Laboratory experiments have shown that some ants will heal the injured legs of their comrades and even perform medical amputation if necessary.
Bart Zijlstra, UNIL
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Bart Zijlstra, UNIL
When an ant’s leg is injured, it will sometimes turn to a companion, who will help bite the leg off, effectively performing a life-saving amputation.
That’s according to some new experiments described in the journal modern biologysuggesting that ants are the only animals other than humans known to use amputation as a medical procedure.
Erik Frank, who studies social wound care, said: “Not only can they do this, but they can even diagnose the wound and tailor treatment accordingly to maximize the patient’s recovery. Chances of survival. “I think it’s really remarkable. “
Post-operative wound care
In the past, his team has studied how termite-hunting ants in the tropics significantly reduce the mortality of injured nestmates by treating their wounds with antibiotic secretions from specialized glands.
But this gland is not present in the common species Florida carpenter ants, or Florida ant. The species nests in rotting wood and fights rivals to defend its home, so Frank wanted to see how the ants would react when faced with the damage of fighting.
His team soon discovered that the ants would cut off injured legs, like Civil War-era microsurgeons. “That really piqued my interest,” he said.
The injured ant will show its leg to a mate, who will lick the wound and then move the leg upward, biting the shoulder joint, for several minutes at a time until the leg is severed. “You can see the other person not moving, not really backing down and taking it,” Frank said.
Nearly all injured ants whose limbs were amputated by their partners survived. At the same time, ants with injured legs often die if they are far away from the nest and do not receive this treatment.
To see how amputation might help, the researchers experimentally infected open wounds on the legs of ants with pathogens. They found that amputations made by the ants can stop the infection from spreading and becoming fatal.
Frank went a step further and personally amputated the ant’s injured leg – essentially copying the ant’s surgical method – to see how the amputee fared. He said this confirmed that “these amputations save the lives of infected people.”
This study convinced other ant experts not involved in these studies, such as Daniel Kronauer of Rockefeller University. “The experiment was very thorough,” Cronauer said. “That sounds reasonable to me.”
“Here’s an ant that lives in a log in the backyard where I grew up in Florida, and they’ve been doing clinical amputations for millions of years,” Clint Penick said. Humans have been doing it for much longer.
“It’s really cool to see something like this, and to see really strong research supporting that this is actually a medical treatment that ants evolved to prevent infection,” Penick said.
Have an amputation instinct?
Interestingly, ants only amputate their legs if they are injured near the middle of their bodies. Wounds under the legs did not elicit this treatment, although ants licked the wounds.
This observation prompted Frank’s team to try amputating ants with injured lower legs infected with the bacteria. They found that ants always died.
Frank and his colleagues were puzzled why amputation only seemed to work for thigh injuries until they took a closer look at the leg’s anatomy. They found that the muscles in the thighs normally help transport blood-like fluid into the ants’ bodies. When the thigh is injured, these muscles become damaged. This means that bacteria or other pathogens from an injury to the upper leg spread to other parts of the body more slowly than bacteria or other pathogens from an injury to the lower leg.
The fact that the ants only perform amputations under certain circumstances is “really cool,” Kronauer said.
“They can see where the leg is injured, right? Depending on where the leg is injured, does amputation make sense,” he noted.
However, he warned that ant medical staff do not assess wounds and consciously weigh the pros and cons of treatment options in the same way that human doctors do.
“I don’t think they have some crazy cognitive abilities,” Cronauer said. “They’ve basically evolved over thousands, maybe even millions, of years to be ‘programmed’ in a certain way to respond to different types of injury.”
Even so, Penick said, humans often think their remedies are uniquely sophisticated, but this common backyard ant actually performs the surgery.
He points out that even if an ant has an injury to its lower leg that cannot be treated by amputation, its nest will still tend to the wound, apparently using some kind of antibacterial secretion, which has often been shown to save lives.
“My own research shows that many ants produce antimicrobials,” Penick added. Amputations, he said, “are just another example of a public health problem that ants have to deal with.”
