Holowka Nicholas B, O'Neill Matthew C, Thompson Nathan E, Demes Brigitte
Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts, 02138.
Department of Anthropology, Stony Brook University, Stony Brook, New York, 11795.
Am J Phys Anthropol. 2017 Sep;164(1):131-147. doi: 10.1002/ajpa.23262. Epub 2017 Jun 8.
Many aspects of chimpanzee ankle and midfoot joint morphology are believed to reflect adaptations for arboreal locomotion. However, terrestrial travel also constitutes a significant component of chimpanzee locomotion, complicating functional interpretations of chimpanzee and fossil hominin foot morphology. Here we tested hypotheses of foot motion and, in keeping with general assumptions, we predicted that chimpanzees would use greater ankle and midfoot joint ranges of motion during travel on arboreal supports than on the ground.
We used a high-speed motion capture system to measure three-dimensional kinematics of the ankle and midfoot joints in two male chimpanzees during three locomotor modes: terrestrial quadrupedalism on a flat runway, arboreal quadrupedalism on a horizontally oriented tree trunk, and climbing on a vertically oriented tree trunk.
Chimpanzees used relatively high ankle joint dorsiflexion angles during all three locomotor modes, although dorsiflexion was greatest in arboreal modes. They used higher subtalar joint coronal plane ranges of motion during terrestrial and arboreal quadrupedalism than during climbing, due in part to their use of high eversion angles in the former. Finally, they used high midfoot inversion angles during arboreal locomotor modes, but used similar midfoot sagittal plane kinematics across all locomotor modes.
The results indicate that chimpanzees use large ranges of motion at their various ankle and midfoot joints during both terrestrial and arboreal locomotion. Therefore, we argue that chimpanzee foot anatomy enables a versatile locomotor repertoire, and urge caution when using foot joint morphology to reconstruct arboreal behavior in fossil hominins.
人们认为黑猩猩踝关节和中足关节形态的许多方面反映了对树栖运动的适应性。然而，陆地行走也是黑猩猩运动的一个重要组成部分，这使得对黑猩猩和化石人族足部形态的功能解释变得复杂。在这里，我们测试了足部运动的假设，并且与一般假设一致，我们预测黑猩猩在通过树栖支撑物移动时，踝关节和中足关节的活动范围会比在地面上移动时更大。
我们使用高速动作捕捉系统，测量了两只雄性黑猩猩在三种运动模式下踝关节和中足关节的三维运动学数据：在平坦跑道上的地面四足行走模式、在水平树干上的树栖四足行走模式以及在垂直树干上的攀爬模式。
在所有三种运动模式下，黑猩猩的踝关节背屈角度都相对较高，尽管在树栖模式下背屈角度最大。在地面和树栖四足行走模式中，它们距下关节冠状面的活动范围比攀爬时更大，部分原因是它们在前者中使用了较高的外翻角度。最后，它们在树栖运动模式下使用了较高的中足内翻角度，但在所有运动模式下中足矢状面的运动学数据相似。
结果表明，黑猩猩在陆地和树栖运动过程中，其踝关节和中足关节的活动范围都很大。因此，我们认为黑猩猩的足部解剖结构使其具有多种运动方式，并且在利用足部关节形态重建化石人族的树栖行为时要谨慎。
