I spent a couple weeks with hunter-gatherers in the Amazon. While I was there, one Waorani man told me that his ancestors planted edible food in the forest. When they gather it now, they're just reaping what they sowed.

At the time, I thought it was a cute origin myth. But a new study found that he was completely right.

Scientists from the University of Exeter examined soil in the Amazon and found that there was something strange about it. This was no untouched rainforest dirt. It had clearly been affected by humans. Ancient peoples had used fire, manure and compost to make the soil richer.

That allowed them to plant more edible trees, which explains why there are so many more edible plants in the jungle than you'd expect. Ancient peoples had farmed maize, manioc, sweet potato and squash there 4,500 years ago.

Oh, and they were better at it than us.

LollyKnit/CC BY 2.0

Modern farmers clearcut the rainforest, which destroys the soil's nutrients over time and doesn't actually give you much food, a fun fact that makes me want to bash my head into a tree.

"People thousands of years ago developed a nutrient rich soil," explained Dr. Yoshi Maezumi, the University of Exeter professor who led the study. "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."

It was so efficient that they could grow crops in unusual places. Conventional wisdom states that the ancients should only have been able to grow maize near nutrient-rich lakes. But these ancient farmers grew it all over the place.

"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," explained Maezumi. "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."