do high levels of the hormone progesterone create bad dads?
Testosterone is the hormone most often linked to male dominance and aggression, but a new study indicates that the hormone progesterone may play a bigger role in how males react to their offspring. Adult male mice rarely show nurturing behavior toward their offspring, and frequently attack and kill them shortly after the babies are born. Studies have shown that testosterone levels, correlated with adult intermale aggression in animals, do not correlate reliably with paternal nurturing or aggression in mice. Looking for another explanation, Johanna Schneider et al. investigated the effects of progesterone-a hormone produced in large amounts by females, and in much smaller amounts by males-on the parenting behavior of male mice. The researchers created progesterone receptor “knock-out” (PRKO) mice, missing the gene that encodes these receptors (meaning that the mice are not affected by progesterone). Lead researcher Jon Levine reports, “In male knockout mice we noticed something quite st
