Francoise Barbira-Freedman, a medical anthropologist at Cambridge University, described how she discovered the remedy, which is derived from the rare Acmella oleracea plant, while visiting the tribe in the rainforest.

BBC: Herbal dental remedy a 'potent anaesthetic'

The plant, Desert Rock, is owned jointly by the tribe's power authority and Houston-based Sithe Global Power, which in turn is majority-owned by Blackstone, a large private-equity firm.

ECONOMIST: New Mexico