Most of the edible plants in the rainforest were planted by humans over 4500 years ago, new study finds. Modern farmers should look to these ancient forest gardeners for the key to sustainable food production.
Ancient humans were practicing a form of agriculture known as horticulture or permaculture in the Amazonian rainforest 4500 years ago, which researchers have concluded is responsible for the overwhelming abundance of edible plants we now find there.
They say the long-term success of the “forest-gardening” method of food production serves as a model of sustainability for modern farmers.
The study is the first detailed history of long-term human land use in the region conducted by archaeologists, paleoecologists, botanists and ecologists from the University of Exeter in England.
It shows that humans had a more profound effect on the supposedly “untouched” rainforest than previously thought, introducing crops to new areas, boosting the number of edible tree species and using fire to improve the nutrient content of soil,
The researchers found evidence of maize, sweet potato, manioc and squash farming as early as 4,500 years ago in Eastern Brazil.
While the “farmers” practice some clearing of the under-story of the the rainforest, it was nothing like the clear-cutting of forests the Americas have seen since the arrival of the Europeans. The canopy of the forest remained intact, as a protector of the soil and crops.
“Ancient communities likely did clear some understory trees and weeds for farming, but they maintained a closed canopy forest, enriched in edible plants which could bring them food,” said Amazonian paleoecologist Yoshi Maezumi, who led the study.
Rather than depleting the soil and moving on to clear the next section of land, ancient horticulturalists reused the same soil again and again, improving it by adding manure and food waste (aka composting).
“People thousands of years ago developed a nutrient-rich soil called Amazonian Dark Earths,” Maezumi said. “They farmed in a way which involved continuous enrichment and reusing of the soil, rather than expanding the amount of land they clear-cut for farming. This was a much more sustainable way of farming.”
“This is a very different use of the land to that of today, where large areas of land in the Amazon is cleared and planted for industrial scale grain, soya bean farming and cattle grazing. We hope modern conservationists can learn lessons from indigenous land use in the Amazon to inform management decisions about how to safeguard modern forests.”
Permaculturist and author of Gaia’s Garden Toby Hemenway hypothesized the Amazon rainforest was a man-made forest garden years ago. He also believed much of North America was covered in human-made food forests before the Europeans got here.
“The trees were loaded with walnuts, chestnuts, hickory nuts, beech nuts and acorns, and the rivers with “salmon so thick you couldn’t walk across,” he said. “Unfortunately, the people who tended those food forests were exterminated.”
Learn more about forest gardening, as a sustainable alternative to agriculture, in Hemenway’s book Gaia’s Garden: