Rats will free another rat from a tight squeeze, and they're willing to give up a feed of sugar to do it. However, rats addicted to heroin are less noble, leaving their species-mate trapped if they have to pass up a hit to provide assistance. The discovery could help pave the way to understanding, and eventually tackling, the way social isolation and drug addiction interact in humans as well as rodents.
Three years ago, a study revealed that rats will give up a bite of chocolate to rescue a fellow rat from an unpleasant, though not dangerous, situation, and even share the chocolate with the rat they saved afterward. IFLScience reported the paper, and we're glad we did because our coverage inspired a new round of research.
Seven Tomek, a graduate student at Arizona State University, read the IFLScience article and told us: “I saw the potential of extending it within addiction research.” Although addiction research relies heavily on animal models, these, Tomek said, “are lacking because one thing that is incredibly important in the human condition and a reoccurring theme of humans acquiring and maintaining addiction is the social and relationship aspects we experience.”
To see a testable model for measuring prosocial behavior in animals excited Tomek and she "couldn't wait to incorporate it with drugs of abuse.”
In Tomek's version of the study, 64 rats were housed in pairs to bond. For two weeks, one rat from each pair would be placed in an uncomfortably small plastic tube, while its mate, dubbed the “saver” rat, was trained in how to free the trapped rat. Seven of the savers failed to live up to their name and were dumped from the study.