Monday, November 6, 2017

Houses, housing, and inquality in the distant past

When people talk about the relationship of residences--the places where people live--to social inequality and other aspects of society today, they talk about "housing." But when archaeologists talk about residences, we usually talk about "houses," and not "housing." This distinction is on my mind because I just finished reading Mathew Desmond's outstanding book, Evicted: Poverty and Profit in the American City (2016). This is the best book I have read in a long time and there is much to talk about. Go read the book, it's really fantastic; I'll devote a blog post to the book before long. But first I want to use the book as a stimulus to explore the differences between they way archaeologists talk about houses in the past and the way sociologists (and others) talk about housing in the present. One of the questions on my mind is methodological: how can archaeologists get at issues of housing and inequality in our studies of ancient urban houses?

Houses in the past
Aztec commoner house

When archaeologists talk about residences in the past, the focus is on the house, or the physical structure in which people live. We are concerned with how these were built: what were the construction materials and where did they come from? What kind of techniques were used by the builders? How big were houses? How much effort and materials were needed to build a house? Can we estimate the number of people (or at least the number of households) who lived in a specific house? Our focus on these things is natural, given the kind of fragmentary evidence we have about houses in the past.

Size variation in Aztec houses at 2 settlements
Archaeologists have found that the size of houses can be a good measure of inequality in the past. This information can be used for social class analysis (Olson and Smith 2016), or for the study of continuous wealth inequality using measures like the Gini index, based on the assumption that house size was an index of household wealth ( Smith et al. 2014). For the first, time, archaeologists are beginning to accumulate enough cases of inequality in house size, measured with the Gini index, to draw some conclusions about past inequality (Kohler et al. 2017; Kohler and Smith 2018). As more archaeologists quantify their data on houses and settlements, our understanding  of levels of past inequality will continue to improve.

While this is a productive development in the archaeology of social inequality, reading Matthew Desmond's book Evicted makes me wonder if we can do better by using the concept of housing.

Housing today

The study of how housing relates to social inequality today goes far beyond the topics of architecture and house size. Major questions include: Who builds housing units? Who owns them? How do residents get access to housing? And can residents who rent create a stable pattern that avoids frequent moves? These are the issues explored in Evicted through detailed case-study ethnography, coupled with scholarly documentation of patterns in the endnotes. Can archaeologists get at any of this?
My typology of premodern urban house types

When archaeologists use the term "housing," the word is usually used informally and not analytically. That is, we may use the word, but just to talk about the standard issues of ancient house form and size outlined above. I was rooting around for a relevant scholarly definition of "housing," getting frustrated that writers on housing today don't see the need to define the term. Maybe "everybody knows" what it means, but still, it is sloppy practice to not define one's terms. Then I checked my own paper on the topic (Smith 2014a) to see how I defined the term. Oops! No definition! I am guilty here too. In that paper I talk about types of urban house units in the premodern world, but "housing" is not used as a formal concept.

Housing in the past?
Standardized housing in Mexico today

Can archaeologists approach the question of who built housing in cases where we lack written documents? I think that the analysis of standardization in housing can allow us to make reasonable inferences on whether housing was built by the state or another formal institution (e.g., a temple community), or by residents themselves. But standardization of architectural forms is a tricky question. Today, some housing is obviously standardized--such as contemporary Mexican ex-urban developments or mid-twentieth century socialist housing in Europe--and other housing is clearly informal, which usually means non-standardized.

First, precisely what is or is not standardized? It can be the size of a dwelling, principles of layout, materials used, construction methods. Second, who is doing the standardizing? Individual self-builders? While this often leads to variability in house form, when builders deliberately stick to a cultural norm, as in much vernacular architecture, the result can be standardized forms. Or is standardization created by professional builders and architects? By the state? Or by the capitalist market and zoning regulations (as in urban and suburban developments today)?

It turns out that standardized housing is a complex topic, one that is not very well researched in the fields of housing and architecture (and almost never by archaeologists). Drawing on my model of premodern urban planning (Smith 2007), an archaeologist might associate standardization of housing over an entire city, or city sector, with the actions of the state (e.g., Olynthus or Teotihuacan). Standardized housing on the scale of a neighborhood might be created by the state or by professional builders working for clients. And nonstandardized housing suggests auto-construction by house owners (Turner 1991; Ward 1973).

Another domain where archaeologists can begin to approach issues of housing and inequality, parallel to scholars of the modern world, is residential stability.  In another paper (Smith 2014b), I cited contemporary social-science research showing that urban residential stability is associated with higher standards of living, lower levels of crime, and other measures of community well-being (one thread of this research is referred to as social disorganization theory). I drew on sociologists such as Robert Sampson (2012). I argued that similar dynamics (linking residential stability to positive community outcomes) probably characterized premodern cities as well. I presented some evidence from my studies of Aztec communities showing that the houses I excavated in wealthier communities tended to be occupied continuously over long periods, whereas the houses in less well-off communities showed more discontinuity in occupation. I develop this argument in my (award-winning!) popular book, At Home with the Aztecs (Smith 2016). I wish I had been able to read Desmond's Evicted before writing my book. It is the most eloquent (and empirically compelling) discussion of the negative effects of the lack of residential stability, caused by evictions.
Each bar is a house. Yautepec houses had more stability than at Calxitlahuaca
But these efforts are just a beginning. Archaeologists need to take a closer look at research on contemporary cities and housing, and devise creative ways to put that knowledge to work in explaining the past. And scholars of contemporary housing might pay attention to some of the better archaeological research to get an idea of the longevity of patterns and the historical depth of systems of social inequality. But a point I make in Smith (2010) is that unless archaeologists analyze our data in ways that foster comparison and conceptual advance, it won't be comparable at all to the modern world, and any such comparisons will be facile and superficial.


Desmond, Matthew  (2016)  Evicted: Poverty and Profit in the American City. Broadway Books, New York.

Kohler, Timothy and Michael E. Smith (editors)  (2018)  Ten Thousand Years of Inequality: The Archaeology of Wealth Differences. University of Arizona Press (in press), Tucson.

Kohler, Timothy A., Michael E. Smith, Amy Bogaard, Gary M. Feinman, Christina E. Peterson, Aleen Betzenhauser, Matthew C. Pailes, Elizabeth C. Stone, Anna Marie Prentiss, Timothy Dennehy, Laura Ellyson, Linda M. Nicholas, Ronald K. Faulseit, Amy Styring, Jade Whitlam, Mattia Fochesato, Thomas A. Foor and Samuel Bowles  (2017)  Greater Post-Neolithic Wealth Disparities in Eurasia than in North and Mesoamerica. Nature (in press).

Olson, Jan Marie and Michael E. Smith  (2016)  Material Expressions of Wealth and Social Class at Aztec-Period Sites in Morelos, Mexico. Ancient Mesoamerica 27(1):133-147.

Sampson, Robert J.  (2012)  Great American City: Chicago and the Enduring Neighborhood Effect. University of Chicago Press, Chicago.

Smith, Michael E.  (2007)  Form and Meaning in the Earliest Cities: A New Approach to Ancient Urban Planning. Journal of Planning History 6(1):3-47.

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, Michael E.  (2014a)  Housing in Premodern Cities: Patterns of Social and Spatial Variation. International Journal of Architectural Research 8(3):207-222.

Smith, Michael E.  (2014b)  Peasant Mobility, Local Migration, and Premodern Urbanization. World Archaeology 46(4):516-533.

Smith, Michael E.  (2016)  At Home with the Aztecs: An Archaeologist Uncovers their Domestic Life. Routledge, New York.

Smith, Michael E., Timothy Dennehy, April Kamp-Whittaker, Emily Colon and Rebecca Harkness  (2014)  Quantitative Measures of Wealth Inequality in Ancient Central Mexican Communities. Advances in Archaeological Practice 2(4):311-323.

Turner, John F. C.  (1991)  Housing by People: Towards Autonomy in Building Environments. Marion Boyars, London.

Ward, Colin  (1973)  We House, You are Housed, They are Homeless (chapter 6). In Anarchy in Action, pp. 67-73. George Allen and Unwin, London.

Tuesday, October 10, 2017

Burial goods and wealth in urban, state societies

I am looking for comparative and conceptual works related to a project of examining burial goods at Teotihuacan for evidence of wealth or status variation. My needs right how are highly specific; they are set out in numbered bullets below. In brief, I would like to find comparative or analogical cases that provide a justification or warrant for using grave goods to monitor wealth or status in state-level societies. I have had trouble finding anything, so perhaps this does not exist, or perhaps I am just looking in the wrong places and readers can point me in the correct direction.

Let me begin with another, parallel, case to illustrate what I am looking for: the relationship of wealth and house size. I have been involved in using the sizes of houses to monitor wealth for many decades, publishing both empirical studies and conceptual works (Kohler and Smith 2018; Olson and Smith 2016; Smith 1975, 1992, 1993, 2014, 2016; Smith et al. 2014) . If you ask how I justify using the size of houses as a measure of wealth, I can provide many citations to ethnographies, ethnoarchaeological studies, and historical and archaeological works. They show that in many or most cases with quantitative data (and within a given society or settlement system), wealthy households (as measured from documentary or other independent evidence) live in bigger houses. There is strong cross-cultural support for this claim, which justifies using house size to measure wealth in the absence of independent wealth data. We will include a list of such studies when our book on wealth variation in archaeology comes out (Kohler and Smith 2018). If your reaction is, "But I can think of exceptions," then you don't get the point. This is a statistical relationship, not an invariant relationship, so of course there are exceptions. If you think that the exceptions invalidate my claim, then either you have dozens of cases I haven't seen, or else you may want to take a statistics class.

Does such evidence exist for burial goods? I don’t want to get involved in arguments about the Binford-Saxe model, the postprocessual critique, or particularistic claims that this or that ethnographic case don't fit the model that burial goods reflect wealth (Ucko 1969). I want some hard comparative evidence so that I can make an empirical judgment about the likely strength of the relationship between burial goods and wealth in urban, state societies. Here is what I want:

  •          Best case: Ethnographic, historical, or archaeological cases (state society, ideally Premodern) with these characteristics:
    • a.   There is a good sample of households of known wealth
    • b.   There are burials with burial goods that can be linked to those households. That is, either the burials are spatially associated with individual houses, or else there is textual data linking households to burials. The wealth measures should be independent of the burials.
    • c.    It would be nice also to have independent data about the extent of wealth and class variation in the society.
  •          Second-best case: Ethnographic, historical, or archaeological cases (state society, ideally Premodern) with these characteristics:
    • a.   There is a good sample of burials with burial goods
    • b.   There is independent data about the extent of wealth and class variation in the society. That is, the burials could be from a cemetery and thus not linked to individual houses or households.
  •          Third-best case: Archaeological studies of a sample of burials with burial goods that use quantitative analysis to reach conclusions about the nature and extent of wealth or class variation in the society.

If you can help me out with citations, please email me!  Thanks.


Kohler, Timothy and Michael E. Smith (editors)
2018 Ten Thousand Years of Inequality: The Archaeology of Wealth Differences. University of Arizona Press (in press), Tucson.

Olson, Jan Marie and Michael E. Smith
2016 Material Expressions of Wealth and Social Class at Aztec-Period Sites in Morelos, Mexico. Ancient Mesoamerica 27 (1): 133-147.

Smith, Michael E.
1975 Temples, Residences, and Artifacts at Classic Teotihuacan. Senior Honors Thesis, Department of Anthropology, Brandeis University.

1992 Archaeological Research at Aztec-Period Rural Sites in Morelos, Mexico. Volume 1, Excavations and Architecture / Investigaciones arqueológicas en sitios rurales de la época Azteca en Morelos, Tomo 1, excavaciones y arquitectura. Memoirs in Latin American Archaeology, vol. 4. University of Pittsburgh, Pittsburgh.

1993 New World Complex Societies: Recent Economic, Social, and Political Studies. Journal of Archaeological Research 1: 5-41.

2014 Housing in Premodern Cities: Patterns of Social and Spatial Variation. International Journal of Architectural Research 8 (3): 207-222.

2016 Quality of Life and Prosperity in Ancient Households and Communities. In The Oxford Handbook of Historical Ecology and Applied Archaeology (book in press), edited by Christian Isendahl and Daryl Stump. Oxford University Press, New York.

Smith, Michael E., Timothy Dennehy, April Kamp-Whittaker, Emily Colon, and Rebecca Harkness
2014 Quantitative Measures of Wealth Inequality in Ancient Central Mexican Communities. Advances in Archaeological Practice 2 (4): 311-323.

Ucko, Peter J.
1969 Ethnography and Archaeological Interpretation of Funerary Remains. World Archaeology 1 (2): 262-280.

Tuesday, March 28, 2017

Cities through the ages: One thing or many?

I am in rainy Vancouver, BC. Tomorrow I will give a lecture at Green College, University of British Columbia, with this title ("Cities through the ages: One thing or many?"), and then Thursday I head downtown for the annual meeting of the Society for American Archaeology. I first gave a talk with this title at the Santa Fe Institute in 2013. At that time I developed an argument that there are, and have been, only two basic types of cities. I called them economic cities and political cities. Most contemporary cities are economic cities (dominated by capitalist economic processes), and that most ancient cities were political cities (dominated by political dynamics). The implication (it seemed to me, though incorrectly) was that the models of urban scaling that had been worked out for modern cities should not apply to ancient cities.

The urban scaling group (Luis Bettencourt, Jose Lobo, and Scott Ortman) had invited me to SFI to explore the possibility of applying the scaling models to ancient cities. I arrived ready to tell them to forget it. Ancient and modern cities were just too different in their economies, and I mistakenly believed that the scaling regularities of modern cities derived from capitalist agglomeration processes. But within a few hours of talking with these guys, they convinced me that the basic model that explains the modern scaling results is general enough to apply to ancient cities too. I had to scramble to modify my public lecture (the next day) to incorporate this insight (Bettencourt 2013).
Tenochtitlan, the Aztec capital

So, here I am, nearly four years later, giving a talk with the same title. But now I have TWO answers to the question, "One thing or many?" From the perspective of how cities operate and how they grow, I still see two very different types of cities: economic and political. Many of the economic models of contemporary cities simply do not apply to ancient cities. But from the perspective of  how people use the built environment of settlements, and how people interact with others, and the generative implications of those interactions, there is only one type of city. In fact, I should say there is only one type of settlement, because the patterns apply to non-urban settlements as well.

The City as Two Things: Economic and Political Cities

Most contemporary cities, and some past cities, are "economic cities." Their growth and operations are dominated by the commercial economy. Relevant concepts are agglomeration processes and agglomeration effects. Wage labor employees are matched with jobs in cities; urban public goods are shared by individuals and firms; and an educated workforce leads to prductivity gains (Duranton and Puga 2004). Sounds pretty standard for modern urban economics, but many of these things just plain don't apply to ancient cities. Many of these lacked wage labor and formal education. Agglomeration effects were much smaller or very different.

In some modern cities, politics dominates economics. These tend to be the large mega-capitals of developing nations. They are known as primate cities - not primates as in Planet of the Apes - but primate in the sense that the largest city in the system is far too large. It is too large because it is a political capital in a nation-state where politics dominates economics. See DeLong and Schleiffer (1993), or Ades and Glaeser (1995) on primate cities.

But this was the standard kind of city in the ancient world. Even in a heavily (noncapitalist) commercialized economy such as Classical Rome, politics played a heavy role in urban growth and operation, and thus many of the basic urban dynamics were quite different. Much economic activity in Rome was "unproductive" in that it was oriented at luxury, not growth of productivity (Baumol 1990).
Energized crowding at work

The City as One Thing: Energized Crowding and Social Interactions

But when we look at how social interactions in the built environment lead to highly regular patterns relating settlement population to other features, there is only one basic type of settlement. This is not a claim based on theory; it is an empirical conclusion. Luis Bettencourt's (2013) model of scaling derives the quantitative relationships between population and other urban features from the basic features of social interactions within the built environment. And this model explains both the regularities of scaling in contemporary urban systems and the same regularities in ancient urban systems. See some of my prior posts on scaling for more details :

Energized crowding turns cities into social reactors - 2016

Settlement scaling and social science theory - 2016

Urban scaling: Cities as social reactors - 2013

 But if you have doubts that the archaeological results are the same as the modern results, look at this table (from Smith 2017).

To me, these studies reach the most amazing results of any research I have ever been involved with. Why should there be such regularities in the sizes of settlements within settlement systems? How can the ancient systems have the same quantitative patterns as the modern systems? The cities are different. The societies and economies are different. People work and play differently. They move about differently. But somehow, the aggregate activities of people interacting in settlements produce the same kinds of quantitative patterns anyplace we look. Well, almost anyplace - it turns out that mobile hunter-gatherers have different patterns. But that is a different story..........

My talk tomorrow will be in Green College, UBC, a residential college for graduate students, postdocs, and faculty. This is a fascinating intellectual community in a gorgeous natural and built environment. It is part of a diverse series called, "The next urban planet: Rethinking the city in tome." What a great title for a series of lectures! I am staying in the Green College Guesthouse, where I have a cozy gas fire to keep out the damp and cold. I look forward to spending time with archaeologists, urban scholars, and others at UBC tomorrow.


Ades, Alberto F. and Edward L. Glaeser  (1995)  Trade and Circuses: Explaining Urban Giants. Quarterly Journal of Economics 110:195-227.

Baumol, William J.  (1990)  Entrepreneurship: Productive, Unproductive, and Destructive. Journal of Political Economy 98(5):893-921.

Bettencourt, Luís M. A.  (2013)  The Origins of Scaling in Cities. Science 340:1438-1441.

de Long, J. Bradford and Andrei Shleifer  (1993)  Princes and Merchants: European City Growth Before the Industrial Revolution. Journal of Law and Economics 36:671-702.

Duranton, Gilles and Diego Puga  (2004)  Micro-Foundation of Urban Agglomeration Economies. In Handbook of Regional and Urban Economics, edited by J. Vernon Henderson and Jacques-François Thisse, pp. 2064-2117. vol. 4. Elsevier, Amsterdam.

Smith, Michael E.  (2017)  The Generative Role of Settlement Aggregation and Urbanization. In Coming Together: Comparative Approaches to Population Aggregation and Early Urbanization, edited by Attila Gyucha. State University of New York Press, Albany.

Monday, December 5, 2016

Ramses II vs. Pericles, or Darth Vader vs. the Rebel Alliance

I still struggle to fight off the stereotypes about ancient states and empires that I learned as a student. Anthropological archaeology has long been concerned with the rise of state societies, and the nature of states in the ancient world. This is what got me interested in archaeology in the first place. I came across my decades-old graduate school application personal essay at the back of a file drawer, and found that I had written that I wanted to get a Ph.D. in archaeology to explain the origins of states in Mesoamerica. (Well, I think I probably phrased it as the "rise of THE state").

Back then, we were taught that all ancient states were despotic, ruled by ego-maniac kings who strove to control all aspects of society. Rameses II, played by Yul Brynner in the movie the Ten Commandments, is a good model for these ancient states. The Egyptian pharaohs ruled with an iron fist. Just look at his face! Any talk about democracy or council-rule prior to Classical Athens was written off as the fantasy of ancient writers. Ancient kings were autocrats who oppressed their subjects

Then I read Blanton and Fargher's 2008 book, Collective Action in the Formation of Pre-Modern States, which turned my views of ancient states and empires upside down (well, maybe I am being a bit dramatic here. Blanton et al 1996 was a first step in this direction; and other works, by Margaret Levi and Michael Mann, for example, contributed to this trend). By making a detailed and semi-quantitative analysis of thirty premodern states (from historical and ethnographic data), Blanton and Fargher identified a continuum of political regimes that runs from autocratic at one end to collective at the other. It turns out that collective states--where rulers have less power and people have more say--were not all that unusual in the past. The Greeks didn't invent democracy; similar processes and institutions were found in many ancient societies.

Blanton and Fargher identify three scales that run from low to high: Bureaucratization; Control over principals (rulers); and Public goods provision. Regimes that score high on these scales had more collective forms of rule, while those that scored lower were more autocratic. They then devise a causal model to explain variation in governmental form. It runs like this. If a regime relies on taxing its subjects for revenue, then it has to treat them well. Otherwise people will not pay taxes, and will leave or rebel. So there has to be a way to get rid of terrible rulers, and the ruler has to provide public goods (roads, canals, and other services and facilities). This produces a collective regime that is responsive to its population. On the other hand, if a regime gets its revenue from external sources (imperial tribute, conquest, taxing trade), then it does not have to be nice to its subjects. It can let them starve, not provide any public goods, and the ruler can be exploitative. These are the autocratic regimes. This scheme fits the evidence quite well.

By using a series of measures for each of the 3 scales, Blanton and Fargher come up with a summary collective measure for each society in their sample. The most autocratic regimes included 12th century England, Bali and some African kingdoms. Darth Vader and the evil empire in Star Wars would fit in here. The most collective are Athens, Venice, and Ming China; also the Rebel Alliance. In the middle are the Yoruba, Inka and Aztec polities.

There is a strong counter-intuitive element to this scheme. It turns out that the most autocratic regimes had the least concern for their subjects. These rulers didn't try to control their subjects; they left them alone to struggle to get by. This goes against the old idea that despotic rulers wanted to control the behavior of their subjects. On the contrary, autocratic rules didn't care what their subjects did. But collective regimes, on the other hand, DID need to interfere in people's lives. If they were going to tax their subjects effectively, they had to monitor them; hence Bureaucratization was a main features of more collective polities. Collective regimes had to keep their subject happy, so they provided public services. Collective regimes were far more intrusive into the lives of ordinary people than were autocratic regimes. This is the counter-intuitive part.

The work of Blanton and Fargher was a major breakthrough in our understanding of early states and their forms of government. Unfortunately, they did not devote enough attention to methods to measure their scales using archaeological data. They did publish a few articles with some ideas about archaeological cases. But the rest of us now have our work cut out for us. We need to devise methods to distinguish collective from autocratic regimes in the distant past, and we need to use these concepts to analyze political change and social patterns in the distant past.

Blanton, Richard E., Gary M. Feinman, Stephen A. Kowalewski and Peter N. Peregrine  (1996)  A Dual-Processual Theory for the Evolution of Mesoamerican Civilization. Current Anthropology 37:1-14.

Blanton, Richard E. and Lane F. Fargher  (2008)  Collective Action in the Formation of Pre-Modern States. Springer, New York.

QUESTION: Why is Darth Vader holding my cat ???????

Tuesday, November 22, 2016

Teotihuacan in the news: 1966 and 2016

I was looking for some biograhical material on Rene Millon, director of the Teotihuacan Mapping Project. I came across this story, from Popular Mechanics magazine in July 1966:

This was from the early days of the Teotihuacan Mapping Project, when they were in the middle of making surface artifact collections and digging test excavations.  And now, 50 years later, here is another press item from Teotihuacan:

Wow, knowledge really does advance through time. Back in 1966 no one had any idea they would find rabbit bones at Teotihuacan, and asking questions about animal keeping and diet like this were out of the question. Our analytical methods, as well as our stock of excavated archaeological contexts, are now far beyond what they were in 1966. This rabbit study, by a couple of archaeologists who started out as anthropology majors at Arizona State University, shows the kind of detailed questions we can now ask about the past (see bibliography below).

But as an archaeologist and scholar, I like to try to stand above the weeds now and then and take a broad perspective on the past. Archaeology is not just about mapping a site or figuring out what people ate for dinner. We need to take facts like these--established from rigorous fieldwork and laboratory analyses--and put together a broad view of life, society, and cities in the past. When we do this, it turns out that many things are not all that different from life, society, and cities today. This insight is the basis for the "Wide Urban World."

And when you turn to your turkey dinner for the Thanksgiving holiday this week, don't just think back to the Native Americans and Pilgrims and the first Thanksgiving meal. Think, instead, about the Mayas and Teotihuacanos of ancient Mesoamerica, the ones who first domesticated the turkey in the first place.


Somerville, Andrew D., Nawa Sugiyama, Linda R. Manzanilla, and Margaret J. Schoeninger
2016    Animal Management at the Ancient Metropolis of Teotihuacan, Mexico: Stable Isotopoe Analysis of Leporid (Cottontail and Jackrabbit) Bone Mineral. PLOS-One 11 (8): e0159982.

2016    Leporid management and specialized food production at Teotihuacan: stable isotope data from cottontail and jackrabbit bone collagen. Archaeological and Anthropological Sciences  (online first).

Pyramids of Teotihuacan in the 19th century

Tuesday, November 15, 2016

Energized Crowding Turns Cities into Social Reactors

What is is about cities that makes them exciting and dynamic? Things are happening in cities and people are attracted to them. As Jane Jacobs said, “Cities have the capability of providing something for everybody, only because, and only when, they are created by everybody.” Some cities never sleep. Cities are the setting for activities that just aren't found in smaller settlements. The more people in a city, the more activity and the more excitement. This is not just a feature of contemporary cities:  ancient cities like Teotihuacan were also bustling, dynamic, and attractive places. Architectural historian Spiro Kostof coined the term "energized crowding" to describe this aspect of urban life and society.

Energized crowding doesn't just describe the condition of life in cities - it describes the basic social forces that lead cities to grow and to transform life and society. This is the basis of the work on settlement scaling by the Social Reactors Project: me and Jose Lobo at Arizona State University, Scott Ortman at the University of Colorado, and Luis Bettencourt at the Santa Fe Institute. Check out our website. In our model, the process of energized crowding turns cities into social reactors.

As the number of people in a settlement increases, the number of potential social interactions grows at an exponential rate (see graph). As settlements grow larger, the effects of social interaction are amplified. These include positive, negative, and neutral effects. Let's start with the negative side of things. As we as individuals have to deal with more and more people, we get overloaded. Too many people, too much going on. This is called scalar stress. Some of the effects are highly negative--more people means more crime, more poverty, more social alienation. But scalar stress is offset by one of the big "nuetral" effects of growing settlement: the formation of neighborhoods. As cities grow, people adjust their activities so that they can live life on a smaller scale--the neighborhood. As I have said many times in this blog, neighborhoods are one of the very few universals of the urban experience. Here are a few posts on this (out of many.....):
 But there are also positive effects of energized crowding. Urban economists and economic geographers have known for a long time that when businesses and industries concentrate themselves in cities, it leads to economies of scale and thus major gains in productivity. These effects are called agglomeration effects, as in this diagram:
But it turns out that the positive effects of concentration and energized crowding are not limited to the modern industrial economy. In fact, they occur in cities before the industrial revolution, whether medieval European cities, or cities in the Roman or Inka empires. This fact alone shows that these effects are not due to factories, wage labor, advanced transportation, or other attributes of modern economies. In fact, these effects arise primarily out of the very act of social interaction within the built environment.

This realization was a real breakthrough in our understanding of the nature of city size and its role in generating the social and economic properties of cities. The key paper is Bettencourt (2013). Luis derives a quantitative model that predicts characteristics of cities based on their sizes, within a given region or urban system. The beauty of the model is that its conditions are general enough to fit cities before the modern era. In fact they also should work for non-urban settlements in agricultural village societies (and they do!).

Below is my diagram of energized crowding (from Smith 2017). When population grows, leading to higher densities, energized crowding increases. This can happen from regional population growth, or it can arise from the process of people moving into cities. The three results shown here are the negative, neutral, and positive outcomes of energized crowding.

In the time since Luis's 2013 article, our group has been scouring archaeology and history for cases where we can try out the model. Scott Ortman initiated this work with his studies of the settlement in the prehispanic Basin of Mexico. We've published a number of studies, and a bunch more are in the pipeline. Scott has even found the same scaling effects in village societies. The data requirements are heavy (a sample of 30 or more settlements from a given region and time period, with population estimates and other quantitative data to scale against population). If you think you know of any such cases, please let me know!

We have found the same quantitative relationships in modern and ancient settlement systems. This suggests that the same or very similar fundamental social processes operate when humans come together in settlements, whether today or two thousand years ago. Energized crowding--which is at a much higher level in larger settlements--has measurable effects on the density of settlement, and on the levels of economic and social outputs. In this figure, Graph A shows economic output measures for the modern U.S. economy, while Graph B shows wealth output for the ancient Inka economy. Quantitatively these two graphs are nearly identical. Both exhibit "superlinear scaling," with beta coefficients of 1.13.

So, how far can we push these relationships? Are they universal? Well, not quite. Hunter-gatherer campsites show very different patterns from the agricultural societies we have studied so far. This is something we are working on now. But for most systems we have examined, we find similar patterns, and when we apply Luis's model, we conclude that energized crowding turns settlements into social reactors.

For some other posts on the scaling work, see:
See our project website for more information.

Bettencourt, Luís M. A.  2013    The Origins of Scaling in Cities. Science 340: 1438-1441.

Cesaretti, Rudolf, Luís M. A. Bettencourt, Jose Lobo, Scott Ortman, and Michael E. Smith 2016    Population-Area Relationship in Medieval European Cities. PLOS-One: 11:(10) e162678.  .

Ortman, Scott G., Andrew H.F. Cabaniss, Jennie O. Sturm, and Luís M. A. Bettencourt
2014    The Pre-History of Urban Scaling. PLOS-one 9 (2): e87902.

2015    Settlement Scaling and Increasing Returns in an Ancient Society. Science Advances 1 (1): e1400066.

Ortman, Scott G. and Grant D. Coffey  2015    Universal Scaling: Evidence from Village-Level Societies. SFI Working Paper, vol. 15-10-044. Santa Fe Institute, Santa Fe. 

Ortman, Scott G., Kaitlyn E. Davis, José Lobo, Michael E. Smith, Luis M.A. Bettencourt, and Aaron Trumbo  2016    Settlement Scaling and Economic Change in the Central Andes. Journal of Archaeological Science 73: 94-106.  .

Smith, Michael E.  2017    The Generative Role of Settlement Aggregation and Urbanization. In Coming Together: Comparative Approaches to Population Aggregation and Early Urbanization, edited by Attila Gyucha. State University of New York Press, Albany.