Climate change had a significant impact on Amazonian communities before the arrival of Europeans, according to a study

Climate change had a significant impact on the people who lived in the Amazon rainforest before the arrival of Europeans and was the cause of the disappearance of many indigenous groups, according to a new study.

Researchers have found that large changes in temperature and rainfall caused communities to disappear long before 1492. Other cultures, however, still flourished just before the Spanish colonization of the Americas.

A new analysis of what the climate was like in the Amazon from 700 to 1300 AD shows that climate change led to the end of communities that farmed intensively and had a strong class structure. Those who lived without political hierarchy, who grew a greater variety of crops and took more care of the land so that it remained fertile, adapted and were less affected.

During this period the Amazon was home to dozens of sophisticated communities living in flourishing towns and villages. Conflict between these communities and migration also contributed to the downfall of some of them.

According to Jonas Gregorio de Souza, from Pompeu Fabra University, who led the research for the University of Exeter some Amazonian communities were in decline or had changed dramatically before 1492. Our research shows that climate change was one of the factors responsible, but some groups survived because they had been working with their natural environment rather than against it. Those who farmed intensively, and were under more pressure to produce surplus food due to a strong class structure, were less able to cope

Mouth of the Amazon and Marajó Island / public domain photo on Wikimedia Commons

It is believed that the population of the indigenous communities decreased between 90% and 95% after the Europeans arrived, due to epidemics and violence. Prior to this, as many as 10 million people had lived in the Amazon, and this loss reshaped the landscape and cultural geography of the entire region.

The experts investigated the climate of ancient Amazonia by analyzing pollen and carbon remains, lake sediments and stalagmites. This allowed them to track how much rain there was in the region from year to year. They also analyzed the archaeological remains that show the products cultivated by the communities in the past, and the structures in which they lived.

In the eastern Amazon, the Marayo elite lived on large mounds, each of which could have housed as many as 2,000 people. These chiefdoms disintegrated after 1200. This was thought to be due to the arrival of nomadic Aruã foragers, but the study suggests that decreased rainfall also had something to do with it. Communities used the mounds to manage water, and the wealthy monopolized the resources. This made them sensitive to prolonged drought.

But at the same time the culture of Santarém, established around the year 1100, was flourishing. They grew a variety of crops – corn, sweet potatoes, squash – and worked to enrich the forest, which allowed times of drought to have less of an impact on it.

Experts have found communities in the Amazon that built canals to handle seasonal flooding. In the southern Amazon, inhabitants fortified their ditches, walled plazas, causeways, and roads as the climate became more volatile.

According to José Iriarte, from the University of Exeter: This study adds to growing evidence that the millennium preceding the European encounter was a period of long-distance migration, conflict, the disintegration of complex societies, and social reorganization in lowland South America. It shows that the weather had a real impact.

The research, part of the Pre-Columbian Transformations on an Amazon Scale project, funded by the European Research Council, was carried out by academics from the University of Exeter, Pennsylvania State University, Baylor University, the University of Bern, the University of São Paulo, the Geophysical Institute of Peru, the University of Northumbria, the Federal University of Pará, the French National Center for Scientific Research, the University of Utah, the University of Reading, and the University of Amsterdam.

The study was published in the journal Nature Ecology and Evolution.


Climate change and cultural resilience in late pre-Columbian Amazonia, Jonas Gregorio de Souza, Mark Robinson, S. Yoshi Maezumi, José Capriles, Julie A. Hoggarth, Umberto Lombardo, Valdir Felipe Novello, James Apaéstegui, Bronwen Whitney, Dunia Urrego, Daiana Travassos Alves, Stephen Rostain, Mitchell J. Power, Francis E. Mayle, Francisco William da Cruz Jr, Henry Hooghiemstra & José Iriarte. Nature Ecology & Evolution (2019), / University of Exeter.

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