In the history of teeth, perhaps no tooth is as famous as the saber tooth.

These long, knife-like canines seem almost perfectly suited to killing prey. They evolved at least five times in mammals, especially saber-toothed cats saber-toothed tigerwho wore a serrated saber nearly a foot long.

But behind the sabertooth's fearsome appearance lies a conundrum.

"They could be really fragile," paleontologist says Emily RayfieldUniversity of Bristol. "In some animals, these extremely elongated canine teeth are very sharp, but they can also break easily."

Generally speaking, canines have two main jobs, which can sometimes come into conflict.

"They need to be sharp enough to be able to pierce and cut through things. But on the other hand, they also need to be strong enough to avoid breaking while doing the job," Rayfield said. Rayfield and her colleagues report that sabertooth takes this trade-off to an extreme. modern biologybecome They are able to pierce their prey as far as possibleultimately sacrificing durability.

Researchers believe this peak performance may have ultimately led to the saber-toothed tiger predator's demise.

The team came to this conclusion after analyzing nearly 100 canine teeth ranging from ultra-sharp to ultra-strong, including those from saber-toothed tigers, snow leopards, wolverines and pandas. First, they tested each tooth's durability using the same computer models that engineers use to test the strength of different materials.

"While you can do it to cars and bridges, you can also do it to teeth," Rayfield said.

To measure puncture performance, the team conducted practical experiments. They created a stainless steel 3D model of each tooth and then "bited" it into gel to measure the force required for each bite.

"It's kind of like a very hard jelly," Rayfield said. "You can imagine that really sharp teeth don't require a lot of force to get through the gel, whereas really blunt teeth require a lot of force to get through the gel."

Taken together, these data reveal the relative strength and puncture performance of all these teeth. It turns out that in order to achieve puncture performance, the saber teeth are stretched to the limit

"They all evolved toward this shape, which makes them very good at piercing, but probably to the best possible degree to prevent breakage," Rehfield said. "Any increase in resistance to breakage means their Puncture performance will get worse."

Renfield believes that saber-toothed predators may have targeted soft tissue, given their strengths and relative weaknesses. These advantages have helped saber-toothed cats, including saber-toothed tigerbecoming the top predators of their era. But Rayfield suspects that bringing them to such a high degree of specialization may have ultimately contributed to their decline, since saber-toothed animals don't exist today.

The results "make us think about whether they have actually reached some kind of peak performance, meaning that when the environment changes or new predators (such as humans) appear on the scene, these animals are simply unable to adapt and change," she said.

In some ways, Rayfield said, saber teeth represent the pinnacle of evolution, the best design for canine teeth to pierce prey. But they also show that being too good at something can sometimes be an evolutionary dead end.