Wednesday, April 26, 2006

Exaptation and Snakes on a plane

I heard the expression snakes on a plane the other week and being etymologically oriented as well as entomologically oriented, I had to check this new phrase out. According to, "snakes on a plane" means something around "Cest la vie",and "Shit happens" and the phrase relates to a working title for a movie of the same name, and popularized by a screenwriter Josh Friedman in his blog, in an entry protesting a proposed change in the title of the movie. Friedman explains his ire about the change in an entry you can read for yourself. Warning, if you don't like certain four letter words, you might want to be content with this quote

"In fact, during the two or three days that precedes my phone call with the studio, I become obsessed with the concept. Not as a movie. But as a sort of philosophy. Somewhere in between "Cest la vie", "Whattya gonna do?" and "Shit happens" falls my new zen koan "Snakes on a Plane".

WIFE: "Honey you stepped in dog poop again. "
ME: "Snakes on a Plane..."
DOCTOR: "Your cholesterol is 290. Perhaps you want to mix in a walk once in a while."
ME: "Snakes on a Plane..."
WIFE: "Honey while you were on your cholesterol walk you stepped in dog poop again."

Now what is this exaptation stuff? Exaptation is the evolution of new adaptations from adaptations that evolved in a different context. For example, leaves which evolved mainly as organs that carry out photosynthesis, become thorns in cacti and become adaptations that protect the cacti from grazing animals.

So today I used "snakes in a plane" to illustrate a parallel between cultural and biological evolution. The "snake" is a basically a cultural exaptation-from a movie title to a phrase meaning "that's life or "s__t happens". OK I am don't use scatological terms usually..I might quote them but will not use them. Some biologists view cultural evolution as having a close correspondence with biological evolution. I think the analogy is going a bit too far, but ideas do seem to take on a life of their own, meanings become exapted (perhaps coopted), and the results of this maybe quite creative and unexpected. That is one of the fun things about language and one of the fun things about the results of biological evolution!

Other links:

This reference defines an exaptation as being slightly different than an adaptation. An adaptation is a feature produced by natural selection for its current function and an exaptation is a feature that evolved for some other function other than its current function-so the feature is co-opted by natural selection for a new function. So feathers are an adaptation for insulation but an exaptation for flight. See:

Personally I think that this is a bit of an artificial distinction and I prefer to think of exaptations as a particular type of adaptation. After all given the tendency of evolution to reuse and reshape existing features, there is a certain sense that most adaptations involve exaptation. See for instance:, which views the distinction between adaptation and exaptation as as merely a technical one, a matter of taste.

Here is a fun explanation of exaptation in terms of the Jerry rigged solution used to save Apollo 13:

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