“Bolivia is believed to be the chili’s motherland, home to dozens of wild species that may be the ancestors of all the world’s chili varieties—from the mild bell pepper to the medium jalapeño to the rough-skinned naga jolokia, the hottest pepper ever tested. The heat-generating compound in chilies, capsaicin, has long been known to affect taste buds, nerve cells and nasal membranes (it puts the sting in pepper spray). But its function in wild chili plants has been mysterious.

Which is why Tewksbury and his colleagues have made multiple trips to Bolivia over the past four years. They’re most interested in mild chilies, especially those growing near hot ones of the same species—the idea being that a wild chili lacking capsaicin might serve as a kind of exception that proves the rule, betraying the secret purpose of this curiously beloved spice.” via Smithsonian Magazine.