New evidence shows the Maya collapse was more than just drought

It appears this pattern has existed for a very long time.

Early Cities and Agrarian Life

The first cities around the world were created by rural communities. These early residents were farmers, or agriculturists, who depended on land-extensive forms of production. Their livelihoods encouraged them to live in small, scattered settlements to reduce the effort and time required to reach their fields.

Even in ancient times, however, urban life was costlier in many respects. People living in cities faced higher exposure to infectious diseases that spread easily in crowds, greater competition for land and essential resources and increasing inequality. Surprisingly, many farmers still accepted these drawbacks and chose city life.

What explains this choice?

Investigating a Long-Running Debate

UC Santa Barbara archaeologist Douglas Kennett, who has spent years examining the development of Classic Maya cities, notes that researchers have debated this question for decades. According to Kennett, the explanation is complex and involves several intertwined factors that contributed to both the growth and eventual decline of these ancient urban centers.

Kennett and colleagues from multiple institutions examined this issue in detail in a study published in the Proceedings of the National Academy of Sciences. Their work applies population ecology theory to quantify the forces that shaped urbanization across the Classic Maya Lowlands.

Forces Behind the Rise of Maya Cities

"We determined that the rise and expansion of Classic Maya cities resulted from the interaction of climate downturns, intergroup conflict and the presence of strong economies of scale realized through capital investments in agricultural infrastructure," Kennett said. "These factors promoted the coevolution of urbanism, systemic inequality and patron-client relationships in cities."

Using the same analytical approach, he explained, the team also identified the conditions that triggered deurbanization. According to their findings, people began to leave "when the benefits of urban living no longer outweighed the costs, as environments were degraded near cities and climate amelioration improved the livability of rural areas where people would have more freedom and autonomy."

Climate, Conflict and New Data

The researchers originally focused on the role of climate change, particularly drought, in the decline of Classic Maya cities. Since 2012, the team has compiled archaeological information on population shifts, conflict and investments in agricultural systems. Their work gained new momentum when high-resolution climate records became available.

"We also capitalized on major developments in computational modeling that allowed us to look at the relationships between these datasets in ways not previously possible," Kennett said.

A Unified Model of Urban Change

The study brings together several previously competing explanations for ancient urban growth and decline, including environmental pressures, warfare and economic dynamics. It does so in a single, flexible model grounded in population ecology. This framework also helps explain why agrarian societies, which normally benefit from living spread out, sometimes gathered in cities despite the financial and social costs.

"The biggest surprise for me was that the abandonment of cities occurred under improving climatic conditions," Kennett noted. "We have long thought that the decline of Classic Maya cities partially resulted from an extended period of drought. It turns out to be a much more complicated and interesting story."

Insights for Understanding Urban Evolution

Overall, the research offers valuable guidance for interpreting both past and future patterns of urban growth and decline. By identifying broad principles that influence how populations concentrate and disperse, the study contributes to a deeper understanding of urban evolution across different eras and environments.