Oral histories are suspect. The reason we know so little about native Americans is that they never learned to write so the stories passed down changed from year to year. Once you go past the common age of the written word, to the time when only religious people wrote books and those books were primarily science and theology, oral tradition is all that remains. But when something becomes popular, academic interest takes hold, so when Jacob and Wilhelm Grimm published Children's and Household Tales 200 years ago, scholars began to think about the true origins of the tales. 200 years later, the similarities between those tales and others from various parts of the world are evident. Did they 'evolve'?
Phylogenetics in this case is not investigating evolutionary relationships between biological species but rather the descent with modification of stories. To do so, the author created a taxonomy tree that represents relationships of common ancestry based on shared traits, counting on the fact that these tales evolved gradually over time, with new parts of the story added and others lost as they get passed down from generation to generation.
The Phylogeny of Little Red Riding Hood: Map of the approximate locations from which tales were sourced. Numbers in the circles refer to the variants listed in the Supporting Information. doi:10.1371/journal.pone.0078871
A Bayesian analysis can do anything if you try. Its accuracy is, of course, another matter.
By focusing on "Little Red Riding Hood" and related tales, the author analyzed 72 plot variables, such as character of the protagonist (e.g., single child versus group of siblings, male versus female), the character of the villain (e.g., wolf, ogre, or tiger), the tricks used by the villain to deceive the victim (e.g., false voice or disguised paws), and so on.
The author found that the African tales are not actually of the "Little Red Riding Hood" type, but instead are related to a tale called "The Wolf and the Kids." East Asian tales did not group with either type but probably evolved by blending together elements of both types of stories.
To the authors, the finding suggest that phylogenetics can be used to identify distinct groups of folktales spread over wide regions and cultures, which may help us better understand the development and "evolution" of oral narratives in these contexts.
Durham University anthropologist Jamshid J. Tehrani says, "Folktales are excellent targets for phylogenetic analysis because, like biological species, they evolve over generations and adapt to new environments as they spread from region to region. Since folktales are mainly transmitted via oral tradition, it can be difficult to study their development using conventional tools of literary analysis, because there are so few historical texts. My study shows how we can overcome these difficulties by using the same approach that biologists have used to fill the gaps in the fossil record."
Citation: Tehrani JJ (2013) The Phylogeny of Little Red Riding Hood. PLoS ONE 8(11): e78871. doi:10.1371/journal.pone.0078871