Dads who spend time with their children have lower levels of testosterone than single guys, according to a study that suggests family men experience a biological shift that may awaken their nurturing side. While higher testosterone is considered beneficial for finding a partner, the male virility hormone drops once a stable relationship is formed and slides again during child-rearing, according to the study, published today in the Proceedings of the National Academy of Sciences. Researchers examined more than 600 men in the Philippines over about a five-year period.
