Tuesday, February 22, 2011

What is a city? Definitions of the urban

What is a city? How do we distinguish urban from non-urban settlements in ways that make sense? Does it matter how we define cities, or is definition just a sterile typological exercise? Definition is crucial for comparison. If we are going to compare cities, or parts of cities, then it helps to have a clear and explicit notion of what we are talking about. In my field, archaeology, there are two main kinds of definitions of the city, based on two of the important characteristics of cities. The demographic definition is based on the idea that cities are big places with lots of people, while the functional definition flows from the notion that cities have an impact on their surroundings. Neither definition is “correct” or “best.” Rather, they are more or less useful for various kinds of purposes.

The Demographic Definition

This definition was first codified by sociologist Louis Wirth in his influential 1938 paper, “Urbanism as a way of life” (Wirth 1938).  Cities, according to Wirth, are defined by four characteristics:

1.      Permanence
2.      Large population size
3.      High population density
4.      Social heterogeneity
This sounds pretty good to most modern ears. It certainly fits contemporary cities, although there is always room for quibbling with quantitative definitions (How many people? How much heterogeneity?). To use the demographic definition, one looks at a settlement, makes some measurements, and decides whether or not it is a city.

The Functional Definition of Urban

Although there may be precursors, most modern functional definitions of cities derive from mid-20th century economic geography, where central place theory focused on the regional distribution of retail market centers. Market centers provisioned a hinterland, and the larger the hinterland (and the more goods and services provided), the more important the center. In these models retail marketing is an urban function—an activity or institution located within a settlement that affects people and places beyond the settlement. Later developments in anthropology and geography expanded the notion of urban function beyond economics to include politics and religion (Fox 1977). From this perspective, the Classic Maya jungle cities can be considered urban because their kings ruled city-states larger than the individual settlement, and their temples were the focus of worship for peasants as well as urban dwellers. From the demographic perspective, on the other hand, the Maya centers were not big enough to be called cities. To use the functional definition, one cannot simply look at a settlement and decide whether it is urban; one has to look at the entire regional context, including the hinterland and other nearby settlements. If the settlement in question was the setting for people and institutions that impacted a larger realm, it can be considered an urban settlement.

I generally prefer the functional definition, and I’ve argued in its favor on and off over the years (Smith 1989, 2008). I don’t feel that it is inherently better than the demographic definition, only that it contributes more to advancing research and understanding in some of the topics I work on. A good example is the Classic Maya, the urban status of whose capitals was the subject of a lengthy debate. In a series of publications starting in the 1960s, William Sanders applied Louis Wirth’s demographic definition of urbanism to ancient Mesoamerica. In his perspective, Teotihuacan (over 100,000 population; density ca. 5,000/km sq) was a clearly a city, but Tikal and the other Maya centers were not sufficiently big or dense or socially complex to be called cities. If the goal is to analyze how large dense cities differ from smaller more dispersed settlements, then the demographic definition makes sense. The urban experience must have been radically different for the residents of Teotihuacan compared to the residents of Tikal or Copan.

On the other hand, if one is interested in how the Maya centers affected their hinterlands, or the nature of their political, religious or economic influence, or how the inhabitants of the Maya landscape were linked together by polities or market systems or religious communities, then the demographic definition is of little help. The functional definition of urbanism acknowledges Tikal and Copan as urban centers, and this helps us understand how Maya society worked on a regional scale.

One of the things I like about the functional definition of urbanism is that it allows us to talk about different kinds of cities: political capitals, religious centers, economic centers, and other types. Sometimes the type of city differs among urban traditions. Swahili cities were trade centers, whereas most Maya cities were political-religious centers. And sometimes a single society has different functional types of cities. Just as the United States today has such diverse cities as Washington, DC, New York City, and Miami, so too did Aztec central Mexico have an imperial capital (Tenochtitlan), ritual centers (Malinalco), and city-state capitals (many examples).

Definitions help orient us in a field, they aid comparison, and they help us understand urban societies and their transformations. There is more to say about the topic, which I will return to in a future post.


Fox, Richard G.
1977    Urban Anthropology: Cities in their Cultural Settings. Prentice-Hall, Englewood Cliffs.

Smith, Michael E.
1989    Cities, Towns, and Urbanism: Comment on Sanders and Webster. American Anthropologist 91:454-461.

2008    Aztec City-State Capitals. University Press of Florida, Gainesville.

Wirth, Louis
1938    Urbanism as a Way of Life. American Journal of Sociology 44:1-24.

Wednesday, February 16, 2011

How do we compare cities? OR, Does this logo make sense?

I had fun creating the logo for this blog. Can you identify the places? (I almost wrote, "can you identify the CITIES". Oops. One of them is not a city. Oops, maybe THREE of them aren't cities. How do we define cities? Well, that will be another post).

These are the places in the logo above:
1. Chichen Itza
2. Stonehenge
3. A generic Medieval European city gate
4. New York City
5. Angkor

Now Stonehenge was definitly NOT a city. So what is it doing in my logo? This is actually a serious question. I didn't pick Stonehenge for aesthetic purposes (well, not entirely for aesthetic reasons). Its inclusion can be viewed as an intellectual statement about comparative urbanism.

Stonehenge is relevant to comparative urbanism because as a large public monument, it shares physical properties, and social implications, with urban public monuments (such as the other elements of the logo). Monuments communicate information about their builders and about their social context, and they have an influence on individuals and society. These issues are part of architectural communication theory, a body of thought associated with Amos Rapoport (his best book, in my mind, is The Meaning of the Built Environment: A Nonverbal Communication Approach, Univ. Arizona Press, 1990). Or see my paper on urban theory, where I cover this and other theoretical approaches to ancient cities.

Cities are complex and messy things, and it is difficult to compare them. As a scholar, I find it far too complicated to make big comparisons of whole cities. Much more useful are comparisons of specific parts of cities (housing, or streets, or parks), or comparisons of specific urban processes (transportation, or manufacturing), or specific urban conditions (homelessness, or health care, or symbolic meaning, or poverty).

Stonehenge was not a city, and it was not part of a state-level society. As such, whole-settlement comparisons of Stonehenge with, say, the four cities in the logo, would not be very informative. On the other hand, specific smaller-scale comparisons of the monument of Stonehenge with some ancient urban monuments could be enlightening and might help us better understand the role of monuments in society. So Stonehenge, while NOT an urban feature, is relevant to research in comparative urbanism that focuses on a smaller scale than whole cities. It is definitely relevant to the wide urban world (and it looks pretty good, too).

Sunday, February 13, 2011

Were ancient cities sustainable ?


As an archaeologist, I have a very different view of sustainability than most scholars who study the contemporary world. For sustainability today, one of the standard definitions is that of Gro Harlem Bruntland: “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” There is much debate and discussion about this definition and its usefulness, but the dual components of current practices and potential future outcomes are fundamental for most writers.

Archaeology deals with human society over long time spans—centuries and even millennia. For me, a sustainable society is one that lasts for a long time. In central Mexico, Teotihuacan society flourished for five centuries or more, while many of the societies that came later were only around for a couple of centuries before collapsing. Teotihuacan was far more sustainable. People sometimes wonder why Classic Maya civilization collapsed, assuming that their society and practices must have been defective. But the Maya cities lasted even longer than Teotihuacan. My own society in the USA has lasted less than half as long as the Classic Maya, so perhaps the Maya had a more sustainable society than we have today.

As for urban sustainability, consider these three definitions:

• “a sustainable city is one in which the community has agreed on a set of sustainability principles and has further agreed to pursue their development” (Munier 2007:17).
• “For cities, I have defined sustainability as reducing Ecological Footprint (energy, water, land materials, waste) while simultaneously improving quality of life (health, housing, employment, community) within the capacity constraints of the city” (Newman 2006).
• “when we talk about urban sustainability, we should consider several issues: survival of the settlement through time, environmental impacts on landscapes, and quality of life for inhabitants” (Grant 2004:24).

The first definition cannot be applied to ancient cities. Even if people in ancient Babylon, say, had agreed on sustainability principles (a laughable idea), we would not have any evidence of this today. The second definition at least makes sense to an archaeologist. But only the third definition (by Jill Grant) is really applicable to ancient cities.

The study of modern urban sustainability does not ask whether cities will fail or not, but whether a given quality of urban life can continue into the future. One reason for this neglect of what seems an obvious question to an archaeologist is the fact that, in the words of Thomas Campanella (2006:142), “the modern city is virtually indestructible.” Research on the effects of natural disasters on contemporary and recent cities shows that modern cities (from Beirut to New Orleans) nearly always survive just about anything that nature or people can throw at them.

The reasons for the resiliency of modern cities in the face of physical disaster are listed by Campanella (2006:142):

1. modern nation states have a vested interest in the well-being of their cities.
2. private property laws ensure the continuing organization of urban space, even after physical destruction.
3. the modern insurance industry lessens economic impacts of disasters.
4. urban infrastructure is complex and multilayered, and is rarely destroyed totally.

These conditions do not hold for most preindustrial cities, making it difficult to compare ancient urban sustainability (how long did cities survive?) with modern sustainability (can present lifestyles continue into the future?). Campanella (2006:141) goes on to suggest that the situation was only slightly different in the past. He asserts that after A.D. 1100 very few cities were destroyed or abandoned. Now any archaeologist who has undertaken a landscape survey knows this is not the case; landscapes all over the world are littered with destroyed and abandoned urban sites. Many ancient cities failed, but should we consider them sustainable or not? This is a topic that needs much more research by archaeologists. The current infatuation with societal collapse (e.g., Diamond 2004) takes our perspective away from sustainability and gives a biased picture of ancient societies. Instead of claiming that the Classic Maya were deficient because their cities collapsed, perhaps we should call them wildly successful for forging a vibrant civilization in a harsh environment that lasted for many hundreds of years.

I find it remarkable that even in the absence of the kind of modern urban safety net described by Campanella, many ancient cities managed to survive for many centuries, and some lasted for millennia (think of Rome or Babylon or Jerusalem). This sure sounds like sustainability to me.

This post is based on some of the themes in Smith (2010).


Campanella, Thomas J.
2006 Urban Resilience and the Recovery of New Orleans. Journal of the American Planning Association 72:141-146.

Diamond, Jared
2004 Collapse: How Societies Choose to Fail or Succeed. Viking, New York.

Grant, Jill
2004 Sustainable Urbanism in Historical Perspective. In Towards Sustainable Cities: East Asian, North American and European Perspectives on Managing Urban Regions, edited by André Sorensen, Peter J. Marcutullio, and Jill Grant, pp. 24-37. Ashgate, Burlington, VT.

Munier, Nolberto
2007 Introduction. In Handbook on Urban Sustainability, edited by Nolberto Munier, pp. 17-88. Springer, Dordrecht.

Newman, Peter
2006 The Environmental Impact of Cities. Environment and Urbanization 18:275-295.

Smith, Michael E.
2010 Sprawl, Squatters, and Sustainable Cities: Can Archaeological Data Shed Light on Modern Urban Issues? Cambridge Archaeological Journal 20:229-253.

Smith, M. (2010). Sprawl, Squatters and Sustainable Cities: Can Archaeological Data Shed Light on Modern Urban Issues? Cambridge Archaeological Journal, 20 (02), 229-253 DOI: 10.1017/S0959774310000259

Sunday, February 6, 2011

Droughts and the decline and rise of urban civilizations


The role of climate change in the collapse of ancient civilizations has become a popular topic, among both scholars and the public. Jared Diamond’s book Collapse (Diamond 2004) remains a best-seller, and it has generated considerable discussion and debate. This week a new technical study on ancient climate in central Mexico was reported (Stahle et al. 2011) (click here for more information) and it may transform our views of urban development in central Mexico. The authors have constructed a tree-ring chronology in the Mexican state of Queretaro that extends back to ca. AD 800. Although there has been a good amount of prior paleo-climatic research on central Mexico, the chronological detail given by tree rings – estimates of year-to-year rainfall patterns – dwarfs the resolution of prior work by limnologists.

Stahle et al. point to four periods of severe multi-decadal drought within their data:

1.      AD 897 – 922.  The authors try to extend the first drought range all the way to the Maya area to correlate with prior work on droughts at the end of the Classic period that may be related to the Classic Maya collapse. To be accepted, however, such an extension will require a lot more data from intermediate areas. But what they do not mention is that this coincides rather closely with the fall of several major cities, such as Xochicalco and Teotenango, at the end of the central Mexican Epiclassic period (ca. 900-950).

2.      AD 1149 – 1167.  The second drought, as pointed out by the authors, falls close to current estimates for the decline of Tula and the Toltec state (they use the incorrect term “empire”).

3.      AD 1378- 1404.  The third drought period does not match any clear demographic or political downfall. In fact, it came at the end of a massive demographic upsurge in central Mexico, and coincided with the expansion of the poorly understood Tepanec Empire (1380-1428). This was the most severe of the four droughts.

4.      AD 1514 – 1539.  The final drought covers the period of the conquest of the Aztec by Cortés (1519-1521) and the early colonial period.

To me, one of the most intriguing findings is NOT one of these periods of drought, but rather the relative absence of major drought between the second and third episodes. This interval, mostly contained within the “Early Aztec” period and the first part of the “Late Aztec” period, witnessed the single most dramatic population surge of the pre-Columbian New World. Populations in central Mexico exploded with a growth rate of over 1% (average annual increase), a very high rate for a preindustrial population. The population data are in Sanders et al. (1979), and I discuss the implications in Smith (2003). Prior paleoclimatological research had suggested a general increase in precipitation starting in the twelfth century AD (e.g., Metcalfe and Davies 2007), and the absence of major prolonged droughts fits this picture.

Not only did populations rise, but it was also a major period of urbanization in central Mexico. Most Aztec cities were founded and grew rapidly into capitals of city-states at this time (Smith 2008).

So, are we ready to read social changes directly off the rainfall record? Not so fast! Archaeologists and paleo-climate scientists have so far not done a very good job relating episodes of climate change (whether drought or temperature change) to episodes of social change. Scholars tend to be polarized into two camps: the environmental determinists and the cultural interpretivists.

Many climate specialists and some archaeologists fall into the first category, environmental detereminists. There was a drought, the civilization collapsed, so we now have it figured out. End of story. This is far too simplistic, however.

Quite a few archaeologists and anthropologists, on the other hand, are cultural interpretivists. In their view, environmental processes never directly cause changes in human society. People are smart, society is resilient, and environmental effects are always mediated and interpreted through cultural understandings. These people get very upset at environmental determinist accounts. Some of them held a whole conference whose purpose was to attack Jared Diamond’s book, Collapse (McAnany and Yoffee 2010).

To me, neither approach is satisfactory, and neither will lead to real understanding of past social change and the role of drought, climate change, and other environmental factors. What is missing is the perspective of historical social science. The environmental determinists apply a simplified natural-science understanding to human society, which is inadequate to model human social dynamics. Their cultural opponents, on the other hand, seem resistant to scientific approaches to the past that employ causal mechanisms. But modern comparative and historical social science research transcends these limitations.

One promising avenue for integrating past climate data with social developments is the field of historical ecology (Balée 2006), and another can be found in transdisciplinary approaches to human-environment interaction (Costanza et al. 2007). But I find these approaches too limited in the realm of social dynamics of complex urban societies. They have little to say about urbanization, social inequality, poverty, collective action, and innumerable other social phenomena that have dominated human society since the Urban Revolution. It seems to me that when the insights of comparative historical social science (e.g., Hedström 2005; Steckel 2007; Tilly 2010) are applied to archaeological and historical research on the ancient past, our understanding of urbanization and other processes will increase tremendously.

In the meantime, the new data by Stahle et al. are of the utmost importance for the history of urbanization and social change in pre-Spanish central Mexico, and I hope it does not take too long to develop appropriate explanatory models to use the new data effectively.


Balée, William
2006    The Research Program of Historical Ecology. Annual Review of Anthropology 35:75-98.

Costanza, Robert, Lisa J. Graumlich, and Will Steffen (editors)
2007    Sustainability or Collapse? An Integrated History and Future of People on Earth. MIT Press, Cambridge, MA.

Diamond, Jared
2004    Collapse: How Societies Choose to Fail or Succeed. Viking, New York.

Hedström, Peter
2005    Dissecting the Social: On the Principles of Analytical Sociology. Cambridge University Press, New York.

McAnany, Patricia A. and Norman Yoffee (editors)
2010    Questioning Collapse: Human Resilience, Ecological Vulnerability, and the Aftermath of Collapse. Cambridge University Press, New York.

Metcalfe, Sarah E. and Sarah Davies
2007    Deciphering Recent Climate Change in Central Mexican Lake Records. Climatic Change 83:169-186.

Sanders, William T., Jeffrey R. Parsons, and Robert S. Santley
1979    The Basin of Mexico: Ecological Processes in the Evolution of a Civilization. Academic Press, New York.

Smith, Michael E.
2003    The Aztecs. 2nd ed. Blackwell Publishers, Oxford. (** 3rd edition coming soon; I shipped the files off to Blackwell today!)

2008    Aztec City-State Capitals. University Press of Florida, Gainesville.

Stahle, David W., José Villanueva-Díaz, Dorian J. Burnette, Julián Cerano Paredes, Richard Heim, Jr., Falko K. Fye, Rodolfo A. Soto, Matthew D. Therrell, Malcolm K. Cleaveland, and D. K. Stahle
2011    Major Mesoamerican Droughts of the Past Millennium. Geophysical Research Letters 38:(in press).

Steckel, Richard H.
2007    Big Social Science History. Social Science History 31:1-34.

Tilly, Charles
2010    Cities, States, and Trust Networks: Chapter 1 of Cities and States in World History. Theoretical Sociology 39:265-280.

Stahle, David W., José Villanueva-Díaz, Dorian J. Burnette, Julián Cerano Paredes, Richard Heim, Jr., Falko K. Fye, Rodolfo A. Soto, Matthew D. Therrell, Malcolm K. Cleaveland, and D. K. Stahle (2011). Major Mesoamerican Droughts of the Past Millennium Geophysical Research Letters