Reactions | But Why Do Dogs Smell Each Other's Butts? | Season 1 | Episode 20 | PBS

Reactions is getting to the bottom of one of the biggest quandaries in science: Why dogs sniff each other’s butts. Spoiler: it's chemistry. Turns out this behavior is just one of many interesting forms of chemical communication in the animal kingdom. Dogs use a special feature called the Jacobsen's Organ to get chemical signals from their nose sent directly to their brain.