Cities, that is to say areas served by urban infrastructure, are now habitats for the majority of the world’s people, nearly two-thirds. Can anyone doubt that this growth will continue, at least for the next few decades? As cities expand, they also morph to suit pressing needs, however various they are. What Delhi, Seoul, Tokyo, London, Mexico City, New York and so many others will be like by the last third of the century, and how they will support their populations, is something to consider if with caution. In this context, it is well to look back on the history of ancient cities informed by new research techniques in archaeology and anthropology and track the social evolution that made those cities happen and fall. And that is what Annalee Newitz has done in four cities with an additional aim: to personalize the life of urban groups and the people in them as much as she can without verging into tricky conjecture. Despite the hyperbole in her subtitle, the “secret” she reveals in each city as thematic focus comes from the new research techniques used. Not only do they detail subsurface physical structures that previously were invisible to us (LIDAR), and how humans transformed natural spaces into habitats (anthropogenic geomorphology), but also something of the kind and quality of daily life (data archaeology), along with forensic and other forms of anthropological interpretation. I should add that the recent criticisms of, and release from, traditional paradigms – for example, the birth of agriculture as the exclusive plot point for the development of cities – also plays its part in Newitz’s coverage.

First, there is Çatalhöyük, the Neolithic proto city in southern Anatolia, Central Turkey. It is founded roughly in 7100 BCE and sustained for some 1100 years until 5950 BCE; one date given to its collapse. Its population reached 7000 or 8000, perhaps more. Was it a city as we understand cities? Apparently not. Rather than a locus for trading and gathering surplus goods – settlers had yet to invent money -- it more generally supported ritual and ceremonial practices. Family dwellings, quite commonly designed, were pitched up against each other, the doorway set on the roof with no discernable street below. As Newitz describes it, the doorway had symbolic significance. It identified the family group, distinguishing it from other families, yet remained open. There was no reason for the kind of privacy that a solid door provides. Nor was the city the sole result of crop and animal domestication. Although some crops were cultivated and some animals domesticated, synergies with hunting and gathering in the wild prevailed. As for funerary rituals, there was the family home with dead relatives buried beneath beds and underneath floors. Other fascinating details have emerged, especially on whether or not hierarchies evolved, with the perception that they didn’t or didn’t enough to matter all that much. Order sustained, families lived and died, and as social pressures mounted with increasing population, disease spread and climate change occurred – with the end of the last Ice Age -- people wandered off. One critical lapse is the author’s failure to note that only about 5% of the area has been excavated. Will the remaining 95% reveal something new? More excavation will tell.

Five millennia later, there is Pompeii. Here, Newitz tracks parallel paths: the city as part of a vast Roman trading nexus connecting different peoples and cultures; how various classes of people intermingled; neighborhood street life with cafes, restaurants, and stores; and more intimate details of daily life, all done in deftly rendered portraits. Generous discussion of gender roles, sexuality, forms of property ownership, and social mobility make this chapter a near contemporary read. The eruption of Mt. Vesuvius in 79 CE, destroying the city as a liveable place while preserving enough of it for posterity, unique among ruins, is a constant.

Angkor in northwest Cambodia follows; a city initially created by Khmer jungle farming, learned over thousands of years, then sustained by a hierarchical “social system based on the regulation of water.” Vast reservoirs were built to keep the rice fields flooded and people drinking during the near six-month dry season. They are still among the largest such reservoirs on Earth. As the population swelled, the water system required labor en masse, and a culture that ritualized it. Who did the work? The answer is clear but its types plural: slaves of various kinds and other inhabitants across classes -- within a society that used debt as its bonding glue. Such people could be slaves as we understand the term but, more than not, the status of debt owed enforced different types of obligation to the reigning king, which could very well mean working the waterways and reservoirs for a period of time. From the 12th century on Angkor flourished, its population in the 13th century reaching an astounding 700,000-900,000. Then, because of poor royal decisions, using the waterways for political ends rather than as life giving technology, and changing climate impacts – enhanced Monsoon rains and more extensive drought --  the capacity of the city to provide lessened. By the 16th century, the majority of its citizens had dispersed; returning the land to what the city came from: Khmer farms and villages. As Newitz concludes, “The Khmer continued to live at Angkor long after their kings were gone” In this sense, Angkor “is not a lost civilization but the living legacy of ordinary people that refused to give up.” The process of dispersal, however, also can be read in relation to our own mega-cities. With unchecked growth and climate change, how long will our mega-cities be able to provide for its citizens?

Cahokia, settled roughly in 600-700 CE and largely abandoned by 1350 CE, concludes the book. The largest such city north of Mesoamerica, it spread over some six square miles in the rich lowlands near the confluence of three rivers: the Missouri, Illinois and Mississippi. At its height, with magnificent pyramids, a grand plaza and protecting walls, it hosted perhaps 30,000 people. Its status as a ceremonial center, with elaborate pageants staged and popular games played (such as chunkey), was wide spread. As a highly stratified society probably led by charismatic figures, its evolution, ending in dispersal, also speaks to what seems a major social change, which includes this possibility: a refusal by the majority of people there to be governed as they were or governed at all. Recently, archaeologists have also determined that previous theories of the city’s collapse – caused by large scale environmental misuse – reflect Western presumptions more than they clarify available evidence. It is a point well taken, and to which Newitz refers.

All in all, this is a congenial read. It frames our current understanding and remaining questions about each city, spiced by the author working on several digs when she needed first-hand experience. But then the question returns: Can we make our mega-cities sustainable or will a new cycle of urban abandonment begin? We’ll surely find out as the century advances.