I understand "empathy" to mean the ability to feel someone's emotions/pain/etc. What this demonstrates is that rats will go to another rat's aid, and nothing about their internal models for doing so.
It is oversimplifying to say something like "oh it's helping the other rat for selfish reason X", but it is equally misleading to apply human models of mind, which we have due to our unique ability to introspect and share that introspection with other members of our species.
Models such as kin selection (http://en.wikipedia.org/wiki/Kin_selection) attempt to explain altruism within an evolutionary model, but even if there is a totally different cause for this particular altruistic behavior (and even if it is shown to be almost wholly altruistic, rather than just indirectly self-beneficial, assuming such a distinction exists), there are very few grounds to assume empathy.
The most interesting result to me is that the rats demonstrate distress at seeing the suffering, and cease upon release. But before talking about empathy again, we must show that the distress is its own separate thing (http://en.wikipedia.org/wiki/Voight-Kampff_test#Voight-Kampf...) rather than mere frustration at failed attempts of rescue.
So, sure, we've learned something, but I don't think we've demonstrated empathy.
There was a time when explorers observed a primitive tribe exhibiting empathy or even morality might exert the same kind of hand-wringing as you did about whether it is actually so.
Same thing happened with chimps and the discovery of tool use. Jane Goodall was met by the same resistance. It is a characteristic, I would assume of the social organism as a whole. We have a lot in common with our little burrowing social friends. Empathy being one of them.
Altruism is also indicated by leaving the sweets for the trapped rat.
Im not a neuroscientist, but I can guess the mirror neurons are at play.
I think what they try to avoid is anthropomorphization. It's not a good idea to make assumptions that assume human-like characteristics -else we end up with cartoons.
It's not to say that animals are incapable, but such assumptions cannot be made without the insight being held suspect.
Much has advanced in science since. We now know the role of various hormones and chemicals that influence our emotions. Oxytocin, adrenaline, etc. The trick to get out of anthropomorphization is to avoid being human-centric when making the observations. i.e. put on an alien hat and observe human behavior the way we might observe animal behavior, and then based on that say that one acts in a similar way to the other, and reason they may have similar motivations.
"What this demonstrates is that rats will go to another rat's aid, and nothing about their internal models for doing so."
The notion of aid implies it has a mental model of the other rat and that it consideres the other rat as a rat that needs help.
I don't understand why people always think of humans as outstanding and totally different from other species. Or do you think that humans are only exhibiting kin selection too and that empathy is nothing but a ideological concept? How do you prove empathy in humans? (And please apply the same rigor.)
I do mention that humans are capable of sharing their introspections with each other. There are a lot of issues with this, and philosophy is busy figuring that stuff out (from qualia on). This is why I choose to accept the common explanation that empathy plays at least some role in human altruism.
I think we should be just as careful ascribing internal models to human actions that we observe, where we might be even more tempted to jump to conclusions because we think we must be familiar what goes on in other humans' minds.
So, to summarize, I think humans really do feel empathy (I know I do, and I choose to believe others do too), and I know humans will often engage in altruistic behavior. I'm not certain that without empathy we wouldn't engage in the altruistic behavior, though it's likely we'd engage in less. So yes, I do actively apply the same rigor to this area where ethics, philosophy of mind, and neuroscience are meeting. It's a fascinating topic! But it's an area that's easily politicized (morality takeaways tend to be applied quickly...) so I always err on the side of careful interpretation.
It is oversimplifying to say something like "oh it's helping the other rat for selfish reason X", but it is equally misleading to apply human models of mind, which we have due to our unique ability to introspect and share that introspection with other members of our species.
Models such as kin selection (http://en.wikipedia.org/wiki/Kin_selection) attempt to explain altruism within an evolutionary model, but even if there is a totally different cause for this particular altruistic behavior (and even if it is shown to be almost wholly altruistic, rather than just indirectly self-beneficial, assuming such a distinction exists), there are very few grounds to assume empathy.
The most interesting result to me is that the rats demonstrate distress at seeing the suffering, and cease upon release. But before talking about empathy again, we must show that the distress is its own separate thing (http://en.wikipedia.org/wiki/Voight-Kampff_test#Voight-Kampf...) rather than mere frustration at failed attempts of rescue.
So, sure, we've learned something, but I don't think we've demonstrated empathy.