Members of the Mashco-Piro tribe observe a group of travelers from across the Alto Madre de Dios river in the Manu National Park in the Amazon basin of southeastern Peru, as photographed through a bird scope October 21, 2011. Survival International has the Mashco-Piro tribe listed as one of around 100 uncontacted indigenous tribes in the world. (Photo by Jean-Paul Van Belle/Reuters)
