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January 24, 2019 by Robert Franklin, Member, National Board of Directors, National Parents Organization

This is a necessary article (Aeon, 1/17/19).  That is, if you want to understand fathers, their relationships to mothers and their kids, you need to read and digest it thoroughly.  The writer, Anna Machin, reprises some of what I’ve said before in this blog, but adds much, much more.  Her astonishing thesis is that it is fathers and the role they play in children’s lives that separate us from other primates.  That of course is a powerful statement, given the amazing and unpredictable evolutionary success of Homo sapiens.  Is it really just about dads?

Well, no.  Countless other factors enter in, but consider Machin’s words:
[T]here is one aspect of human behaviour that is unique to us but is rarely the focus of these discussions. So necessary is this trait to the survival of our species that it is underpinned by an extensive, interrelated web of biological, psychological and behavioural systems that evolved over the past half a million years. Yet, until 10 years ago, we had neglected to try to understand this trait, due to the misguided assumption that it was of no significance – indeed, that it was dispensable. This trait is human fatherhood, and the fact that it doesn’t immediately spring to mind is symptomatic of the overwhelming neglect of this key figure in our society.  
Strong stuff and, as far as I can tell, accurate.  Machin is altogether aware of how neglected fathers are and have been in our society and her article seeks to change that.  But for now, the question arises “How did fatherhood become important for human babies, but not for, say, chimpanzees?”  As I’ve said before, the simple facts of our gestation, immature birth, long period of socialization, etc. all militate in favor of bi-parental childrearing.  But Machin puts meat on the bones of what I’ve said.
As any parent knows, human babies are startlingly dependent when they are born. This is due to the combination of a narrowed birth canal – the consequence of our bipedality – and our unusually large brains, which are six times larger than they should be for a mammal of our body size.
This has meant that, to ensure the survival of mother and baby and the continued existence of our species, we have evolved to exhibit a shortened gestation period, enabling the head to pass safely through the birth canal. The consequence of this is that our babies are born long before their brains are fully developed…
So, evolution selected for those members of our species who could wean their babies earlier and return to reproduction, ensuring the survival of their genes and our species. But because the brain had so much development ahead of it, these changes in gestation and lactation lengths led to a whole new life-history stage – childhood – and the evolution of a uniquely human character: the toddler.  
In short, the long period of time between birth and sexual maturity and the still longer time until an individual can get as much food as he/she consumes militate in favor of other caregivers than just Mom.  Plus, in order to keep the species in survival mode, Mom, once she stopped lactating, became fertile again and soon had another infant to demand all or most of her care.  So who could step in?

Much of the time it was other female members of the social group.
But 500,000 years ago, our ancestors’ brains made another massive leap in size, and suddenly relying on female help alone was not enough. This new brain was energetically hungrier than ever before. Babies were born more helpless still, and the food – meat – now required to fuel our brains was even more complicated to catch and process than before. Mum needed to look beyond her female kin for someone else. Someone who was as genetically invested in her child as she was. This was, of course, dad.
Although Machin doesn’t mention it, Dad was almost certainly a member of the group’s dominant male hierarchy.  If he weren’t, Mom likely wouldn’t have mated with him.  So recruiting Dad to his child’s care and protection simultaneously gave the child the status of a presumptive member of that hierarchy.  That improved the child’s possibility of survival.  Plus,
As time ticked on and the complexity of human life increased, another stage of human life-history evolved: the adolescent. This was a period of learning and exploration before the distractions that accompany sexual maturity start to emerge. With this individual, fathers truly came into their own. For there was much to teach an adolescent about the rules of cooperation, the skills of the hunt, the production of tools, and the knowledge of the landscape and its inhabitants. Mothers, still focused on the production of the next child, would be restricted in the amount of hands-on life experience they could give their teenagers, so it was dad who became the teacher.
The same holds true today. 
In all cultures, regardless of their economic model, fathers teach their children the vital skills to survive in their particular environment. Among the Kipsigis tribe in Kenya, fathers teach their sons about the practical and economic aspects of tea farming. From the age of nine or 10, boys are taken into the fields to learn the necessary practical skills of producing a viable crop, but in addition – and perhaps more vitally – they are allowed to join their fathers at the male-only social events where the deals are made, ensuring that they also have the negotiation skills and the necessary relationships that are vital to success in this tough, marginal habitat.
My guess is that, when American mothers and fathers divorce, the older the child, the more likely he/she is to express a preference for living with Dad.  If so, that would seem to agree with what Machin wrote in the previous quotation.

And of course, as I’ve said too many times to count, all this parenting behavior is rooted in our brain biochemistry.  Back in 2000, Storey, et al found the parenting hormones produced by mothers during pregnancy to be present in fathers who were exposed to their pregnant mates or immediately post-partum when exposed to their newborns.  Her findings were never robustly replicated, but others have studied oxytocin and found exactly that.  Mothers and fathers both increase their level of oxytocin output which leads to caregiving behavior.  But the oxytocin molecule finds receptors in different parts of the brain in males than in females.  Hence, differing parental behaviors.

Machin gives us more.
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.
And yet more.
But crucially, dad has not evolved to be the mirror to mum, a male mother, so to speak…
This is no more clear than in the neural structure of the brain itself. In her 2012 fMRI study, the Israeli psychologist Shir Atzil explored the similarities and differences in brain activity between mothers and fathers when they viewed videos of their children. She found that both parents appeared similarly wired to understand their child’s emotional and practical needs. For both parents, peaks of activity were seen in the areas of the brain linked to empathy. But beyond this, the differences between the parents were stark.
The mother’s peaks in activity were seen in the limbic area of her brain – the ancient core linked to affection and risk-detection. The father’s peaks were in the neocortex and particularly in areas linked to planning, problem solving and social cognition. 
And what if Mom can’t or won’t play the primary caregiver role?  Or what if, similarly, little Andy or Jenny has two daddies?
Where a child was brought up by two fathers, rather than a father and a mother, the plasticity of the human brain had ensured that, in the primary caretaking dad, both areas – mum’s and dad’s – showed high levels of activity so that his child still benefited from a fully rounded developmental environment.
Our understanding of fathers, their unique contributions to children and their hugely important role in our evolution, grows daily.  And everything we learn increases our understanding of the vital role fathers play for their children, their families, society and the species.

I’ll have more to say on Machin’s indispensable piece tomorrow.

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