Experimental and Computational Studies of Bipedal Locomotion in the Bipedally Trained Japanese Macaque

Abstract

Japanese macaques trained as performing monkeys have a remarkable ability to walk bipedally. This shift toward bipedalism in an inherently quadrupedal primate could be regarded as a modern analogue for the evolution of bipedal locomotion and offers an interesting model for understanding the emergence of human bipedalism. Here, we review the results of our recent experimental studies of bipedal locomotion in trained Japanese macaques to explore the unique characteristics of their bipedal locomotion. We then describe the development of an anatomically based, whole-body musculoskeletal model of the Japanese macaque for biomechanical analyses and predictive simulations of locomotion. Such constructive studies of locomotion based on a mathematical model of the musculoskeletal system allow computational investigation of the mechanisms of bipedal walking. To understand the diversification of locomotor patterns in primates and the emergence of erect bipedal walking in the human lineage, field studies of locomotion and performance, in terms of selection, are indispensable. Our approach allows quantification of functional consequences of morphological variations in the musculoskeletal system, hopefully helping to identify the causal relationship between morphology and performance and as such complement data collected in the wild.