To the window! To the wall! Till the sweat drips from my balls! Skeet, skeet, skeet, skeet!
Even though chili fruits are popular amongst humans for being hot, they didn’t evolve this character to keep foodies and so-called “chili-heads” happy. Previous research indicates that chilis, Capsicum spp., evolved their characteristic “heat” or pungency as a chemical defence to protect their fruits from fungal infections and from being eaten by herbivores. Chili pungency is created by capsaicinoids, a group of molecules that are produced by the plant and sequestered in its fruits. Capsaicinoids trigger that familiar burning sensation by interacting with a receptor located in pain- and heat-sensing neurons in mammals (including humans).
In contrast, birds lack this specific receptor protein, so their pain- and heat-sensing neurons remain undisturbed by capsaicinoids, which is the reason they eat chili fruits with impunity. Additionally, because birds lack teeth, they don’t damage chili seeds, which pass unharmed through their digestive tracts. For these reasons, wild chili fruits are bright red, a colour that attracts birds, so the plants effectively employ birds to disperse their seeds far and wide.
