Between 750 and 900 AD, the population and political power of the Maya lowlands in Central America declined dramatically. Over the years, researchers have repeatedly linked this decline to periods of severe drought.
This explanation has long dominated scientific thinking. But new findings based on a 3,300-year-old sediment record suggest the story may be more complicated than a simple climate crisis.
Benjamin Gwyneth, a geography professor at the Université de Montréal who studies environmental change and its impact on the Maya, is investigating the Itzán archaeological site in present-day Guatemala.
By analyzing sediment cores from nearby Lake Laguna Itazan, Gwyneth and her team are piecing together a long-term record of both environmental conditions and human activity in the region.
Surprisingly, their results showed no sign of drought in Itzán during a period when the Maya population declined. Nevertheless, the local population collapsed at approximately the same time that communities experiencing drought in other parts of Guatemala and Mexico collapsed.
So what is the reason for the decline?
Clues found in sediments reveal human and environmental history
To answer that question, the researchers examined three types of geochemical markers preserved in lake sediments. These include polycyclic aromatic hydrocarbons, which increase the intensity of cutting and burning fires; leaf wax, which depicts vegetation and rainfall patterns; and fecal stanols, which help estimate population size.
Together, these indicators allowed the team to track changes in population, farming practices, and climate over thousands of years, from the earliest signs of human presence around Laguna Itazan about 4,000 years ago until the site was abandoned about 1,000 years ago.
“The data showed that the first permanent settlements appeared 3,200 years ago,” Gwyneth said. “Slashing and burning fueled fire and population growth. During the Preclassic period, 3,500 to 2,000 years ago, the Maya used fire extensively. They practiced agriculture by using fire to clear forest and then growing crops on the fertile ashes, cutting and burning.
Changes in Maya agriculture and urban development
During the Classic period, between 1,600 and 1,000 years ago, the data show a major change. Population density increased significantly, yet the use of fire declined rapidly.
“This probably means that most of the land was cleared, which could have led to a change in farming strategy,” Gwyneth said.
Evidence points to more intensive farming methods, such as ridge and furrow plowing and more concentrated gardening practices, to limit erosion. “Fire is no longer an important component of their agricultural practices,” Gwyneth said. “This change reflects gradual urbanization and suggests that the Maya were changing agricultural strategies to feed the growing population.”
These findings match what researchers already understand about the Maya at their peak. Their society was highly organized, urbanized, and supported by advanced agricultural techniques adapted to local conditions.
Stable climate in Itzán challenges drought theory
Another important piece of evidence comes from hydrogen isotope analysis, which helps to reconstruct past precipitation patterns. Unlike places in the far north that face drought, Itzán appears to have maintained a stable climate.
“Itazan is located near the Cordillera, where atmospheric currents from the Caribbean regularly generate orographic (mountain-related) rainfall,” Gwyneth explains. “While other Maya areas suffered devastating droughts, Itzán featured a stable climate.”
The discovery is particularly significant because some scholars have proposed that the Maya decline began in the southwestern lowlands, where Itzán is located. If drought did not affect the region, it was likely not the initial trigger.
Gwyneth continued, “Even though there were no drought conditions locally, the Itazán population declined rapidly during the Terminal Classic period, 1,140 to 1,000 years ago.” “A dramatic decline in population indicators was observed, signs of agriculture disappeared, the site was abandoned.”
This raises an important question: Why did communities with reliable water and favorable conditions suffer the same decline as drought-affected areas?
Interconnected Maya Cities and a Mass Collapse
“The answer lies in the interconnectedness of Maya societies,” Gwyneth said. “Cities did not exist in isolation; they formed a complex network of trading relationships, political alliances, and economic dependencies.
“When the central lowlands were hit by drought, it would have triggered a wide range of crises: wars between cities over resources, the collapse of royal dynasties, mass migration, disruption of trade routes, and so on.”
Under this scenario, Itzaan did not collapse due to local environmental stress. Instead, as the larger system unraveled, it was pulled into broader regional disintegration.
Because Maya cities were so closely interconnected, problems in one area could spread quickly. Drought in key areas can cause instability that spreads outward, causing a chain reaction throughout the civilization.
Gwyneth concludes, “The transformation or “collapse” of Maya civilization was not the mechanical result of a uniform climate disaster; it was a complex phenomenon in which climate, social organization, economic networks, and political dynamics were interconnected.”
“regional socio-political and economic factors played a decisive role.”
Gwyneth believes these insights have significance beyond ancient history to inform how interconnected societies can respond to environmental challenges today.