The break-ups of Reese Witherspoon and Ryan Phillippe’s and Britney Spears and Kevin Federline’s marriages are merely the latest in a long line of celebrity splits. Like Jennifer Aniston and Brad Pitt before them, Reese and Ryan were considered solid Hollywood gold -- people who could weather the temptations of fame and come through it together (most would not say the same of Britney and Kevin). But I guess all good dramas have an unexpected ending, and Reese and Ryan's marriage was not destined for happily ever after.

What is it about celebrity marriages that seems doomed for disaster?

While the rest of us often look longingly at the bottomless pockets and jet-setting lives of our Hollywood gods and goddesses, these exotic trappings don't bode well for a lasting, committed relationship. Time spent apart, too much temptation and too little consequence are just some of the challenges to monogamy, which is difficult enough for us regular folks.

In fact, Australian scientists recently discovered that female promiscuity is beneficial to marsupials: more sex with more partners ensures that the strongest sperm wins and more babies survive. So now it's not just males who glean an evolutionary advantage by spreading their seed (in marsupials at least).

Maybe celebrities provide their own sort of scientific study. In a world where financial imperatives do not apply and people can live their wildest dreams, monogamy doesn't stand a fighting chance. Celebrities live in a mythic world. It's a high speed, Technicolor land of peak experiences, often followed by crushing lows. Real relationships are difficult to sustain in such an unforgiving climate. As artists, celebrities are inspired by the idea of monogamy when they first fall in love, but eventually more primal urges win out...because they can.

Maybe the benefit of being caught between the animals and our modern-day gods and goddesses is that we get a shot at that all-too-rare thing these days: a loving, lifelong, committed relationship.

And maybe Brad and Angelina have it right after all, by not marrying!

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