Testosterone Drops in New Dads

According to a new study, testosterone levels in new dads drop significantly, suggesting that men may be wired to nurture.

Northwestern University anthropologists speculate that the drop in the primary male sex hormone signals that fathers evolved to care for kids, not just to hunt for game and drop it in mom's lap.

Their findings are published in the latest issue of the Proceedings of the National Academy of Sciences.

The anthropologists, led by doctoral candidate Lee Gettler, measured testosterone levels in more than 600 men in and around the large city of Cebu, in the Philippines, before the men married and then again after marriage and fatherhood. Fathers showed marked declines in salivary testosterone, with those who were both newly partnered and with newborns showing a dramatic drop of 34 percent from the levels taken when they were single.

Source: msnbc.com