Eric Clapton, Paul McCartney, and Michael Douglas prove that women do not mind hitching themselves to drastically older men. Stephen Proulx, a zoologist at the University of Toronto, has developed an evolutionary model that makes this behavior easier to understand: It's not just about money, but it's not just about genes either.
The prevailing biological theory for matches between younger women and older men is that mature males have proved the superior fitness of their DNA by the mere fact that they are still around. Using game theory and computer modeling, Proulx argues instead that age-divergent coupling is rooted in appearance. Nearly every animal uses some form of signaling display, such as a peacock's plumage or a buck's antler battles. Such displays cost the animal a lot of energy, and become increasingly hard to maintain with age, so a good display by an elderly male is a more reliable indicator of genetic quality than a comparable show by a younger, stronger one.
In human terms, an older man flaunting a new Porsche is more persuasive to a potential mate than a young man making a similar display. The show of wealth tends to reflect the fitness over time of the older man; from a young upstart, it might mean he has traded long-term for short-term success. "It loosely translates to a young guy not blowing his college savings on a sports car, while a 65-year-old figures, 'What the hell,'" Proulx says. "I call it the 'Revenge of the Nerds' effect."