Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes

by Nathan H. Lents

Part of why humans are so out of step with other mammals when it comes to childbirth is because human infants are simply born too early. This is due to our species’ massive craniums and the females’ relatively narrow hips. Human gestation time is similar to that of chimps and gorillas, even though humans’ much larger brains require more time and cognitive development in order to reach their full potential. However, the size of the female pelvis limits how large the fetus’s head can grow while still in utero. If it grows too large, there is no way to get it out, and both baby and mother can perish. The compromise is that fetal gestation is cut short, and human babies are born way before they are ready.