Experimental Studies on Primate Locomotion

Over the past forty years, many studies have collected empirical data documenting aspects of the locomotor behavior of anthropoid primates (monkeys and apes). The results of some of this research have revealed unusual characteristics of the form of quadrupedalism that primates display. This has in turn led to suggestions of distinctiveness in primates among mammals in such things as patterns of neural control of movement. However, based largely on data for anthropoids only, such conclusions are premature without comparable data on prosimian primates. The goals of the proposed study, therefore, are to undertake a set of laboratory based studies concerning aspects of locomotor behavior among prosimian primates in order to supplement the currently sparse empirical data base, and allow comparisons with the better-documented locomotor behavior of anthropoid primates as well as nonprimate mammals. The specific questions this study will address include documentation of patterns of muscle recruitment during quadrupedal locomotion in a variety of prosimian species including Lemur catta, Eulemur. fulvus, and E. rubriventer using the technique of electromyography (EMG); analysis of issues associated with the mechanics of leaping, a locomotor behavior that displays its most specialized development among certain prosimian species such as Propithecus coquereli using force-plate recordings; and examination of the locomotor behavior of Daubentonia madagascariensis, the Aye-aye, one of the most enigmatic of prosimian species, using a combination of motion analysis, EMG and force-plate recordings to attempt to interpret some of its many unusual postcranial morphological features. The results of this research will significantly expand our empirical data base on primate locomotor behavior, permitting legitimate conclusions regarding what is or isn't characteristic of the Order. Such information will contribute to a more precise definition of what it means to be a primate, and what factors were involved in the origins of the Order and its eventual dispersal and diversification.