After one of the most expensive celebrity divorces in history, Neil Diamond is getting back on the horse. Yes, the Jewish Elvis has proposed to his manager, Katie McNeil. The 70-year-old Diamond is certainly young at heart. Not only is his bride to be 30 years his junior, he also proposed via a micropoem on Twitter.

Diamond is hardly unique in marrying a woman several decades younger. Indeed, it has become de rigueur for powerful men in their golden years to find a far younger lady to share their bed. When guys hear about older men bedding women young enough to be their daughters, reaction ranges from “Ew, gross” to “Right on, bro.” But regardless of any personal opinions, science has already closed the case. Older men bedding younger women is an evolutionary adaptation, and a particularly useful one.

A 2007 study of Sami “reindeer people” in Finland found that men’s “evolutionary fitness” peaked when they married women 14.6 years younger than themselves. This is apparently the point where the fertility and reproductive value of women and the masculine skills of men intersect to provide the greatest evolutionary benefit. This age difference led to the greatest chance of having children who lived to see adulthood.

Having these skills is particularly important in a traditional society like that of the Sami. But having man-skills is also important in a contemporary society. While you won’t have to hunt and fish to feed your family, you will have to know how to get and keep gainful employment. Knowing how to repair your own house and change your own oil aren’t bad skills, either. You’ll spend less money on maintenance and more money getting your kid private dance lessons to improve his or her “evolutionary desirability.”

The drive to marry and bed younger women isn’t just about a prosperous union, however. Another 2007 study, of hunter-gatherer groups, found that older men laying younger women is responsible for longer life spans. In traditional societies, men sire children well into their 80s. One subject of the study was still cranking out babies at 95. This not only increases the birth rate overall, it also means older men are passing along their longevity genes. Mother Nature, it seems, prefers May-December romances for more reasons than one.

And let’s be honest—younger women just like older men, too. Think about what you were like in your early twenties. Are you really surprised how many women your age were dating older guys? Older men are more mature, established and capable. Fewer things are sexier than power, whether that’s the power to get things done around the house or the power that comes with making partner at a currency trading firm. A lady doesn’t need to have creepy daddy issues to respond to that kind of aphrodisiac.

Don’t ask us what Demi sees in Ashton, though.