There's also horizontal "translation" -- as a child I had a book which was plainly European fairy tales translated linguistically and culturally into India (e.g. a princess whose wicked stepmother forced her to separate rice and sand).

I wonder how many stories suffer "mutations" that break them from their previous incarnations. The article mentions "The Smith and The Devil", and speculates that metal-working technology would have been around at the time of its origin, but I'm not sure if that's any more likely than the profession of the protagonist changing over time.

At the very least, in Russia there are many tales of Ivan outwitting the Devil, regardless of his profession. Maybe that's just a horizontal transfer and the story taking advantage of a previously unoccupied memetic niche...

I don't think there is a single folklorist who is convinced by this phylogenetic speculation. If you know some, I am eager to hear about them.

Interesting use of Bayesian inference to prove the brothers Grimm were mostly plagiarists