AYESHA RASCOE, HOST:
One day, Jonathan Losos found himself trying to capture a lizard on a research trip near the Bahamas. He's a professor of biology at Washington University in St. Louis.
JONATHAN LOSOS: It was a wily little lizard. It was taking a while, but I finally caught it, and it wasn't until I was holding it in my hand that I realized that it was missing its entire hind leg.
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LOSOS: And yet it was a very fat and sassy lizard. It was doing well, obviously getting enough to eat.
RASCOE: Losos was confused. This seemed to go against research he's been doing his entire career.
LOSOS: Lizards with longer legs usually survive better than lizards with shorter legs. And that was - just a fraction of a millimeter of leg length could make a difference between life and death. And so the idea that a lizard without a leg at all could survive just seemed preposterous. But yet, there they were.
RASCOE: So how did the slippery guy manage to make it? To investigate, Losos and another researcher named James Stroud held the Lizard Olympics.
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LOSOS: We'd make them run along a little raceway for two meters and film them as they did that. James also measured one jumping. And to do that, you just put the lizard on a little perch, and you poke it in its rump. And when all goes well, it jumps off, and you measure how it jumps and so on. It turned out that missing one hind leg, this lizard was inept at jumping.
RASCOE: But it didn't matter. These little pirate lizards were adjusting their behavior to compensate for the injury.
LOSOS: The two lizards that we studied did things differently. One of them took longer strides so that it would cover more ground in each stride, which presumably compensated for being short one leg. The other one bent its body more, that - when lizards run, they often twist their torso. Well, the lizard missing its hind leg undulated more, which allowed it also to take longer strides and run faster.
RASCOE: It contradicted Darwin's theory of natural selection.
LOSOS: You would expect these lizards missing part of a leg to be selected out very quickly. What this seems to suggest is that natural selection isn't so omnipresent, so occurring all the time, that probably most times, lizards like this with an injury - they don't last very long, but sometimes they can survive.
RASCOE: Losos says there are a few possible theories for why this happens.
LOSOS: One reason is that sometimes losing a leg doesn't matter because maybe there are no predators around. Or maybe some lizards are so particularly strong in other attributes that they can make up for missing part of a leg, that their other legs are really powerful or they have really great muscles. Yet another idea is that they have ways of compensating in their behavior.
RASCOE: But more importantly, did the lizards get a prize at the Olympics?
LOSOS: Well, they get ribbons - that's the standard in our field - and an extra fruit fly.
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RASCOE: That was Jonathan Losos, professor of biology at Washington University in St. Louis.
(SOUNDBITE OF CORY WONG & METROPOLE ORKEST'S "BURNING") Transcript provided by NPR, Copyright NPR.
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