Mankind's chili habit

Tasteless, colourless, odourless and painful, pure capsaicin is a curious substance. It does no lasting damage, but the body's natural response to even a modest dose (such as that found in a chili pepper) is self-defence: sweat pours, the pulse quickens, the tongue flinches, tears may roll. But then something else kicks in: pain relief. The bloodstream floods with endorphins—the closest thing to morphine that the body produces. The result is a high. And the more capsaicin you ingest, the bigger and better it gets.

Which is why the diet in the rich world is heating up. Hot chilies, once the preserve of aficionados with exotic tastes for cuisine from places such as India, Thailand or Mexico, are now a staple ingredient in everything from ready meals to cocktails.