Tehrani and da Silva recorded the presence of each Tales of Magic to 50 Indo-European populations, and used these maps to reconstruct the stories' evolutionary relationships. They were successful for 76 of the 275 tales, tracing their ancestries back by hundreds or thousands of years. These results vindicate a view espoused by no less a teller of stories than Wilhelm Grimm—half of the fraternal duo whose names are almost synonymous with fairy tales. He and his brother Jacob were assembling German peasant tales at a time of great advances in linguistics. Researchers were unmasking the commonalities between Indo-European languages (which include English, Spanish, Hindi, Russian, and German), and positing that those tongues shared a common ancestor. In 1884, the Grimms suggested that the same applied to oral traditions like folktales. Those they compiled were part of a grand cultural tradition that stretched from Scandinavia to South Asia, and many were probably thousands of years old.

Many folklorists disagreed. Some have claimed that many classic fairy tales are recent inventions that followed the advent of mass-printed literature. Others noted that human stories, unlike human genes, aren't just passed down vertically through generations, but horizontally within generations. “They’re passed across societies through trade, exchange, migration, and conquest,” says Tehrani. “The consensus was that these processes would have destroyed any deep signatures of descent from ancient ancestral populations.”

Not so. Tehrani and da Silva found that although neighboring cultures can easily exchange stories, they also often reject the tales of their neighbors. Several stories were less likely to appear in one population if they were told within an adjacent one.

Meanwhile, a quarter of the Tales of Magic showed clear signatures of shared descent from ancient ancestors. “Most people would assume that folktales are rapidly changing and easily exchanged between social groups,” says Simon Greenhill from the Australian National University. “But this shows that many tales are actually surprisingly stable over time and seem to track population history well.” Similarly, a recent study found that flood “myths” among Aboriginal Australians can be traced back to real sea level rises 7,000 years ago.

Many of the Tales of Magic were similarly ancient, as the Grimms suggested. Beauty and the Beast and Rumpelstiltskin were first written down in the 17th and 18th centuries respectively, but they are actually between 2,500 and 6,000 years old—not quite tales as old as time, but perhaps as old as wheels and writing.

The Smith and the Devil is probably 6,000 years old, too. In this story, a crafty blacksmith sells his soul to an evil supernatural entity in exchange for awesome smithing powers, which he then uses to leash the entity to an immovable object. The basic tale has been adapted in everything from Faust to blues lore, but the most ancient version, involving the blacksmith, comes from the Bronze Age! It predates the last common ancestor of all Indo-European languages. “It's constantly being updated and recycled, but it's older than Christianity,” says Tehrani.