Paul Kathleen S, Stojanowski Christopher M
Center for Bioarchaeological Research, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, 85287.
Am J Phys Anthropol. 2017 Sep;164(1):97-116. doi: 10.1002/ajpa.23260. Epub 2017 Jun 19.
Dental morphology plays a key role in reconstructing population history and evolutionary relationships at global, regional, and intracemetery scales. At the inter-individual level, it is assumed that close biological kin exhibit greater phenotypic similarity than non-relatives. Heritability estimates provide one measure of phenotypic resemblance but are not easily incorporated into analyses of archaeological samples. In this study we evaluate the assumption that relatives are more similar phenotypically than non-relatives. We compare results for permanent dental morphology to those obtained using deciduous dental morphology in a matched dataset (Paul & Stojanowski, ).
Permanent trait expression was scored from dental casts representing 69 sibling pairs, curated as part of the longitudinal Burlington Growth Study. Simulating a biodistance approach, 22 morphological traits of permanent tooth crowns were used to generate 69 inter-relative and 2,076 non-relative Euclidean distances. Following distance ordination, family-specific dispersion values were calculated from multidimensional scaling coordinates. Output was compared to that of a previous study that focused on deciduous crown variation in the same set of individuals (Paul & Stojanowski, ). Mantel tests were used to evaluate the correlation of a proxy genetic distance matrix to both the permanent and deciduous dental distance matrices.
On average, inter-relative distances generated from morphological traits of permanent tooth crowns were smaller than expected by chance based on resampling (p < 0.001). While family-specific dispersion varied greatly for both permanent and deciduous datasets, over 75% of the families exhibited greater dispersion with permanent traits. This suggests that morphological traits of the permanent dentition provide a less faithful reflection of biological relatedness than morphological traits of the deciduous dentition. Mantel tests indicate that both the deciduous and permanent distance matrices are significantly correlated with a matrix of genetic relatedness coefficients; however, the magnitude of the correlations was low.
Overall, morphological traits of permanent tooth crowns perform moderately well in distinguishing relatives from non-relatives, but deciduous crown variations may provide a more direct reflection of the underlying genetic structure of intra-site or intra-cemetery samples. These findings have implications for bioarchaeological research and biodistance practices. In particular, morphological traits of the deciduous dentition should be incorporated into standard data collection protocols because of their stronger signal of relatedness.
牙齿形态在全球、区域和墓地内部尺度上重建人群历史和进化关系方面起着关键作用。在个体层面，一般认为生物学上的近亲比非亲属表现出更大的表型相似性。遗传力估计提供了一种表型相似性的度量，但不容易纳入考古样本分析中。在本研究中，我们评估亲属在表型上比非亲属更相似这一假设。我们将恒牙形态的结果与在匹配数据集中使用乳牙形态获得的结果进行比较（保罗和斯托亚诺夫斯基， ）。
从代表69对兄弟姐妹的牙模上对恒牙特征表达进行评分，这些牙模是纵向伯灵顿生长研究的一部分。模拟生物距离方法，使用恒牙冠的22个形态特征生成69个亲属间和2076个非亲属间的欧氏距离。在距离排序之后，从多维标度坐标计算特定家族的离散值。将输出结果与之前一项关注同一组个体乳牙冠变异的研究结果进行比较（保罗和斯托亚诺夫斯基， ）。使用曼特尔检验来评估代理遗传距离矩阵与恒牙和乳牙距离矩阵的相关性。
平均而言，由恒牙冠形态特征产生的亲属间距离比基于重采样的随机预期值要小（p < 0.001）。虽然特定家族的离散度在恒牙和乳牙数据集中都有很大差异，但超过75%的家族在恒牙特征上表现出更大的离散度。这表明恒牙列的形态特征比乳牙列的形态特征对生物学亲缘关系的反映更不准确。曼特尔检验表明，乳牙和恒牙距离矩阵都与遗传相关系数矩阵显著相关；然而，相关性的程度较低。
总体而言，恒牙冠的形态特征在区分亲属和非亲属方面表现中等，但乳牙冠变异可能更直接地反映了遗址内或墓地内样本的潜在遗传结构。这些发现对生物考古学研究和生物距离实践具有启示意义。特别是，乳牙列的形态特征因其更强的亲缘关系信号，应纳入标准数据收集方案中。
