This research explainer revisits findings described by Université de Montréal and published by ScienceDaily on April 27, 2026; it is not a newly announced October discovery.
Sediment Analysis Reveals Stable Climate at Ancient Itzan
The mysterious collapse of the Classic Maya civilization may not have been driven solely by prolonged drought after all, according to new archaeological research. Findings from lake sediments in Guatemala show that the key lowland city of Itzan enjoyed a stable climate even as its population abruptly vanished toward the end of the Classic period. For decades, researchers have linked the dramatic drop in population and political power across the Central American lowlands to severe environmental drying. However, sediment records stretching back 3,300 years suggest a much more complex historical reality.
Benjamin Gwinneth, a geography professor at the Université de Montréal who studies environmental change and its impact on the Maya, investigated the archaeological site near Laguna Itzan in present-day Guatemala. By analyzing sediment cores, Gwinneth and his research team tracked long-term environmental shifts and human activity. The data revealed no evidence of local drought during the Terminal Classic period when the city’s population collapsed.
Shifting Agricultural Practices and Urban Growth
The sediment cores preserved three distinct types of geochemical markers: polycyclic aromatic hydrocarbons indicating slash-and-burn fire intensity, leaf waxes reflecting vegetation and rainfall, and fecal stanols used to estimate population size. These indicators charted human presence from the earliest permanent settlements established 3,200 years ago until the site’s abandonment roughly a thousand years ago.
During the Preclassic period, between 3,500 and 2,000 years ago, the Maya used fire extensively to clear forests for agriculture. By the Classic period, between 1,600 and 1,000 years ago, population density increased significantly while the use of fire dropped sharply. According to the research team, this transition reflected gradual urbanization and intensive farming methods, such as ridge and furrow ploughing designed to limit soil erosion and feed a growing populace.
The Regional Cascading Collapse of Interconnected Cities
Hydrogen isotope analysis demonstrated that Itzan maintained reliable rainfall patterns due to its location near the Cordillera, where atmospheric currents from the Caribbean generate regular orographic precipitation. While neighboring regions suffered devastating droughts, Itzan’s water supply remained secure, yet its population plummeted and the site was ultimately abandoned between 1,140 and 1,000 years ago.
Researchers conclude that Itzan’s downfall was driven by the deep interconnectedness of Maya societies. Rather than succumbing to local environmental stress, the city was pulled into a broader regional breakdown. As drought struck key rival centers, it triggered a cascading series of crises including resource wars, disrupted trade routes, political collapse, and mass migrations that dragged stable communities down with them.