Schmitt Daniel
Department of Biological Anthropology and Anatomy, Duke University Medical Center, Durham, North Carolina 27710, USA.
Am J Phys Anthropol. 2003 Sep;122(1):28-37. doi: 10.1002/ajpa.10214.
Several features that appear to differentiate the walking gaits of most primates from those of most other mammals (the prevalence of diagonal-sequence footfalls, high degrees of humeral protraction, and low forelimb vs. hindlimb peak vertical forces) are believed to have evolved in response to requirements of locomotion on thin arboreal supports by early primates that had developed clawless grasping hands and feet. This putative relationship between anatomy, behavior, and ecology is tested here by examining gait mechanics in the common marmoset (Callithrix jacchus), a primate that has sharp claws and reduced pedal grasping, and that spends much of its time clinging on large trunks. Kinematic and kinetic data were collected on three male Callithrix jacchus as they walked across a force platform attached to the ground or to raised horizontal poles. The vast majority of all walking gaits were lateral-sequence. For all steps, the humerus was retracted (<90 degrees relative to a horizontal axis) or held in a neutral (90 degrees ) position at forelimb touchdown. Peak vertical forces on the forelimb were always higher than those on the hindlimb. These three features of the walking gaits of C. jacchus separate it from any other primate studied (including other callitrichids). The walking gaits of C. jacchus are mechanically more similar to those of small, nonprimate mammals. The results of this study support previous models that suggest that the unusual suite of features that typify the walking gaits of most primates are adaptations to the requirements of locomotion on thin arboreal supports. These data, along with data from other primates and marsupials, suggest that primate postcranial and locomotor characteristics are part of a basal adaptation for walking on thin branches.
大多数灵长类动物的行走步态与大多数其他哺乳动物的行走步态之间似乎存在一些差异特征（对角序列足落地的普遍性、肱骨高度前伸以及前肢与后肢垂直力峰值较低），据信这些特征是早期灵长类动物为适应在细树枝上移动的需求而进化出来的，这些灵长类动物已发育出无爪的抓握手脚。本文通过研究普通狨猴（Callithrix jacchus）的步态力学来检验这种解剖结构、行为和生态之间的假定关系，普通狨猴是一种具有锋利爪子且足部抓握能力减弱、大部分时间都依附在大树干上的灵长类动物。在三只雄性普通狨猴走过连接在地面或升高的水平杆上的测力平台时收集了运动学和动力学数据。所有行走步态中的绝大多数都是侧序列的。对于所有步骤，在肢体着地时，肱骨后缩（相对于水平轴小于90度）或保持在中立（90度）位置。前肢的垂直力峰值总是高于后肢。普通狨猴行走步态的这三个特征使其与其他任何已研究的灵长类动物（包括其他狨科动物）区分开来。普通狨猴的行走步态在力学上更类似于小型非灵长类哺乳动物。这项研究的结果支持了先前的模型，这些模型表明，大多数灵长类动物典型的异常特征组合是对在细树枝上移动需求所做出的适应。这些数据，连同来自其他灵长类动物和有袋动物的数据表明，灵长类动物的颅后和运动特征是在细树枝上行走的基础适应的一部分。
