Here's the good news: Having a secret mommy crush doesn't mean you're a bad person, about to have an affair, in a bad marriage and/or that you married the wrong guy. So why do these crushes happen?

Secret crushes can make a woman feel like a woman again. It's hard to feel like your sexy self when you're constantly cleaning up dirty laundry, dirty diapers, helping the kids with homework or cooking all the time. Sometimes being a mom and wife, although terrific in countless ways, can get a woman feeling more like a servant than a supermodel.

Having a crush is really less about the other person and more about us having the feelings we want to have, i.e., like feeling alive, excited, exciting and beautiful. Sometimes crushes are motivators to do something nice for yourself, like work out or buy something pretty and new, activities that some moms have a hard time doing for themselves. Secret crushes, when not acted on, are safe, sexy yet simultaneously ego-boosting. This intoxicating feeling often happens during transitional moments in a woman's life.

So the next time you find yourself having a secret crush, just enjoy it! All it really means is that you're still alive and remember what it's like to feel like an attractive woman. Then go and use that extra zest for life to enjoy your fabulous husband and wonderful kids. Happy fantasizing!

The study, published in the Aug. 29 issue of PLoS ONE, notes that while women often lose their reproductive capacity around age 50, men can often remain productive into their 70s. From an evolutionary perspective, women who can no longer reproduce are non-players, and since "it takes two," men partnered with menopausal women are also irrelevant.

More interesting, when old men father children, their genes seem to increase the lifespan of both sexes over evolutionary time.

Thus, Charles Darwin would say it's advantageous for males to live longer lives providing they can find a woman capable of reproducing. Natural selection should favor longevity-boosting genes, which would get passed down from fathers to both sons and daughters. So women would benefit as well in future generations, the scientists say.

"By increasing the survival of men you have a spillover effect on women because men pass their genes to children of both sexes," said study team member Cedric Puleston, a doctoral candidate at Stanford University.