The evolution of indiscriminate altruism in a cooperatively breeding mammal

Kin selection theory suggests that altruistic behaviours can increase the fitness of altruists when recipients are genetic relatives. Although selection can often favour the ability of organisms to preferentially cooperate with close kin, indiscriminately helping all group mates may yield comparable fitness returns if relatedness within groups is very high. Here, we show that meerkats (Suricata suricatta) are largely indiscriminate altruists who do not alter the amount of help provided to pups or group mates in response to their relatedness to them. We present a model showing that indiscriminate altruism may yield greater fitness payoffs than kin discrimination where most group members are close relatives and errors occur in the assessment of kinship. The presence of errors in the assessment of kinship provides a feasible explanation for associations between kin discriminative helping and group relatedness in cooperative breeding vertebrates.