Situated in the remote southwestern region of the Amazon Basin and said to have the highest biological diversity of any rainforest in the world is Peru's Manu Biosphere Reserve. Manu covers a total of 4.5 million acres of pristine rainforest from the crystalline cloud-forest streams to the sluggish, chocolate-brown rivers of the dense lowland jungle. Manu's environment has been unchanged for thousands of years, thus allowing more species of plants and animals to evolve here than in any...