Ancient climate change in South America caused population collapse as populations could not adapt

Archaeologists estimate that the ancient populations of South America have declined significantly about 8,000 years ago, as they struggle to cope with sudden changes in climate.

Hunter-gatherers quickly populated South America about 14,000 years ago, settling in areas ranging from the high Andes to the Amazon rainforest and Patagonian grasslands at the tip of the continent, according to the authors of the report. study published in the newspaper. Scientific reports.

Previous research has shown that about 8,200 years ago, around the beginning of the Middle Holocene, which lasted about 4,200 years, the population of South America dropped. During the middle Holocene, South America became globally more arid.

To find out more, the team looked at population and climate data, including radiocarbon dates and marine sediments, which could provide insight into millennial rainfall.

Philip Riris, co-author of the study and postdoctoral fellow of the British Academy at the Institute of Archeology of the University College of London, explained in a statement: "Unpredictable rainfall, especially under the tropics, seem to have had a negative impact Colombian populations up to 6000 years. "

After this period, populations seemed to grow again, he said in a statement. "This recovery appears to be correlated with cultural practices surrounding tropical plant management and early cultivation, potentially serving as a buffer when wild resources are less predictable."

Researchers are not climatologists and have not been able to confirm the causes of climate change in the region. However, it is known that climate change occurred during the middle Holocene was a global phenomenon, said Riris. Newsweek.

"Our paper develops the argument that about 8,200 years ago, the global climate (and South America in particular) experienced such a rapid and unpredictable change that it limited the ability of some people to adapt quickly enough, "he said. Newsweek.

Riris said Newsweek the fact that the size of the population was more or less "in line with expectations" in the years preceding the decline suggests that Aboriginal populations were already developing strategies to deal with abrupt climate change.

"[The] The abandonment of certain areas and the need to adapt quickly to new circumstances may have favored the exploration of alternative strategies and new forms of livelihood, such as the integration of local plants. ", did he declare.

"Considered in the context of at least 14,000 years of human presence in South America, the events of the Middle Holocene are a key element in the history of cultural resilience to abrupt and unexpected changes. . "

The researchers studied the Torres del Paine National Park in Patagonia, Chile, to better understand the impact of ancient climate change. Getty Images

This is the first time researchers have demonstrated the impact of climate change on South America at the continental level in the middle Holocene, while previous studies have focused on local and regional effects said Riris Newsweek.

Then further research is needed on the lowland areas of South America, particularly the remote parts of the tropical rainforests of the Guyanas and the Amazon.

"Unfortunately, many of them are currently illegally registered or targeted for resource extraction. More corroborating evidence, such as skeletal or genomic studies, would also help clarify some of the issues, "said Riris. Newsweek.

Patrick Ryan Williams, Assistant Curator and Professor of Anthropology at the Field Museum of Natural History and the University of Illinois at Chicago, who was not involved in the work, said Newsweek"Understanding the relationship between climate change and human demographics can reveal important information about how climate affects human populations over time. The purpose of the study is commendable. However, the approach presented here poses some problems. "

He added that it was problematic to match radiocarbon dates to population estimates of a region "since radiocarbon dates do not constitute a random sample of the population".

"They are skewed by researchers' interest and radiocarbon dates will be overrepresented by a history of researchers focused on the early inhabitants of South America (thus raising radiocarbon representation at the beginning of the Holocene) and by research focused on early urban planning and the development of complexity that coincides with the 4200 cal BP [“calibrated years before the present”] radiocarbon dates rise after the mid-Holocene). "