The scoville scale is used to measure how spicy as pepper or chili is. The jalapeno can have a rating as high as 8,000 units, and for many sensitive palates, that’s plenty. The world’s hottest peppers approach an incredible 1.5 million scoville units – so hot, a tribe in northeast India consumes them for sport. Best-selling science writer Mary Roach visited the Naga tribes to observe their competitive and cultural history with the scorching Naga King Chili. Roach is author of many books – most recently is Gulp: Adventures on the Alimentary Canal… and she wrote about the Naga King Chili for Smithsonian magazine.