Raised fields in the Bolivian Llanos de Moxos region. Photo courtesy of Umberto Lombardo/University of Exeter
June 17 (UPI) -- Long before Europeans arrived in the Americas, the people of the Amazon were being significantly impacted by climate change, a new report suggests.
While some adaptive Amazonian populations flourished prior to 1492, others disappeared in the wake of dramatic shifts in temperature and rainfall, according to a new survey.
Scientists analyzed climate and archaeological data related to the period between 700 to 1300. Their findings -- published Monday in the journal Nature Ecology and Evolution -- showed groups that featured rigid social hierarchies and farmed intensively declined and dissolved in the wake of ancient climate change. Groups without social classes and groups that practiced more sustainable farming practices were able to successfully adapt to climate change.
Migration and conflict between groups also contributed to the decline of some groups in the Amazon.
"Some Amazon communities were in decline or had changed drastically before 1492," lead researcher Jonas Gregorio de Souza, who conducted the study while at the University of Exeter, said in a news release. "Our research shows climate change was one of the responsible factors, but some groups survived because they had been working with their natural environment rather than against it. Those who farmed intensively, and had more pressure to produce surplus food because of a strong class structure, were less able to cope."
To track the climate shifts that impacted early Amazonian groups, scientists studied pollen and charcoal remains, as well as stalagmites and lake sediment cores. Analysis of archeological remains helped researchers identify varying social structures and the farming strategies used by different groups.
Scientists found evidence of social classes among the Marajoara people of the eastern Amazon. The elites lived in large mounds. Researchers determined that several factors, including a decline in rainfall totals, precipitated the dissolution of the Marajoara by around 1200.
Conversely, the people of the Santarém culture, which emerged around 1100, were flourishing around the same time. They grew a diversity of crops and used restorative forest management practices.
Archaeologists have previously found evidence that people of the Amazon used canals and other types of infrastructure to manage seasonal floods.
"This study adds to the growing evidence that the millennium preceding the European encounter was a period of long-distance migrations, conflict, disintegration of complex societies and social reorganization across lowland South America," said Jose Iriarte from the University of Exeter. "It shows the weather had a real impact."