WHY ARE HUMAN beings born in a state so immature that it takes 8 to 10 months before the human infant can even crawl, and another 4 to 6 months before he can walk and talk? That a good many years will elapse before the human child will cease to depend upon others for his very survival constitutes yet another evidence of the fact that man is born and remains more immature for a longer period than any other animal.
The newborn elephant and the fallow deer can run with the herd shortly after they are born. By the age of 6 weeks, the infant seal has been taught by his mother to navigate his watery world for himself. These animals all have long gestation periods, presumably because animals that give birth to small litters, which they are unable to protect as efficiently as predatory animals can, must give birth
Montagu A. Neonatal and Infant Immaturity in Man. JAMA. 1961;178(1):56-57. doi:10.1001/jama.1961.73040400014011