A common perception is that societies of the past are not very useful for understanding the present because they were so much smaller and simpler. In a paper published this week in Science Advances, Social Reactors Project researchers Scott Ortman and Jose Lobo argue that this is precisely why they ARE useful. The archaeological record provides examples of societies where properties that are changing rapidly today were relatively constant, and this can make it easier to isolate cause and effect. Ortman and Lobo use the example of the Northern Rio Grande Pueblos, a case where both technology and regional population were stable over a multi-century period, to document the role of agglomeration in economic development. It has been difficult to see this effect in contemporary data because population and technological change are confounding variables. But the archaeological record shows that the phenomenon of agglomeration-driven growth is likely to always be there in the background. The paper is available here.