New Study Reinforces Biological Bases of Men’s and Women’s Parenting

I’ve written before about the fact that both mothers and fathers experience the same hormonal bonding to their children both before and after birth. Now, Lisa Belkin at the New York Times brings to our attention a new study of the nonapeptide oxytocin that seems to play a role in both mother-child and father-child bonding post-partum. Read about it here (New York Times, 9/2/10).

A little background. Mammals, as we know, are born immature. They therefore require long periods of care by their parents (or someone), in order to grow to adulthood. Without that nurturing and protection they’d die very shortly after birth.

But there are many problems with asking adults to devote their time and energies to anything but their own survival. Immature mammals eat but, if they’re predators, they don’t kill. Lactating females require vastly more calories to survive than do males and non-lactating females, and yet, due to childcare responsibilities they too are impaired when it comes to predation. Immature mammals are easy prey for predators, thus placing added strains on adult members of the group.

In short, the birth of an infant makes life difficult for adult mammals. That’s why serum levels of the hormone cortisol rise during and after pregnancy. Cortisol is sometimes called the “stress hormone,” and that’s what infants do – they cause stress.

So why do adult mammals care for infants given that it’s not in their individual interest to do so? The answer is that nature has provided certain hormones such as prolactin, to do the job. When a female is pregnant, her prolactin levels go up. When she’s nursing, oxytocin levels rise. Experiments with laboratory animals show that, nonexpectant adults, when injected with prolactin and cortisol start behaving like expectant parents.

Likewise, after birth, the levels of the sex steroids testosterone and estradiol drop, thereby muting sexual behavior and aggression.

All of this has been well known for years about mammals in the wild and about human females. But gradually we’re learning that human males experience the same things that females do. Back in 2000, researchers at Memorial University in St. John’s, Newfoundland discovered that men experienced elevated levels of prolactin during their partner’s pregnancy. That was followed by a drop in testosterone levels. As in women, these hormonal changes were key to preparing fathers for fatherhood.

The new research cited by Belkin finds that oxytocin levels in new fathers is equal to that of new mothers at both six weeks and six months postpartum. Exactly what stimulates the hormonal changes in males seems to be uncertain, but it may have to do with female pheromones or possibly visual stimuli.

But there’s a catch that Belkin doesn’t mention. In a society in which 40% of births are to single mothers, a man’s involvement with the mother of his child during pregnancy, may be limited. It also may be zero. Therefore, that separation likely deprives him of the one vital thing that nature provides to connect all mammals to their offspring – prolonged exposure to his pregnant partner.

Our legal system imposes no requirement on women that they inform men that they’ve fathered children. In decades and centuries past, that was less of a problem because there was such a stigma attached to unmarried childbearing. That meant that, in the overwhelming majority of cases, fathers were present during pregnancy. But we’ve abandoned the stigma and failed to replace it with anything legal, moral or otherwise that would connect mothers to fathers. The inevitable result is that fathers are often denied the vital hormonal connection to their children that every parental mammal requires.

We then wonder why men aren’t more involved in their children’s lives.

The more of this type of information that comes out, the more the case is made that women should not be able to keep children from their fathers. Mothers should be legally required to inform fathers of their pregnancy and he should have the right, from the start, to involvement in his child’s life and upbringing.

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