Valentine's Day: Secret of monogamy in the animal kingdom? They cheat

Happy Valentine's Day! It's the perfect day to look at monogamy in the animal kingdom. But if your first thoughts are warm and cuddly, you can wipe away those Disney delusions.

When it comes to monogamy among animals, there are few ladies and many tramps.


Certain species have been held up historically as models of monogamy -- swans, gibbons, the wolf pack's alpha male and female. But scientific research over time has chipped away at those paragons of virtue.

Animals cheat.

Birds, in particular, were thought to be sexually steadfast with their mates. "Turns out they weren't as monogamous as we thought," Gerald Borgia, biology professor at the University of Maryland, told the Los Angeles Times.

Researchers found that, across avian species, as many as 30% of baby birds in nests were fathered by a male other than the one helping to care for them, he said.

Male alpha wolves are known to stray with other pack members, especially close relatives, PBS' "Nature" reports. And among red foxes, thought to be so loyal, 80% of cubs in one study were the product of moms' philandering.

So, sexual monogamy is extremely rare. In sum: "Contrary to the early assumption of sexual exclusivity between socially paired individuals, it is now evident that sperm competition can also play a prominent role in partnerships of socially monogamous individuals, who may interact sexually and reproduce with multiple partners" ("Monogamy: Mating Strategies and Partnerships in Birds, Humans and Other Mammals").

Yet socially monogamous bonds do exist between pairs of animals. Sometimes those bonds last only so long as it takes to mate and raise young; for others, they last a lifetime.

Can monogamy among humans be compared with other animals' monogamy? Borgia thinks so. The unifying theme, he said, is kids. Monogamy is more likely to occur where there is the need for shared parenting.

For Valentine's Day, check out our gallery of socially monogamous, if sexually wandering, animals.

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