Good leaders needed. The coordination needed for large, complicated endeavors (such as building rain-capturing structures used by the Anasazi in the American Southwest, above) and the resulting benefits to members of the group may have triggered such soci

National Park Service

Good leaders needed. The coordination needed for large, complicated endeavors (such as building rain-capturing structures used by the Anasazi in the American Southwest, above) and the resulting benefits to members of the group may have triggered such societies to evolve from bands of egalitarians to groups composed of leaders and followers, a new study suggests.

The benefits of inequality

Sid is a freelance science journalist.

Which would you prefer: egalitarianism or totalitarianism? When it comes down to it, the choice you make may not be as obvious as you think. New research suggests that in the distant past, groups of hunter-gatherers may have recognized and accepted the benefits of living in hierarchical societies, even if they themselves weren’t counted among the well-off. This model could help explain why bands of humans moved from largely egalitarian groups to hierarchical cultures in which social inequality was rife.

How such hierarchical structures gained ground and then proliferated is one of the big mysteries in social evolution. It’s also largely a matter of conjecture, because most of these transitions occurred in the relatively distant past. Researchers have typically posed two scenarios, says Simon Powers, an evolutionary anthropologist at the University of Lausanne in Switzerland. In one, the hierarchy is imposed from above by strong or charismatic individuals, with followers having little, if any, choice in the matter. In the other, those who end up as followers consider their options and willingly buy into an evolving social order.

Archaeological evidence that could help shed light on such societal evolution is noticeably lacking. Modern field studies of egalitarian societies aren't enlightening either. “There’s no recorded shift from one type of society to the other,” says Christopher Boehm, an evolutionary anthropologist at the University of Southern California in Los Angeles who wasn’t involved in the new study. “We have good descriptions of ‘before’ and ‘after,’ but not anything during the actual transition.”

So, Powers and his Lausanne colleague Laurent Lehmann tackled the problem by developing a computer model that considers the social dynamics among individuals in a small group, including each person’s tolerance for authority and the disadvantages they’d suffer if they shifted allegiance to another group or struck out on their own. In the model, a person’s offspring inherits the parent’s values, with some opportunity for gradual change through the generations. The simulation also tracks the evolving social structure’s effect on overall group size and productivity, Powers says.

When the researchers let the model run over several generations, they found that, in general, groups made up of leaders and followers were able to produce or gather more resources than those made up of egalitarian-minded individuals. That, in turn, enabled the hierarchical group to grow more quickly and to better eke out a living. According to the model, groups made up of leaders and followers eventually grew to about twice the size of societies solely composed of egalitarians. And even when leaders skimmed a large portion of a group’s resulting surplus for themselves and their families, their followers received, on average, more resources than they would have if they’d been part of a leaderless band, Powers and Lehmann report online today in the Proceedings of the Royal Society B.

To see how this might have worked in the real world, consider nascent agricultural societies, Powers says. In such groups, widespread cooperation is necessary for large endeavors such as planting and harvesting crops and for building irrigation systems. Having leaders to organize such projects and followers to carry them out may have been a more efficient form of social organization than true egalitarianism. Followers may have been willing to exchange a bit of control over their lives for access to a society-wide increase in resources, Powers says.

Such notions “have been around for a long time in verbal form,” says Paul Hooper, an evolutionary anthropologist at Emory University in Atlanta who wasn’t involved in the research. “What [Powers and Lehmann] have done here is take these ideas and make them work within a very elegant mathematical framework.”

But to be more realistic, the duo’s simulation may need to include more factors, says Kim Sterelny, who studies the evolution of social behavior at Australian National University in Canberra and wasn’t involved in the current work. For example, the benefits of being a leader almost ensure that there would be strong competition (and possibly even conflict) among group members for power. “The [team’s] model idealizes away the costs and inefficiencies of politics,” he suggests. Plus, he notes, the model doesn’t seem to consider the notion that egalitarian members of a group could band together into an “antielite” coalition.

One nice aspect of the team’s simulation, Sterelny notes, is that dissatisfied individuals within a group can, in essence, vote with their feet and leave the group: “If dispersal is relatively low cost, leaders cannot afford to be greedy.” Yet the team’s model also helps explain how despots can rise to and retain power: When the costs of switching allegiance to another group or striking out on one’s own are unacceptably high, Powers says, individuals in the group are essentially stuck in the group, left to make the best of a bad situation.

*Clarification, 6 August, 12:42 p.m.: A sentence has been added to this article to help clarify comments and quotes by evolutionary anthropologist Christopher Boehm.

Posted in Evolution, Social Sciences