Sunday, November 24, 2013

Of Little Red Riding Hood and horses' hooves

Horse's rear hoof.
It evolved from the middle toe.
Evolution has supplied horses with limbs modified for running,  as well as a special feature for locking their knees allowing them to stand for long periods, and a hoof which evolved from an extruded middle toe.  These features enabled the horse to survive on open grassland by successfully fleeing from predators.   Now here's the crux. All this is equally true of a hoofed South America mammal called a litoptern, which went extinct between two and five million years ago, and is unrelated to the horse. It too, lived on open grassland and in order to successfully flee from predators evolved those very same features, even including that middle toe which evolved into a hoof. This I learnt some years ago at a lecture about convergent evolution.  The point being that evolution, when confronting similar challenges, has an uncanny knack of arriving at similar solutions, even at widely separated times and places.

Which brings me to folk tales about wolves.

“The Wolf and the Kids" is a tale popular throughout Europe and the Middle East. A nanny goat warns her kids not to open the door while she is out in the fields, but is overheard by a wolf. When she leaves, the wolf impersonates her and tricks the kids into letting it in, whereupon it devours them. Versions of this tale occur in collections of Aesop's fables, in which a goat kid avoids being eaten by heeding the mother's instruction not to open the door, or seeks further proof of the wolf's identity before turning him away.

The tale may be new to you, but you doubtless know by heart the tale of Little Red Riding Hood. She sets out for her grandmother’s house with a basket of goodies, but a big bad wolf finds out about her itinerary, gobbles up grandma and disguises itself to lure the little girl to her doom. "What big teeth you have!" Little Red Riding Hood remarks before the wolf devours her.

 Little Red Riding Hood at the
door to Grandma's house.
Late 19th century trade card.
Lets look at the parallel between the two stories.  In each we have a wolf who gets dinner by impersonation – of the nanny goat in the first story, and of the grandma in the second.  “The Wolf and the Kids" probably originated in the 1st century AD. “Little Red Riding Hood” arose about a thousand years later. Durham University anthropologist Dr Jamshid Tehrani borrows evolutionary analysis from biology to study similarities among folktales, and claims to show that “Little Red Riding Hood” is descended from “The Wolf and the Kids”. Moreover, “Little Red Riding Hood” evolved from this root once in Europe, and again, quite independently, in Africa.  So, like the horse’s hoof, Little Red Riding Hood has it seems evolved twice.  Dr Tehrani himself draws the parallel with convergent evolution: “The fact that Little Red Riding Hood 'evolved twice' from the same starting point suggests it holds a powerful appeal that attracts our imaginations” he says. 

His article appeared in the open access journal PLOS ONE. If you can follow it all, you're a better man than I am, but luckily there’s a press release, and a very readable account from NBC News.

The best-known version of Little Red Riding Hood was published by the Brothers Grimm 200 years ago, based on a 17th-century story by the Frenchman Charles Perrault who distilled it from oral retellings in France, Austria and northern Italy.  You'll find both on the University of Pittsburgh site along with six other related stories,  which folklorists group together and classify as tales of type 333 in the Aarne-Thompson-Uther system.

Dr Tehrani traces the ancestry and development of Little Red Riding Hood by observing features such as: is the victim single or a group of siblings, goat or human, eaten in their own home or a relative’s.  I found out a bit about classifying folktales when I researched the story of King Midas and his asses ears, a couple of years ago.

That's all I want to say about wolves, but I should have told you more about the lecture on convergent evolution.  One of the first I ever attended in Cork, in December 2005, it was by the Cambridge Professor Simon Conway Morris and his talk explored the heretical suggestion that  evolution has a destination, or even a destiny.  He had recently published his book Life’s Solution – Inevitable Humans in a Lonely Universe,  and argued that in the light of what we know about convergent evolution we should expect intelligent extraterrestrial life, if we ever come across it, to be strikingly similar to ourselves.