Ethics and Altruism Grooming_ coalitions_ and reciprocal altruism

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					                                                                      JASs forum
Ethics and Altruism                                                   Journal of Anthropological Sciences
                                                                              Vol. 85 (2007), pp. 235-236

Grooming, coalitions, and reciprocal altruism in primates

Gabriele Schino

Istituto di Scienze e Tecnologie della Cognizione, Consiglio Nazionale delle Ricerche, Roma

    The study of primate altruistic behaviours              Preliminary meta-analytical data also show
can help to shed light on the evolution of             that primates reciprocate amount of grooming
human altruism. In particular, as it provides          received, that is they groom their group mates
information on patterns of altruism in species         in relation to the grooming received, and that
that may lack advanced cognitive abilities such        the degree of grooming reciprocation is inversely
as the capacity for empathy and score-keeping.         related to the tendency to direct grooming up
    Grooming and agonistic coalitions represent        the hierarchy (Schino & Aureli, in preparation).
two traditional examples of primate reciprocal              Knowledge of these general patterns
altruism (Trivers, 1971). Seyfarth (1977)              of grooming distribution among primates
developed an influential theoretical model to           is to be complemented with an improved
explain the distribution of grooming among             understanding of the proximate mechanisms
female primates. This model assumed females            underlying reciprocal exchanges. Recent data on
compete for accessing and grooming high-ranking        the temporal relations between grooming and
group mates in order to exchange grooming for          agonistic support in Japanese macaques (Schino
later support during aggressive confrontations.        et al., 2007) suggest reciprocal exchanges are not
    Despite its enormous influence on the               based on a short-term temporal contingency,
ethological literature, data supporting Seyfarth's     but much more detailed data are needed on this
model were until recently scantier than generally      topic. As for the cognitive basis of reciprocation,
assumed. In the last few years, meta-analytical        at the moment, both emotion-based and
techniques have been applied to published data         cognition-based        proximate        mechanisms
on primate grooming and agonistic coalitions,          have been proposed (Brosnan & de Waal,
and have shown that primate grooming does              2002), but their relative prevalence is unclear.
satisfy most of the assumptions and predictions             The data reviewed above highlight that
of Seyfarth's model (Schino, 2001; 2007).              nonhuman primates show a variety of altruistic
Primates direct their grooming preferentially to       behaviours whose evolution is likely to be based,
higher-ranking animals and, as a results, high-        beside kin selection, on the selective mechanism
ranking animals receive overall more grooming          initially identified by Robert Trivers (1971), that
than their lower-ranking group mates. Primates         is, reciprocal altruism. These altruistic behaviours
also compete for accessing high-ranking group          are deployed strategically among group members
mates, as shown by the significant relation             in order to maximize received return benefits.
between the groomer's rank and its ability to          These observations are relevant to the evolution
distribute grooming in relation to the recipient's     of our own species as they provide both
rank. This preference for grooming high-               evidence that altruistic behaviour predates the
ranking group mates is explained, as originally        evolution of human-like cognitive abilities, and
assumed by Seyfarth's model, by the exchange           support to the notion that the need to navigate
that occur between grooming and rank-related           a complex social environment favoured the
benefits, for example agonistic coalitions.             initial evolution of improved cognitive abilities.

     the JASs is published by the Istituto Italiano di Antropologia          
  236            JASs forum: Ethics, Altruism and Evolution

References                                         Schino G., Polizzi di Sorrentino E. & Tiddi B.
                                                     2007. Grooming and coalitions in Japanese
Brosnan, S.F., de Waal. F.B.M. 2002. A proximate     macaques (Macaca fuscata): partner choice
  perspective on reciprocal altruism. Human          and the time frame of reciprocation. J. Comp.
  Nature, 13: 129-152.                               Psychol., 121: 181-188.
Schino G. 2001. Grooming, competition and          Seyfarth R.M. 1977. A model of social grooming
  social rank among female primates: a meta-         among adult female monkeys. J. Theor. Biol.,
  analysis. Anim. Behav., 62: 265-271.               65: 671-698.
Schino G. 2007. Grooming and agonistic             Trivers R.L. 1971. The evolution of reciprocal
  support: a meta-analysis of primate reciprocal     altruism. Q. Rev. Biol., 46: 35-57.
  altruism. Behav. Ecol., 18: 115–120.

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