[Science!] Turns out those embattled plygs may be onto a good thing after all: A British study suggests that men with multiple wives live longer than monogamists.
The article suggests a behavioral explanation--they stay alive longer because they have to, with so many children to support. I imagine the kids and wives simply won't let the poor old dude enter senescence and kick off like a normal person.
Still, as we've learned from TV ads about spry octogenarians endlessly waterskiing and canoodling, men are biologically capable of fathering children well past the age when they should probably stop. So, in cultures that have practiced monogamy since prehistoric times, it seems there could be some natural selection at work here, as well: Over the millenia, men who carry genes contributing to longevity have more time to create greater numbers of offspring--but only if they are given access throughout their long, long lives to women of childbearing age.
A man in a monogamous culture, of course, loses that evolutionary opportunity since, once the mother of his children advances past childbearing age, his only opportunities for reproduction are illicit (and, come to think of it, probably life-shortening, if his wife finds out about it).