What: The competitive mating strategies of three colors of common side-blotched lizard, namely the orange male, blue male, and yellow male.

Why: The male common side-blotched lizard wants the same things we all do: relative safety, insects to eat, and a honey to hunker down with. The female common side-blotched lizard is a yellow-throated beauty, who will mate with any male that comes along. She has three choices of mates, each with its unique features. The orange male is stronger than all the other lizards, and territorial about his women. The blue male is not as strong as the orange lizard, who will chase him away. But he’s stronger than the yellow male, and since he forms stronger pair-bonds than the orange male does, he’s more attentive to the ladies he muscles away from the yellow guys. The wimpy yellow lizard, however, has got something that the others don’t: he’s yellow. Yup, he looks just like all the female lizards. Now, this metrosexuality is never gonna fool a blue lizard, who’s a stickler for detail. But it works wonders on the big ol’ orange lizard, who assumes the yellow male is a yellow female, and lets him pass unmolested—right until the yellow male steals his females away. Does this sound familiar? It might, because you know this trifurcated mating strategy by another name: rock-paper-scissors.

Impact: Rock-paper-scissors! Orange beats blue, blue beats yellow, yellow beats orange. This is straight-up game theory writ large on the biotic canvas. Somehow, this most elemental of Nashian match-ups has remained in equilibrium for millennia. Check out this territory map and you’ll see how strongly the strategies overlap. None of the three types of male has to leave the area, for there’s always somebody he can beat out in the mating scheme.
For more info, go to this more scientific site.

Personal Connection: As a game designer of some proficiency, I know a lot about rock-paper-scissors. In my time at Wizards of the Coast, I and the other R&D folks did a lot of analysis of the game, concluding there were major strategic elements based on how well you knew the other players. The official R&D shirt sported the words “Rock is Strong.” But no matter how much we know about it, I must accede that the side-blotched lizards know a heck of a lot more.

Other Contenders: the delightful dance of the blue-footed booby; the problematic efforts of the male hedgehog, which shows the difficulty of seducing someone made entirely out of swords; the lush intertwining of leopard slugs, and trust me, you have never seen anything as disturbingly cool as that; a really killer pickup line, as demonstrated here by Bruce Springsteen.