Infant Feeding in Prehistory
Prehistoric patterns of human infant feeding are important for understanding the forces that have shaped the nutritional requirements of today’s infants and the biological capacities of their mothers to satisfy these requirements through lactation. The primary sources of data to reconstruct such patterns are observational studies of nonhuman primates in the wild, particularly the great apes, and ethnographic studies of contemporary peoples whose nomadic lifestyle and level of material culture probably approximate those of the first humans.
As a mammalian class, virtually all primates – prosimians, monkeys, and apes, as well as humans – follow a k-strategy of reproduction. That is, they have a small number of infants, most born as singletons, in whom considerable parental attention and effort are invested. The consequence is that a relatively high number of offspring live to adulthood, with the success of such a strategy depending on close physical contact for protection. Thus, nonhuman primate parents carry, rather than cache, their infants – a constant contact that is reinforced by primate milks. These are uniformly high in sugar and low in satiety-producing fat – a milk composition more suited to a frequent-snacking pattern of eating than to one of large, isolated meals. Frequent nursing episodes enhance the amount and, possibly, the energy density of milk (Quandt 1984a). They also delay the return of ovulation, leading to longer birth intervals. Such a biobehavioral complex involving infant feeding, infant care, and birth spacing was doubtless encouraged by the selection process in primate evolution, and consequently, infant feeding became an integral part of the reproductive process, as is demonstrated by studies of human foragers.