Hello Baby, Goodbye Testosterone?

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The Scoop

There might be a biological reason behind why men suddenly show their sensitive sides more often when they become new dads—and it has everything to do with decreasing levels of testosterone. So what gives?

In a study from Northwestern University, researchers tracked hormones levels in a group of 600 men over five years. In the group, those who never became fathers saw a 14 percent drop in their testosterone levels, a dip considered to a normal factor of aging. But men who became dads saw testosterone levels plummet an average of 34 percent. Testosterone tanked even more in men with newborns. In this group, testosterone levels dropped a whopping 50 percent—and their levels remained low until their kid was a toddler. But the guys with the lowest hormone levels? Stay-at-home dads who spent more than three hours a day caring for children.

Your Guy

What is it about diapers that makes a man's main sex hormone seem to head for the hills? According to a report in the New York Times, it could be that men's bodies evolved hormonal systems that helped them commit to their families once children were born. In other words, while higher levels of testosterone may help men be more successful at finding a mate, high testosterone levels may hinder the nurturing required for childcare. Some experts even say that lowered levels of testosterone in new dads may help them to be more faithful in their relationships.

The findings, researchers say, could almost be demonized, "like, 'Oh my God, fathers, don't take care of your kids because your testosterone will drop way down,'" says Lee Gettler, an anthropologist at Northwestern University and co-author of the study (quote via the NY Times). "But this should be viewed as, 'Oh it's great, women aren't the only ones biologically adapted to be parents.'"