Sexy and Dangerous

Animals evolved their colors to be sexy. But mostly, to be dangerous. Amphibians, reptiles, fish, insects, birds and even mammals sometimes use bright colors to attract mates. Think of the iridescent plumage of peacocks. Or the bright greens, yellows and oranges of a male iguana. But animals are about five times as likely to use bold color—especially red, yellow, black and white—to warn predators that they’re poisonous, foul-smelling or bad tasting. Think of the red hourglass on the black widow spider. Or the high contrast stripes on bees, wasps and skunks. But bright colors also make them more visible to predators; so how did this trait develop? Scientists looked at three coloration schemes across more than a thousand species, and found they fell into three groups: Camouflaged. Brightly colored. And Hidden-signal—which flash colors only when threatened. Their research suggests that some hidden-signal types developed chemical deterrents. Then, as generations passed, both their poison and coloration increased, spreading to other parts of the body until a brightly colored, highly venomous species emerged. Still, many species remained camouflaged, but developed strong poisons. While others evolved to mimic the dangerous coloration of their peers, but remained harmless. It can be hard to know which is which. So, if you ever see a brightly colored or a well-camouflaged wild animal, best to look but don’t touch.