Even if they do not always show it, human beings are clearly capable of empathy. Other primates such as chimps have been observed acting in a way that is best explained by empathy. Rather than acting for their own benefit, they sometimes act because they share the feeling or distress of another chimp. Such behavior is said to be “empathy-driven.”
Once it was thought that only human beings could feel empathy. Now researchers are finding that empathy-driven behavior is more widespread than previously imagined. Not just other primates but even rodents, it seems, are biologically capable of empathy. For all the differences between the human and the rat brain, we share fundamental circuits that make it possible to feel the emotions of another, particularly when the other is in pain or distress.
In a simple experiment reported in the December 9 issue of the journal Science, researchers provide solid evidence that the much-maligned rat is capable of acting in a way that is most easily explained by empathy.
"This is the first evidence of helping behavior triggered by empathy in rats," said Jean Decety, a member of the research team at the University of Chicago. "There are a lot of ideas in the literature showing that empathy is not unique to humans, and it has been well demonstrated in apes, but in rodents it was not very clear. We put together in one series of experiments evidence of helping behavior based on empathy in rodents, and that's really the first time it's been seen," Decety said in a release issued by the University.
In order to act in a way that is empathy-driven, an animal must be capable of “emotional contagion.” To test whether rats have this capacity, an experiment was designed Chicago psychology graduate student Inbal Ben-Ami Bartal. Two rats were placed in an enclosure, one of them roaming freely while the other was locked inside a tube. The free rat, in time, could discover how to open the lock, but there was no reward for doing so.
The experiment was designed observe whether rats show they are capable of emotional contagion. Was the free rat biologically capable of emotional concern or what the paper defines as “an other-oriented emotional response elicited by and congruent with the perceived welfare of an individual in distress”?
The free rats not only learned to open the container but did so repeatedly when it held another rat, something they did not do if it was empty or if it contained a stuffed animal.
Even more striking was their behavior when chocolate chips were involved. In one variation on the experiment, two enclosures were used, one with an enclosed rat and the other with five pieces of chocolate. The free rat has a choice: free the cagemate or eat the chocolate first. In the absence of empathy, the free rat will make the selfish choice. But at least half the time, the rat freed its cagemate first. According to the report, “these results show that the value of freeing a trapped cagemate is on par with that of accessing chocolate chips.”
"On its face, this is more than empathy, this is pro-social behavior," said Jeffrey Mogil of McGill University, who was not involved in the study. "It's more than has been shown before by a long shot.”
Without claiming to know what rats think, the authors conclude their report with their opinion that “the free rat was not simply empathetically sensitive to another rat’s distress but acted intentionally to liberate a trapped” member of their own species.
If rats are indeed capable of empathetic feelings, then it becomes clear that the biological substrate for shared emotion is deep in our evolutionary past and deep in the earlier parts of our brains. Far from being uniquely human, empathy seems to be widely shared. What is uniquely human, perhaps, is the way we override it with self-interest.
As I prepared this post, I was interrupted several times by others who were speaking of the history of racism in America and particularly the history of slavery. When I saw the pictures of rats in their enclosure, my mind went to chains and slave ships. If empathy is so deep in our mammalian evolution, so deeply rooted in our brains, what extraordinary rationalizations do we conjure up to negate it?
The paper, "Empathy and Pro-Social Behavior in Rats," is published Dec. 9 by the journal Science. http://www.sciencemag.org/content/334/6061/1427.abstract