This is where phylogenetic approaches can come in useful. To investigate the evolution of ‘Little Red Riding Hood’ and its variants, Tehrani gathered together almost sixty different versions of the story, spanning multiple continents. In place of a genetic sequence, he summarised each story based on a set of seventy-two plot features, such as the type of lead character, the trick used to deceive them, and how the story ended. He then estimated how these features evolved, resulting in a phylogenetic tree that mapped the relationship between the stories.[19] His analysis would produce an unexpected conclusion: based on the phylogenetic tree, it seemed that ‘The Wolf and the Kids’ and ‘Little Red Riding Hood’ had come first. Contrary to common belief, ‘The Tiger Grandmother’ was apparently a blend of existing tales, rather than being the original version from which others evolved.
Evolutionary thinking has a long history in the study of language and culture. Decades before Darwin drew his tree of life, linguist William Jones had been interested in how languages emerge, a field known as ‘philology’. In 1786, Jones noted the similarities between Greek, Sanskrit, and Latin: ‘no philologer could examine them all three, without believing them to have sprung from some common source, which, perhaps, no longer exists.’[20] In evolutionary terms, he was suggesting that these languages had evolved from a single common ancestor. Jones’s ideas would later influence many other scholars, including the Brothers Grimm, who were keen linguists. As well as collecting together different variants of folktales, they tried to study how the use of language had changed over time.[21]
Modern phylogenetic methods make it possible to analyse the evolution of such stories in much more detail. After studying ‘Little Red Riding Hood’, Jamie Tehrani worked with Sara Graça da Silva at the University of Lisbon to examine a much wider range of stories, tracing the evolution of 275 folktales in total. The pair found that some tales have a long history; stories such as ‘Rumplestiltskin’ and ‘Beauty and the Beast’ may have originally emerged over 4,000 years ago. This would mean they are as old as the Indo-European languages through which they spread. Although many folktales eventually travelled widely, da Silva and Tehrani also found traces of local rivalry in storytelling. ‘Spatial proximity appears to have had a negative effect on the tales’ distributions,’ they noted, ‘suggesting that societies were more likely to reject than adopt these stories from their neighbours.’[22]
Folktales are often tied to a country’s identity, even if their origins are not. When the Brothers Grimm compiled their collection of traditional ‘German’ stories, they noticed that there were similarities with tales in many other cultures, from Indian to Arabic. Phylogenetic analysis confirms just how much story borrowing there has been. ‘There’s not a great deal that’s special about any one country’s oral tradition,’ Tehrani said. ‘In fact, they’re highly globalised.’
Why did humans start telling stories in the first place? One explanation is that tales help us preserve useful information. There’s evidence that storytelling is a highly valued skill in hunter-gatherer societies, leading to suggestions that stories took hold in the early stages of human history because good storytellers were more desirable as mates.[23] There are two competing theories about what sort of story-based information we have evolved to value. Some researchers suggest that stories relating to survival are most important: deep down, we want information about where food and dangers are. This would explain why tales that evoke reactions like disgust are memorable; we don’t want to poison ourselves. Others have argued that because social interactions dominate human life, socially relevant information is most useful. This would imply that we preferentially remember details about relationships and actions that break social norms.[24]
To test these two theories, Tehrani and his colleagues once ran an experiment looking at the spread of urban legends. Their study mimicked the children’s game of ‘broken telephone’: tales were passed from one person to another, then to another, with the final version showing how much was remembered. They found that stories containing survival or social information were more memorable than neutral stories, with the social stories outperforming the survival ones.
Other factors can also boost the success of stories. Earlier broken telephone experiments found that tales tend to become shorter and simpler as they spread: people remember the gist but forget the details. Surprises can help a tale as well. There’s evidence that tales are catchier if they include counter-intuitive ideas. However, there is a balance to be struck. Stories need some surprising features, but not too many. Successful folk tales generally have a lot of familiar elements, combined with a couple of absurd twists. Take Goldilocks, the story of a girl who explores the family home of a mother, father, and baby. The twist, of course, being that it’s a family of bears. This narrative trick also explains the attraction of conspiracy theories, which take real-life events and add an unexpected slant.[25]
Then there’s the structure of a story. Goldilocks’ popularity might not be down to her, but rather the three bears. They turn the story into a sequence of memorable triplets: the bowls of porridge are too hot, too cold, just right; the beds are too soft, too hard, just right. This rhetorical trick is known as the ‘rule of three’ and crops up regularly in politics, from the speeches of Abraham Lincoln to Barack Obama.[26] Why are lists of three so powerful? It might have something to do with the mathematical importance of triplets: in general, we need at least three items in a sequence to establish (or break) a pattern.[27]
Patterns can also help with the spread of individual words. As language evolves, new words often have to compete to displace already popular ones. In such situations, we might expect people to prefer words that follow consistent rules. For example, past tense verbs often end in ‘…ed’,
