Myth 81: “Chameleons Have Two Brains”

Walking through a wonderful rainforest in eastern Madagascar, two of my guides confronted me with a very strange question: Is it true that chameleons have two brains? They explained that tourists had repeatedly told them this. The justification was that the huge eyes move independently, each receiving separate pictures of the environment, and therefore they must be operated by separate brains.

The reality: this nonsense comes from the same kitchen as the statement that hippopotamuses do not have an anus. The supposed "reasoning" behind that myth is that the hippo's body is so huge because all the food they eat stays inside. In other words, their massive size is explained by the idea that nothing is ever expelled. This is, of course, biologically absurd.

To be explicit, chameleons have only one brain, which operates both eyes. They possess a special arrangement of the optic nerves that supports the extreme mobility of the eyes, including rotation and the protruding and retracting of the iris. But the brain remains single.

Independent eye movement is typical for many vertebrates. All reptiles can move their eyes independently, and in some cases simultaneously. In chameleons, this ability is simply more obvious.