A detailed review of evidence, slated to be published in the Journal Evolutionary Anthropology, challenges the obstetrical dilemma - the theory of trade‐off between selection for a larger birth canal (permitting successful passage of a big‐brained human neonate) and the smaller pelvic dimensions required for bipedal locomotion. In the review, Assistant Anthropology Professor Anna Warrener argued that the evidence to date does not offer strong support for the obstetrical dilemma, and that scientists have not paid enough attention to possible alternatives.

A Theory of Childbirth’s Evolution May Not Be What You’re Expecting
The New York Times, July 30