September 30, 2019

Birth, bipedalism, and the evolution of the human hip

Kristi Lewton, University of Southern California

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Locomotion, gestation, and childbirth have had a significant impact on human culture and biology, including the morphology of the human hip. One of the most fundamental features of the human lineage is walking on two legs, and the emergence of this novel behavior had spectacular evolutionary consequences; the advent of material culture, extensive migrations and landscape use, and complex systems of trade were all contingent on obligate bipedality. Humans also have unusually large neonates, which has been thought to result in an ‘obstetrical dilemma’ in which there is an evolutionary tradeoff in females between having hips wide enough to accommodate the birth of a large infant, but also narrow enough to allow for efficient bipedal locomotion. This research uses integrative methods including biomechanical models, the comparative method, and morphological integration to examine tradeoffs, constraints, and adaptations of the human pelvis.