Self-Medication in Animals Much More Widespread Than Believed

Apr. 11, 2013 — It's been known for decades that animals such as chimpanzees seek out medicinal herbs to treat their diseases. But in recent years, the list of animal pharmacists has grown much longer, and it now appears that the practice of animal self-medication is a lot more widespread than previously thought, according to a University of Michigan ecologist and his colleagues.

Animals use medications to treat various ailments through both learned and innate behaviors. The fact that moths, ants and fruit flies are now known to self-medicate has profound implications for the ecology and evolution of animal hosts and their parasites, according to Mark Hunter, a professor in the Department of Ecology and Evolutionary Biology and at the School of Natural Resources and Environment.

In addition, because plants remain the most promising source of future pharmaceuticals, studies of animal medication may lead the way in discovering new drugs to relieve human suffering, Hunter and two colleagues wrote in a review article titled "Self-Medication in Animals," to be published online today in the journal Science.

"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."

A parasite-infected monarch butterfly lays her 

eggs on medicinal tropical milkweed that will help 

to protect her offspring from disease. 

(Credit: Image credit Jaap de Roode)

Much of the work in this field has focused on cases in which animals, such as baboons and woolly bear caterpillars, medicate themselves. One recent study has suggested that house sparrows and finches add high-nicotine cigarette butts to their nests to reduce mite infestations.

But less attention has been given to the many cases in which animals medicate their offspring or other kin, according to Hunter and his colleagues. 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.

Hunter and his colleagues suggest that researchers in the field should "de-emphasize the 'self' in self-medication" and base their studies on a more inclusive framework.

Continued:  http://www.sciencedaily.com/releases/2013/04/130411142716.htm