Altruistic Meerkats

Natural History, Oct, 2000 by Richard Milner

Altruism, according to evolutionary biologist W. D. Hamilton, sometimes evolves among social species if the altruistic individuals share a large number of genes with the individuals they are helping. Evidence to support Hamilton's kin-selection model has been found for various social insects as well as for hyenas, kingfishers, and mole rats--all of which show a high degree of relatedness between the helpers and the broods they assist in rearing. Mammalogist Tim H. Clutton-Brock, of the University of Cambridge, and colleagues recently tested the hypothesis on a population of meerkats (Suricata suricatta), a desert-adapted mongoose that lives in southern Africa.

Most meerkat young are born to a single dominant female. After she gives birth, one or two helpers remain in her burrow each day to "baby-sit" while the rest of the group members Leave to forage. Baby-sitters usually spend up to three weeks caring for the litter, an exertion that results in considerable weight loss.

Clutton-Brock's team studied fifteen groups of meerkats in the Kalahari Desert to see if the meerkats that gave the most help were in fact those whose genes were most like those of the infants they nurtured. The results, however, were negative. In their analysis of 114 helpers--most of known pedigree--the researchers found "no indication that the large differences in contributions to baby-sitting that exist among helpers are related to differences in their kinship to the Litter they were caring for." ("Individual Contributions to Baby-sitting in a Cooperative Mongoose, Suricata suricatta," Proceedings of the Royal Society of London B 267, 2000)