Looking like a drowned rat? Never fear, a dry rat may come to your rescue.
An experiment testing whether empathy can drive behaviour in rats has found that, when a dry rat observes a distressed rat trapped in a wet chamber, it will free it from its cage.
Not only are these rats willing to help others, they do so faster if they themselves have previously suffered a soaking.
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鈥淭his suggests that knowing that soaking is distressing enhances the rats鈥� motivation to help their cage mate,鈥� says Nobuya Sato of Kwansei Gakuin University in Japan. 鈥淲e think this comes from empathy.鈥�
We knew that some non-humans feel empathy, but proving that it can motivate friendly and helpful behaviours towards others in non-primates has long been a challenge.
Set me free
Then, in 2011, of the University of Chicago and her colleagues showed that rats would free their cage mates if they were trapped in a distressing restrainer apparatus.
That experiment provided compelling evidence that rats could empathise with another鈥檚 discomfort, but questions remained over whether they were really acting solely to help their cage mate out. Perhaps they were just freeing them so that they could have someone to play with.
To test this, Sato put some rats in an unpleasantly wet chamber, and others in a dry one. He was surprised to see that rats showed no interest in freeing individuals that were housed in a dry chamber 鈥� they only helped rats that were soaked and distressed.
鈥淲hen the rat is in the space without the pool, they don鈥檛 open it for him. They don鈥檛 see a problem,鈥� says Mason, who likens this to how a human might behave. 鈥淲e鈥檙e probably not that different. If somebody looks like they鈥檙e happy and they鈥檙e just hanging out, why would you help them?鈥�
Evolutionary behaviour
Sato鈥檚 team also showed that rats learned to open the door to free a wet rat more quickly if they themselves had previously been soaked.
This could suggest that a bad experience made their empathetic actions more urgent. 鈥淚t shows that memory can facilitate emotional empathy,鈥� says Mason.
Empathetic helping behaviour in mammals is thought to have evolved from maternal behaviour. It makes evolutionary sense for a mother to be able to guess the emotional states of her offspring, and to act accordingly 鈥� feeding, cleaning, warming or comforting them as appropriate.
This work, together with Mason鈥檚 2011 study, shows that the benefits of helpful empathy extend beyond the juvenile stage, says Mason. 鈥淭hey generalise to mammals more broadly 鈥� both genders, throughout their lifespan.鈥�
But there may be another explanation for the speedier rescue actions. It is possible, says Sato, that these rats opened the chamber quicker because they had already observed how the door mechanism works when they were soaked. His team plans to test if this was the case in their next experiments.
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