Political complexity evolves in small steps, study suggests
Political complexity in human society evolves in small, incremental steps, according to new, EU-funded research published in the journal Nature. The scientists, whose work is highlighted on the cover of the journal, arrived at their conclusions after using methods which are usually applied to the study of biological evolution. EU support for the work, which involved scientists in Japan, New Zealand and the UK, came from the European Research Council (ERC) project CULTRWORLD ('The evolution of cultural norms in real world settings') with funding amounting to EUR 1.8 million. 'A broad historical pattern of increasing political complexity, from small groups of related individuals to large societies, has been observed across the world since the end of the last ice age,' said Professor Russell Gray of the University of Auckland in New Zealand, one of the authors of the paper. 'There has been considerable debate about whether this occurs through a series of small and incremental steps, from tribes to chiefdoms to states, or though larger non-sequential jumps. The role of decreases in complexity in the overall pattern has also been unclear.' However, until now there has been a lack of what the researchers describe as 'rigorous, quantitative' tests to investigate which theories best reflect reality. Biologists have long used genetic data to construct phylogenetic trees. More recently, linguistic researchers have found that by comparing basic vocabularies in different languages, it is possible to construct trees that shed light on the history of populations. 'By mapping data about the characteristics of societies onto the tips of these trees, we can use phylogenetic comparative methods to make inferences about what societies were like in the past and how they have changed over time,' the researchers write. 'In this study, we statistically evaluate competing models of political evolution using data from Austronesian-speaking societies of the Pacific and island South-East Asia.' In total, the team tested 6 models of political evolution in 84 societies. The models under investigation include those based on traditional theories, in which political complexity changes in small steps, as well as models that allow large, non-sequential steps. The model that best fit the data is one in which political complexity rises and falls in a series of small steps. 'Our results indicate that political evolution is constrained to follow only incremental increases in complexity,' the researchers note. 'This could be due to such factors as an evolved social psychology adapted to life in small-scale groups, the difficulty in reorganising existing institutions that rely on the coordination of large numbers of individuals, or the requirement for the development of other institutions before more hierarchical organisation is stable.' According to the team, the findings are also in line with the idea that the evolution of more hierarchical forms of political organisation arise when smaller, pre-existing units join together. For example, in the Hawaii of the early 1800s, states were formed when one complex chiefdom conquered neighbouring chiefdoms. Interestingly, another model that fit the data well was one in which increases in complexity are always small, but decreases in complexity can be large. In other words, complexity can fall by several steps in one go. 'This could occur if small, peripheral groups break away from the control of a centralised state or complex chiefdom to found new societies with fewer levels of political organisation, or it could occur as part of a rapid, more wide-spread societal collapse and the breakdown of political institutions,' the researchers speculate. The scientists conclude: 'Despite the numerous contingent pathways of human history, there are regularities in cultural evolution that can be detected using computational phylogenetic methods.'
Countries
Japan, New Zealand, United Kingdom