What happens when a man becomes a dad?

A recent scientific study from Northwestern University has discovered that after a man becomes a dad, his testosterone levels go down. Less testosterone means less aggression, but it also means less sex drive. My own unscientific studies have confirmed that dads in their 20s and 30s are less likely to talk inappropriately about hot women, a result, perhaps, of lower testosterone and higher respect for women's bodies. Ogling (even at pretty moms at the playground) also seems to suffer a statistically significant decline.

There have been no studies establishing a link between fatherhood and a decreased attachment to athletic teams. Indeed, I observed one recent father over a series of Monday nights this past fall (also Sunday afternoons), and while his sex drive may have been lower—as evidenced by his not even noticing our waitress—his desire for his team to drive and score a touchdown seemed, if anything, enhanced. Hypothesis: With fewer masculine outlets, the remaining ones become more important. On the other hand…

Because my pop pals drink less, when they do drink they get just as hammered as they used to—but from less. Men who could formerly survive a few rounds of bourbon effortlessly are suddenly getting pretty silly when they split a growler five ways around their kitchen table. Implications for further research: This switch from hard alcohol to beer, while a good attempt at being responsible, might also be a contributing factor to the high percentage of fathers with beer bellies. And in truth…

A recent Scientific American article gathered the research on couvade (the medical term for men experiencing pregnancy symptoms), and up to 80 percent of soon-to-be fathers experience some combination of weight gain, bloating and even nausea. My own experience suggests that at least some of these symptoms are, er, exploited. When a pregnant woman suddenly needs pickles, fruit and iron, I get it. But when my buddy suddenly has a weird craving for pepperoni pizza, bacon cheeseburgers and buffalo wings, he's just looking for an excuse to avoid salad. There's good news…

I've also observed new dads losing a lot of weight. It's probably a result of not sleeping much and the huge amounts of energy these guys are expending to keep their newborns healthy and happy. But Daddy Skinny-Fat is definitely the latest body trend. Co-morbidities include exhaustion, irritability, that glazed look in their eyes, not having any unstained shirts, and not knowing who Gotye is. Which is ironic because…

There is an increasing body of research involving fatherhood and the brain. A Princeton University psychologist has studied male marmosets, who, like men, share parenting duties. Father marmosets develop more neurons in their prefrontal cortex than non-fathers do, suggesting that being a dad actually improves memory. To see the proof, look no further than the dads I know. I can barely remember to pay my bills on time, and yet these guys manage to do everything I do, plus they feed, clothe, change and generally keep alive another human being. And yet…