Previous studies have shown that lab rats tend to help their fellow rats in trouble, and a new study has found brain regions responsible for prioritizing which should they save first - with the findings suggesting that humans are the same.
The new study suggests that altruism is driven by social bonding and familiarity instead of absolute appeals toward guilt or sympathy and that the same mechanism is at work for both rodents and humans. Researchers from the University of California (UC) Berkeley present their findings in the report "Neural correlates of ingroup bias for prosociality in rats," appearing in the latest eLife journal.
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Finding the Triggers for Prosocial Behavior
According to the Handbook of Child Psychology, prosocial behavior is social behavior intended to benefit others, ultimately benefiting society or the population as a whole. In their paper, researchers explain that the specific act of helping others in need tends to happen preferentially in response to the distress of the responders' own group members.
"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," explains Daniel Kaufer, senior author of the study and neuroscience and integrative biology at UC Berkeley, in a news release from the university.
The study comes when nativism and conflicts between religious, ethnic, and racial groups have seen a sharp spike around the world following the coronavirus pandemic. The findings suggest that social integration, instead of segregation, might be the key to better cohabitation among humans.
"Priming a common group membership may be a more powerful driver for inducing prosocial motivation than increasing empathy," adds Inbal Ben-Ami Bartal, lead author of the study and a psychobiology assistant professor at Tel-Aviv University in Israel.
Bartal adds that finding a neural network in rats similar to those in humans provides new proof that empathy and care for others are driven by a shared neurobiological mechanism in mammals. They arrived at these findings using modern technology such as photometry, immunohistochemistry, calcium imaging, and other diagnostic tools. These efforts reveal how lab rats experience empathy as their fellow lab rats are placed in distress.
Mapping Empathy and Prosocial Behavior in Lab Rats
In the UC Berkeley study, more than 60 pairs of caged rats were monitored over two weeks. There were pairs of lab rats belonging to the same strain or "tribe," while others were not. In each of the trials, one of the lab rats would be placed in a transparent cylinder while the other was left to roam freely outside the cylinder.
Researchers found out that rats free to move consistently showed empathy towards their trapped fellow; only those from the same tribe actively worked to release the other one - shown as their lean towards the cylinder or butt their heads against the enclosure door.
Monitoring the brain activity of the rats showed that while they sensed the distress of their partner, the reward centers of their brain were only triggered when the rat in the enclosure belonged to the same group as they did.
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