Scientific Papers - 2007

Female wild-type rats (Rattus norvegicus) were trained to pull a stick which was fixed to a tray with an oat flake on it, which their partner could reach but which they could not themselves access. Rats were placed in pairs in cages with a wire mesh between them. It was found that rats who had been provided with a treat from their partner in the cage were 20% more likely to reciprocate and pull the stick to deliver the oat flake for a rat who was a stranger to them.

The researchers discounted alternative hypotheses which might have given these results (such as instrumental and classical conditioning, social learning and imitation).

The rats were even more likely to help another rat who had helped them before. "Theoretical models showed that the existence of direct reciprocity in a population will induce the evolution of generalized reciprocity, entailing much higher levels of cooperation overall." A rat may preferentially cooperate with a rat with whom he or she is familiar, but for the overall promotion of a stable society, rats will also cooperate with unknown or unrelated rats.

Carrying out an altruistic act activates areas in the human brain associated with reward processing; rats who have had electrodes implanted in those areas will repeatedly press the bar that stimulates those electrodes. The brain of a rat equips him or her to "feel good" too.

The capacity of rats for altruism indicates that rats have the cognitive abilities required to live in a complex society, and that they are aware of their environment and the actions of others. It is possible that other social animals also have this type of awareness.
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