Deep within the Amazon, Mark Robinson was up to his knees in buried treasure. Together with an international team of scientists, Robinson was on an expedition to a remote patch of forest in Iténez, northwest Bolivia, close to the border with Brazil. Getting there had not been easy. To avoid a 10-hour boat ride, they took a hair-raising flight to the nearest village, Versalles, where the plane had to circle back over a grass runway to avoid landing on a herd of grazing animals. Then came a long trek through thick rainforest, navigating over gnarled roots and past marauding armies of ants. "It's hot, it's humid, you're getting bitten constantly," says Robinson, a senior lecturer in archaeology at the University of Exeter.