Friendships and the Savannah baboon

How do you define friendships in primatology?

Olive-baboons-allogrooming-whilst-female-suckles-young.jpgFriendships are described as high rates of association between anestrus (non estrous ie no sexual activity) and lactating females with unrelated males of any rank (Strum, 1974; Altmann, 1980; Smuts, 1985).

Olive-baboons-allogrooming.jpg Female and male friendship is a unique occurrence  within mammals. In most mammal groups the two different sexes generally only interact in courtship or mating. Males will attempt to monopolize females while females attempt to find the fittest male (Greenwood, 1980). Males and females also will often associate more when females are in estrous. For examples female chimps when in estrous have been described as more sociable and more likely to join males in smaller bisexual groups. However, when they are no longer in estrous they are generally found in close proximity to their offspring instead of the males (Pepper et al. 1999). Thus female and male friendship outside of courtship and mating is highly unusual.

Yellow-baboon-grooming-adult-female-with-infant.jpg

Female and male friendships were first documented in Savannah baboons (Ransom & Ransom, 1971). Savannah baboons are part of the Papio genus. Within Papio there are three species the exhibit female and male friendship: the olive baboon (Papio anubis), yellow baboon (Papio cynocephalus) and Chacma baboons (Papio ursinus). They are found in groups of multifemale and males and have a polygynandrous mating system (multiple partners for both the males and females); male rank however does affect access to females (Swedell, 2011). They are also characterized by female philopatry and male dispersal (females have very close bonds). Hamadryas baboons (Papio hamadryas) do not have female and male friendships. They also differ in their group structure compared to other savannah baboons. Females and males are within one male units in which several females only mate and affiliate with a specific male (Kummer, 1968), although both sexes disperse males tend to be philopatric (Swedell et al. 2011). Hamadryas baboons do not exhibit female and male friendship but the savanna baboons do suggesting a link to the differing group structure and the development of opposite sex friendships (Kummer, 1968; Swedell, 2006; Pines et al., 2011).

Female-southern-chacma-baboon-with-young-grooming-male.jpg

Male and female friendships also have differing benefits for the females.

  • Yellow and savanna baboons
    • Low infanticide rates thus friendships function as a protection against harassment of the female and her infant from other females and males (Lemasson et al. 2008; Nguyen et al. 2009)
  • Chacma baboons
    • Higher infanticide rates thus friendships may function as a counter against infanticidal immigrant males (Busse and Hamilton, 1981; Palombit et al., 1997)

Southern-chacma-baboons-allogrooming.jpg

Hypothesis for male and female friendship

  1. Anti infanticide
    1. Female benefit from protection by males friend from infanticidal males (Altmann et al., 1978)
    2. Chacma baboons only
  2. Female harassment hypothesis
    1. Males protect females from harassment by high ranking females (Altmann, 1980; Wasser, 1983)
    2. Yellow and Savanna baboons
  3. Male caretaker hypothesis
    1. Female develops friendship and males develop relationship with the infant (Ransom & Ransom, 1971). This would help protect the females investment in her offspring by providing added protection, access and socialization for the infant (Altmann & Altmann, 1970; Altman, 1980; Anderson, 1992)

Grey-footed-chacma-baboon-copulation.jpg

But what do the males get out of it?

  1. Possible mating opportunities with the female (Wittenberger and Tilson, 1980)

Work Cited

Altmann, Jeanne. 1980. Baboon Mothers and Infants. Cambridge, Mass.: Howard University Press.

Altmann, S. A. & Altmann, J. 1970. Baboon Ecology. Chicago: The University of Chicago Press.

Altmann, J., Altmann, S. A. & Hausfater, G. 1978. Primate infant’s effects on mother’s future reproduction. Science, 201, 1028–1029.

Busse, C. & Hamilton, W. J. III 1981. Infant carrying by male chacma baboons. Science, 212, 1281–1283.

Greenwood PJ. Mating systems, philopatry and dispersal in birds and mammals. Anim Behav. 1980;28:1140–1162. doi: 10.1016/S0003-3472(80)80103-5.

Kummer, H. 1968. Social organization of hamadryas baboons, a field study. Chicago: University of Chicago Press

Lemasson, A., Palombit, R. A. & Jubin, R. 2008. Friendships between males and lactating females in a free-ranging group of olive baboons (Papio hamadryas anubis): evidence from playback experiments. Behavioral Ecology and Sociobi- ology, 62, 1027–1035.

Nguyen, N., Van Horn, R. C., Alberts, S. C. & Altmann, J. 2009. ‘Friendships’ between new mothers and adult males: adaptive benefits and determinants in wild baboons (Papio cynocephalus). Behavioral Ecology and Sociobiology, 63, 1331–1344.

Pepper JW, Mitani JC, Watts DP. 1999. General gregariousness and specific social preferences among wild chimpanzees. Int J Prim 20(5): 613-32.

Ransom, T. W. & Ransom, B. S. 1971. Adult male– infant relations among baboons (Papio anubis). Folia primatol., 16, 179–195.

Palombit, R. A., Seyfarth, R. M. & Cheney, D. L. 1997. The adaptive value of ‘friendships’ to female baboons: experimental and observational evidence. Animal Behaviour, 54, 599–614.

Smuts, B. B. 1985. Sex and Friendship in Baboons. New York: Aldine.

Strum, S. C. 1974. Life with the Pumphouse Gang: new insights into baboon behavior. Natn. Geogr., 147, 672–691.

Strum, S. C. 1987. Almost Human. New York: Random House.

Swedell, L. 2006. Strategies of sex and survival Hamadryas baboons: through a female lens. Pearson Prentice Hall, Upper Saddle River, New Jersey

Swedell, L. 2011. African Papionins: diversity of social organization and ecological flexibility. In: Campbell CJ, Fuentes A, MacKinnon KC, Panger M, Bearder SK, editors. Primates in perspective. 2. New York: Oxford University Press; pp. 241–277.

Wasser, S. K. 1983. Reproductive competition and cooperation among yellow baboons. In: Social Behav- ior of Female Vertebrates (Ed. by S. K. Wasser),

Wittenberger JF, Tilson RL. 1980. The evolution of monogamy hypotheses and evidence. Annu Rev Ecol Syst; 11:197–232.

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