As Fernando Santos-Granero approached the Yanesha village in the Peruvian Amazon, he heard commotion from a thatched-roof house. Women were shouting, and the children who weren't crying were chasing some especially naughty pigs. A grandmother was beside herself in fear, as illness was certain to befall her.

The grandmother had entrusted her most important personal ornaments – chest bands of plaited palm fibers adorned with desiccated birds - to a granddaughter who was supposed to make sure they did not fall from a rooftop while drying. The child forgot and the ornaments, which the grandmother had received many decades ago when she reached womanhood, were blown to the ground where pigs trampled and devoured them.

"That night the grandmother fell ill," recalls Fernando, a STRI staff anthropologist, who first thought she was distraught over the loss of her objects. He later learned Yanesha health notions had a very different explanation.

The Yanesha believe that some objects are living beings possessing a soul. "Personal objects, especially clothes or ornaments, are thought to be imbued with the soul of the person who owns them," says Fernando, whose insights are based on decades of personal observation. "Losing part of your soul results in disease. So that is why the grandmother had fallen ill."