200409 forest islands

Amazonia domesticated plants early

Southwest Amazonia has been confirmed as one of the earliest centres of plant domestication in the world.

From their arrival 10,000 years ago, human inhabitants in what is now Llanos de Moxos in northern Bolivia created thousands of artificial forest islands as they tamed wild plants to produce food, a new study shows.

They  began growing manioc and squash, a development the researchers suggest is as significant as the cultivation of rice in China, grains and pulses in the Middle East, maize, beans and squash in Mesoamerica, and potatoes and quinoa in the Andes.

The international team undertook a large-scale analysis of 61 archaeological sites identified by remote sensing, retrieving samples from 30 forest islands and carrying out archaeological excavations in four of them.

Their findings are published in the journal Nature.

“Archaeologists, geographers and biologists have argued for many years that southwestern Amazonia was a probable centre of early plant domestication because many important cultivars like manioc, squash, peanuts and some varieties of chilli pepper and beans are genetically very close to wild plants living here,” says lead author Umberto Lombardo, from the University of Bern, Switzerland. 

“However, until this recent study, scientists had neither searched for, nor excavated, old archaeological sites in this region that might document the pre-Columbian domestication of these globally important crops.”

The forest islands remained above water level even when the savannah area flooded during the wet season, allowing trees and plants to grow. This shows that small-scale communities began to shape the Amazon 8000 years earlier than previously thought, the researchers say.

They documented the earliest evidence in the Amazon of manioc (10,350 years ago), squash (10,250) and maize (6850)

The plants were no doubt chosen because they were carbohydrate-rich and easy to cook, and they likely provided a considerable part of the calories consumed by the first inhabitants of the region, supplemented by fish and some meat.

“Genetic and archaeological evidence suggests there were at least four areas of the world where humans domesticated plants around 11,000 years ago, two in the Old World and two in the New World,” says co-author Jose Iriarte from the University of Exeter, UK. 

“This research helps us to prove southwest Amazonia is likely the fifth.”

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