The prime years of adulthood —production and biocultural reproduction

All over the world, women reproduce, care for their offspring, and undertake considerable physical labor. The women in the photographs are carrying heavy loads of vegetation (top left), building material (bottom center), breaking stones into gravel (right), and caring for an infant (bottom left). Men also reproduce and work, but the burden of caring for infants and children falls disproportionately on women. A mother working alone cannot do all the production needed to successfully reproduce and support her infants. Even the help of one man, for example the father, is usually not sufficient. People depend on a network of biocultural relations for successful reproduction. Ethnographic research among contemporary human foragers provides detailed examples of the extent of biocultural reproduction. Anthropologist Frank Marlowe lived with the Hadza people of north-central Tanzania for many years. Marlow reported that during the first year that Hadza women are breast-feeding an infant the mothers’ ability to produce food is reduced to an average of 1,713 kcals/day. This compared to an average food production of 3,016 kcals/day for women without offspring less than 8 years old. Food contributions of married men increased from an average of 2,990 kcals/day to 3,851 kcals per/day during the first year of breast-feeding by their wives. The women’s decrease in food productivity averaged 1,307 kcals/day and the increase of food provisioning by husbands averaged only 861 kcals/day. The shortfall of 446 kcals/day is made up by increased provisioning by other members of the camp, especially maternal grandmothers of the nursing infant. Courtney Meehan lived with the Aka, tropical forest foragers of the Central African Republic, and observed mothers with infants less than 35 months old. She recorded behavior and calculated the mothers’ energy expenditure. Assistance from grandmothers provided a one-to-one energy exchange of maternal direct care, while direct infant care from fathers decreased maternal care by almost 4 to 1. In other words, in this traditional hunting and gathering society fathers provided four times more help than grandmothers. This is unusual for human societies, as it is more often the caser that maternal grandmothers provide the most help for infant and child care. These are important resource transfers between family members to mother and child. The extra efforts that the others make come at a significant cost in terms of time and energy, but the helpers are obliged and willing to make the effort because it increases the likelihood of biocultural survival of their social group.

Only the human species practices this type of intense biocultural reproduction. The non-human apes (chimpanzee, bonobo, gorilla, and orangutan) do not even practice cooperative breeding, where infant care is shared by non-breeding adults. When in human history the practice of biocultural reproduction evolved is an active topic of research. [Barry Bogin]