Gait Mechanics in Primate and Nonprimate Quadrupeds

我们这个目——灵长类动物——的起源被认为与运动行为的根本变化有关，这种变化是为了响应在森林冠层的薄而灵活的末端树枝上移动和觅食的机械需求。灵长类动物的四足行走在脚步顺序、肢体和关节运动、肌肉补充和峰值负荷分布等方面与其他哺乳动物不同。虽然这些数据已经表明灵长类动物的行走方式是不寻常的，但最近的研究表明，灵长类动物的行走方式与非灵长类动物的行走方式有更根本的不同。在大多数动物的行走过程中，质心（COM）上下移动，就好像它在一个僵硬的倒立钟摆的末端。大多数动物在行走过程中，通过适当的时间上下移动质心，可以通过势能和动能的交换来保存肌肉能量。相比之下，在跑步过程中，COM像一个弹跳的球一样运动，能量储存和恢复发生在肌腱和肌肉中。实际上，我们对四足灵长类动物的前额皮质运动一无所知，但一些研究表明，灵长类动物的行走步态异常柔顺。这样的行走方式涉及肘部和膝关节的深度屈曲，这表明髋部走一条更平坦的路径，势能和动能的交换最小。如果是这样的话，那么这将代表灵长类动物与其他哺乳动物相比在运动机制上的根本转变。然而，没有直接的经验数据描述灵长类动物的COM运动。在这项研究中，五种灵长类动物（两种原猿、一种新大陆猴和两种旧大陆猴）和一种非灵长类动物（家猫）将研究在陆地上行走，而灵长类动物则研究在一个力平台上的树支撑。力的数据将用于确定垂直和前后加速度，速度，和位移的COM的整个身体和前肢和后肢。从这些值可以计算出动能和势能的振荡以及能量回收的百分比。这项研究验证了灵长类动物的行走步态在哺乳动物中不寻常的假设，因为它们不符合倒立摆模型。这种电位差不是一个微不足道的数学区别，也不是简单的程度差异，而是一种突然的适应性转变。了解灵长类动物的行走机制将有助于揭示灵长类动物运动的起源，以及诸如摆动手臂和两足行走等特殊运动行为的起源。除了提高我们对灵长类动物运动进化的理解，这个项目在两个层面上有利于科学教育。该项目将直接涉及本科生和研究生，重点是女性和少数民族学生的参与。此外，本项目的研究技术、数据和结果将被纳入普通人类学课程以及高级研究生和本科课程。

The origin of our Order-Primates-is believed to be associated with a fundamental change in locomotor behavior in response to the mechanical requirements of moving and foraging on thin flexible terminal branches of the forest canopy. The quadrupedal walking of primates differs from other mammals in footfall sequence, limb and joint excursions, muscle recruitment, and peak load distribution. Although these data already suggest that primates are unusual in their walking patterns, recent research has suggested a more fundamental way in which the walking of primates differs from nonprimate mammals. During walking in most animals, the center of mass (COM) moves up and down as if it on the end of a stiff upside-down pendulum. By moving their center of mass up and down with appropriate timing during walking, most animals can conserve muscular energy through the exchange of potential and kinetic energy. In contrast, during running the COM moves like a bouncing ball and energy storage and recovery occurs in tendons and muscles. Virtually nothing is known about the movements of the COM in quadrupedal primates, but some research has suggested that primates use unusually compliant walking gaits. Such walking gaits involve deep elbow and knee yield, suggesting that the COM follows a flatter path with minimal exchange of potential and kinetic energy. If this is the case then this would represent a fundamental shift in the locomotor mechanics of primates compared to other mammals. However, no direct empirical data exist describing the movement of the COM in primates. In this study five primate species (two prosimians, one New World monkey, and two Old World monkeys) and one nonprimate species (domestic cat) will be studied walking on terrestrial and, for the primates, arboreal supports across a force platform. Force data will be used to determine vertical and fore-aft accelerations, velocities, and displacements of the COM of the whole body and the forequarters and hindquarters. From these values the oscillations of kinetic and potential energy as well as the percentage of energy recovery can be calculated. This study tests the hypothesis that walking gaits of primates are unusual among mammals in that they do not conform to an inverted pendulum model. This potential difference is not a trivial mathematical distinction nor is it simply a difference of degree but rather an abrupt adaptive shift. Understanding the mechanics of walking in primates will shed light on the origins of primate locomotion and the origin of specialized locomotor behaviors such as arm-swinging and bipedalism. Aside from improving our understanding of primate locomotor evolution, this project benefits scientific education at two levels. This project will directly involve undergraduate and graduate students with a strong emphasis on female and minority student participation. In addition, the research techniques, data, and results developed from this project will be incorporated into general anthropology courses and advanced graduate and undergraduate courses.