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Example of a small farm on a river island in the Amazon in Brazil. 10,000 years ago people made forest islands by domesticating plants in the Amazon. Source: Silvio /Adobe Stock

Earliest Amazon Inhabitants Created Thousands of 'Forest Islands'

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The earliest human inhabitants of the Amazon created thousands of artificial forest islands as they tamed wild plants to grow food, a new study shows.

The discovery of the mounds is the latest evidence to show the extensive impact people had on the area. From their arrival 10,000 years ago they transformed the landscape when they began cultivating manioc and squash.

View of La Chacra forest island in the Bolivian Llanos de Moxos. (José Capriles/PSU)

View of La Chacra forest island in the Bolivian Llanos de Moxos. ( José Capriles/PSU )

4,700 Forest Islands in the Amazonia Region of Bolivia

This led to the creation of 4,700 of the forest islands in what is now Llanos de Moxos in northern Bolivia, the team has found. This savannah area floods from December to March and is extremely dry from July to October, but the mounds remain above the water level during the rainy season allowing trees to grow on them. The mounds promoted landscape diversity, and show that small-scale communities began to shape the Amazon 8,000 years earlier than previously thought.

Forest islands found in the Amazon study region. A-f are considered anthropic and g-I are said to be natural. (Lombardo et al.)

Forest islands found in the Amazon study region. A-f are considered anthropic and g-I are said to be natural. (Lombardo et al.)

One of the Earliest Centers of Plant Domestication in the World

The research confirms this part of the Amazon is one of the earliest centers of plant domestication in the world. Using microscopic plant silica bodies, called phytoliths, found well preserved in tropical forests, experts have documented the earliest evidence found in the Amazon of manioc -10,350 years ago, squash -- 10,250 years ago, and maize -- 6,850 years ago. The plants grown on the forest islands were chosen because they were carbohydrate-rich and easy to cook, and they probably provided a considerable part of the calories consumed by the first inhabitants of the region , supplemented by fish and some meat.

Burials documented at the Llanos de Moxos site SM3 forest island. (Capriles et al.)

Burials documented at the Llanos de Moxos site SM3 forest island. ( Capriles et al .)

The study, in the journal Nature, was conducted by Umberto Lombardo and Heinz Veit from the University of Bern, Jose Iriarte and Lautaro Hilbert from the University of Exeter, Javier Ruiz-Pérez from Pompeu Fabra University and José Capriles from Pennsylvania State University.

The study involved an unprecedented large scale regional analysis of 61 archaeological sites, identified by remote sensing, now patches of forest surrounded by savannah. Samples were retrieved from 30 forest islands and archaeological excavations carried out in four of them.

Aerial view of forest islands in the Amazonian region of Bolivia. (Umberto Lombardo)

Aerial view of forest islands in the Amazonian region of Bolivia. ( Umberto Lombardo )

Dr Lombardo said: "Archaeologists, geographers, and biologists have argued for many years that southwestern Amazonia was a probable center of early plant domestication because many important cultivars like manioc, squash, peanuts and some varieties of chili pepper and beans are genetically very close to wild plants living here. However, until this recent study, scientist had neither searched for, nor excavated, old archaeological sites in this region that might document the pre-Columbian domestication of these globally important crops."

Professor Iriarte said: "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. This research helps us to prove South West Amazonia is likely the fifth.

The phytoliths found by the scientists include a. maize b. manioc, and c. squash, among other plants. (Lombardo et al.)

The phytoliths found by the scientists include a. maize b. manioc, and c. squash, among other plants. (Lombardo et al.)

“Colonizers Who Cultivated Plants” in the Amazon

"The evidence we have found shows the earliest inhabitants of the area were not just tropical hunter-gatherers , but colonizers who cultivated plants. This opens the door to suggest that they already ate a mixed diet when they arrived in the region."

Javier Ruiz-Pérez said: "Through an extensive archaeological survey including excavations and after analyzing dozens of radiocarbon dates and phytolith samples, we demonstrated that pre-Columbian peoples adapted to and modified the seasonally flooded savannahs of south-western Amazonia by building thousands of mounds where to settle and by cultivating and even domesticating plants since the beginning of the Holocene."

Top Image: Example of a small farm on a river island in the Amazon in Brazil. 10,000 years ago people made forest islands by domesticating plants in the Amazon. Source: Silvio /Adobe Stock

The article, originally titled ‘ Earliest humans in the Amazon created thousands of 'forest islands' as they tamed wild plants ’ was first published on Science Daily.

Source: University of Exeter. "Earliest humans in the Amazon created thousands of 'forest islands' as they tamed wild plants." ScienceDaily. ScienceDaily, 8 April 2020.

References

Umberto Lombardo, José Iriarte, Lautaro Hilbert, Javier Ruiz-Pérez, José M. Capriles, Heinz Veit. Early Holocene crop cultivation and landscape modification in Amazonia .’ Nature, 2020; DOI: 10.1038/s41586-020-2162-7

Comments

Certain areas of the Amazon have soils modified heavily (ie. improved) by ancient agriculture. Thus, that these vegetation islands are not natural should be no surprise.

Vast chunks of the Amazon were cleared. Even if just a small percentage of the area in total, that's still a vast chunk given the size of the Amazon Basin.

This would mean that the virgin forests of southern american djungles aren't?

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