LONDON - When it comes to mating, guppies treasure their ugly friends - because they look so good by comparison.
An article published today by Britain's Royal Society says that male guppies prefer to associate with their drab-colored counterparts when females were around.
"Males actively choose the social context that maximizes their relative attractiveness," the article said. Or, as lead author Clelia Gasparini put it, "If you are surrounded by ugly friends, you look better."
Gasparini and her colleagues at Italy's University of Padua built their theory on a kind of guppy dating game. An aquarium was set up with one female in partition on either end. Guppy bachelorette No. 1 had two attractive, brightly colored males placed on either side of her. Guppy bachelorette No. 2 was stuck with uglier, drab-colored fish.
When a male guppy was put in the middle of the tank, and given the choice of which female to sidle up to, Bachelorette No. 2 was the more popular pick, with male guppies spending about 62 percent of their time hanging around her side of the aquarium.
What's more, the researchers found that the time guppies spent with bachelorette No. 2 correlated with their unattractiveness. The uglier the guppy, the less likely it was that he would hang around the brightly colored fish placed next to bachelorette No. 1.