Ancient settlers once farmed on thousands of artificial forest islands

Over 10,000 years ago, ancient human settlers began the construction of around 4,700 artificial forest islands in ancient Amazonia, according to the results of a recently-published paper. Archaeologists believe that the islands were used for farming, and that they can still be seen to this day.

In recent years, archaeologists have discovered four incredibly ancient regions located in the Middle East, China, and Modern Day Mexico and South America, where early humans first began to cultivate plant life for food. However, there was also reason to suspect that a fifth ancient plant cultivation region may have been active in southwestern Amazonia – modern-day Bolivia – as the wild relatives of several globally important crops including squash, manioc and maize grew in this area.

A new study has found evidence that there was indeed an advanced cultivation effort underway in ancient Amazonia over 10,000 years ago, and that humans dramatically reshaped the virgin land in their quest to grow food by creating a vast network of artificial islands.

The savanna terrain that was modified for farming regularly flooded from December to March, and experienced arid conditions between July and October. Hardly ideal farmland.

Forest islands seen from above
Forest islands seen from above

Umberto Lombardo

The team used satellite data to map 6,643 forest islands located in present-day Llanos de Moxos, Bolivia. Of these, 82 were surveyed, samples were taken from 30, and four were excavated.

Sixty-three of the islands were found to harbor dark sediments rich in organic matter including charcoal, burnt earth, animal bones and shells, which are indications of human occupation. It was concluded that they were not existing landscape features, and had instead been constructed completely artificially for the purpose of cultivating food.

Based on their findings, the researchers extrapolated that ancient settlers gradually built around 4,700 islands on which to grow food, with construction starting over 10,000 years ago. These forest islands had an average size of 0.5 hectares (1.2 acres), and were raised 0.5-3m (1.6-9.8 ft) above the savanna in order to remain above the water level during the wet season.

The scientists were able to identify a number of the crops harvested on the islands based on organic remains extracted from the samples, and even put an estimated date on how long ago they were cultivated.

It is thought that manioc was cultivated on the forest islands around 10,350 years ago, while squash was harvested around 100 years later. Maize arrived on the islands more recently, roughly 6,850 years back. The results indicate that plant cultivation took place in the region 8,000 years earlier than had previously been thought.

Incredibly, the islands are still visible in modern day Bolivia, appearing as isolated patches of forest surrounded by savanna. The research reveals that humans started modifying the landscape of ancient Amazonia to suit their needs very soon after they arrived, and that the region was one of the earliest centers of plant domestication.

The paper has been published in the journal Nature.

Source: University of Exeter

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