ScienceDaily (Oct. 3, 2008) — Although anthropologists and
evolutionary biologists are still debating this question, a new study
supports the view that the first egalitarian societies may have
appeared tens of thousands of years before the French Revolution,
Marx, and Lenin.
These societies emerged rapidly through intense power struggle and
their origin had dramatic implications for humanity. In many mammals
living in groups, including hyenas, meerkats, and dolphins, group
members form coalitions and alliances that allow them to increase
their dominance status and their access to mates and other resources.
Alliances are especially common in great apes, some of whom have very
intense social life, where they are constantly engaged in a political
maneuvering as vividly described in Frans de Waal's "Chimpanzee
politics".
In spite of this, the great apes' societies are very hierarchical with
each animal occupying a particular place in the existing dominance
hierarchy. A major function of coalitions in apes is to maintain or
change the dominance ranking. When an alpha male is well established,
he usually can intimidate any hostile coalition or the entire
community.
In sharp contrast, most known hunter-gatherer societies are
egalitarian. Their weak leaders merely assist a consensus-seeking
process when the group needs to make decisions, but otherwise all main
political actors behave as equal. Some anthropologists argue that in
egalitarian societies the pyramid of power is turned upside down with
potential subordinates being able to express dominance over potential
alpha-individuals by creating large, group-wide political alliance.
What were the reasons for such a drastic change in the group's social
organization during the origin of our own "uniquely unique" species?
Some evolutionary biologists theorize that at some point in the
Pleistocene, humans reached a level of ecological dominance that
dramatically transformed the natural selection landscape. Instead of
traditional "hostile forces of nature", the competitive interactions
among members of the same group became the most dominant evolutionary
factor. According to this still controversial view, known as the
"social brain" or "Machiavellian intelligence" hypothesis, more
intelligent individuals were able to take advantage of other members
of their group, achieve higher social status, and leave more offspring
who inherited their parent's genes for larger brain size and
intelligence. As a result of this runaway process, the average brain
size and intelligenc e were increasing across the whole human lineage.
Also increasing were the abilities to keep track of within-group
social interactions, to remember friends and their allies and enemies,
and to attract and use allies. At some point, physically weaker
members of the group started forming successful and stable large
coalitions against strong individuals who otherwise would achieve
alpha-status and usurp the majority of the crucial resources.
Eventually, an egalitarian society was established. Although some of
its components are well supported by data, this scenario remains
highly controversial. One reason is its complexity which makes it
difficult to interpret the data and to intuit the consequences of
interactions between multiple evolutionary, ecological, behavioral,
and social factors acting simultaneously. It is also tricky to
evaluate relevant time-scales and figure out possible evolutionary
dynamics.
A new article in PLoS One makes steps towards answering these
challenges. The paper is co-authored by Sergey Gavrilets, a
theoretical evolutionary biologist, and two computer scientists, Edgar
Duenez-Guzman and Michael Vose, all from the University of Tennessee,
Knoxville.
The researchers built a complex mathematical model describing the
process of alliance formation which they then studied using analytical
methods and large-scale numerical simulations. The model focuses on a
group of individuals who vary strongly in their fighting abilities. If
all conflicts were exclusively between pairs of individuals, a
hierarchy would emerge with a few strongest individuals getting most
of the resource. However, there is also a tendency (very small
initially) for individuals to interfere in an ongoing dyadic conflict
thus biasing its outcome one way or another. Positive outcomes of such
interferences increase the affinities between individuals while
negative outcomes decrease them. Naturally, larger coalitions have
higher probability of winning a conflict.
Gavrilets and colleagues identified conditions under which alliances
can emerge in the group: increasing group size, growing awareness of
ongoing conflicts, better abilities in attracting allies and building
complex coalitions, and better memories of past events.
Most interestingly, the model shows that the shift from a group with
no alliances to one or more alliances typically occurs suddenly,
within several generations, in a phase-transition like fashion. Even
more surprisingly, under certain conditions (which include some
cultural inheritance of social networks) a single alliance comprising
all members of the group can emerge in which resources are divided
evenly. That is, the competition among non-equal individuals can
paradoxically result in their eventual equality.
Gavrilets and colleagues argue that such an "egalitarian revolution"
could also follow a change in the mating system that would increase
father-son social bonds or an increase in fidelity of cultural
inheritance of social networks. Interestingly, the fact that mother-
daughter social bonds are often very strong in apes suggests
(everything else being the same) that females could more easily
achieve egalitarian societies.
The model also highlights the importance of the presence of outsiders
(or "scapegoats") for stability of small alliances. The researchers
suggest that the establishment of a stable group-wide egalitarian
alliance should create conditions promoting the origin of conscience,
moralistic aggression, altruism, and other cultural norms favoring
group interests over those of individuals. Increasing within-group
cohesion should also promote the group efficiency in between-group
conflicts and intensify cultural group selection.
"Our language probably emerged to simplify the formation and improve
the efficiency of coalitions and alliances," says Gavrilets. The
scientists caution that one should be careful in applying their model
to contemporary humans (whether members of modern societies or hunter-
gathers). In contemporary humans, an individual's decision to join
coalitions is strongly affected by his/her estimates of costs,
benefits, and risks associated as well as by cultural beliefs and
traditions. These are the factors explicitly left outside of the
modeling framework.
In humans, a secondary transition from egalitarian societies to
hierarchical states took place as the first civilizations were
emerging. How can it be understood in terms of the model discussed?
One can speculate that technological and cultural advances made the
coalition size much less important in controlling the outcome of a
conflict than the individuals' ability to directly control and use
resources (e.g. weapons, information, food) that strongly influence
the outcomes of conflicts.
Journal reference:
1. Gavrilets et al. Dynamics of Alliance Formation and the
Egalitarian Revolution. PLoS ONE, 2008; 3 (10): e3293 DOI: 10.1371/
journal.pone.0003293
Adapted from materials provided by Public Library of Science, via
EurekAlert!, a service of AAAS.
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