Evolution of a despotic society: an individual-based model
C. K. Hemelrjik
Dept. of Information Technology and Anthropological Inst. and
Museum
University of Zurich
Donnerstag, 31.01.2002, 17 Uhr c.t., VHF 210
Single behavioural differences between egalitarian and despotic
animal societies are often assumed to reflect specific adaptations.
However, in the present talk, I will show in an individual-based
model, how many behavioural traits of egalitarian and despotic
societies arise as emergent characteristics from the feedback
between the developing social-spatial structure and the dominance
hierarchy. The artificial individuals live in a homogeneous world and
only aggregate and, upon meeting one another, may perform
dominance interactions in which the effects of winning and losing
are self-reinforcing. The behaviour of these individuals is studied in
a similar way to that of real animals. It will be shown that by
varying intensity of aggression only one may switch from
egalitarian to despotic societies. Differences between the two
types of societies appear to correspond closely to those between
despotic and egalitarian macaque species in the real world.
Additionally, artificial despotic societies show a clearer spatial
centrality of dominants and, counter-intuitively, more female
dominance than the egalitarian ones (particularly during periods of
sexual attraction). Because of the correspondence with patterns in
real animals, the model makes it worthwhile to compare despotic
and egalitarian species on social-spatial structure and inter-sexual
dominance relations too. Furthermore, it presents us with
parsimonious hypotheses, which can be tested in real animals, for
patterns of aggression, social positive and sexual behaviour.
As regards the evolution of despotic societies, multiple-level
selection processes may be involved, such as individual selection
towards higher intensity of aggression and self-organization and
group-selection towards a steeper hierarchy.
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