Redux: Squirrel & Snake Physics


This was originally posted June 8, 2010 and probably ten people read it.  I hope you don’t mind my running it again.  It reminds me of my favorite Abstruse Goose.  The picture’s a little alarming, but justly so.

I had two trees in the front yard, and I’d watch the squirrels jump between them, across maybe a four-foot gap, and they did it at speed.  They’d race out along the branch to its spindly end and the instant it bent under their weight, they’d go airborne and land on the other tree’s spindly end-branch, no hesitation, no wobble, no recovery, a fraction of a second, then tear down the next branch.

Squirrels – this is well-known – have tiny little brains specially evolved for this.  They put the altitude of the starting point, the altitude of the target point, the distance between the points, air resistance, squirrel velocity, and the acceleration due to gravity into a kinematics equation that accounts for all three dimensions and probably contains some integrals and derivatives and for all I know, square roots.  They solve the equation at the split second of the jump and they always nail it.

Another creature that does something like this is the paradise tree snake, which hangs off a branch in a J, accelerates up and out, widens its rib cage and flattens its round self into a sort of D, undulates through the air at 8 meters per second, can make 90 degree turns, and maintains the glide ratio of a flying squirrel; and I’d tell you all about their mental calculations but I’m too shaken by the prospect of airborne snakes and need to go nap.


Source for squirrel kinematics:  my husband the physicist

Squirrel photoRay Eye  

Snake photo: Magnus Manske

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6 thoughts on “Redux: Squirrel & Snake Physics

  1. I enjoyed the paraphrase of a physicist’s kinematics equation. Was that same physicist the authority for the statement that the purpose of the evolution of a squirrel’s brain is “well known”?

  2. Rosie: Not sure whether the snake or the squirrel applies to your driving but in either case, would you let me know next time you’re out?

    Gail: Smart aleck. No, I made that up my own self.

  3. Love the photo and would love to see an airborne snake!

    But I must quibble that squirrels will not always nail it. Squirrels do make mistakes and fall out of trees. I’ve both seen it myself (not pretty) and talked to others who’ve seen falling, fallen, and broken squirrels. There’s heavy selection for making those calculations correctly. I assume the same applies to the snakes.

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