According to a new study, chimpanzees, like humans, must contend with a confined bony birth canal when giving birth. In humans, the problem was exacerbated by our unique form of upright walking since ...

Medical intervention in human birth has become so widespread that spontaneous delivery is an increasingly rare event. Yet convincing evidence reveals an underlying 24-hour biorhythm, reflecting a ...

3D simulation of the birth canal of chimpanzees with (B) the fetal head in a fully extended position, the typical head alignment in apes, and (C) the fetal head in a fully flexed position, the usual ...