Parenting and families.

Parenting in Homo sapiens is rather different to parenting in most other primates. Our long developmental period and relatively short birth intervals mean that offspring are ‘stacked’, with mothers having to simultaneously look after several dependent children at different developmental stages. This creates a high burden of care for mothers, which mothers appear to alleviate by co-opting other relatives into helping out. This cooperative breeding strategy introduces complexity into ‘parental’ investment: various individuals may be investing in children, not just parents, but also grandparents, older siblings of the child and potentially step-parents. The stacking of human offspring also introduces complexity into the allocation of parental investment across children within the same family, given that a number of children of different ages will be competing with one another for parental resources. This chapter surveys the relevant literature on human parental investment. It first introduces parental investment theory, and then discusses the issue of who invests in human children. Mothers clearly invest, but who else helps out? This section ends with a brief discussion of familial conflict, since family relationships may be competitive, as well as cooperative. The second half of the chapter starts by considering what is invested in children, and then moves on to a detailed examination of who is invested in, with particular reference to parental investment biases according to sex and birth order. Throughout, ecological variation in parenting and parental investment patterns are considered