Rats prefer to help their own kind

Scientists discovered that lab rats will rescue a fellow rat in distress, but not a rat they consider an outsider

August 26, 2021
The Scitech

A decade after scientists discovered that lab rats will rescue a fellow rat in distress, but not a rat they consider an outsider, new UC Berkeley research pinpoints the brain regions that drive rats to prioritize their nearest and dearest in times of crisis. It also suggests humans may share the same neural bias. The findings, published on July 13, in the journal eLife, suggest that altruism, whether in rodents or humans, is motivated by social bonding and familiarity rather than sympathy or guilt. “We have found that the group identity of the distressed rat dramatically influences the neural response and decision to help, revealing the biological mechanism of ingroup bias,” said study senior author Daniela Kaufer, a professor of neuroscience and integrative biology at UC Berkeley.

“Priming a common group membership may be a more powerful driver for inducing pro-social motivation than increasing empathy,” said study lead author Inbal Ben-Ami Bartal, an assistant professor of psychobiology at Tel-Aviv University in Israel. “The finding of a similar neural network involved in empathic helping in rats, as in humans, provides new evidence that caring for others is based on a shared neurobiological mechanism across mammals,” Bartal said.

Using fiber photometry, immunohistochemistry, calcium imaging and other diagnostic tools, researchers found that all the rats they studied experienced empathy in response to another rat’s signs of distress. However, to act on that empathy, the helper rat’s neural reward circuitry had to be triggered, and that only occurred if the trapped rat was of the same type as the helper rat, or member of its ingroup. Specifically, the rats’ empathy correlated with the brain’s sensory and orbitofrontal regions, as well as with the anterior insula. Meanwhile, the rodents’ decision to help was linked to activity in the nucleus accumbens, a reward center with neurotransmitters that include dopamine and serotonin. For the study, more than 60 pairs of caged rats were monitored over the course of two weeks. Some of the pairs were of the same strain or genetic tribe while others were not. “Overall, the findings suggest that empathy alone doesn’t predict helping behavior, and that’s really a crucial point,” she said. “So, if you want to motivate people to help others who are suffering, it may be that you have to increase their feeling of belonging and group membership, and work toward a common identity.”

Source: UC Berkeley news release