A time-honored tradition for choosing teams, riding shotgun, and settling other childish disputes, the game called rock-paper-scissors has been around far longer than humans have been playing it. Similar nontransitive games, in which no one strategy reigns over all others, are played out among certain lizards, microbes, and marine organisms. And some biologists are suggesting that, rather than being a mere biological oddity, the rock-paper-scissors dynamic is a widespread phenomenon that maintains genetic diversity within species and ecosystems.
"If the environment underlying the system is homogeneous, intuition would suggest there's going to be a good competitor that drives out all the others," says Ben Kerr, research associate at the University of Minnesota. "In rock-paper-scissors, the system itself has all the cogs and gears to generate diversity."
In California, rock-paper-scissors is played out between three male morphs of the side-blotched lizard, which are distinguished by their throat colors. Big, testosterone-pumped, orange-throated ...
