Economic Geography and State Emergence

Explanation

The goal of the project is to test the hypothesis that the economic behaviors proposed by Paul Krugman's "New Economic Geography" framework can explain hierarchically organized settlement networks in emergent state societies. Our test will apply Krugman's model and knowledge of caloric resource distributions to an agent-based model that attempts to reproduce the settlement and network structures observed in the Tiwanaku and Roman empires. Our test will help to clarify the degree to which economic networks create a context for the emergence of social competition and inequality. This page is intended to facilitate the project's progress, and is organized with the a final paper structure in mind.

Introduction to Tiwanaku Empire Settlement Hierearchies

As a state-level society that emerged in-situ, the Tiwanaku Empire presents an ideal case for exploring the role economic geography plays in structuring hierarchically organized societies. From a relatively even distribution of Early Formative Period (ca. 2000-1300 B.C.) small hamlets arose the increasingly nucleated regional centers of the Middle Formative Period (ca. 1300-500 B.C.). Stanish (2003) identifies at least 13 such centers in an incomplete sample. During the Upper Formative Period (ca. 500 B.C. - A.D. 400), two regional centers--Pucara and Tiwanaku/Chiripa--grew an order of magnitude larger than any of the other centers. Finally, by A.D. 400, the urban capitol of Tiwanaku emerged as the largest occupational center with a core population somewhere between 30 and 60,000 inhabitants. By A.D. 1000, the Tiwanaku Empire, which had become a conquest state, began to collapse.

Attendant to the demographic changes witnessed in the rise of the Tiwanaku Empire, were clear economic and politico-religious changes. During the Middle Formative Period, ceramic production becomes more specialized in the regional centers. The Yaya-Mama stylistic tradition also emerges and is manifest in the design of stone statues, or stelae, that are concentrated in the regional centers. Stanish (2003) argues that this new tradition is tied to elites and a pan-regional ideology. In the Upper Formative Period, communal architecure such as sunken courts and artificial mountains, or pyramids, appear at the regional centers. Janusek (2006) argues that architectural design and icongraphy at Tiwanaku was designed to coopt the power of nature as well as to integrate diverse cultural groups. He further suggests that Tiwanaku's success in "outcompeting" other regional centers stems from its uniquely integrative religious tradition.

Stanish (2003) hypothesizes that population centers are located as a function of resource access and peer polity competition. To test the idea, Griffin and Stanish (2007) created an agent-based model wherein agricultural productivity, migration, competition, and trade contribute to differential population aggregation. The model does a good job of approximating the empirical distributions. And, although the ABM fairly clearly shows that socio-religious unity may be more of a symptom than a cause of Tiwanaku's rise, the ABM's complexity makes it difficult to assess the degree to which any given factor drives the pattern. Our approach, then, will serve to clarify the degree to which formal economic processes drove the emergence of Tiwanaku, and created a context for the development of the elaborate social, political, and religious traditions that characterize Tiwanaku.

Implementing a Spatial Model of the New Economic Geography

• Agent Behavior
• Environmental Parameters
  • Agricultural productivity: 269-6960 kcal/ha. These figures are derived from Griffin and Stanish (2007:Table A-2) as follows: For each of the five agricultural strategies, the table reports the number of days fallow, caloric yields (kcal/ha), and production costs (person-days/ha. We first adjust the productivity estimates to factor in fallow time. Unfortunately, Griffin and Stanish do not report how many years a field remains productive--only how long it must be fallow. My communication with a modern Andean farmer (Albino Pilco Quispe) suggests that crop rotation allows for a field to stay productive for 3 years. Accordingly, the agricultural yields are multiplied by 3/7 or 3/4 depending on the published fallow values. In order to convert these values into net yields/ha, we next convert the production costs to caloric costs assuming 1 person day equals 2 kcal. For each agricultural strategy, this value is subtracted to from the adjusted yields to derive the net kcal/ha reported above.
  • average hunter-gatherer group size: 25 (Kelly 2007:205-213). This provides a justification for setting initial group sizes. Kelly's review suggests that 25 offers an optimal tradeoff between reproductive viability and resource sustainability.
  • average minimum territory size: 3-68 ha. If we assume that an average individual requires 730 kcal/year, then an average village would require approximately 18,250 kcal/year necessitating between 3 and 68 ha. (I think I need to re-evaluate these numbers--seems a bit low).
  • Birth/death rate: As a first approximation, we can reason that 50% of the population is female. Kelly's summation of 42 data points from hunter-gatherer populations around the world suggests total fertility rates from 0.81-8.5 with a median of 4.7. (In progess)

References

Griffin, Arthur F., and Charles Stanish 2007 An Agent-Based Model of Prehistoric Settlement Patterns and Political Consolidation. Structure and Dynamics: eJournal of Anthropological and Related Sciences 2(2):1-47.

Gumerman, George J., Alan C. Swedlund, Jefferey S. Dean, and Joshua M. Epstein 2003 The Evolution of Social Behavior in the Prehistoric American Southwest. Artificial Life 9:435-444.

Krugman, Paul 1991 Increasing Returns and Economic Geography. Journal of Political Economy 99(3):483-499.

Janusek, John Wayne 2006 The Changing 'Nature' of Tiwanaku Religion and the Rise of an Andean State. World Archaeology 38(3):469-492.

Rauch, Jonathan 2002 Seeing Around Corners. The Atlantic Monthly, April:35-48.

Stanish, Charles 2003 Ancient Titicaca: The Evolution of Complex Society in Southern Peru and Northern Bolivia. University of California Press, Berkeley.

Original Proposal (Do not Edit)

Economic Geography in the Lake Titicaca Basin

By A.D. 1200, the Tiwanaku Empire reached an apex in population and social complexity. The distribution of settlement sizes at that time approximated a power-law or log-normal distribution with the urban center of Tiwanaku as the capitol. Archaeologists such as Stanish, Janusek, and others have argued that, while economic factors drive early settlement patterns, differential growth in settlements is primarily a function of competing political polities. They argue that polities with the most integrative religious traditions continued to grow relative to surrounding communities. In this project, we wish to explore the possibility that a simpler economic /demographic model can explain the emergence of such settlement patterns through time. Specifically, we intend to follow the general modeling framework created by Paul Krugman, which he calls the “New Economic Geography.”

Our working method would be to use the behaviors proposed by Krugman in an agent-based model that predicts the spatial distributions of the empirical settlement patterns in the Lake Titicaca Basin. The model explains settlement change by assuming that separate forces encourage production to simultaneously concentrate and disperse. The centrifugal forces that encourage dispersed production come from the uniformly distributed farming population which demands goods. Transportation costs mean that production should be close to farmers and therefore dispersed across the landscape to serve farmers efficiently. At the same time, we assume that increasing returns to scale obtains for production, meaning that larger production facilities can produce at lower marginal costs. This centripetal force encourages production to be centered in one area. In addition, production centered in one area attracts more workers and increases local demand for the product. Depending on model parameters, these dynamics can give rise to a dominant production and population centered, as seen in the Lake Titicaca data.

We don’t think we can take this project on by ourselves, so we are writing to see if we can get 1 or 2 more people interested and then move forward. If interested, please talk to Randy Haas or Jeremy Barofsky. Thanks!