A possible australopithecine forefather?
Smithsonian Museum of Natural History
Imagine your distant forefathers. How do you see them? Are they defined by being hunters and provisioners? Do you envision them sitting calmly holding an infant in their laps while a fire sparks at night? Do you celebrate some vision of them fighting off threatening strangers who would be only too happy to disappear with a female of one’s own group, but not her child? Suppose you had to capture some vision of an early father (let’s say you are designing a museum exhibit)—how do you portray some archetypal aspect of early human fatherhood?
Scholars have long contemplated the evolutionary roots to human fatherhood. They should—as involved fathering stands out as a distinguishing characteristic of what makes us human. Much of the discussion has centered on food provisioning, in which fathers provide resources like game meat as part of a sexual division of labor and of benefit to their offspring. But there’s more to the story than that. Here, drawing upon a new review paper, I present seven take-home points concerning the evolution of human fatherhood.
Human paternal care is facultative. Dad’s care is not required. You and many others before you might have survived if dad had not been there. There are studies suggesting that the presence of a father has less of an impact on child survival than grandmothers. How human paternal care is expressed is quite variable.
Paternal care may not be required, but may be beneficial to others. It may be beneficial to mothers—helping them have shorter inter-birth intervals (IBIs), or the time between births. Shorter IBIs ultimately facilitate mothers having higher lifetime reproductive success than their foremothers without lacking such paternal care. Paternal care may also aid kids’ social and reproductive success. Fathers’ resources or social connections may beneficially aid a child’s social trajectory.
The evolution and expression of human paternal care is best viewed as a triadic phenomenon (mom, dad, child). It takes two—mom and dad—to make a baby, but many aspects of human fatherhood are best viewed as contingent upon the relationship with a child’s mother. That is especially true for young, nursing infants, for whom mom is the most important feature of her/his environment, while dad’s interactions entail being granted access and coordinating efforts with a mother. Moreover, comparative evidence suggests that the long-term partnerships within which humans tend to reproduce likely preceded (rather than coincided with or caused) the evolution of human paternal care.
Human paternal care evolved in mosaic fashion. Despite the emphasis in many models of the evolution of human fatherhood on one factor such as male provisioning, there are different components of paternal care: protection, provisioning, direct childcare, wealth transfers, social and moral training. Each of those components may have evolved at different times and in different contexts. Paternal protection likely has the deepest ancestry, whereas wealth transfers building on heritable stores of resources like land or livestock are the most recent of these.
Many elements of human involvement in family life are consistent with a reduction in mating effort. Involved human fathers may have evolved to pursue fewer alternative mating opportunities, focusing instead on typically one or otherwise few ongoing sexual partnerships. Time and effort devoted to paternal care may have come at expense to male coalitionary and fighting behaviors. A putative reduction in body size sexual dimorphism among our hominin ancestors may be consistent with these kinds of changes over an evolutionary time scale. There are also developmental (within the life course) aspects to fathers’ involvement in family life entailing a reduction in mating effort—as human males shift from early- to prime-adulthood, they also tend to invest less in mating effort, with that measurable in many ways including reduced male-male violent encounters over social status.
Mixed families, including stepfathers, likely have a deep evolutionary history. Few models of the evolution of human fatherhood directly focus upon stepfathers. Those that do often feature expectations of reduced childcare and/or greater risk of harm to a stepchild, and that investment by stepfathers can be viewed as mating effort. Data from recently studied hunter-gatherers indicate stepfathers are typically present, as among the !Kung or Hadza or Aka, and thus suggest that family dynamics have long entailed these kinds of mating/parenting effort considerations of step- and biological fathers.
Evolutionary depictions of human fathers entail more diversity than imagined. All models of human fatherhood tend to feature prime-aged fathers at the expense of greater variation among fathers. Humans father offspring at a wider age range than is the case among our great ape cousins such as chimpanzees. For all of the kinds of paternal care men may provide (e.g., direct care, provisioning), there is variation in those domains across men, meaning that typological accounts mask the greater variation occurring behind the theoretical scenes. Human male reproductive skew is likely also lower than other great apes, which is part of more egalitarian male-male social relationships and a package by which a higher fraction of human males likely father (and care for subsequently) offspring than other apes.
Take these seven take-home points together, and you have the foundations underlying the evolution of human fatherhood.
Gray, P. B., & Crittenden, A. N. (2014). Father Darwin: Effects of Children on Men, Viewed from an Evolutionary Perspective. Fathering, 12, 121-142.