Rats have a bad reputation. If you betray someone or inform upon associates, you are said to rat on them. A scab laborer is a rat.
It turns out that rats may not be that ratty after all. In fact, rats display traits that we like to think are distinctively human.
In a University of Chicago experiment, a rat releases another rat from a cage. The free rat learned how to open the cage and did so with increasing frequency, even when there was no reward. Additionally, when the freed rat had a cache of chocolate, it would often save one piece for the captive.
“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.
This study and others seem to indicate that not only are rats empathetic, they are also pro-social. They appear to demonstrate both the inner state that identifies with another but then take the next step and act upon it. Primatologist Franz de Waals calls the study groundbreaking. “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.” http://www.washingtonpost.com/national/health-science/a-new-model-of-emp...
Other scientists remain more skeptical. Alex Kacelnik of the Department of Zoology at Oxford University says, “Empathy has been proposed as the motivation behind the sort of 'pro-social' rescue behavior in which one individual tries to free another,” said Professor Kacelnik, lead author of the article, 'however, the reproductive benefits of this kind of behavior are relatively well understood as, in nature, they are helping individuals to which they are likely to be genetically related or whose survival is otherwise beneficial to the actor.
“To prove empathy any experiment must show an individual understands another's feelings and is driven by the psychological goal of improving another's wellbeing. Our view is that, so far, there is no proof of this outside of humans.” http://www.sciencedaily.com/releases/2012/08/120812160800.htm
Further studies involving brain imagery may unravel the matter more fully. But the question of empathy in other animals may never be fully settled, for such matters get into psychological territory that raises deep philosophical questions such as the distinction (if there is one) between brain and mind and the relation between thought and feeling.
What we can say is that rats seem to have empathy and act pro-socially. This is a good thing to know, for it shows that both these traits may well be part of the human psyche that precedes learning. It doesn’t demonstrate that humans are good by nature, but it does make a strong case that being good is part of human nature.