Portion of mural by Diego Rivera showing the Aztec city of Tenochtitlan, photograph by Wolfgang Sauber. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic, and 1.0 Generic agreement.

Note: This article appeared in The Santa Fe New Mexican on March 3, 2014.

By Scott Ortman, Assistant Professor, Department of Anthropology, University of Colorado Boulder, and former Omidyar Fellow, Santa Fe Institute

Over the past few centuries, human societies have changed dramatically. We travel, make things, treat illnesses, and communicate in ways our ancestors could have never imagined. All this has led some to conclude that human societies are fundamentally different today than they were in the past. I'm not so sure. Research I’ve been doing lately suggests just the opposite: our technologies might have changed in amazing ways, but our societies still follow some of the same basic rules that shaped ancient civilizations.

I’ve had the privilege of seeing this first hand in several ways. As an archaeologist, I have studied continuities between the past and present, particularly here in New Mexico. My collaborations with contemporary Pueblo people in particular have helped me see that the political debates we read about in the news every day have been part of all human societies all along, even those organized on a smaller scale. More recently, I’ve been part of a team that found an even deeper connection between ancient civilizations and the modern world.

It all started when I attended a lecture by the Santa Fe Institute’s Geoffrey West on mathematical regularities of modern cities. This is an emerging and very exciting area of research that is demonstrating that cities throughout the modern world follow similar mathematical rules.

After that talk it occurred to me that I had on my computer data from an archaeological survey gathered 50 years ago in the Valley of Mexico, before it was paved over by today's Mexico City. From the 13th century to the beginning of the 16th century when the Spanish arrived, this area was the heartland of the Aztec Empire. I was curious whether this ancient New World civilization – which had no connection to the modern world or even to Old World cities – followed the same rules as the modern cities. So I checked it out, and lo and behold, it appeared that they might!

This was an intriguing result with potentially deep implications since, let's be honest, about the only things ancient Mexican cities have in common with today's cities is that they were created by humans living on the same planet. Needless to say, I contacted West and SFI Professor Luis Bettencourt to tell them about my little experiment. They responded with similar amazement, and shortly thereafter, Bettencourt and I began collaborating to see whether this initial result really stood up to scrutiny.

Bettencourt has long studied how modern cities vary with size. He's done it by analyzing vast amounts of municipal data and developing a series of formulas that derive the observed mathematical relationships from basic elements of human social life. His work suggests that scaling relationships seen in modern cities emerge from individuals finding an intuitive balance between the costs of moving around with the benefits of the social interactions this moving around enables.

Because these are properties of human social networks regardless of the context, I reasoned this theory should apply to ancient civilizations too, and that we could test it by applying it to the archaeological data from Pre-Hispanic Central Mexico that I had been playing around with.

Working together, our team – myself, Bettencourt, Jennie Sturm (University of New Mexico) and Andrew Cabaniss (University of North Carolina-Chapel Hill) – compiled, standardized, and analyzed a great deal more data from obscure archaeological reports for several thousand Aztec settlements. Our work paid off. It showed that the ancient settlement system of the Valley of Mexico is not only consistent with our theory, but also exhibits the same relative mathematical scaling properties observed in modern cities. Our findings, which have just been published in a scientific journal, suggest that the basic principles of human settlement organization may apply to the entire range of human history, regardless of how far apart settlements might be in time, space, or culture.

The implications are potentially profound. Despite the fact that today’s cities are very different from those of the past, they lie on a continuum with the earliest human settlements. This can give us new insight into how and why cities emerged in the first place. It also suggests that if we can learn more about the ways past peoples have successfully concentrated their social networks in space – despite environmental or technological constraints – we might be able to design better-functioning cities in the future.

By working together, we hit upon something none of us could have recognized or demonstrated on our own from the narrow perspectives of our individual fields. I think this is a good example of why scientific research, especially when it bridges disciplines, is critically important for our future, even if we’re not always sure exactly where that research is going.

This column is the latest in the "Science in a Complex World" series written by researchers at the Santa Fe Institute and published in The Santa Fe New Mexican.