Since at least the 19th century we’ve believed that lemmings engage in cult-like suicidal behavior and jump off cliffs en masse during migration. While it’s true that during population explosions, lemmings seek out new habitat and occasionally fall off cliffs on unfamiliar turf, but group suicide? Nope. Curiously, mass plunges aren't even the strangest false fact that poor lemmings have to endure. The 16th-century geographer Zeigler of Strasbourg proposed that lemmings fell out of the sky during storms, and then suffered mass extinctions when the spring grass began to sprout. Impressive.