Link: Biomechanical demands of hip width

Boston University’s research office has a nice article about Kristi Lewton’s research on pelvic biomechanics: “In defense of wide hips”. The piece refers to Lewton’s investigation of the “obstetrical dilemma”, the hypothesis that the demands of bipedalism for a shortened pelvis may have sharpened the constraint on gestation time in hominins because of the demands of birthing infants.

If the basic assumptions of the obstetric dilemma are right, says Lewton, participants with wider hips should run and walk less efficiently than those with narrow ones. But that wasn’t what Lewton and her team found. Instead, they found no connection at all between hip width and efficiency: wide-hipped runners moved just as well as their narrow-hipped peers. Lewton and her colleagues published their results in March 2015 in the online journal PLOS ONE. The work was supported by grants from the National Science Foundation and The Leakey Foundation.
“This ‘trade-off’ between hips wide enough for a big baby and small enough for efficient locomotion does not seem to occur,” says Lewton. “That means that we have to rewrite all of the anthropology textbooks! Even outside of textbooks, the general public thinks that if your hips are wide, you’re a bad biped, and that does not seem to be the case.”

The research paper discussed in the article is the recent one by Anna Warrener and colleagues, “A Wider Pelvis Does Not Increase Locomotor Cost in Humans, with Implications for the Evolution of Childbirth”.

Reference

Warrener AG, Lewton KL, Pontzer H, Lieberman DE (2015) A Wider Pelvis Does Not Increase Locomotor Cost in Humans, with Implications for the Evolution of Childbirth. PLoS ONE 10(3): e0118903. doi:10.1371/journal.pone.0118903