It was soon obvious that Mr. Kunchikuy had a first-rate mind, so Mr. McMeekin sponsored his education and a home-stay visit to Boston, where in the winter he encountered a puzzling white substance that was very cold. His tribal language, Shiwiar, has no word for snow, ice, freezing or even anything very cold. So after his return, it was tough to describe to his friends how his host family had taken him ice skating and snow-boarding.

Mr. Kunchikuy now speaks fluent English, on top of his other languages  Shiwiar, Spanish, Quichua, Achuar and Shuar, not to mention his mastery at calling monkeys and birds in the jungle. He became a naturalist and guide at the Yachana Foundation’s 18-room eco-lodge, which tourists reach by riding in a canoe for nearly three hours.

Now 30, Mr. Kunchikuy points wildlife out to American tourists and demonstrates that grubs can be tasty. He also displays his impressive collection of scars, from vampire bats, a piranha, a caiman, a stingray, and a shaman who operated on his chest to block another shaman’s black magic. In his spare time, he demonstrates how to shoot a blowgun.

“It has a range of up to 150 feet,” he explained. “It’s better than a shotgun, because it’s silent. You can shoot repeatedly if you miss the first time.” (Keep an eye on nytimes.com in the coming days for a video of Mr. Kunchikuy using his blowgun to spear a papaya balanced on my head  but don’t tell my wife.)

Yet the traditions he grew up with are eroding, much like the rain forest. Loggers are chipping inexorably away at the Amazon, robbing the planet of biodiversity and of a great carbon sink that absorbs our greenhouse gas emissions. On top of that, the deforestation itself, including slash-and-burn clearing, accounts for 20 percent of global carbon emissions, the same amount as that produced by the United States or China. Several studies declare that the low-hanging fruit in the war against climate change is keeping these forests alive.

In my next column, on Thursday, I’ll tell you how Mr. McMeekin and Mr. Kunchikuy are doing just that.