Dogs possess an evolutionarily developed fine sense of smell, and with training they are able to detect odors produced from cancer, which is a type of volatile organic compound (VOC). Similarly, ants have a highly developed olfactory system and can be trained to detect VOCs. Unlike dogs that require months to train, ants can be trained more quickly and at a much lower cost, according to researchers at the Université Sorbonne Paris Nord and PSL Research University in France.
Building on previous work that showed individual worker ants could rapidly learn to associate an olfactory stimulus with a food reward via classical conditioning and then retain the information for several days, investigators used the same classical conditioning to train 36 individual ants to associate a human cancer cell sample (IGROV-1, ovarian cancer) with a food reward in three training trials. Not only were the ants able to detect the presence of the ovarian cancer cells, but detection took less time with each consecutive trial.
Additional tests showed that ants were able to distinguish between cancerous cells and healthy cells, as well as discriminate between the types of cancerous cells. Again, after a simple three-trial protocol, ants exposed to two breast cell lines (MCF-7 and MCF-10A) and healthy cells were able to discriminate between the cancerous cell lines and healthy cells. The ants were also able to differentiate between breast cancer cell lines (MCF-7 and MDA-MD-231).
Future research will focus on broadening the range of cancer-related odors that can be detected by ants. The investigators suggested their approach to training ants could be used for other complex odor detection tasks, including other diseases, spoiled food, narcotics, or explosives.
Source: iScience, March 18, 2022.