Paper on how communal ritual makes social hierarchy more effective

Our contribution to the “Special Issue on Social Learning and Cultural Evolution with Cognitive Systems“, edited by Peter Andras and James Borg, has been accepted for publication in the journal Cognitive Systems Research.

Here is the title and abstract. Clicking the title will open a pre-print version.

Modeling collective rule at ancient Teotihuacan as a complex adaptive system: Communal ritual makes social hierarchy more effective

Tom Froese and Linda R. Manzanilla

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 collective rule still remains poorly understood as well. Previously we used a computational model of this city’s hypothetical sociopolitical network to show that in principle collective rule based on communal ritual could be an effective strategy of ensuring widespread social coordination, as long as we assume that the network’s structure could be transformed via social learning and local leaders were not strongly subdivided. Here we extended this model to investigate whether increased social hierarchy could mitigate the negative effects of such strong divisions. We found a special synergy between social hierarchy and communal ritual: only their combination improved the extent of social coordination, whereas the introduction of centralization and top-down influence by themselves had no effect. This finding is consistent with portrayals of the Teotihuacan elite as religious specialists serving the public good, in particular by synchronizing the city’s ritual calendar with the rhythms of the stars.


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.

News about model of ancient Teotihuacan

A news report based on an interview I gave to Ciencia UNAM has been published on their web portal:

Santillán, M. L. (Feb. 23, 2015). Modelo matemático revela la organización política de Teotihuacán. Ciencia UNAM. Mexico: Universidad Nacional Autónoma de México. Retrieved from

It describes the social network model we made about the collective government of ancient Teotihuacan, Mexico.

Article: Computational Aspects of Ancient Social Heterarchies

The latest issue of The Journal of Sociocybernetics has just been released. It includes a contribution that arose from this year’s collaboration with my Colombian colleagues. I thank the many Colombian archaeologists and anthropologists who kindly took the time to meet with us and who provided many helpful comments and insights.

Computational Aspects of Ancient Social Heterarchies: Learning how to Address Contemporary Global Challenges

Nathalie Mezza-Garcia, Tom Froese, Nelson Fernández

As hierarchically and centrally controlled computational systems, contemporary political systems have limitations in their information processing and action capacities to face the current social crises and challenges. In contrast, some older cultures whose political structure was more heterarchically organized, such as found in pre-Hispanic Colombia, were adaptive even without advanced scientific knowledge and without powerful top-down control. In this context, we propose that creating and analyzing computer models of their decentralized processes of management can provide a broader perspective on the possibilities of political organization. In terms of self-optimization, this approach seeks the promotion of social systems with a balance of flexibility and robustness, i.e., systems that do not rely on the current ideal of rule-based control of all systemic aspects.

Tayrona vessel
Vessel produced by the Tayrona in the Sierra Nevada de Santa Marta between 900 and 1600 AD showing a ritual scene. (Photo courtesy of Museo de Oro, Bogotá)

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: