Scientists studying the Amazon rain forest are tangled in a debate of nature versus nurture.
Many ecologists tend to think that before Europeans arrived in the Americas, the vast wilderness was pristine and untouched by humans. But several archaeologists argue that ancient civilizations once thrived in its thickets and played a role in its development.
Now, researchers have found evidence that indigenous people may have domesticated and cultivated Amazonian plants and trees thousands of years ago, further supporting the idea that ancient humans helped shape the forest.
“Large areas of the Amazon are less pristine than we may think,” said Hans ter Steege, a tropical ecologist at the Naturalis Biodiversity Center in the Netherlands, and an author of a paper published in Science on Thursday. “The people who lived there before Columbus left serious footprints that still persist in the composition as we see today.”
He was one of more than a hundred researchers who found that domesticated tree and palm species — like cacao, cashews, the açaí palm, the Brazil nut and rubber — were five times more likely to dominate the modern Amazonian forest than nondomesticated plants.
Carolina Levis, a doctoral student at the National Institute for Amazonian Research in Brazil and Wageningen University and Research Center in the Netherlands, was the lead author on the study. She and her team looked at a database from the Amazon Tree Diversity Network containing 1,170 plots of forest. Most plots measured approximately 2.5 acres each and had previously been investigated on foot by ecologists who counted and identified the plant species in the plots. Ms. Levis then identified 85 domestic plants to analyze.
One way the team determined that a plant had been domesticated was a look at its fruit. They found, for example, some peach palms that bore fruit weighing 200 grams, or 0.44 pounds, when the fruit grown in the wild matured to about one gram. Several of the domesticated plants they identified are still grown by South Americans…
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