Like father, like son
Erica Mannis discusses a new theory on the evolution of fatherhood in humans
Paternal care in humans is principal to our way of life. However, this is not seen in most other primates, and is one of our greatest behavioural differences. It is unknown when fatherhood started; previous theories have attributed it to females exchanging sexual fidelity for provisions and food from their mate. A new theory developed by economists and anthropologists disputes this, attributing partnership and parental provisioning to changing ecological conditions.
In a distinctive change from parental methods of our ancestors the Great Apes, the father’s parental investment in provisioning can last up to two decades in modern hunter-gathers. Scientists have investigated this development – ‘the emergence of fatherhood’ – but it’s roots have long remained a mystery.
The economic approach of the new theory is dependent on benefits of a ‘fit’ between exclusive partners allowing strengths of both males and females to provide for their offspring.
Its roots have long remained a mystery
Ecological change has driven many adaptations in hominins; bipedal locomotion, flexible diets and success living in diverse environments. This change is not a lone event.
The driving force in parental provisioning is complementarities. Synergistic effects that increase per capita benefits, such as division of labour and pooling of resources are complementarities, dependant on cooperation.
It is estimated this dependence on complementarities developed five to eight million years ago, alongside the gradual drying climate in Africa driving a need for a diverse, nutritious diet.
The sexes specialised in acquiring different foods. Males obtained proteins and fats whilst women collected carbohydrates. The paired foods gave higher returns, with food sharing reducing starvation risks.
The sexes specialised in acquiring different foods
These complementarities meant the food provided by the father had a greater impact on the survival of his offspring. Therefore, he would have greater Darwinian fitness over a male who had high sexual fidelity but did not provide for his offspring.
This evolutionary game theory shows the clear advantage of provisioning males over non-provisioning fathers. Should this provisioning trait be passed onto his biological sons over time this behaviour would increase across the population. The theoretical link of paternal evolution to ecological change will allow for novel predictions in the evolutionary timeline.
