features have begun to analyze the functional or biomechanical morphology of these features, relating them to cranial robusticity, or how robust the crania are in structure. Cranial robusticity is also related to cranial size and thickness, but also expressed by a series of morphological features (referred to as cranial superstructures) including the uplifting ridge, torus and tubercles on the cranial surface. The expression of these robust features is influenced by both genetic and environmental factors and can be very different among populations. Although the evolution of modern Homo sapiens is characterized by skeletal gracilization, a number of robust features still occur in some fossils of early modern humans, as well as recent and modern human skeletons.
This analysis of 21 cranial non-metric features in Chinese, African and European modern human populations indicates that most of the examined features show interpopulation differences related to cranial robusticity, and therefore these types of features must have played a significant role in the formation and diversifications of modern Chinese populations．