Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; Paleoanthropology, Senckenberg Center for Human Evolution and Paleoecology, University of Tübingen, Tübingen, Germany.
Anat Rec (Hoboken). 2014 Feb;297(2):261-72. doi: 10.1002/ar.22843. Epub 2013 Dec 18.
Investigating ontogenetic variation and allometry in the mandible can provide valuable insight and aid in addressing questions related to the ontogeny of the skull. Here, patterns of ontogenetic shape change and allometric trajectories were examined in the mandible of 187 sub-adult and adult humans, bonobos, and chimpanzees. Procrustes-based geometric morphometrics was employed to quantify and analyze mandibular form. Thirty three-dimensional landmarks were used to capture the overall morphology of the mandible, and the landmarks were analyzed as a whole and subdivided into separate anterior and posterior units. Principal component analyses in Procrustes shape-space and form-space, and multivariate regressions were used to examine patterns of ontogenetic and allometric shape change. Results suggest that humans are distinct from Pan both in their mandibular morphology, particularly in the anterior-alveolar region, and direction of allometric trajectory. Chimpanzees and bonobos have parallel ontogenetic trajectories, but also show differences in mandibular shape. Species-specific features and adult mandibular shape are established before or by the eruption of the deciduous dentition. This suggests that developmental processes prior to deciduous teeth eruption have a stronger effect establishing taxa-specific phenotypes than later postnatal effects. This additionally implies that divergent trajectories between Pan and Homo do not contribute much to the adult mandibular shape after deciduous teeth eruption. Separate analyses of the anterior-alveolar region and ascending ramus show that these regions are semi-independent in their developmental pattern of shape change and allometry. This implies that allometric variation and ontogenetic shape change in the hominoid mandible is decoupled.
研究下颌骨的个体发育变异和异速生长可以提供有价值的见解，并有助于解决与颅骨个体发育相关的问题。在这里，研究人员检查了 187 名亚成体和成年人类、黑猩猩和大猩猩的下颌骨的个体发育形状变化和异速生长轨迹。采用基于 Procrustes 的几何形态测量法来量化和分析下颌骨的形态。使用 33 个三维标志点来捕捉下颌骨的整体形态，并且将标志点作为一个整体进行分析，并分为单独的前、后单元进行分析。在 Procrustes 形状空间和形态空间中进行主成分分析和多元回归分析，以研究个体发育和异速生长形状变化的模式。结果表明，人类的下颌骨形态与 Pan 明显不同，特别是在前牙槽区域和异速生长轨迹的方向上。黑猩猩和倭黑猩猩具有相似的个体发育轨迹，但在下颌骨形状上也存在差异。物种特异性特征和成年下颌骨形状在乳牙萌出之前或同时形成。这表明，乳牙萌出前的发育过程比后期的产后影响更能有效地建立特定于分类群的表型。这还意味着 Pan 和 Homo 之间的分歧轨迹对乳牙萌出后成年下颌骨形状的影响不大。对前牙槽区域和升支的单独分析表明，这些区域在其形状变化和异速生长的发育模式上是半独立的。这意味着人科动物下颌骨的异速生长和个体发育形状变化是解耦的。
