News FocusEvolutionary Biology

The Burdens of Being a Biped

Science  25 May 2012:
Vol. 336, Issue 6084, pp. 974
DOI: 10.1126/science.336.6084.974

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Summary

Just as many dental problems are rooted in our evolutionary history (see main text), a number of musculoskeletal issues are also traceable to our past, in particular to the switch to walking upright more than 7 million years ago. Shifting from a four-legged support system to a two-legged one put extra stress on the legs and vertebrae. Adaptations in the feet, knees, hips, pelvis, and spine accommodate these forces, but at a cost. Imperfect evolution and constraints on how our bodies could change have left us with vertebrae that break more easily, weaker bones, and feet prone to heel spurs and sprained ankles. Our relatively inactive lifestyles and longer life span only exacerbate our orthopedic imperfections. A brief tour of the body reveals a number of design flaws, the legacy of our past.