The free rat, occasionally hearing distress calls from its compatriot, learned to open the cage and did so with greater efficiency over time. It would release the other animal even if there wasn’t the payoff of a reunion with it. Astonishingly, if given access to a small hoard of chocolate chips, the free rat would usually save at least one treat for the captive — which is a lot to expect of a rat.
The researchers came to the unavoidable conclusion that what they were seeing was empathy — and apparently selfless behavior driven by that mental state.
“There is nothing in it for them except for whatever feeling they get from helping another individual,” said Peggy Mason, the neurobiologist who conducted the experiment along with graduate student Inbal Ben-Ami Bartal and fellow researcher Jean Decety.
“There is a common misconception that sharing and helping is a cultural occurrence. But this is not a cultural event. It is part of our biological inheritance,” she added.
The idea that animals have emotional lives and are capable of detecting emotions in others has been gaining ground for decades. Empathic behavior has been observed in apes and monkeys, and described by many pet owners (especially dog owners). Recently, scientists demonstrated “emotional contagion” in mice, a situation in which one animal’s stress worsens another’s.
But empathy that leads to helping activity — what psychologists term “pro-social behavior” — hasn’t been formally shown in non-primates until now.
If this experiment reported Thursday holds up under scrutiny, it will give neuroscientists a method to study empathy and altruism in a rigorous way.
Do age and gender affect empathic behavior? Will a rat free a rat it doesn’t know? Is more help offered to individuals an animal is related to, either directly or as a member of the same genetic tribe? What are the genes, and their variants, that determine whether one animal helps another and how much? Answering those questions becomes possible now that there is an animal “model” for this behavior.
“The study is truly groundbreaking,” said Frans de Waal, a primatologist at Emory University who has written extensively about empathy. What is particularly interesting, he said, is there appears to be no clear cost benefit trade-off going on.
“We are entering a distinctly psychological realm of emotions and reactions to the emotions of others, which is where most human altruism finds its motivation.”
Jeffrey S. Mogil, the McGill University neuroscientist who showed emotional contagion in mice in 2006, said that “what is amazing about this is that it shows empathy in such a robust way. This is not something that rats would otherwise be doing.”