Data from: Human variation in the shape of the birth canal is significant and geographically structured

The human birth canal shows a tight fit with the size of the neonate,
which can lead to obstetric complications. This is not the case in other
apes, and has been explained as the outcome of conflicting evolutionary
pressures for bipedal locomotion and parturition of a highly-encephalised
fetus. Despite the suggested evolutionary constraints on the female
pelvis, we show that women are, in fact, extremely variable in the shape
of the bony birth canal, with human populations having differently-shaped
pelvic canals. Neutral evolution through genetic drift and differential
migration are largely responsible for the observed pattern of
morphological diversity, which correlates well with neutral genetic
diversity. Climatic adaptation might have played a role, albeit a minor
one, with populations from colder regions showing a more transversally
oval shape of the canal inlet. The significant extent of canal shape
variation among women from different regions of the world has important
implications for modern obstetric practice in multi-ethnic societies, as
modern medical understanding has been largely developed on studies of
European women.