I wrote earlier that I had become a vegetarian as I was able to recognise animal suffering and made a choice to not contribute to it. With not everyone even accepting that animals are capable of feeling pain or suffering, there’s no chance that they would even entertain the possibility of animals being able to recognise suffering in each other and acting to reduce or prevent that suffering. However, research with rats seems to show that they may exhibit empathy, that is recognise when another rat is suffering and act to reduce or stop that suffering.
The experiment revolved around the theme of having one rat restrained and in distress while another rat was free but able to open the door to free the trapped rat. The two rats had previously been cage-mates for two weeks so that they would bond. Trapped rats were recorded given off distress cries and free rats in those cages were more likely to learn to open the door than those in cages without a trapped rat. Free rats in cages with a trapped rat also opened the door faster than free rats with no trapped rat. Female rats appeared to be more empathetic than male rats, both being more likely to learn to release a trapped rat and, once having learned, being faster to release a caged rat.
To see whether the rats were freeing their cage mates for social contact or as a form of empathy the researchers then adjusted the experiment so that the freed rat would be released into a separate area. In this set up the rats still released the trapped rat the same as before but didn’t release empty containers. This showed that the rats didn’t release their cage-mate in order to get social contact.
Lastly they tried to measure how important a cage-mate was by having containers with both a trapped rat and one with chocolate. If the rats only had chocolate available then they learned to open its container in a similar time-frame as when they had a trapped cage-mate. Having learned to release it they would preferentially open the container that had chocolate rather than the empty one. When there was a choice between chocolate and a cage-mate the free rats opened both containers just as quickly. However in the situations with both a cage-mate and chocolate the free rats ate less chocolate than when the rats were exposed to a container with chocolate and one that was empty. That suggests that freeing the cage-mate is important to the rat and that they will eat less of something they like in order to share with their newly-freed cage-mate.
It’s not definite that this shows that rats are altruistic but it does seem like they are recognising distress in other rats and acting to relieve it. In any case it is really interesting and fits nicely with the other recent work that is coming out and supporting the view that animals are a lot more intelligent than they are generally given credit for.