Fathers play a key role in enabling mothers to have babies more quickly one after the other, one reason why humans have expanded to such an extent.
Human parenting is different from most other mammals, including most of our closest relatives, the apes: we wean our infants before they are nutritionally independent. That means the mother can reproduce again faster – we can “stack” our children.
But there is no way that a mother could cope alone while having more babies and still having to feed older children at the same time. Each human infant needs 13 million kilocalories to grow over a (long) period of dependency and that’s more than one person can provide, let alone if there are several children in quick succession. The solution? “Cooperative breeding.” Humans share the care of infants – both males and females get involved. “It takes a village to raise a child” is a truth stretching back to the start of humans.
How do we explain the role of the father in the human family? There are three possibilities. The first is that it’s all about providing food – man, the hunter. The second possibility is that it’s about the survival of children – man, the protector. The third is that it’s about direct core for children – man, the hands-on dad.
We believe that “man the hunter” evolved quite late in evolution. Males were able to obtain higher value and more unpredictable food – namely meat – which, once caught, is shared in the group. This resulted in a specialisation of roles. One theory is that men were motivated by showing off to get the best mate – bringing home big prizes and sharing them out. But that does not fit the other observation that men also spend a lot of time gathering things like fruit and honey, rather less spectacular, and sharing this mainly with their own mate and children; furthermore, this activity increases during the mother’s pregnancy. This activity would add little if the intended function was just to show off.
The “man as protector” is not such a convincing idea. The reality is that in early societies, the death of a father made less impact on the child’s survival than the death or a mother or even the death of another female relative.
The “man as hands-on dad” idea is more convincing. The amount of direct care by human fathers is less than that of mothers and less even than some of our related species, such as owl monkeys, titi monkeys, tamarins and marmosets. Nevertheless, human fathers can attach closely to their infants and are often highly involved in the social development of children. We believe that that fathers have a key role in modelling to boys the kind of behaviour that they are expected to continue when they reach adulthood. And if fathers are involved in caring, as well as in getting food, it is yet more support for mothers to be able to have another child earlier.
So fathers play a key role in enabling mothers to have babies more quickly one after the other, commonly regarded as one reason why humans have expanded to such an extent. Anthropology tells us that hands-on fatherhood is one of the reasons why humankind has flourished so much.