The Real Reason Peppers are Spicy

Why did peppers develop their heat? Scientists once assumed that pepper plants produce capsaicin to deter animals from eating them. But that explanation doesn't quite hold up in nature. Birds aren't affected by capsaicin, which is why you should put pepper seeds in the birdseed to keep squirrels out of it. Hank Green tells us what we know so far about pepper evolution in this SciShow video. (via Digg)