A MARTÍNEZ, HOST:
Sometimes we have a news story asking, whatever happened to that celebrity? Well, this is a story of a celebrity animal. Researchers are asking, whatever happened to the saber-toothed tiger? Kids learn in school about those tigers with canine teeth - the long, pointy ones - which make them look pretty fearsome. Now, they were also really effective for biting, and they evolved multiple times as conditions changed. Now, that leads to a mystery - if those teeth were so effective, why did the tigers go extinct? Here's NPR's Jonathan Lambert.
JONATHAN LAMBERT, BYLINE: Generally speaking, canine teeth have two main jobs.
EMILY RAYFIELD: They need to be sharp enough to puncture and slice things. But on the other hand, they need to be strong enough to avoid breakage when they're doing that job.
LAMBERT: That's paleontologist Emily Rayfield of the University of Bristol. Saber teeth - an extreme canine - are so long and pointy that they're a bit of a conundrum, she says. They seem so lethal, but also fragile. To understand how saber teeth balanced that trade-off, the team analyzed nearly 100 different canines, from saber-toothed cats to panda bears. First, they estimated their strength using engineering computer models.
RAYFIELD: So whereas you can do this for cars and bridges, you can also do it for teeth.
LAMBERT: Then, for puncturability, they created stainless steel models of the teeth that bit down into a gel.
RAYFIELD: It's kind of like a really stiff Jell-O. And you can imagine that really sharp teeth don't need much force to go through the gel, whereas really blunt teeth need a lot of force to go through the gel.
LAMBERT: Combined, these two methods revealed the relative strength and puncture performance of all these teeth. Saber teeth came out on top for puncturing.
RAYFIELD: They'd all evolved towards this kind of shape, which made them really good at puncturing, but to the point where they were actually as good as they could be to resist breakage. So any increase in resisting breakage would mean their puncture performance would get worse.
LAMBERT: That specialization led to huge advantages in capturing prey, which is likely why these teeth evolved so many times. For example, it helped saber-toothed cats become an apex predator of the Pleistocene. But the results, published in the journal Current Biology, suggest it also could have been their downfall.
RAYFIELD: It made us think about whether they'd actually kind of reached a sort of pinnacle in performance that meant that when the environment changed or when there were new predators on the scene - like humans, for example - these animals were simply not able to adapt and change.
LAMBERT: Saber-toothed predators are now all gone, so saber teeth could represent a cautionary tale of evolution - getting too good at one thing just might lead to extinction.
Jonathan Lambert, NPR News.
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