Résumé
One of the central puzzles in the study of sociocultural evolution is how
and why transitions from small-scale human groups to large-scale,
hierarchically more complex ones occurred. Here we develop a spatially
explicit agent-based model as a first step towards understanding the
ecological dynamics of small and large-scale human groups. By analogy with
the interactions between single-celled and multicellular organisms, we
build a theory of group lifecycles as an emergent property of single cell
demographic and expansion behaviours. We find that once the transition
from small-scale to large-scale groups occurs, a few large-scale groups
continue expanding while small-scale groups gradually become scarcer, and
large-scale groups become larger in size and fewer in number over time.
Demographic and expansion behaviours of groups are largely influenced by
the distribution and availability of resources. Our results conform to a
pattern of human political change in which religions and nation states
come to be represented by a few large units and many smaller ones. Future
enhancements of the model should include decision-making rules and
probabilities of fragmentation for large-scale societies. We suggest that
the synthesis of population ecology and social evolution will generate
increasingly plausible models of human group dynamics.