As I said recently, humans are a bi-parental species. That means that nature equips both sexes for parenthood. The exact process by which it does so is complex and far from completely understood, but suffice it to say that not all mammals are bi-parental. Think about grizzly bears and African lions, for example. Males of those species take no part in rearing young and are in fact dangerous to them
Other species, from prairie voles to a vast array of primates including humans involve males to various degrees in parenting. A little over 40% of mammal species are bi-parental while some 93% of birds are.
I’ve reported before on an intriguing study of the levels of the hormones oestradiol, prolactin and cortisol in expecting parents. The study was done back in 2001 and found that the fluctuations in those hormones that produce parenting behavior in other animals and that exist in pregnant women, are also found in those women’s partners. That is, the things that compel adults to care for children are present in both mothers and fathers.
Now my understanding is that more recent research has undercut the findings of the 2001 study, but the question remains, given that humans are bi-parental, what is the biology of fathers’ attachment to children?
In evolutionary terms, the problem with bearing immature children who need a long time to come to sexual maturity is that they decrease the adults’ chances of survival. Immature offspring eat but don’t kill. They can’t defend themselves or the group, they’re slow, weak and uneducated in the arts of survival. Pregnant and lactating females require far more calories to survive than do any other member of the group.
So on one level, it makes no sense for adults to care for offspring. And in fact, many or most reptiles do exactly that; once hatched, the kids are on their own. But mammal babies, particularly human ones, require long periods of care before they can begin to reproduce. Nature therefore equipped us and many other species with the biological apparatus to overcome our tendency to abandon our offspring. The species wouldn’t have gotten very far if it hadn’t.
This article delves into that apparatus in men (Babble.com, 9/23/10). What strikes me most is how insufficient is the evidence of the precise mechanism by which nature recruits human fathers to the cause of childcare.
The author, Heather Turgeon, is a psychotherapist. She noticed that, when she was pregnant and just after she gave birth, her husband changed to become more protective, not just of her and their child, but of others as well. “He’s a dad, and it has changed his brain.”
The biology of fatherhood doesn’t get much play — dad manuals and parenting advice usually focus on how a man can support his partner and take care of her, so she can in turn take care of the baby. But it’s becoming increasingly clear that being a dad (and even preparing to be a dad) programs men differently, down to the level of brain cells and hormones…
When scientists look at the brains of these primates (marmosets), they find that after mom gives birth, the dads actually grow more neuron connections in certain areas of the brain’s prefrontal cortex — regions involved in caretaking and bonding. After becoming fathers, they have more receptors for the chemical vasopressin, which is related to nurturing and attachment…
Not only that, male hormones change while mom is pregnant. Prolactin levels go up in the male marmoset and cotton-top monkeys during pregnancy. And after childbirth, human dads have a drop in cortisol and testosterone (which scientists think makes them less likely to fight and more likely to devote energy to caretaking).
So the human father’s connection to his child exists at the most basic level – the biological. It exists, that is, if Mom allows it. A mother who keeps dad in the dark about a pregnancy or bars him from being present during her pregnancy effectively prevents him from forming those all-important bonds.
But Turgeon tells us Dad’s not the only one effected.
And as Dad is changing, want to guess who else is being affected? Last month, a Scientific American article highlighted research that suggests babies change when dad is around.
That research is on laboratory rats, so it may not be applicable to humans.
The research, however, is strong enough for us to assume that, in humans as in rats, dads and babies change each other. We tend to see characteristically maternal behaviors as the gold standard for attachment, but dads can have just as strong a drive to attach (for example, a recent study found that oxytocin levels rise equally in new moms and dads), even if the result looks different on the outside — moms” soft cuddles and high-pitched “motherese” voices vs. dads” physical play and a tendency to show objects to the baby.
But these are all attachment behaviors, and they all reveal a deeper biological drive to bond, teach, and care for our kids. My husband says that as a father he sees the world through a new lens — it’s part of his identity and he almost can’t remember what life was like before. Becoming a parent changes both mom and dad at the core.
The scientific inquiry into the biology of fathers’ attachment to their children and how those children are impacted by it has barely gotten off the ground. Obviously, that science can and should make an enormous impact on fathers’ rights in the future.
I’m no biologist, but I’d welcome any information readers can provide about advances in research on those topics.