Speculation on posture, locomotion, energy consumption, and blood flow in early hominids

Energy consumption and blood flow allocations were studied in human subjects who were induced to stand and walk in a bent-head, bent-knee way, which is one of the different bipedal behaviours that could be considered for the posture and locomotion of Australopithecus afarensis. In these subjects oxygen consumption was intermediate between modern humans standing/walking normally and humans standing/walking on all fours, and blood flow was lower for the internal carotid and subclavian arteries and higher for the external carotid and femoral arteries. When erect posture is similar to that of modern humans the demands of blood supply required by the general musculature are diminished in view of the relatively efficient modes of human posture and locomotion, but blood flow to the enlarged human brain is markedly increased.