Horseradish, onions and caffeine all activate a group of chemical receptors that can trigger a pain signal. Turns out the same receptors exist in fruitflies, mussels, corals and mule deer. Why has this receptor survived a half-billion years? Because it protects against toxic chemicals – even if they taste good in small doses!

Chocolate doesn’t just tingle the tongue; it’s a soup of many compounds that affect the brain, including caffeine and theobromines. And it’s true: chocolate does affect women differently than men, says Anthony Auger, an assistant professor of psychology at UW-Madison.
Auger, who studies sex differences in the brain, agrees that women have a stronger craving for [...]