Paleontologists and 'neontologists' (those rather boring biologists who study living animals) often use phylogenetic methods to trace the ancestry of the critters they study. These same methods can also be applied to languages and - it turns out - fairytales. We at Extinct have no idea about the trustworthiness or otherwise of the methods for this application, but the results are pretty fascinating (suggesting at least one piece of folk-lore has survived from the bronze-age!).
Here's the original study,
And here's a nice summary.