SignificanceDo human societies from around the world exhibit similarities in the way that they are structured and show commonalities in the ways that they have evolved? To address these long-standing questions, we constructed a database of historical and archaeological information from 30 regions around the world over the last 10,000 years. Our analyses revealed that characteristics, such as social scale, economy, features of governance, and information systems, show strong evolutionary relationships with each other and that complexity of a society across different world regions can be meaningfully measured using a single principal component of variation. Our findings highlight the power of the sciences and humanities working together to rigorously test hypotheses about general rules that may have shaped human history.

Medieval European urbanization presents a line of continuity between earlier cities and modern European urban systems. Yet, many of the spatial, political and economic features of medieval European cities were particular to the Middle Ages, and subsequently changed over the Early Modern Period and Industrial Revolution. There is a long tradition of demographic studies estimating the population sizes of medieval European cities, and comparative analyses of these data have shed much light on the long-term evolution of urban systems. However, the next step—to systematically relate the population size of these cities to their spatial and socioeconomic characteristics—has seldom been taken. This raises a series of interesting questions, as both modern and ancient cities have been observed to obey area-population relationships predicted by settlement scaling theory. To address these questions, we analyze a new dataset for the settled area and population of 173 European cities from the early fourteenth century to determine the relationship between population and settled area. To interpret this data, we develop two related models that lead to differing predictions regarding the quantitative form of the population-area relationship, depending on the level of social mixing present in these cities. Our empirical estimates of model parameters show a strong densification of cities with city population size, consistent with patterns in contemporary cities. Although social life in medieval Europe was orchestrated by hierarchical institutions (e.g., guilds, church, municipal organizations), our results show no statistically significant influence of these institutions on agglomeration effects. The similarities between the empirical patterns of settlement relating area to population observed here support the hypothesis that cities throughout history share common principles of organization that self-consistently relate their socioeconomic networks to structured urban spaces.

Agricultural productivity, and its variation in space and time, plays a fundamental role in many theories of human social evolution. However, we often lack systematic information about the productivity of past agricultural systems on a scale large enough to test these theories properly. The effect of climate on crop yields has received a great deal of attention resulting in a range of empirical and process-based models, yet the focus has primarily been on current or future conditions. In this paper, we argue for a "bottom-up" approach that estimates potential productivity based on information about the agricultural practices and technologies used in past societies. Of key theoretical interest is using this information to estimate the carrying capacity of a given region independently of estimates of population size. We outline how explicit crop yield models can be combined with Currie et al.: Agricultural Productivity in Past Societies. Cliodynamics 6:1 (2015)25 high quality historical and archaeological information about past societies in order to infer the temporal and geographic patterns of change in agricultural productivity and potential. We discuss information we need to collect about past agricultural techniques and practices, and introduce a new databank initiative that we have developed for collating the best available historical and archaeological evidence. A key benefit of our approach lies in making explicit the steps in the estimation of past productivities and carrying capacities, and in being able to assess the effects of different modelling assumptions. This is undoubtedly an ambitious task, yet promises to provide important insights into fundamental aspects of past societies, enabling us to test more rigorously key hypotheses about human socio-cultural evolution.

The Classic Period Maya cities of Caracol and Tikal possessed unique urban morphologies of water management. In part, the built environment at each city reflects adaptations to the hydrology of their landscapes. Caracol exists in a rugged, hilly, and karst environment; its residents invested their landesque capital in constructing agricultural terraces and residential reservoirs. These features created Caracol's anthropogenic garden‐city landscape. This landscape was unified through a dendritic causeway system and the distributed nature of monumental nodes. The landscape of Tikal exhibits a lower slope, is generally smoother, and its residents invested in constructing a large and condensed site core along with their monumental reservoirs. Additionally, the people of Tikal invested in bajo margin agriculture. The differences in urban form and hydrology conditioned the resulting water management strategies employed by both cities; the resulting built environmental features are preserved in the archeological record. Because of its higher slopes, Caracol's landscape presents a greater hazard for soil erosion and faster rainfall runoff. Yet, the construction of distributed residential reservoirs and agricultural terraces acted to collect rainfall, increase soil saturation, and reduce this runoff. Tikal's landscape on the whole presents fewer hazards in terms of soil erosion but perhaps greater issues from torrential rainfall. Water management infrastructure at both cities reflects both their unique urban morphologies and environmental conditions. This article is categorized under: Engineering Water > Planning Water Science of Water > Water and Environmental Change

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