Ants’ sense of smell is so strong that they can smell cancer
A study published this week in the journal Proceedings of the Royal Society B: Biological Sciences highlights the keen sense of ants and highlights how we could one day use animals with sharp noses — or, in the case of ants, sharp antennae — to detect tumors quickly and cheaply. This is important because the earlier the cancer is detected, the better the chances of recovery.
“The results are very promising,” said Baptiste Piqueret, a postdoctoral fellow at the Max Planck Institute for Chemical Ecology in Germany who studies animal behavior and co-authored the paper. However, he added, “It’s important to know that we are far from using them as an everyday way to detect cancer.”
Extending their pair of thin sensory appendages on top of their heads, insects detect and use chemical cues to do almost everything—find food, gather prey, spot colony mates, protect young. This chemical communication helps ants build complex societies of queens and workers that work so in sync with scent that scientists call some colonies “superorganisms.”
For their study, Piqueret’s team transplanted pieces of a human breast cancer tumor into mice and trained 35 ants to associate the urine of tumor-bearing rodents with sugar. Placed in a petri dish, silkworm ants (Formica fusca) spent significantly more time near the urine tubes of “sick” mice compared to the urine of healthy mice.
“The study was well thought out and well executed,” said Federica Pirrone, an associate professor at the University of Milan who was not involved in the ant research but has conducted similar research into dogs’ olfactory abilities.
Piqueret has been fascinated by ants ever since he played with them as a child in his parents’ garden in the French countryside. “I’ve always loved ants,” he said, “watching them, playing with them.”
The way we diagnose cancer today – with blood draws, biopsies and colonoscopies – is often expensive and invasive. Animal behaviorists envision a world where doctors will one day touch species with heightened senses to spot tumors quickly and cheaply.
Dogs can smell the presence of cancer in body odor, past research has shown. Mice can be trained to distinguish between healthy littermates and those with tumors. Nematodes are attracted to certain organic compounds associated with cancer. Even the neurons of wine flies fire in the presence of certain cancer cells.
But ants, Piqueret suggested, may have an advantage over dogs and other animals that take a long time to train.
During the covid quarantine, he brought silk ants to his apartment outside Paris to continue his experiments. He chose the breed because it has a good memory, is easy to train and doesn’t bite (at least not badly, Piqueret said).
Researchers have a lot more work to do before ants or other animals can help make a real diagnosis. Scientists need to examine confounding factors such as diet or age, Pirrone said. Piqueret’s team plans to test the ants’ ability to smell cancer markers in the urine of real patients.
“To have real confirmations, we have to wait for the next steps,” Pirrone said.
If ants are ever used in cancer screening, Piqueret wants to make one thing clear: No, they won’t have to crawl all over you.
“There will be no direct contact between the ants and the patients,” he said. “So even if people are afraid of insects, that’s fine.”
He once had to convince someone familiar with his research that ants bathing at a picnic were not a sign of cancer.
“The ants were not trained,” he said. “They just want to eat sugar.”