Childbirth in humans is much more complex and painful than in great apes. It was long believed that this was a result of humans' larger brains and the narrow dimensions of the mother's pelvis. Researchers at the University of Zurich have now used 3D simulations to show that childbirth was also a highly complex process in early hominins that gave birth to relatively small-brained newborns—with important implications for their cognitive development.