How childbirth went industrial. Human birth is an astonishing natural phenomenon. Carol Burnett once told Bill Cosby how he could understand what the experience was like. “Take your bottom lip,” she said, “pull it as far away from your face as you can, and now pull it over your head.” The process is a solution to an evolutionary problem: how a mammal can walk upright, which requires a small, fixed, bony pelvis, and also possess a large brain, which entails a baby whose head is too big to fit through that small pelvis. Part of the solution is that, in a sense, all human mothers give birth prematurely. Other mammals are born mature enough to walk and seek food within hours; our newborns are small and helpless for months. Even so, human birth is a feat involving an intricate sequence of events.