The difference within

Rubina Raja & Søren M Sindbæk on heterogeneity.

Ask an archaeologist what makes ancient cities urban, and as likely as not they will conjure up an arcane term from the depths of textbook convolution: ‘heterogeneity’. This rare phrase was immortalised in the vocabulary of urban studies in 1938 by American sociologist Louis Wirth. Written in Chicago in the midst of New Deal reformism, Wirth’s paper ‘The urban way of life’ provided what is arguably still the most widely cited definition of what cities are, past or present: ‘large, dense, and permanent settlements of socially heterogeneous individuals’.

In adding ‘heterogeneous’ to ‘large, dense, and permanent’, Wirth suggested that size alone does not make a city. Historically, settlements in agrarian regions have sometimes grown to become very large and dense – the Canadian archaeology legend Bruce Trigger once noted that they could easily be larger than some medieval cities – yet bear very little resemblance to the interaction that we associate with urban places. Confronted with the topic of heterogeneity, or difference within cities, archaeologists often beat around the bush. They have no problem in dealing with ‘large’ and ‘dense’. When exploring an ancient site, these are tangible qualities, which can often be established by archaeological means. But how can we determine degrees of differentness? And why, one might ask, is it important to compare and discuss ‘differentness’ and degrees of it at all?

The answer is in fact simple: in scholarship today, there is a draw towards grand comparisons for several reasons. For one, there are numerous sites across the world where we have a good understanding of time depth, and are also in possession of expansive datasets. But these are often so complex that comparisons between them either seem impossible or have to be reduced to a level where they become overly simplistic. Parallels are therefore often limited to showing apparent similarities that make us nod and say, ‘Oh, this reminds me of…’. Less similar phenomena fall between two stools. Therefore, in order to make meaningful comparisons, we need meaningful lenses through which we can compare cities. Heterogeneity offers such a lens – albeit a challenging one.

Spot the difference

Recently, the question of how to compare degrees of ‘differentness’ was brought up in a special issue of the Journal of Urban Archaeology, issue 8 – a peer-reviewed periodical launched four years ago, with us as the founder editors, and available open-access. Can there be any way of establishing the ‘heterogeneity’ of ancient societies, the issue asked. This problem was put to a group of researchers with specialisms ranging from ancient China to the Andes, via Central Asia, Egypt, Mesopotamia, and the Roman Mediterranean.

What Wirth called heterogeneity, others have labeled diversity or complexity. The latter word invokes mixed feelings in contemporary archaeology. Often used as shorthand for ‘civilisation’, ‘complexity’ is mostly seen as a property of societies deemed rich in temples, monuments, and an elaborate elite culture. In this way, an all-too-convenient link is forged between social hierarchy and human advancement. Wirth was clearly after something more. Critics have countered that much ‘complexity’ is simply a euphemism for social inequality. Does it really make a society more ‘heterogeneous’ to keep some members from enjoying the benefits available to others, they ask. To be a cardinal characteristic of cities, heterogeneity should have more consequence.

Take the example of Roman cities, which have beckoned us since the Middle Ages as icons of urban life. As Miko Flohr argues in the special issue, Imperial-period Roman urbanites had access to a wide range of goods, technology, and resources. Yet Flohr also observes that they used these resources to create more versatile and sophisticated technologies. We can trace how urban building projects led to refinement or rationalisation in the use of materials such as concrete and glass. New skills and knowledge resulted from life in cities and from the range of individuals and groups who were connected in these environments.

How do we compare cities, both ancient and modern? Does seeking similarities between Athens (pictured) and, say, Rome tell us anything profound, or is it the differences that are more instructive Image: Scaliger | Dreamstime

In a similar way, Augusta McMahon shows how developments at the world-famous Tell Brak, a site dating to the early 4th millennium BC in Syria, were conditioned by competition between various influences of power structures in society, which in turn contributed to a rise in social and economic diversity. Even in the earliest urban traditions in Bronze Age China, the role of social heterogeneity as a continuous process of development in material and social technologies can be noted, as Li Min underlined. His survey outlined a continuous Chinese urban tradition, issuing from the Late Shang-period centre of Anyang, dating to the late 2nd millennium BC, and evolving at a number of sites through into the Zhou period in the 1st millennium BC. This points towards the continuing development of material and social technologies pioneered in Anyang – such as bronze-working, oracle bones divination, and literacy – and to closer interaction with different social groups from the highlands beyond the cities.

But to what extent is such combination and innovation a process connected to cities, rather than simply an aspect of well-connected societies? In the same volume, Krzysztof Makowski examines the example of Andean civilisations, prior to the rise of the Incas in the 13th century AD. Societies in pre-Hispanic Peru developed an impressive degree of social heterogeneity. Their worlds involved large ceremonial centres dedicated to public architecture – but few people lived in these places, settling instead in dispersed villages and hamlets. In this case, at least, heterogeneity is not a product of settlement size and density.

A way to approach the issue systematically is to analyse ‘scaling relationships’, as Jack Hanson illustrates. Hanson ranks Roman cities according to size and then explores what kinds of monuments were present in them. As you would expect, larger cities boast more diverse monuments, but there are also cases of cities holding monuments that are unexpected by virtue of their size alone. One example is Gerasa in Jordan, where a hippodrome was constructed. Such a facility is rare in the Roman East, forcing us to question how scaling and regional patterns can be integrated. Might the presence of odd-one-out buildings or the coexistence of very different forms of monumental buildings and the associated displays of power, for example, be a symptom of a heterogeneous society? If so, the highly variable patterns of the surviving archaeological evidence raise problems. Massimo Vidale and Gian Luca Bonora remind us that we need to take into account the filters introduced by climatic variation and distortions in the archaeological record.

How, then, do we transcend the schism that lies within comparing phenomena that are by definition different? How do we begin to tease out contrasts between cities, which in the modern world house more than half of the globe’s population? Can one usefully compare New York and Beijing, Copenhagen and Amsterdam, Rome and Athens? And how much sense does it make to do so? And how does this exercise look when we add in time depth – and expand our interest far into the past – where datasets are often rather less complete than the modern equivalents, adding a whole other layer of complexity? Some attempts to weigh up different cities end up looking like comparisons of apples and oranges.

While comparative research has been prevailing for decades, it seems that we now stand at a threshold where we might begin to compare more targeted factors, like those outlined above, and find out new things about societal differences in the past – within and between cities.

Further reading: To read the special issue of Journal of Urban Archaeology, visit

Rubina Raja is professor of classical archaeology and director of the Centre for Urban Network Evolutions, Aarhus University, Denmark. Together with Søren, she is founding editor of the Journal of Urban Archaeology.
Søren M Sindbæk is professor of medieval archaeology at Aarhus University, Denmark, and co-director of the Centre for Urban Network Evolutions.