Dissertation Research: Thoracic Shape and Arm Mobility in Primates

人类学家认为，人类和猿类（即类人猿）胸部从前到后的扁平增加了肩部手臂运动的范围，因此他们可以向各个方向伸出手臂。这被认为是在分支间来回摆动的必要条件，就像大多数现存的猿类（可能也是我们的类猿祖先）一样。然而，这种关于类人猿解剖学的摆动手臂假说最近受到了其他假说的挑战，这些假说认为类人猿胸部的特殊形状是为了缓慢攀爬（这也需要向各个方向伸出手）或在垂直的树干上攀爬而进化的。不幸的是，像许多其他肩部解剖特征的功能一样，由于完全缺乏灵长类动物肩部活动性的数据，因此无法澄清类人猿扁平胸部的功能。本研究将在3个维度上对镇静动物以及骨骼和韧带的制备物进行视频测量，以比较具有不同形状胸部的动物的手臂运动范围。本研究亦将利用X光测量不同运动行为的灵长类动物的胸部形状，以探讨运动行为与胸部形状之间的关系。拟议研究的结果将提供急需的流动性数据，用于评估人类和灵长类动物肩部功能和进化解剖学研究中的许多假设。

Anthropologists have argued that the front-to-back flattening of the chest of humans and apes (i.e. hominoids) increases the range of arm movement at the shoulder so that they can reach out in all directions. This is supposedly essential for swinging from branch to branch hand-over hand, like most living apes (and presumably, our ape-like ancestors). However, this arm-swinging hypothesis of hominoid anatomy has recently been challenged by other hypotheses, which argue that the special shape of the hominoid chest evolved for slow climbing (which also requires reaching out in all directions) or for climbing on vertical tree trunks. Unfortunately, the function of the flattened chest in hominoids, like the functions of many other shoulder anatomical features, cannot be clarified because of a complete lack of data on shoulder mobility in primates. This study will videographically measure the range of arm movement in 3 dimensions, on sedated animals and on preparations of bones and ligaments, in order to compare the range of arm movement in animals with chests of different shapes. This study will also measure chest shape using x-rays of primate species with different locomotor behaviors, in order to examine the relationship between locomotor behavior and chest shape. The results of the proposed research will provide much-needed mobility data for evaluating numerous hypotheses in the study of the functional and evolutionary anatomy of human and primate shoulders.