Nonhuman primates provide a broad comparative framework within which physical anthropologists can study aspects of the human career and condition. Comparative morphological studies, particularly those that are complemented by biomechanical analyses, provide major clues to the functional significance and evolution of the skeletal and muscular complexes that underpin our bipedalism, dextrous hands, bulbous heads, outstanding noses, and puny jaws. The wide variety of adaptations that primates have made to life in trees and on the ground are reflected in their limb proportions and relative development of muscles.
ree-ranging primates exhibit a trove of physical and behavioral adaptations to fundamentally different ways of life, some of which may resemble those of our late Miocene–early Pleistocene predecessors (i.e., those from about 11 to 2 million years ago). Laboratory and field observations, particularly of great apes, indicate that earlier researchers grossly underestimated the intelligence, cognitive abilities, and sensibilities of nonhuman primates and perhaps also those of Pliocene–early Pleistocene hominins (i.e., those from about 5.3 to 2 million years ago), who left few archaeological clues to their behaviour.