Videos Show Ants Amputating Nest Mates’ Legs to Save Their Lives

The insects seem to know which injuries to treat as they engage in a behavior that seems almost human.

The life of a Florida carpenter ant can be brutal. These half-inch ants are territorial and have violent bouts with ants from rival colonies in the Southeast.

Combat can leave the ants with leg injuries. But as scientists recently discovered, these ants have evolved an effective wound treatment: amputation.

In the journal Current Biology, on Tuesday, researchers report that the ants bite off the injured limbs of their nest mates to prevent infection. Although other ant species are known to tend to the wounds of their injured, typically by licking them clean, this is the first time that an ant species has been known to use amputation to treat an injury.

The ants in the study performed amputations on only certain leg injuries, suggesting that they are methodical in their surgical practices. Aside from humans, no other animal is known to conduct such amputations. The prevalence of the behavior among Florida carpenter ants raises questions about their intelligence and their ability to feel pain.

In early 2020, Dany Buffat, a graduate student at the University of Würzburg in Germany, was observing a colony of Florida carpenter ants in his lab when he noticed something strange. “One ant was biting off another ant’s leg,” said Mr. Buffat, who is now a biologist at the University of Lausanne in Switzerland and is an author of the study. His adviser at Würzburg didn’t believe him at first.

“But then he showed me a video and I knew immediately that we were onto something,” the adviser, Erik Frank, said.