Project Goal
In Scaling in Human Societies, our goal is to understand the how and the why of the expansion of human societies. Why do the majority of people today live in cities? Why do larger cities tend to exhibit higher wages and more innovation, as well as more crime and traffic congestion? How did Homo sapiens transition from the nomadic, small-scale societies of the past into the unified, world-spanning civilization we see today?
We also wish to understand the sustainability of human scaling. Do resource shortages, existential risk, and ecological fragility threaten to topple a growing human civilization? How much longer can that growth continue?
In the coming decades, policymakers must grapple with several fundamental questions related to scaling. What are the implications of the peak and decline of human population that is expected in the 21st century, and is this a trend that could–or should–be reversed? How important are policies to promote the growth of the most prosperous cities, such as by loosening zoning regulations, to economic growth? And for that matter, is economic growth an important and desirable outcome?
Reading List
The articles in this living literature review are self-contained, and any subset of them can be read in any order. This is a living literature review, and these articles will be continually updated and added to. Following is a summary of the project.
Our analysis of Urban Scaling shows how socioeconomic quantities associated with a city, such as incomes and per-capita innovation, grow with the size of the city. In Sources of Agglomeration, we discuss the theory of how this growth occurs. It is not just income and GDP that grow with city size; there is also an observed relationship between City Size and Crime. Larger cities also tend to show a higher Pace of Life, and there is a complicated relationship between Cities and Wellbeing.
What is a city, exactly? An interest invariant throughout human history is that cities tend to be defined by a 30 minute commute radius–known as Marchetti’s Constant–from a central point. Despite its simplifications, the (monocentric) Standard Urban Model is an elegant, easy-to-study idealized model of a city’s growth from a central point. However, large cities tend to develop several centers of economic activity, a phenomenon known as Polycentricity. Within a larger society, both large and small cities tend to develop and form a pattern known as Zipf’s Law.
The growth of cities has important implications for good urbanism. The Rebound Effect, or tendency for total driving to increase after transportation improvements, is important to understand. There have been several attempts to design Car-Free Cities whose outcomes need to be understood. Emerging Transportation Technology such as autonomous vehicles also has important implications for urbanism and can be understood through scaling theory.
Looking beyond individual cities, there has historically been an important relationship between Energy and Economic Growth, though it is not as straightforward as first appears. There has also been an important relationship between Population and Economic Growth, with potentially profound implications as the world undergoes a Demographic Transition toward lower birth rates.
As is the case with cities, Business Scaling has been observed, showing both benefits of economies of scope and costs of hierarchy.
Understanding how cooperation occurs is critical to understanding the past and future of scaling. To approach this question, we need to understand Cooperation in the Paleolithic and The Expansion of Cooperation in the Neolithic. We must also understand that Cooperation in Nonhuman Animals, on a scale resembling human cooperation, is rare. Even among humans, the controversial Dunbar’s Number holds that human communities based on personally knowing all other members are limited to around 150 people.
Civilizational scaling brings about several important sustainability considerations. Although not yet clearly demonstrated, there are fears of Limits to Growth toward civilization as a whole. Environmentalists have debated IPAT and its Variants on how population, affluence, and technology affect overall environmental impacts. Scaling raises the fear of Resource Shortages, though they have rarely come to pass, and there are related fears of Ecological Collapse and Existential Risk. Should these hazards be avoided, there is ongoing research into the Theoretical Limits to Growth. Understanding these limits is essential to assessing the long-run trajectory of human civilization.