Irish Joel D, Guatelli-Steinberg Debbie
Department of Anthropology, University of Alaska Fairbanks, Fairbanks, AK 99775-7720, USA.
J Hum Evol. 2003 Aug;45(2):113-44. doi: 10.1016/s0047-2484(03)00090-3.
Previous research by the first author revealed that, relative to other modern peoples, sub-Saharan Africans exhibit the highest frequencies of ancestral (or plesiomorphic) dental traits and, thus, appear to be least derived dentally from an ancestral hominin state. This determination, in conjunction with various other lines of dental morphological evidence, was interpreted to be supportive of an African origin for modern humans. The present investigation expands upon this work by using: 1) direct observations of fossil hominin teeth, rather than data gleaned from published sources, 2) a single morphological scoring system (the Arizona State University Dental Anthropology System) with consistent trait breakpoints, and 3) data from larger and more varied modern human comparative samples. As before, a multivariate distance statistic, the mean measure of divergence, was used to assess diachronic phenetic affinities among the Plio-Pleistocene hominins and modern humans. The present study also employed principal components analysis on dental trait frequencies across samples. Both methods yielded similar results, which support the previous findings; that is, of all modern human samples, sub-Saharan Africans again exhibit the closest phenetic similarity to various African Plio-Pleistocene hominins-through their shared prevalence of morphologically complex crown and root traits. The fact that sub-Saharan Africans express these apparently plesiomorphic characters, along with additional information on their affinity to other modern populations, evident intra-population heterogeneity, and a world-wide dental cline emanating from the sub-continent, provides further evidence that is consistent with an African origin model.
第一作者之前的研究表明，与其他现代人群相比，撒哈拉以南非洲人表现出最高频率的祖先（或近祖）牙齿特征，因此，从牙齿角度来看，他们似乎最不像从原始人类状态演化而来。这一结论，结合其他各种牙齿形态学证据，被解释为支持现代人类起源于非洲的观点。本研究通过以下方式扩展了这项工作：1）直接观察化石原始人类牙齿，而非从已发表资料中收集的数据；2）使用具有一致特征断点的单一形态评分系统（亚利桑那州立大学牙齿人类学系统）；3）来自更大且更多样化的现代人类比较样本的数据。和之前一样，使用多元距离统计量——平均差异度量，来评估上新世 - 更新世原始人类与现代人类之间的历时表型亲缘关系。本研究还对各样本的牙齿特征频率进行了主成分分析。两种方法得出了相似的结果，支持了之前的发现；也就是说，在所有现代人类样本中，撒哈拉以南非洲人再次表现出与各种非洲上新世 - 更新世原始人类最接近的表型相似性——通过他们共同具有形态复杂的冠部和根部特征。撒哈拉以南非洲人表现出这些明显的近祖特征，以及关于他们与其他现代人群亲缘关系的更多信息、明显的群体内异质性，以及源自该次大陆的全球牙齿渐变群，这些都提供了与非洲起源模型相一致的进一步证据。
