Detected; I reject that it's relevant to the discussion, and I'm disappointed it's the top comment. Lifestyle changes aren't relevant to the research presented in the study. What would be relevant is contrary evidence of hormonal changes in males after their spouses undergo pregnancy, or structural alterations in the brain. Of course each parent is impacted by literally taking care of an infant, but what does that have to do with one gender experiencing grey matter reductions?
You know what's super-interesting? Although it's deeply under-researched and still subject to a lot of argument, there's mounting evidence that men going through a partner's pregnancy experience significant hormonal changes as well. Papers like [1] and [2] are really preliminary (small sample sizes, etc) and don't fully agree, but both show these hormonal changes in men going through pregnancy with a partner. How much is simply the stress of a life change? How much is couvade, or "sympathetic pregnancy"? How much is evolutionarily adaptive? No one knows yet, but it's an interesting piece to the puzzle: apparently the lower testosterone, higher cortisol, and changes in prolactin and estradiol that expectant fathers experience don't have the same neuroanatomical effects as the changes women experience in pregnancy.
