Wednesday, March 23, 2016

Settlement Scaling and Social Science Theory

In this post I explore several branches of social science theory that support the social reactor model of settlement scaling. This is a continuation of my prior post, which explored the basis for comparing urban and village settlement systems. Like that post, this one is exploratory in nature, and I would really welcome feedback on these ideas. This post is a bit more academic and detailed than most in this blog, for which I apologize. Here is an outline of the scheme.

1. Theories of population growth and its effects
  1. Large-scale social consequences of population size
  2. Scalar stress
  3. Dual inheritance theory
2. Community theory
  1. Social interaction generates communities
  2. Social interaction generates successful communities
  3. Communities can accomplish goals
3. Urban economics

Yes, I realize this is a motley collection of themes—some are well-worked out theories or theoretical approaches, one is a discipline, and others are specific research topics or claims. But as Ralph Waldo Emerson said, “A foolish consistency is the hobgoblin of little minds.” I am not any kind of theoretician, and I’m afraid this is the best I can do for now. Don’t like this scheme? Then help me out; send me comments and critiques.

1. Theories of population growth and its effects

The first group of theories focus on the role of population growth—and population size—on society and behavior. This is a long-standing research theme in the social sciences. I divide this area into three categories.

A. Large-scale social consequences of population size

Social scientists have recognized the large-scale social consequence of increasing group size for more than a century. The great sociologist Georg Simmel noted in 1898: “Every quantitative extension of a group requires certain qualitative modifications and adjustments” (Simmel 1898:834).” The growth of larger social groups, and the association between group size and socio-political complexity, have been major themes in the literature on cultural evolution in anthropology. Quantitative analysis directed at this theme was common in anthropology in the 1950s and 1960s (Carneiro 1962; Naroll 1956), and this work even included some early settlement scaling analyses (Cook and Heizer 1965)!

A popular topic of research on population change in the 1960s and 1970s was the role of “population pressure” in generating various social changes (Cohen 1977; Spooner 1972). The resulting consensus held that simplistic models positing population increase as the sole cause of political change were inadequate; for example, Carneiro’s (1970) model of population growth causing warfare, which in turn caused the rise of states, is rarely invoked now, except as a foil or a historical note. But narrower models, focused on economic and environmental variables—such as Netting’s (1993) model of population pressure causing agricultural intensification in smallholder farming—have fared better with time, even appearing in best-selling popular science books (e.g., M.E. Smith 2016a) (well, I hope I do sell a few copies......).

The two relationships mentioned above—(1) group size has increased over time in many areas of the world; and (2) group size is strongly predictive of sociopolitical complexity—might be considered “stylized facts” in archaeology. That is, they are well-documented relationships whose explanation has been the subject of dispute. I am intrigued by the concept of stylized facts in economics, and I’ll probably blog about this on Publishing Archaeology soon. But the relevant conclusion here is that group size is important, and—in some circumstances—has causal effects on social and economic life. This is similar to the claims of the social reactor model, although the cultural evolutionary models tend to gloss over specific social interactions within set places in their pursuit of more general results. If this discussion does not seem sufficiently “theoretical,” then I’ll invoke the “demographic-structural theory” of Jack Goldstone (1991, 2002), further elaborated by Turchin and Nefedov (2009). This is a productive political-economy approach in economic history and historical sociology that melds population increase theory with structural models of power relations.

B. Scalar stress

Archaeologist Gregory Johnson (1982) coined the term “scalar stress” to refer to social stress or difficulties created by increases in the size of a social group. His focus was on the size of the decision-making group, and he analyzed the development of hierarchies of social decision making as group size increases. Research on scalar stress focuses on the negative aspects of larger social groups. The best-known archaeological example is Roland Fletcher’s (1995) model of thresholds in settlement size and density, caused by scalar stress. This kind of analysis of archaeological site size continues today (Alberti 2014).

There is a large literature in social psychology on the role of population density in generating psychological stress (Evans 2001; Spruill 2010), and research on the “urban health penalty”—the negative health consequences of living in dense cities (Vlahov and Galea 2002; Vlahov et al. 2004)—follows a similar tack. In fact, if we step back a bit, there is a major historical line of research in sociology on the negative effects of growing city size. This is too big a topic to get involved in here (and I don’t know if very well......), but one element that remains a topic of discussion after many decades is “social disorganization theory,” concerning the negative social consequences of urban life, particularly in large cities (Kornhauser 1978; Kubrin and Weitzer 2003; Sampson 2004).

Scalar stress and social disorganization theory are relevant to settlement scaling in that they emphasize the negative consequences of life in large cities. Urban scaling of contemporary cities shows that superlinear scaling is not only about positive economic outputs; crime, poverty, and disease rates also exhibit superlinear scaling (thanks to Deborah Strumsky for her nice lecture today at ASU, reminding us about superlinear scaling of disease levels). Social interactions in the built environment have both positive and negative consequences.

C. Dual inheritance theory

Dual inheritance theory is about how human genes and culture evolve separately, yet inter-relatedly; they co-evolve. Starting with Boyd and Richerson (1985), this is now a major line of research in anthropology and biology (Henrich 2015; Richerson and Christiansen 2013). What does it have to do with scaling? A major focus in dual inheritance theory is the mechanisms of cultural transmission. How do people learn from others? How do new traits arise and spread through a population? What are the roles of skill, teaching, prestige, and conformity in the spread of knowledge? Many of these traits depend on population size.

This research is relevant to settlement scaling in its analysis of how the size of social groups relates to technology and other cultural adaptations. No single person in any social group has all of the knowledge needed to survive or to reproduce the group’s culture. Successful cultures require the combined knowledge and skills of many members. Larger groups have a greater diversity of tools and concepts (Henrich 2015), and if a group gets too small, it can lose effective technological adaptations rapidly, as in ancient Tasmania (Henrich 2004).

Unfortunately, the dual inheritance scholars have not thought much about how their models relate to settlements and urbanism; their models lack a spatial dimension. If technological diversity depends on group size, then perhaps larger settlements have distinctive technological attributes compared to smaller settlements. But the emphasis on learning and cultural transmission of dual inheritance research does relate to the social interaction basis of the social reactor model.

2. Community theory

By “community theory” I mean work from a political-economy perspective that studies communities as sites of social interaction. This perspective diverges from a common approach to communities in archaeology, in which the emphasis is on idealist and social constructionist models that claim communities are generated by shared meanings in people’s heads. For some discussion of these differences, see two posts on Publishing Archaeology:  here,  and here. I sometimes wish I worked in a discipline that didn’t have so much silliness and ridiculousness taken seriously as theory.

The three sections that follow are not distinct theoretical approaches; they are major claims of the political-economy approach to communities. This approach—particularly these three claims—is broadly supportive of the social reactor model of settlements.

A. Social interaction generates communities (“connection, not affection”)

The dominant view in the social sciences views communities as generated from processes of social interaction. This goes back to Emile Durkheim at least. Sociologist Steven Brint (2001) shows different definitions of community in a nice tree diagram:

Notice that neighborhood groups and other social communities (lower left) are based on activities and frequent interactions. Here is how economists Sam Bowles and Herbert Gintis (Bowles and Gintis: F420) define community:

“By community we mean a group of people who interact directly, frequently and in multi-faceted ways. People who work together are usually communities in this sense, as are some neighbourhoods, groups of friends, professional and business networks, gangs, and sports leagues. The list suggests that connection, not affection, is the defining characteristic of a community. Whether one is born into a community or one entered by choice, there are normally significant costs to moving from one to another.”  (p.F420)

Most definitions of community in the social sciences are based on three factors: social interaction, spatial locality, and some kind of common ties (Hillery 1955; Jabareen and Carmon 2010). My definition of neighborhood—intended to be useful for archaeologists—is quite similar (M.E. Smith 2010). Again, see my prior blog posts for a critique of the social constructionist views of community in archaeology (here, and here), or see my paper on quality of life (M.E. Smith 2016b).

B. Social interaction generates successful communities

Social interaction is emphasized in a number of normative theories of successful communities. Anthropologists and archaeologists, take note: planning and other social scientists use the term “normative” in a very different way than it is used in anthropology and archaeology. Normative in these other fields means theory with an evaluative dimension; for example, theory about what makes for “good city design” (Lynch 1981) is called normative theory. I discuss this briefly in Smith (2011).

How to use urban design to promote social interactions is a major component of normative planning theory. Social interactions—with friends, neighbors, and other residents—are seen as one of the prime indicators of successful cities and towns. Social interaction—particularly in reference to neighborhood physical facilities like parks, playgrounds, and pedestrian-friendly streets—is a key dimension of social cohesion in cities (R.A. Smith 1975). Urban planners give considerable attention to designing neighborhoods and streets that promote interactions (Kısar Koramaz 2014). Stable neighborhoods facilitate social interaction, which promotes social cohesion or integration (Brower 2011).

Here are some passages from Robert Putnam and Lewis Feldstein, in their book on social capital and successful communities in the U.S. today:

“Again and again, we find that one key to creating social capital is to build in redundancy of contact. … Common spaces for commonplace encounters are prerequisites for common conversations and common debate ... Urban planning, architecture, and technology can each fosters redundancy and multistrandedness by creating opportunities for encounters that knit together existing ties. Because local arrays of built space and communications technology act as ‘background structural factors’ in most of our cases, their true importance is not always manifest.” (Putnam and Feldstein 2003:291)

C. Communities can accomplish goals

Communities are important not just as places where people live, but also because they can accomplish tasks and get things done. The great social scientist Charles Tilly (one of my intellectual heroes) asked, “Do communities act?” (Tilly 1973). He was discussing the ways in which communities in early modern France applied resources toward common goals. This line of analysis has continued in several branches of the social sciences. Bowles and Gintis, for example, note that communities can solve problems that are difficult for markets or states to solve. See their typology, based on the differing types of social relations that characterize the three kinds of institution:

Bowles and Gintis (2002:F422-F423) state:

“communities solve problems that might otherwise appear as classic market failures or state failures: namely, insufficient provision of local public goods such as neighborhood amenities, the absence of insurance and other risk-sharing opportunities even when these would be mutually beneficial, exclusion of the poor from credit markets, and excessive and ineffective monitoring of work effort. Communities can sometimes do what governments and markets fail to do because their members, but not outsiders, have crucial information about other members’ behaviours, capacities, and needs. Members use this information to uphold norms.”

The ability of communities to act—effectively and with positive outcomes—is at the heart of the work of Elinor Ostrom (1990, 2005). One of her basic arguments parallels precisely the argument of Bowles and Gintis: local communities can manage common-pool resources more successfully and sustainably than either states (government ownership) or markets (privatization). Here is her basic model:

Notice the role of face-to-face communication on the left side. Basic social interactions within a community promotes trust, reputation and reciprocity.

The upshot of this perspective on communities is that social interactions in a specific spatial locale have a variety of positive effects for residents. These effects are felt on both the individual and the group levels. To these basic findings of social science research, the social reactor model of settlement scaling adds two things: (1) social interactions in a given built environment have an even wider range of specific outcomes than social-science research might suggest; and (2) they exhibit a surprising level quantitative regularity.

3. Urban economics

I’ve just about run out of steam here. I guess that’s a convenient excuse to avoiding talking about a discipline I know little about. So let me just cite an article that not only has a fantastic title—“Buzz”—but also provides an excellent introduction to the role of face-to-face interaction in cities (Storper and Venables 2004). And I will close with two brief quotes from urban economist Edward Glaeser’s excellent book, The Triumph of Cities (Glaeser 2011):

“The central theme of this book is that cities magnify humanity’s strengths. Our social species’ greatest talent is the ability to learn from each other, and we learn more deeply and thoroughly when we’re face-to-face.” (p.250)

“Cities enable the collaboration that makes humanity shine most brightly. Because humans learn so much from other humans, we learn more when there are more people around us.”  (p. 247)


Alberti, Gianmarco
2014 Modeling Group Size and Scalar Stress by Logistic Regression from an Archaeological Perspective. PLOS-one 9 (3): e91510.

Bowles, Samuel and Herbert Gintis
2002 Social Capital and Community Governance. The Economic Journal 112 (483): F419-F436.

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Brint, Steven
2001 Gemeinschaft Revisited: A Critique and Reconstruction of the Community Concept. Sociological Theory 19: 1-23.

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1982 Organizational Structure and Scalar Stress. In Theory and Explanation in Archaeology: The Southamton Conference, edited by Colin Renfrew, Michael J. Rowlands, and Barbara A. Wegraves, pp. 389-421. Academic press, New York.

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Saturday, March 19, 2016

Settlement Scaling: Continuities from Villages to Cities

I used to make a big deal about definitions of urbanism, and how to distinguish cities from other settlements. This is a worthwhile effort, useful for many purposes. But I now find that overemphasizing the distinction between, say, villages and cities can get in the way of understanding some of the major social dynamics of these settlements. Key dimensions of social life show remarkable similarities between villages and cities. For years I questioned the similar notion that major differences characterized rural and urban life, based on my excavations at Aztec sites (Smith 2008, 2016). In some settings around the world, rural and urban lifestyles and social conditions are radically different, but in others—such as Aztec-period Morelos, Mexico—they are quite similar. But my topic here is more general: what are some of the similarities or continuities between social life in villages and cities? This question relates closely to research on settlement scaling.

Our research group on settlement scaling (AKA “urban scaling”) now has a project name and a website—the Social Reactors Project: Human Settlements andNetworks in History. I have been thinking a lot lately about how the work in scaling relates to other research issues and themes in archaeology and the social sciences more generally. This is the first of several posts about the social and scientific context of this research. These are exploratory posts—me thinking aloud about connections between research domains—and not reports of well-established (and published) ideas. I welcome feedback, particularly if I say something dumb.

One of the remarkable empirical findings of the work on settlement scaling is that village settlement systems exhibit some of the same quantitative regularities as do contemporary (and historical/ancient) urban systems. See the project website or previous posts (here,  or here) on this. This finding is predicted from the “social reactors” perspective on scaling. The actions of large numbers of people gathered in specific places have predictable quantitative outcomes in key social domains. The foundation of the social reactors approach is a mathematical model based on the number of people who interact socially within a given built environment. This model is presented in Bettencourt (2013). But does the finding of continuities between village and urban systems make sense from other perspectives? My answer is yes. Here I will focus on two areas: neighborhood formation; and the process of settlement aggregation. Recent research in these areas supports the scaling results by showing how settlement size plays a similar role in both village and city settlement systems.

The universality of neighborhoods

I have claimed for a number of years now that the division of urban residents into neighborhoods is one of the few universals of cities around the world and through history (Smith 2010, 2012). A few years ago I got a bunch of undergraduates together to test this idea by investigating whether neighborhoods existed in what we called “semi-urban settlements” (Smith et al. 2015). These are settlements that are not true cities, but do have large numbers of people gathered together, often for a short period of time. The idea was that if semi-urban settlements exhibit neighborhood organization, this would support the claim that neighborhoods are universal traits of cities.

Each student took one or more types of semi-urban settlements, and looked at maps and read reports to look for the division of the settlement into spatial zones that had some social significance. We identified a total 17 types of semi-urban settlement, of which 11 had enough information to evaluate the presence or absence of neighborhoods. Ten of those eleven settlement types did indeed show neighborhood organization (only disaster camps lacked neighborhoods). Here is the total list of semi-urban settlements we looked at:

Sometimes of these settlements are created forcibly by authorities for their own purposes (“force” in the table), and in other cases the settlements are created by necessity. And in still other cases, the settlements are created by the individual actions of residents ("volunteer" in the table). The fact that ten out of the eleven settlement types we studied show clear neighborhood organization supports the contention that neighborhoods are a universal feature of urban, and urban-like settlements. In other words, when settlement reach a certain size, neighborhood organization—whether imposed or generated by residents—is inevitable.

But the universality of neighborhood organization goes beyond this. In reviewing my notes, I see that apart from some brief mentions here and there (Smith 2010, 2011), I never published my findings on rural neighborhoods. So, here is a brief summary. In many traditional settlement systems, neighborhood-like spatial clusters are found in rural areas. In my paper on Classic Maya neighborhoods, I show that these rural settlement clusters are functionally equivalent to urban neighborhoods, and that they are the kind of unit that serves as an urban neighborhood in low-density tropical cities, such as the Classic Maya or the Khmer (Smith 2011).

Here are two examples of named social groups that serve as neighborhoods in both urban and rural settings: the Aztec calpolli, and the north African darb. The calpolli was a group of Aztec households with common economic activities. In rural areas, nobles owned the farmland, but decisions on how to divide up plots was made by the calpolli, whose members lived together in a village. Only calpolli members had direct access to land. In urban areas, a calpolli was an urban neighborhood whose members often had similar economic specialization. Each calpolli had a temple and a school. For discussion, see: Smith and Novic (2012); for a non-technical account, see my new book (Smith 2016:chapter 7).

In traditional north African societies, the darb is a unit similar to the calpolli—a neighborhood in urban centers, and a village or village section in rural areas. In rural areas, the darb:

“functions as an intermediate structure between the family and the village. It was once described to me as the ‘middle branch’ (al-far’ al-wasat). It is primarily the place where events pertaining to the individual take on a public or communal significance. (Saad 1998:115).

In urban settlements, the darb is a neighborhood (typically called a “quarter” in English-language descriptions), a social division of a town or city (Eickelman 1974). For more examples of rural neighborhoods, see my discussion of highland Maya rural neighborhoods (Smith 2011). See also Anthony Kaye’s discussion of rural neighborhoods in the slave communities of the antebellum southern U.S. (Kaye 2002, 2007a, 2007b).

The implication of these cases is that when human settlements reach a certain size, the residents will create neighborhoods, whether they live in an urban center or in a rural area, in a city or in a village. Unless, of course, the neighborhoods have been pre-established by the builders or authorities. Two obvious questions—How large a population is required to trigger neighborhood formation? and, How big are neighborhoods?—cannot be answered with current information. Years ago, when I started working on neighborhoods, I tried to track neighborhood size, but the data are just too scattered and I gave up.

Settlement aggregation

When I first learned about Luis Bettencourt’s scaling model, and realized that it predicted similar quantitative patterns for village settlements as for cities, I was skeptical. One of my concerns focused on the nature of population movements in the two kinds of settings. The fact that people can move around, into and out of cities and regions, seemed important for the development of the scaling regularities. I don’t think such movement is an absolute requirement of the formal model, but for some settlements to grow larger than others, people have to be able to move around. Thus I was curious about two processes. First, did people in the past really move around very much? Or were farmers and peasants “tied to the land,” as in traditional models? Second, was the process of village aggregation—people moving into villages—similar to the process or urbanization (in the sense of people moving into cities)?

To answer these questions, I reviewed the published literature on spatial mobility and village aggregation in premodern societies. In brief, the evidence supports the scaling model, in that mobility and movement could be substantial in the past, and village aggregation was quite similar to rural-to-urban migration. The journal World Archaeology was just assembling a special issue on past migration and mobility, so I published the paper there (Smith 2014).

I was amazed at the extent of spatial mobility in late medieval and early modern European villages. Robin Osborne (1991) had reviewed the literature earlier, and I updated his analysis. In a famous example published by Peter Laslett, censuses were taken in two 17th century villages twelve years apart. In the second enumeration, only 38% of the original residents were still in the villages! While the mobility rate may have been particularly high in Britain for structural reasons, there are many examples of considerable social turnover in peasant settings around the world.

In looking at aggregation processes, studies of three different domains coincide in identifying defense as one of the key drivers of such movement. First, most archaeologists agree that the basic cause for the aggregation of population into early villages was the need for defense (Bandy and Fox 2010; Birch 2013). Second, the same factor is identified for the nucleation of settlement in rural parts of the developing world (Silberfein 1989). And third, defense was one of the predominant drivers of urbanization before the modern era in many regions (Adams 1981; Flannery and Marcus 2012). In other words, movement into town, or into the village, was in many cases caused by the same forces—the need for defense and protection.


These considerations of neighborhood formation and premodern settlement aggregation lend support to the social reactor model of settlement scaling. While the idea that village systems exhibit the same quantitative properties as urban systems may seem strange at first, it becomes more comprehensible when we focus on population size and its implications. If we get too hung up on defining urbanism and highlighting differences between urban and non-urban contexts (yes, guilty as charged…..), this can blind us to some remarkable similarities in these two kinds of settings. The key factor uniting them is the role of population size in generating certain kinds of processes and outputs.

While it is possible to claim that the data on neighborhoods and aggregation processes support the scaling model, it is also possible to turn this around and claim that the scaling results support the models from neighborhood and aggregation analysis. But I think the most productive approach is to point out that research in these three distinct domains (and probably others as well) all point to similar conclusions: Many social processes transcend the traditional urban / non-urban distinction; these all involve the consequences of the numbers of people who live or work (and interact) in a settlement; and, human settlement dynamics are remarkably similar around the world and through history.

Stay tuned for more exploration of the context of settlement scaling. Next topic: scaling and social science theory.


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