Editor's Summary

13 December 2007

The mother load

Backache is a leading cause of workplace absenteeism — testament to the difficulties of walking upright, a distinctive feature of humans and our hominin ancestors. But women face an extra evolutionary problem, given that for most of human history and prehistory, adult females have spent much of their lives either pregnant or nursing. Pregnancy makes the instability of upright walking even worse by constantly shifting the body's centre of gravity. Whitcome et al. detail those anatomical adaptations peculiar to female spines that balance the fetal load, and find that the bipedal australopithecines — but not the non-bipedal chimpanzee — had similar adaptations.

Letter: Fetal load and the evolution of lumbar lordosis in bipedal hominins

Katherine K. Whitcome, Liza J. Shapiro & Daniel E. Lieberman

doi:10.1038/nature06342

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