Living Reference Work Entry

Encyclopedia of Evolutionary Psychological Science

pp 1-9

Date: Latest Version

Psychology of Reciprocal Altruism




Different forms of reciprocal altruism – taking turns offering altruistic help – require different psychological building blocks.


A pair of pied flycatchers busily snatch insects to bring back to their nest and feed to their young. Suddenly, an owl appears close to the nest, posing a serious predation threat to their offspring. The pair fly straight to the owl, shrieking and dive bombing it to chase it away. A nearby pair of flycatchers detects the ruckus and also arrives to attack the predator. Another nearby pair, however, fails to help. An hour later, two owls appear, one at each of the neighboring nests. What should the original pair do? Krams et al. (2008) conducted this experiment and found that, out of 32 pairs of flycatchers, 2 stayed at the nest, 30 attacked the owl near the pair who helped them previously, and none attacked the owl near the pair who did not help them before. This willingness to pay a cost to cooperate or help another wh ...

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