ABSTRACT
Sociality, the preference for living in a community rather than in isolation, is central to human survival and reproduction. Human social life continues the mammalian system of caretaking, in which females produce milk, infants suckle, and females and young maintain contact through olfactory, tactile, and vocal modes of communication. Mammalian innovations in anatomy and physiology provide a basis for profound changes in energetics and, consequently, for social behavior. Mammalian females of all species maintain nutritional warehouses for reproduction. Mammalian bones store calcium, which is mobilized during pregnancy and transferred through the placenta for bone and tooth formation in the fetus. Primate social life builds upon mammalian biology and behavior and further expands the time and energy put into the caretaking of young. The expanded mammalian brain requires continual oxygen and nourishment during fetal and infant growth and throughout life, which is achieved through body temperature regulation and steady food supply.
