International Symposium on the Sociopolitical Organization of Teotihuacan

It has been 5 years since I moved to Mexico to create a computational model of the sociopolitical organization of ancient Teotihuacan. I am happy to report that this project has matured. I am involved in the organization of the International Symposium on the Sociopolitical Organization of Teotihuacan, which will bring together the world’s leading experts working on this topic.


At the symposium I will I gave talk on the latest results of the model. The title and abstract are as follows:

A computational model of Teotihuacan’s collective government: New insights into role of the city’s division into districts

Tom Froese

Experts remain divided about the nature of the sociopolitical system of ancient Teotihuacan, which was one of the earliest and largest urban civilizations of the Americas. Excavations hoping to find compelling evidence of powerful rulers, such as a royal tomb, keep coming away empty-handed. But the alternative possibility of a corporate or collective government still remains poorly understood. There is a lack of evidence of a powerful bureaucracy, such as durable record keeping, but a decentralized network limited to the level of neighborhood representatives seems susceptible to problems of collective action.

Previously we used a computational model to show that in principle this latter worry is unfounded, as long as we assume that the network’s topology could be transformed via community rituals and was not strongly subdivided. Here we extend this model to investigate whether increased social hierarchy could mitigate the negative effects of strong divisions. We found a special synergy between hierarchy and community ritual in that only their combination improved the extent of cooperation, which is consistent with portrayals of the elite as religious specialists serving the public good and with the apparent absence of extensive secular institutions.

Current work is investigating whether a reduction in the city’s number of districts could reduce the necessity for this kind of centralized hierarchy.

81st Annual Meeting of the Society for American Archaeology

Teotihuacan-style_incense_burner_depicting_a_ruler_and_his_court,_Maya,_Early_Classic_Period,_250-600_AD,_ceramic_-_Royal_Ontario_Museum_-_DSC04482This year’s Annual Meeting of the Society for American Archaeology (SAA) will take place April 6-10, in Orlando, Florida.

I will present a continuation of my ongoing project to model the collective political organization of ancient Teotihuacan in collaboration with archaeologist Linda Manzanilla.

Our contribution was invited to take place in a special session: “The Rise and Decline of Teotihuacan: Urbanism, Daily Life, and Regional Relations through Time”.

The title and abstract are as follows:

A network theoretical analysis of the emergence of co-rulership in ancient Teotihuacan, Central Mexico

Tom Froese and Linda R. Manzanilla

The political organization of Teotihuacan continues to be unknown. While some researchers see evidence for a powerful centralized hierarchy, others argue for a more collective form of government. We created an abstract computer model of hypothetical social relations among neighborhood-level representatives to show that such a distributed political network could in principle have been sufficient for globally optimal decision making, as long as there are community rituals and sections of the city are not too independent (Froese, Gershenson and Manzanilla 2014). These conditions were most likely satisfied during the early periods of the city. However, there is evidence that during the final stages some neighborhood centers become more isolated and independent, and the city as a whole became organized into four districts. Our model suggests that such social fractioning would have undermined a purely horizontally organized collective government. But Manzanilla has hypothesized that four co-rulers governed the city at the district level during this period. We therefore introduced this hierarchical level into our model to verify if such a mixed organization could have addressed some of the issues associated with a fractioning of the underlying social system. We discuss our modeling results in the context of archeological evidence.

Paper: A Mathematical Model of the Collective Social Organization of Ancient Teotihuacan

Ever since I first visited the ancient ruins of Teotihuacan several years ago, I wanted to learn as much as possible about its unique culture. Here is one of the products of that quest: a paper combining complex systems modeling with Mesoamerican archaeology and the anthropology of ritual.

Can government be self-organized? A mathematical model of the collective social organization of ancient Teotihuacan, Central Mexico

Tom Froese, Carlos Gershenson and Linda R. Manzanilla

Teotihuacan was the first urban civilization of Mesoamerica and one of the largest of the ancient world. Following a tradition in archaeology to equate social complexity with centralized hierarchy, it is widely believed that the city’s origin and growth was controlled by a lineage of powerful individuals. However, much data is indicative of a government of co-rulers, and artistic traditions expressed an egalitarian ideology. Yet this alternative keeps being marginalized because the problems of collective action make it difficult to conceive how such a coalition could have functioned in principle. We therefore devised a mathematical model of the city’s hypothetical network of representatives as a formal proof of concept that widespread cooperation was realizable in a fully distributed manner. In the model, decisions become self-organized into globally optimal configurations even though local representatives behave and modify their relations in a rational and selfish manner. This self-optimization crucially depends on occasional communal interruptions of normal activity, and it is impeded when sections of the network are too independent. We relate these insights to theories about community-wide rituals at Teotihuacan and the city’s eventual disintegration.

DOI: 10.1371/journal.pone.0109966

Section of a mural painting of ancient Teotihuacan, Mexico

Here is a recording of a little news clip about the article that was rotated for a week on MVS Radio y Radio Fórmula in Mexico starting on the 10th of November: