Anthropologist Carla Handley is sitting cross-legged in a mud-walled house in a Kenyan village called Merti. She's meeting with a man dressed in a flowing blue robe and a woven cap of red and white.

Peru’s Manu Biosphere Reserve is the largest rainforest reserve in the world and one of the most biodiverse spots on the planet. Manu is a UNESCO-protected area the size of Connecticut and Delaware ...