In order to walk upright, the hips and birth canal of women had to narrow, while the brain of the fetus kept getting larger. The combination meant that, as Yuval Noah Harari writes in Sapiens, “Death in childbirth became a major hazard for human females. Women who gave birth earlier, when the infant’s brain and head were still relatively small and supple, fared better and lived to have more children. Natural selection consequently favoured earlier births.”[22] Giving birth to utterly helpless little creatures had enormous consequences for our species.
