Animals Self-Medicate To Protect Future Generations, Study Shows

Self-medication in animals is more calculating and widespread than previously thought, according to researchers at the University of Michigan, who say the discovery may prove to have some medicinal benefit for humans as well. 

It has been known for some time that some mammals, such as the chimpanzee, will seek medicinal herbs to treat their afflictions. Now researchers have learned that the behavior is present lower down the food chain as well, with self-medication reportedly observed in insects such as butterflies, ants and fruit flies.

Wood ants incorporate an antimicrobial resin from conifer trees into their nests, preventing microbial growth in the colony. Parasite-infected monarch butterflies protect their offspring against high levels of parasite growth by laying their eggs on anti-parasitic milkweed. 

Mark Hunter, an ecology and evolutionary biology professor at University of Michigan, reports that the realization has profound implications for the ecology and evolution of hosts and their parasites, but that the "self" part of self-medication should be de-emphasized, because animals don't just medicate for individual health, but for the health of future generations as well.

"Perhaps the biggest surprise for us was that animals like fruit flies and butterflies can choose food for their offspring that minimizes the impacts of disease in the next generation," Hunter said in a press statement. "There are strong parallels with the emerging field of epigenetics in humans, where we now understand that dietary choices made by parents influence the long-term health of their children."

In the article "Self-Medication in Animals,"  which was published online April 11 in the journal Science, Hunter and two colleagues state that because plants remain the most promising source of new pharmaceuticals, studies of animal medication may lead the way in discovering new drugs to treat human ailments.

"When we watch animals foraging for food in nature, we now have to ask, are they visiting the grocery store or are they visiting the pharmacy?" Hunter said. "We can learn a lot about how to treat parasites and disease by watching other animals."