Homo sapiens newborns, by contrast, are helpless and have to be held if they demand physical contact; they are characterized by their near-complete dependency on adult care for years. Newborn chimpanzees’ brains are close to 40 percent of adult size, but grow to nearly 80 percent of adult size within a year. Newborn Homo sapiens’ brains are around one-quarter of the size they will achieve at adulthood and only begin to approach adult size when they reach the early stages of puberty. Partly this is an adaptation to enable them to escape their mothers’ wombs through birth canals dangerously
...more
