Science, Tech & Environment
We were looking for a tributary of the Amazon that starts in the Brazilian state of Mato Grosso. The answer is the Xingu River. Researchers working near the source of the river have un-covered traces of ancient settlements -- known as "lost cities" -- buried under a thick layer of jungle. Lisa Mullins speaks with Michael Heckenberger, a professor of Anthropology at the University of Florida who led an expedition to the region.