ARI SHAPIRO, HOST:
Ants often have to defend their nests against invaders. And in these fights, their legs can get injured. Scientists now say that some ants will treat these wounds using an old mainstay of battlefield medicine - amputation. NPR's Nell Greenfieldboyce reports.
NELL GREENFIELDBOYCE, BYLINE: Clinical amputation is something that humans have done for at least 30,000 years. It turns out that ants may have been doing it even longer. That's according to a new scientific report in the journal Current Biology.
ERIK FRANK: This is the first example of medical amputations in the animal kingdom that we are describing here.
GREENFIELDBOYCE: Erik Frank studies ants at the University of Wurzburg in Germany. In the past, he's studied how certain ants in the tropics will treat their buddies' wounds by applying antibiotic secretions from a special gland. But he recently started studying Florida carpenter ants that don't have this gland, and he immediately observed something surprising. Ants with an injury on the upper part of a leg would present that leg to a nestmate who would gnaw it off at the shoulder. Frank says the injured one would endure the procedure stoically.
FRANK: Not moving, not really flinching and accepting it.
GREENFIELDBOYCE: Once the leg was severed and fell off, the wounded ant would patiently wait for more medical care.
FRANK: The other one will come back and lick the little stump that's left, and it will still be presenting it. So it's clearly collaborating and wants the same thing as the one that is treating it of having this leg removed.
GREENFIELDBOYCE: And here's why. Frank's lab experiments show that without amputation, infection from the open wound will spread and almost always be fatal. Interestingly, however, amputation is only life-saving when the injury is in the upper part of the leg. And the ants seem to know that because when the wound is lower down, they won't amputate. Instead, they spend more time licking and tending the damaged area, presumably treating it with antibiotic compounds. Frank says it's really striking to him that not only can the ants perform amputations.
FRANK: But they're even able to diagnose the wounds and, depending on the location, adapt the treatment accordingly to maximize the survival chances of the injured.
GREENFIELDBOYCE: Researchers who study ants and who weren't involved in this study were equally impressed, like Clint Penick of Auburn University.
CLINT PENICK: This is an ant that I grew up with in my backyard. And so it's really interesting to see such a sophisticated behavior, you know, that's literally happening in people's backyards from a common carpenter ant.
GREENFIELDBOYCE: He says ants produce all kinds of antimicrobial compounds and have evolved to have a remarkable set of medical treatments, which includes therapeutic amputation.
Nell Greenfieldboyce, NPR News.
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