"We could use that difference in male dominant and submissive color as a measure of their ability to change color," Stuart-Fox said.
Next they presented the chameleons with a model snake and a stuffed bird to see how well the chameleons could blend into their background when faced with a predator.
"We found that the species that change [the] most are the ones with the most conspicuous displays, whereas there was no relationship between how much they change color and the variety of backgrounds they had to match," she said.
"That suggested to us that it was selection for social communication that was the primary factor driving the evolution of color change in this group," she concluded.
The study appears in this month's PLoS Biology.
This means that chameleons primarily evolved the ability to change color to stick out to each another—and not to blend in.
"The study is particularly interesting insofar as it helps clarify a common misconception that is in textbooks and [is] widely perceived by the public and scientists alike: that chameleons are masters of camouflage," said Roger Hanlon, a senior scientist at the Marine Biological Laboratory in Woods Hole, Massachusetts.
"You look at TV commercials and you see changing chameleons," said Hanlon, who was not affiliated with the research.
"Well that's great, but the camouflage changeability story lacks a scientific basis. There's just no meat to that hamburger."
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