Why do people move to cities—and why do they leave?
Today, the reasons might include jobs, lifestyle, pollution, or even a pandemic.
But these same questions were relevant more than a thousand years ago to the ancient Maya civilization of Central America.
According to a new study by UC Santa Barbara archaeologist Douglas Kennett and his team, the rise and fall of Classic Maya cities were shaped by a mix of environment, economics, and human behavior.
Their research, published in the Proceedings of the National Academy of Sciences, uses theories from population ecology to understand how Maya cities grew and declined between 250 and 900 CE.
The Maya were farmers who depended heavily on the land. Living in the countryside made sense—it kept them close to their crops.
Yet, over time, many people began to cluster into cities, despite the challenges of crowded living, limited space, and the spread of disease. So why did they choose urban life?
Kennett explains that during periods of climate stress—especially droughts—city life offered new advantages. Cities provided strong social networks, protection during times of conflict, and access to infrastructure that made food production more reliable.
Investments in large-scale agricultural systems, such as irrigation or terracing, allowed cities to support more people. As a result, urban centers became powerful and economically efficient, even if they were unequal.
But the very success of these cities also planted the seeds of their decline. Over time, environmental damage around the cities made life harder. Forests were cleared, soils were depleted, and water sources became unreliable. Meanwhile, as the climate improved, rural areas became more livable again.
Many people likely realized they could have more freedom and stability by returning to the countryside, away from the pressures of urban life.
Surprisingly, Kennett and his team found that many Maya cities were abandoned not during times of drought, but when the climate was actually improving. This challenges the long-held belief that dry conditions alone caused the collapse. Instead, it seems that when rural life became more appealing again, the cities lost their pull.
By combining data on climate, conflict, population, and agriculture with advanced computer modeling, the researchers showed how multiple forces—social, environmental, and economic—worked together to shape the Maya world.
The study doesn’t just shed light on ancient history. It also offers lessons for modern cities, where similar trade-offs between urban density, resource limits, and environmental change continue to shape where and how people live.
The story of the Maya reminds us that the balance between the costs and benefits of city life has always been a delicate one.
