In 1969, character actor Jack Somack made an Alka-Seltzer commercial that today would go viral. He bites into some spaghetti and states: “Mama-Mia, that’s-a one spicy meatball.”

How spicy do you like your food, pimento mild or habanero hot? I’m somewhere in between, enjoying the flavor of the pepper and not the heat.

Humans are known to eat some really strange stuff – the wet animal market in Wuhan comes to mind – but since chilies have a built-in defense mechanism, why do we eat them? Their natural ingredient, capsaicin, is an example of what scientist call “directed deterrence.” That means p...