According to legend, the patron saint of Ireland chased the slithering reptiles into the sea after they began attacking him during a 40-day fast he undertook on top of a hill. (Related: "St. Patrick's Day: Facts, Myths, and Traditions.")It's admittedly an unlikely tale. Ireland is one of only a handful of places worldwide—including New Zealand, Iceland, Greenland, and Antarctica—that Indiana Jones and other snake-averse humans can visit without fear. But snakes were certainly not chased out of Ireland by St. Patrick, who had nothing to do with Ireland's snake-free status, Nigel Monaghan, keeper of natural history at the National Museum of Ireland in Dublin, told National Geographic. Monaghan, who has trawled through vast collections of fossil and other records of Irish animals, has found no evidence of snakes ever existing in Ireland. "At no time has there ever been any suggestion of snakes in Ireland. [There was] nothing for St. Patrick to banish," Monaghan said. (Read about the top ten St. Patrick's Day celebrations.) So what did happen? Snakes likely couldn't reach Ireland. Most scientists point to the most recent Ice Age, which kept the island too cold for reptiles until it ended 10,000 years ago. After the Ice Age, surrounding seas may have kept snakes from colonizing the Emerald Isle. No Leg to Stand On Once the ice caps and woolly mammoths retreated northward, snakes returned to northern and western Europe, spreading as far as the Arctic Circle. But snakes have not existed in Ireland for thousands of years. Britain, which had a land bridge to mainland Europe until about 6,500 years ago, was colonized by three snake species: the venomous adder, the grass snake, and the smooth snake. But Ireland's land link to Britain was cut some 2,000 years earlier by seas swollen by the melting glaciers, Monaghan noted. Animals that reached Ireland before the sea became an impassable barrier included brown bears, wild boars, and lynx—but "snakes never made it," he said.