Stojanowski Christopher M, Johnson Kent M
Center for Bioarchaeological Research, School of Human Evolution and Social Change, Arizona State University, AZ.
Am J Phys Anthropol. 2015 Mar;156(3):349-62. doi: 10.1002/ajpa.22653. Epub 2014 Nov 3.
Dental morphology provides important information on human evolution and interpopulation relationships. Dental wear is one of the major limitations of morphological data analysis. Wear figures heavily in existing debates about patterns of New World dental variation with some scholars finding evidence for a more generalized dentition in early New World populations (Powell: Doctoral Dissertation, Texas A&M University, TX (1995)) and others questioning these findings based on the probable effects of dental wear on trait scores (Turner, The First Americans: the Pleistocene Colonization of the New World. San Francisco: California Academy of Sciences (2002) 123-158; Turner: Am J Phys Anthropol 130 (2006) 455-461; Turner and Scott, Handbook of paleoanthropology, Vol. III: Phylogeny of Hominids. New York: Springer (2007) 1901-1941). Here we evaluate these competing claims using data from the Early Archaic Windover sample. Results confirm the dental distinctiveness of Windover with respect to other Old World Asian (i.e., sinodont/sundadont) populations. However, comparison of our results to those of Powell (1995) also highlights significant interobserver error. Statistical analysis of matched wear and morphology scores suggests trait downgrading for some traits. Patterns of missing data present a more challenging (and potentially serious) problem. Use of Little's MCAR test for missing data mechanisms indicates a complex process of data collection in which incidental and opportunistic recording of both highly worn and unerupted teeth introduce a "missing not at random" mechanism into our dataset that biases dental trait frequencies. We conclude that patterns of missingness and formal research designs for "planned missingness" are needed to help mitigate this bias.
牙齿形态学为人类进化和群体间关系提供了重要信息。牙齿磨损是形态数据分析的主要限制因素之一。在关于新大陆牙齿变异模式的现有争论中，磨损问题至关重要。一些学者发现早期新大陆人群的牙列更为普遍的证据（鲍威尔：博士论文，德克萨斯农工大学，德克萨斯州（1995年）），而另一些人则基于牙齿磨损对性状评分的可能影响对这些发现提出质疑（特纳，《最早的美洲人：更新世时期新大陆的殖民化》。旧金山：加利福尼亚科学院（2002年）第123 - 158页；特纳：《美国体质人类学杂志》130（2006年）第455 - 461页；特纳和斯科特，《古人类学手册》，第三卷：人科动物系统发育。纽约：施普林格（2007年）第1901 - 1941页）。在此，我们使用早期古风时期温多弗样本的数据来评估这些相互竞争的观点。结果证实了温多弗相对于其他旧世界亚洲（即，辛诺齿/巽他齿）人群的牙齿独特性。然而，将我们的结果与鲍威尔（1995年）的结果进行比较也凸显了显著的观察者间误差。对匹配的磨损和形态评分进行统计分析表明，某些性状存在性状降级。缺失数据的模式带来了一个更具挑战性（且可能很严重）的问题。使用利特尔的缺失完全随机检验来分析缺失数据机制表明，数据收集过程复杂，其中对高度磨损和未萌出牙齿的偶然和机会性记录在我们的数据集中引入了一种“非随机缺失”机制，从而使牙齿性状频率产生偏差。我们得出结论，需要缺失模式和针对“有计划缺失”的正式研究设计来帮助减轻这种偏差。
