Last week, the United Nations voted on an appeal by Bolivia to amend the international treaty that prohibits the chewing of coca leaf. Bolivia won a partial victory — a tiny sign that the world may be ever so slowly coming to its senses on the insanely harsh treatment of this humble, mostly harmless plant and the people, mostly South American natives, who enjoy it in its raw form. (Ricardo Cortés is the author of A Secret History of Coffee, Coca & Cola)