Why are we born with a small brain?
All human babies are born underdeveloped, literally premature compared to cubs of any other species. No animal has a childhood as long as humans, and no offspring is born with such a small brain relative to adult brain mass: a human newborn has only 30% of it.
All researchers agree that we are forced to give birth to immature human beings due to the impressive size of their brains. The classic explanation is the midwifery dilemma, that is, a history of conflict between uprightness and a large head.
Anthropologist Holly Dunsworth calculates that to give birth to more mature babies, it would have been enough to increase the width of the birth canal by only three centimeters, although evolution at some point stopped the expansion of the hips anyway. We probably have to be born prematurely for our brains to develop in interaction with the external environment, because there is rather little stimulus in the uterus in general.
