Department of Anthropology, Center for the Study of Human Origins, New York University, New York, NY, 10003; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, D-04103, Germany.
Am J Phys Anthropol. 2014 May;154(1):104-14. doi: 10.1002/ajpa.22477. Epub 2014 Jan 30.
The aims of this study were to investigate the effect of allometry on the shape of dm(2) and M(1) crown outlines and to examine whether the trajectory and magnitude of scaling are shared between species. The sample included 160 recent Homo sapiens, 28 Upper Paleolithic H. sapiens, 10 early H. sapiens, and 33 H. neanderthalensis (Neandertal) individuals. Of these, 97 were dm(2) /M(1) pairs from the same individuals. A two-block partial least squares analysis of paired individuals revealed a significant correlation in crown shape between dm(2) and M(1) . A principal component analysis confirmed that Neandertal and H. sapiens dm(2) and M(1) shapes differ significantly and that this difference is primarily related to hypocone size and projection. Allometry accounted for a small but significant proportion of the total morphological variance. We found the magnitude of the allometric effect to be significantly stronger in Neandertals than in H. sapiens. Procrustes distances were significantly different between the two tooth classes in Neandertals, but not among H. sapiens groups. Nevertheless, we could not reject the null hypothesis that the two species share the same allometric trajectory. Although size clearly contributes to the unique shape of the Neandertal dm(2) and M(1) , the largest H. sapiens teeth do not exhibit the most Neandertal-like morphology. Hence, additional factors must contribute to the differences in dm(2) and M(1) crown shape between these two species. We suggest an investigation of the role of timing and rate of development on the shapes of the dm(2) and M(1) may provide further answers.
本研究的目的是探讨同形性对 dm(2)和 M(1)牙冠轮廓形状的影响，并检验种间是否存在轨迹和比例缩放的共享性。样本包括 160 名现代人类、28 名旧石器时代晚期人类、10 名早期人类和 33 名尼安德特人（Neandertal）个体。其中，97 对为同一个体的 dm(2)/M(1)对。对配对个体的两区块偏最小二乘分析显示 dm(2)和 M(1)之间的牙冠形状存在显著相关性。主成分分析证实，尼安德特人和人类的 dm(2)和 M(1)形状存在显著差异，这种差异主要与小尖牙的大小和投影有关。同形性解释了总形态变异的一小部分，但具有统计学意义。我们发现，与人类相比，尼安德特人的同形性效应的幅度要大得多。尼安德特人的两种牙齿类别的 Procrustes 距离存在显著差异，但人类群体之间没有差异。尽管如此，我们不能拒绝两个物种具有相同的比例缩放轨迹的零假设。虽然大小显然对尼安德特人的 dm(2)和 M(1)的独特形状有贡献，但最大的人类牙齿并不表现出最类似尼安德特人的形态。因此，其他因素必须对这两个物种的 dm(2)和 M(1)牙冠形状差异做出贡献。我们建议研究发育时间和速度对 dm(2)和 M(1)形状的作用可能会提供进一步的答案。
