The collapse of Maya civilization: drought doesn’t explain everything

Gwinneth and his team focused on three geochemical indicators in the Itzan lakebed sediment: polycyclic aromatic hydrocarbons, which reveal the intensity of slash-and-burn fires; leaf waxes, which indicate vegetation type and precipitation levels; and fecal stanols, which can be used to estimate population density.

These indicators were used to simultaneously reconstruct the evolution of the population, agricultural practices and climate over time, from the first evidence of human activity around Laguna Itzan 4,000 years ago until the site was abandoned about 1,000 years ago.

“The data revealed that the first permanent settlements appeared 3,200 years ago,” said Gwinneth. “There were slash-and-burn fires and an increase in population. During the Preclassic period, between 3,500 and 2,000 years ago, the Maya used fire extensively. They practiced slash-and-burn agriculture, using fire to clear the forest and then growing crops on the fertile ashes.”

A radical change occurred during the Classic period, between 1,600 and 1,000 years ago: although populations were much denser, the use of fire decreased considerably. “This probably means that most of the land had been cleared, which could have led to a change in agricultural strategy,” said Gwinneth.

The data suggest a major intensification of agriculture, including ridge and furrow ploughing to reduce erosion and intensive gardening. “Fire was no longer an important component of their farming practices,” Gwinneth said. “This transformation reflects gradual urbanization and suggests that the Maya were changing agricultural strategies to feed a growing population.”

This change in agricultural practices is consistent with what archaeologists and anthropologists know about the Maya civilization at its peak: it was a complex, urbanized society with increasing specialization and advanced agricultural techniques adapted to the environment.

The stable climate riddle

However, analysis of hydrogen isotopes has shown that, unlike Maya sites further north that suffered drought, Itzan seems to have had a stable climate due to its geography.

“Itzan is located near the Cordillera, where atmospheric currents from the Caribbean generate regular orographic (mountain-related) rainfall,” Gwinneth explained. “While other Maya regions suffered devastating droughts, Itzan appeared to have a stable climate.”

Gwinneth considers this discovery significant because some archaeologists have argued that the Maya collapse began in the southwestern region, where Itzan is located. If Itzan did not experience drought, this can't have been the initial cause of the decline, he said.

“Even though there were no drought conditions locally, the population of Itzan declined sharply during the Terminal Classic period, between 1,140 and 1,000 years ago,” Gwinneth continued. “Population markers show a dramatic fall, signs of agriculture disappear, the site was abandoned.”

How can we explain that a community with water and favourable conditions suffered the same fate as its neighbours, who were afflicted by drought?

“The answer lies in the interconnectedness of Maya societies,” said Gwinneth. “The cities did not exist in isolation; they formed a complex network of trading relationships, political alliances and economic dependence. 

"When the central lowlands were hit by drought, this may have triggered a cascading series of crises: wars between cities over resources, the collapse of royal dynasties, mass migrations, disruption of trade routes, and so on.”

According to this theory, Itzan fell into ruin not because it lacked water but because it was caught up in the turmoil when the system of which it was a part collapsed.

The interdependence of Maya cities explains why drought didn’t have to occur everywhere to cause widespread collapse: its impact spread far beyond the directly affected areas, creating a devastating domino effect across the entire region.

“The transformation or “collapse” of the Maya civilization was not a mechanical result of a uniform climate catastrophe; it was a complex phenomenon in which climate, social organization, economic networks and political dynamics were intertwined,” Gwinneth concluded. 

“Regional socio-political and economic factors played a decisive role.”

Gwinneth believes these findings are relevant to our own day, as they may shed light on how civilizations respond to environmental change.