Life in the bustling city seems to bear little resemblance to the simplicity of early human existence. Contemporary urbanites differ from their hunter-gatherer ancestors in nearly every way, from their diets to their economic and social networks. Still, under the surface of these lifestyles are statistical regularities that hold for primitive and modern societies alike.

“This vastly complex world we live in is all about ecological interactions, and somehow all those ecological interactions, that vast complexity, evolved out of our evolutionary background as hunter-gatherers,” says SFI Postdoctoral Fellow Marcus Hamilton. “So what are those statistical signatures and what’s the theory to explain them?”

Hamilton, an anthropologist, is working with SFI’s scaling group in search of these statistical signatures. From its analysis of large data sets for contemporary and traditional societies, the group has found that as human populations change in size from small tribes to cities of millions, economies of scale emerge at each level of growth, suggesting, for example, that large populations are more efficient at procuring energy for their members and distributing it among them.

“What seems to happen is that as human systems evolve, they evolve new technologies, and you see grade shifts where hunter-gatherer
systems suddenly evolve into agricultural systems, for example,” he says. “But you see the same economies of scale maintained in this new level of complexity, so the whole system has ramped itself up another level, but it seems to be showing, fundamentally, the same dynamics.”

Hamilton and his colleagues believe these economies of scale to be universal signatures of human cooperation. Beyond patterns of energy consumption, the group also searches for patterns in human movement, navigation, social networks, and market systems.

His work has contemporary implications. Recent modeling results with collaborators published in Frontiers in Ecology and the Environment suggest that United Nations projections that the world human population will stop growing around 10 billion people at the end of this century are improbable.

“My interest is in question-driven science – are there general principles to human ecology and, if there are, what are they? That’s a very interdisciplinary question and one I couldn’t tackle by myself,” he says. “SFI is the ideal place to be doing this kind of research.”