Three-way mating game of North American lizard found in distant Europea...(gain. Such rock-paper-scissors games...)

Such rock-paper-scissors games may prove to be commonplace throughout the animal kingdom, Sinervo said. The dynamic may just be harder for biologists to find in animals that don't broadcast their affiliation with bright colors. Mammals, for example, may use scent as their signal.

"I like to think of it this way," Sinervo said. "If we were Labrador retrievers, maybe we could smell the rock-paper-scissors game all over the place."

Showy male lizards could be just the most obvious examples. Sinervo speculated that the population booms and busts of lemmings, voles, and hares could come from a similar interplay among reproductive genes in females.

Humans are not immune to the dynamic either. We are far more complex than lizards, but that just means we find more opportunities to adopt the role of aggressor, cooperator, or deceiver. "We play games along an economic axis, a reproductive axis, a familial axis, a political axis. We've constructed all this complexity around ourselves," Sinervo said.

Systems with more than three competing strategies could occur, Sinervo said, but they would tend to simplify themselves into a triangular rock-paper-scissors arrangement because triangular relationships are mathematically more stable.

Sinervo is now trying to map the genes responsible for the behavioral strategies of the European common lizard. This would settle the question as to whether the two species' last common ancestor engaged in similar struggles back in the time of the earliest dinosaurs. The alternative is that the behavior--and the accompanying color patches--evolved at least twice.

"That tells you how ancient the game is," Sinervo said. "If the same genes are involved in both species, then it's been played since the time snakes and lizards diverged. These lizards separated from each other even before the Atlantic ripped open. They may have been playing the same old broken record for 175 million year
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