Archaeology
Bradley T. Lepper commentary: Measuring a society's political evolution
Sunday, December 5, 2010 02:59 AM
By Bradley T. Lepper
The Columbus Dispatch
Ever since Charles Darwin presented his powerful theory explaining the evolution of life from simple to complex forms, anthropologists have debated the extent to which the rise of complex human societies can be understood within a similar evolutionary framework.
Cultural evolutionists argue that bands, based on simple family ties, evolved into more highly organized tribes and then into chiefdoms led by a political leader who inherited his or her office. Chiefdoms might then evolve into states with a much more complex political organization.
Critics say this proposed sequence is overly simplistic in its reliance on a "unilinear" sequence of a limited number of levels of complexity. They assert that there could be circumstances in which chiefdoms emerge directly from bands, for example, or states might develop along alternative historical trajectories.
Thomas Currie, an anthropologist at University College London, and several colleagues recently wrote in the journal Nature that "These ideas have been debated largely in the absence of rigorous quantitative tests."
They noted that whereas archaeology has "a central role in answering such questions," other data can be used to supplement the sometimes meager archaeological record. With that in mind, Currie and his co-researchers turned to the well-studied languages of the indigenous cultures of Austronesia, a region that encompasses the islands of southeast Asia and the South Pacific and extends as far west as Madagascar.
Currie and colleagues considered the similarities and differences in the languages of 84 Austronesian societies and constructed a sample of 1,000 "phylogenetic trees," such as those used by biologists to study the evolutionary histories of organisms. These trees represent possible alternative lines of descent among the various societies.
Then they considered each society's level of political complexity, which they defined in terms of "the number of hierarchical decision-making levels." The team applied a number of statistical techniques to "estimate the probable rates of change between different forms of organization over the phylogenetic trees."
Finally, they compared their results with the expectations derived from six models for the evolution of complex societies. The models ranged from a strict unilinear model with societies only able to increase complexity in small increments to models that permit a variety of alternative routes to complexity.
The results show definitively that political complexity increases only incrementally as predicted by cultural evolutionists. Large and nonsequential increases were not observed.
An additional aspect of cultural evolution concerns the question of decreasing political complexity. Currie and his team found that declines in complexity - in contrast to increases - sometimes can be catastrophic, knocking a society back several levels in one stroke.
Of course, these conclusions do not in any way support the once-common view that increasing political complexity is a measure of social "progress" or that less-complex societies are somehow more "primitive."
Explaining the rise and fall of social complexity, whether in the Ohio or Nile valleys, is one of archaeology's big questions.
This study brings us one step closer to understanding the processes of cultural evolution.
Bradley T. Lepper is curator of archaeology at the Ohio Historical Society.
blepper@ohiohistory.orghttp://www.dispatch.com/live/content/science/stories/2010/12/05/measuring-a-societys-political-evolution.html?sid=101