Fathers are so critical to the survival of our children and our species that evolution has not left their suitability for the role to chance. Like mothers, fathers have been shaped by evolution to be biologically, psychologically and behaviourally primed to parent. We can no longer say that mothering is instinctive yet fathering is learned.
The hormonal and brain changes seen in new mothers are mirrored in fathers. Irreversible reductions in testosterone and changes in oxytocin levels prepare a man to be a sensitive and responsive father, attuned to his child’s needs and primed to bond – and critically, less motivated by the search for a new mate. As a man’s testosterone drops, the reward of chemical dopamine increases; this means that he receives the most wonderful neurochemical reward of all whenever he interacts with his child. His brain structure alters in those regions critical to parenting. Within the ancient, limbic core of the brain, regions linked to affection, nurturing and threat-detection see increases in grey and white matter. Likewise enhanced by connectivity and the sheer number of neurons are the higher cognitive zones of the neocortex that promote empathy, problem solving and planning.
But crucially, dad has not evolved to be the mirror to mum, a male mother, so to speak. Evolution hates redundancy and will not select for roles that duplicate each other if one type of individual can fulfil the role alone. Rather, dad’s role has evolved to complement mum’s.