“Deforestation, cattle ranching, illegal mining, and outside colonization threaten their existence," Walker continued. "Most of these tribes are swidden horticulturalists and so their slash-and-burn fields are observable in satellite images. But, they do move around, sometimes in response to external threats, and this movement requires constant monitoring if there is to be any hope of preserving their habitat and culture.”
There are somewhere between 70 and 100 uncontacted groups in Amazonia. Brushes with modern society are often violent--one previously isolated tribe was recently forced to relocate after a run-in with drug traffickers, according to The Ecologist.
If you're curious, here is a video of another isolated tribe in Brazil.
Source: www.popsci.com By Douglas Main