Wiki has a short article on Fart Lighting, but doesn’t credit anyone with discovering the technique. Cecil, Snopes and the Durham University Fart Lighting Society also appear silent on when the flammable nature of farts was discovered; although the farting society does jokingly mention Rene Descartes.
So when did someone discover that farts are flammable? I vaguely recall some stories about medieval French jesters, and it seems like something Roger Bacon might have tried, but how far back does it really go? Were there roman fart lighters? Greek? Does some fragment of the epic of Gilgamesh tell of Sumerian fart lighters, or is fart lighting actually a recently discovered trick?