If you like to bet on fights, take heed: Chameleons with the brightest markings usually win. In lab studies pitting one male veiled chameleon (Chamaeleo calyptratus, pictured) against another, researchers looked at how aggression and fighting abilities correlated with the brightness of 28 different patches on various parts of the lizards’ bodies, as well as how quickly those patches brightened or changed color. Videos showed that during the first phase of an encounter—from a distance, when males typically provide opponents with a good look at their sides—the male with the brightest stripes on its side was more likely to make the first move toward its opponent. Once foes were in close proximity and face-to-face, the male with the brightest patches on its head usually won the fight. How quickly the head patches brightened was also important, the researchers report online today in Biology Letters. The faster the flash, the more often that male bested its foe. It’s not yet clear, the researchers say, but a male’s ability to change color rapidly may be a sign of its ability to quickly ramp up adrenaline and other hormones needed to take on an opponent successfully—and that wimpier chameleons learn to recognize this.