It turns out that the túngara frog can sometimes snub an obvious mate choice in favor of a lessor suitor. In a study published Thursday in Science, researchers showed that the Central American frogs can be tricked into picking "ugly" mates -- even when their prince charming is just within hopping distance.
The trick is to give the female three choices. If just two males are up for consideration, she'll always pick the one that's more "attractive" (which in this case means having a long, low croaking call that repeats rapidly). But throw in a third dude, and she's likely to pick the second best option. At least when those dudes are actually just speakers playing looped mating calls, as they were in the new study.
This so-called "Decoy Effect" is often seen in humans -- it's even touted as a way to help business owners increase sales. Here's the gist: With just two products to pick from, you're likely to either want the cheapest one or the one with the best features. But adding a third option that's similar to one of the other two makes you more likely to select the third, "best" candidate.
In the case of the túngara frog, ladies were much more attracted to a fast call than a deep one. But when an even slower, deeper call was introduced, the frogs flocked to the previous loser -- the voice that was deep and moderately slow.
The researchers call this switch irrational because, well, it doesn't make sense for the addition of a lesser candidate to make a choice mate into a loser. One mate should be better than the other, in an evolutionary sense. And it's possible that these female frogs are making the wrong choice, flustered by the number of options or confused by the relative unattractiveness of the third candidate.
But it's possible this fickle selection could reveal things we don't yet understand about mating -- in frogs or otherwise.
“In some in cases irrational decisions can be looked at as the better way to have gone,” Study author Amanda Lea of the University of Texas told TIME. “Going with your intuition is often better. It just depends on how you weigh your costs and benefits.”
In future studies, Lea and her colleagues will try to figure out whether there really is some benefit to choosing the lesser of two dud dudes.