A new study sheds some interesting light on what being a father does to the human body, reports the New York Times (and, no, it has nothing to do with sympathy weight gain or getting covered in spit-up or pee). Once a man becomes a dad, his testosterone levels take a significant dip, especially if he’s a hands-on dad, the study published in The Proceedings of the National Academy of Sciences found. Researchers say this big life change and the resulting biological change is hard scientific evidence that men are hormonally wired to be involved in their children’s lives.
Researchers first measured testosterone levels in a group of men in the Philippines at age 21, when they were single and childless, and then again five years later. Though testosterone levels drop with age in all men, men who had children showed a decline nearly double that of their childless counterparts. And while all dads experienced a significant decrease, especially in the first month of baby’s life, dads who did even more diapering, feeding, and general caring for their kids had experienced an even greater drop.
Dads, don’t panic. This is all quite good news, in fact. Drops in testosterone didn’t infringe on the subjects’ man-ness; they all maintained deep voices, hairy chests, and a healthy sperm count. Researchers also believe this kind of change can mean lower chances of prostate cancer, since high lifetime testosterone levels are a risk factor. What one study author thinks this means is that men with higher testosterone levels to begin with are more likely to become fathers in the first place because they tend to be more aggressive or stand out as better mates. Once they attract mates, lower testosterone levels help support stable family lives, making them good caregivers for little ones.
So moms, don’t feel you have to handle all the late-night feedings and diaper changes on your own—just wake up dad and remind him it’s good for his health.