 It's Living on Earth. I'm Ainsley O'Neill. And I'm Jenny Doering. In a moment, we'll turn a page in the history books with Peter Dykstra. But first, this note on emerging science from Don Lyman. Some snakes and lizards have horns or spikes on their heads. But why? In the past, studies have hypothesized that these horns might be for courtship, defense, or camouflage.