Tiny Lizards Play Real-Life Rock-Paper-Scissors

A small lizard in the western United States uses a "rock-paper-scissors" system to survive and mate, according to new research. Scientists studying side-blotched lizards have found their biology creates three main male types. Each type has a different strategy that beats one competitor but loses to another, just like the children's hand game. An orange-throated male is aggressive and dominates blue-throated males. However, orange males cannot guard mates closely, so yellow-throated "sneaker" males steal their females. The strategy completes when blue-throated males, who are good guards, defeat the yellow sneakers. This cycle is driven by genetics and hormones. The new study maps the precise biological mechanisms—involving genes for color and stress hormones—that create and maintain this three-strategy competition in nature. The discovery shows how complex survival "games" can evolve from simple biological rules.