Chameleons Use Color to Communicate, Not Hide

Though most people believe chameleons use their color-changing abilities for camouflage, a new study released today proves this is incorrect. In fact, chameleons evolved the ability to transform skin color quickly to send messages to other chameleons. In a careful analysis of how and when chameleons change color, a group of researchers from South Africa and Australia showed that chameleons use color to stand out in their environments, and to signal whether they are active or passive in a conflict. Chameleons can shift to one color and back in a millisecond, too fast for a predator to see — but slow enough for other chameleons to get the message.

Write the researchers:

Overall, our results suggest that the ability to exhibit striking changes in colour evolved as a strategy to facilitate social signalling and not, as popularly believed, camouflage.
The researchers acknowledge that chameleons do use color-change for crypsis, or camouflage, but say that the ability to change colors swiftly was evolved primarily for signal transmission, or communication.

For evo-geeks, that means the chameleon's special power of color-changing is primarily the result of sexual selection, not natural selection. And it's further proof that animal communication is far more ubiquitous than we ever realized. Not only are chameleons communicating, but their need to exchange information with each other is driving their evolution. Image by Jerome Delay/AP.

Selection for Social Signalling Drives the Evolution of Chameleon Colour Change [PLoS Biology]