Primate babies' large heads create challenging births

Primate babies can face difficult births due to large head sizes relative to their mothers' pelvic canals. New research indicates some small primates, like squirrel monkeys, have heads nearly twice the size of their mother's pelvic space, presenting significant birthing challenges. This study, published in Nature Ecology & Evolution, also identified evolutionary adaptations in some species, such as galagos, whose pelvic bones do not fuse, aiding in childbirth.