Three meerkats (Suricata suricatta) engage in a bout of social grooming. While allogrooming can reduce ectoparasite loads of groomed individuals, recent research suggests that social grooming also plays an important role in diffusing conflict, and may act as a currency exchanged for other societal benefits. Among meerkats, dominant females receive more and provide less grooming than subordinates. In general, subordinates appear to use allogrooming to placate dominant females, which is arguably most important for subordinate females, who otherwise risk eviction, owing to reproductive conflict among female colony members.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 10, “Cooperation.” N. Kutsukake and T. H. Clutton-Brock, “Social function of allogrooming in cooperatively breeding meerkats,” Animal Behaviour 72 (2006), pp. 1059–1068.
Susan Lingle, University of Winnipeg
Mule deer (Odocoileus hemionus) females engage in highly cooperative aggressive defense against coyotes (Canis latrans), protecting fawns and even adults. They will defend fawns that are not their own offspring, including those of another species, as shown in this video of mule deer approaching a speaker emitting a white-tailed deer (Odocoileus virginianus) fawn distress call. The adaptive basis of such apparent altruism remains unclear, though such nondiscriminating and aggressive defense of young, regardless of their identity, may act as a general deterrent to predators.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: Norton, 2013), Chap. 10, “Cooperation”; Chap. 12, “Antipredator Behavior”; Chap. 13, “Communication.” S. Lingle, D. Rendall, W. F. Wilson, R. W. DeYoung. & S. M. Pellis, Altruism and recognition in the antipredator defence of deer: 2. Why mule deer help nonoffspring fawns, Animal Behaviour 73 (2007), pp. 907–16.
© Jack P. Hailman
Allogrooming, wherein one individual grooms another, is perhaps the most common form of cooperative behavior displayed by animals. At the most proximate level, recipients benefit via the removal of dirt, debris, ectoparasites, or potential disease-causing bacteria. Allogrooming also contributes tangibly to the maintenance of amicable relationships in social groups and to the formation and reinforcement of both parent-offspring and pair bonds. Here an adult Magellanic penguin (Spheniscus magellanicus) preens the feathers of its offspring, removing fleas that otherwise are a significant burden on chicks and juveniles.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 10, “Cooperation.” A. N. Radford and M. A. Du Plessis, “Dual function of allopreening in the cooperatively breeding green woodhoopoe, Phoeniculus purpureus,” Behavioral Ecology and Sociobiology 61 (2006), pp. 221–230.
Gerald G. Carter, Organization for Bat Conservation, 2011
Common vampire bats (Desmodus rotundus) are found throughout South and Central America, except in southern Argentina. As their name implies, these bats feed on the blood of other vertebrates, including cattle, horses, pigs, dogs, birds, and even humans. Vampire bats typically feed by inflicting a wound with their front teeth in their host and sucking up blood flowing from that wound with their highly modified mouthparts. As shown in the video, roosting vampire bats share blood with conspecifics, and although close relatives are not excluded from such blood sharing, relatedness is by no means a prerequisite for this apparently altruistic behavior. Rather, repeated interactions among known associates promote cooperation through the benefits of reciprocal altruism.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: Norton, 2013), Chap. 2, “The Evolution of Behavior”; Chap. 9, “Kinship”; Chap. 10, “Cooperation.” G. S. Wilkinson, Reciprocal food sharing in the vampire bat, Nature 308 (1984), pp. 181–84.