New moms aren’t the only parents whose bodies are going through transformations — new dads can experience physical change, too, and not only due to lack of sleep. According to biologist Marlene Zuk, author of Paleofantasy: What Evolution Really Tells Us About Sex, Diet, and How We Live, “fathers have been shown to have biological changes in testosterone when a baby is born”. The effect of those changes is “keeping him with the family”, she says.
It’s been known for a long time that fathers had lower levels of testosterone than childless men, says the National Science Foundation, but until recently it wasn’t clear if that might be because men with less testosterone were more likely to settle down in the first place. Research in the past few years shows that, in fact, men with higher testosterone were more likely to start long-term relationships and become fathers — but their testosterone levels declined greatly after that. They were lowest in men who spent three hours or more per day taking care of children.
Not that spending time with the kids emasculates a father, or that this would be a good thing — but it apparently can make him a little more cooperative and a little less competitive. And, after all, Mom is going to need all the cooperation she can get, not to mention that constantly beating a small child at checkers does not lead to a happy home life.
Speaking of that, it’s long been known that fathers’ involvement — or lack of it — has a tremendous effect on children. Maybe it shouldn’t come as a surprise that it affects the fathers themselves too.
It’s obvious that motherhood changes a woman’s hormones; how fatherhood changes a man’s is less clear. But obviously, human fathers are somehow attuned to their children to a point where it can cause physical change in them. A father is much more than the man who got the mother pregnant, and as sociologist David Popenoe says, “Fathers are far more than just ‘second adults’ in the home.”
So, Dad — if you’re feeling more mellow and less aggressive since the baby was born, it’s just a mysterious, but completely natural part of fatherhood.