Department of Anatomy, College of Graduate Studies, Midwestern University, Glendale, AZ 85308, USA.
Department of Anthropology, Washington University in St. Louis, St. Louis, MO 63130, USA; Palaeo-Research Institute, University of Johannesburg, Auckland Park, Johannesburg 2092, South Africa.
J Hum Evol. 2023 Sep;182:103401. doi: 10.1016/j.jhevol.2023.103401. Epub 2023 Aug 28.
Quantifying and characterizing the pattern of trait covariances is crucial for understanding how population-level patterns of integration might constrain or facilitate craniofacial evolution related to the feeding system. This study addresses an important gap in our knowledge by investigating magnitudes and patterns of morphological integration of biomechanically informative traits in the skulls of Homo sapiens, Pan troglodytes, and Gorilla gorilla. We predicted a lower magnitude of integration among human biomechanical traits since humans eat a softer, less biomechanically challenging diet than apes. Indeed, compared to African apes, the magnitudes of integration were lower in H. sapiens skulls for form data (raw dimensions) but were similar or higher for shape data (raw dimensions scaled by geometric mean). Patterns of morphological integration were generally similar, but not identical, across the three species, particularly for the form data compared to the shape data. Traits that load heavily on the primary axis of variation in morphospace are generally associated with size and/or shape of the temporalis and masseter muscles and with dimensions related to the constrained lever model of jaw biomechanics. Given the conserved nature of morphological integration, skull adaptations for food processing in African apes and humans may have been constrained to occur along certain paths of high evolvability. The conserved pattern of functional integration also indicates that extant hominine species can operate as reasonable analogues for extinct hominins in studies that require population-level patterns of trait variance/covariance.
量化和描述性状协变模式对于理解群体水平的整合模式如何限制或促进与摄食系统相关的颅面进化至关重要。本研究通过研究人类、黑猩猩和大猩猩头骨中具有生物力学信息的特征的形态整合幅度和模式，填补了我们知识中的一个重要空白。我们预测人类的生物力学特征的整合幅度会较低，因为人类的饮食比猿类更软，生物力学挑战性更小。事实上，与非洲猿类相比，人类头骨的形态整合幅度在形式数据（原始维度）方面较低，但在形状数据（通过几何均值缩放的原始维度）方面相似或更高。形态整合的模式在三个物种中通常是相似的，但不完全相同，特别是与形状数据相比，形式数据更是如此。在形态空间中主要变异轴上负荷较重的特征通常与颞肌和咬肌的大小和/或形状以及与约束杆模型的颌骨生物力学相关的维度有关。鉴于形态整合的保守性质，非洲猿类和人类的头骨适应食物处理的特征可能受到限制，只能沿着某些具有高进化能力的路径发生。功能整合的保守模式还表明，在需要群体水平的特征方差/协方差模式的研究中，现生人类物种可以作为已灭绝人类的合理类比。
