The end of the road in Labrea, a town Walker described as so isolated that it felt like a step back in time. This is the town's port, on the Purus River. The Transamazon Highway stops here; indigenous lands lie on the other side.
Leaving Labrea, on the road to Humaita. Here, two children in a typical dwelling look at the researchers as they pass by, on their way out of the Amazon.
Walker said the trip yielded more good stories than bad ones, and, despite encountering the gold mine and the logging operation, he's encouraged that the Brazilian government seems to be taking environmental protection seriously. But he worried that if demand for bio-fuels continues to grow, more of the forest might be destroyed to make room for agriculture. In the wake of the BP oil disaster, Walker said, this threat has only grown.
"Where is the ethanol going to come from?" Walker said. "There could be some unanticipated costs as we switch to bio-fuels. We need to be very careful about the global reach of the supply chains, because they could reach all the way into the western Transamazon," he said. Which, at least for now, is one of the least touched areas of the rainforest.