We can safely file this study under "not helpful":
Testosterone, that most male of hormones, takes a dive after a man becomes a parent. And the more he gets involved in caring for his children—changing diapers, jiggling the boy or girl on his knee, reading “Goodnight Moon” for the umpteenth time—the lower his testosterone drops. So says the first large study measuring testosterone in men when they were single and childless and several years after they had children. Experts say the research has implications for understanding the biology of fatherhood, hormone roles in men and even health issues like prostate cancer.
“The real take-home message,” said Peter Ellison, a professor of human evolutionary biology at Harvard who was not involved in the study, is that “male parental care is important. It’s important enough that it’s actually shaped the physiology of men.... My hope would be that this kind of research has an impact on the American male. It would make them realize that we’re meant to be active fathers and participate in the care of our offspring.”
Those thumping sounds you heard this morning were millions insecure American men dropping infants and backing out of nurseries. Oh, and then there's this: other studies have shown that women prefer less manly men as mates and co-parents—you know, men with lower testosterone levels—but when women are ovulating, when they're horny, they prefer (and sometimes seek out) men with more masculine traits and higher testosterone levels. But there's a silver lining, guys:
While testosterone isn't necessarily a good thing in itself—research suggests that it can inhibit immune function, and eunuchs, who have low levels of testosterone, tend to live longer than normal males—its presence can be indicative of quality.
So, hey, it's not all bad news!
Some are pointing to this study and saying that it's proof that men are wired for monogamy. But it looks more like men are rewired for monogamy.