Why are so many societies based on hierarchy rather than egalitarian values, despite the fact that evidence suggests ancient human communities were often fairly egalitarian? Stanford researchers wanted to find out. So they designed a computer simulation that compared two basic types of societies: egalitarian ones, in which all resources are shared equally, and hierarchical societies, in which some groups have greater access to resources than others.
The researchers found that the hierarchical societies all but guaranteed unequal access to resources, which in turn destabilized the population. Since not everyone in class-based societies could be guaranteed fair access to resources, this gave people incentive to migrate away to new area. Essentially, creating a society in which the lower classes were forced to survive on substandard conditions could actually drive migration and expansion of that same class-based, oppressive culture.
For their part, the egalitarian societies dealt with scarcity by sharing the burden equally. Nobody was necessarily particularly happy with this situation, but at least everyone was basically sharing the deprivation equally. That's more likely to hold a society together than a hierarchical one, which by extension means people are less likely to leave and form new groups elsewhere.
It's worth pointing out that we're not talking about recent expansion or the movement of civilizations in the historic past - this doesn't really speak to the last 500 years of imperialism, for instance. Instead, this is peering back a lot further into the first origins of complex societies some tens of thousands of years ago. Since that period lies beyond the scope of historical record or even much by way of archaeological data, we're left to speculation and indirect means - like this computer simulation - to figure out what drove these initial societies.
We do know from later evidence that hierarchical societies became the norm, dominating or replacing many of the more egalitarian societies that had preceded them. A lot of this is tied to agriculture and the control of resources, as well as the development of wealth transfer systems such as inheritance from generation to generation. But researchers are also looking for a more fundamental process at work here, and this model might reveal one.
Lead author Deborah Rogers explains:
"The fact that unequal societies today vastly outnumber egalitarian societies may not be due to the replacement of the ethic of equality by a more selfish ethic, as originally thought by many researchers. Instead, it appears that the stratified societies simply spread and took over, crowding out the egalitarian populations.
"This is not just an academic exercise. Inequalities in socioeconomic status are increasing sharply around the world. Understanding the causes and consequences of inequality and how to reduce it is one of the central challenges of our time."
Via PLoS ONE. Image from Modern Warfare 2.