September 25, 2012

The miracle of walking

WITHOUT DOUBT, the way a sailor walks on a rolling deck is one of the greatest achievements of human evolution. Few of us pause to consider the magic behind that simple-looking act, but it is, in fact, one of the great wonders of Nature.

There was a time many years ago when I became fascinated by the way people walk in ordinary circumstances, that is, on flat, stable ground.  Something that we take for granted, and what appears to be absolutely simple, is actually absurdly complicated.  Lifting one foot, moving it forward, and placing it down in synchronicity with another foot doing exactly the opposite is a triumph of muscular control and planning.

And then there’s the business of turning. Human perambulation performed in a straight line ahead is difficult enough, but the act of turning corners simply boggles the mind. Have you ever thought how you turn corners with such apparent ease? Just think about how many muscles have to be moved in the correct order, and the balance that has to be kept, and the furniture that has to be missed.

Going around corners is theoretically impossible. I mean, say you wish to turn to the right. The computer that are you pleased to call your brain immediately goes into panic mode. It can hardly get the orders out fast enough.

What you have to do is (a) take longer strides with your left leg than your right leg, or (b) take shorter strides with your right leg than your left leg. This makes the two legs move at different speeds. The left leg, in fact, tries to overtake the right leg, quite forgetting that it is joined to the right leg at the trunk. If it were allowed to continue in this foolish way it would eventually sever itself from your body and you would fall over for want of a prop on the left side; but fortunately we have in our trunks nerves that sense pain.

It is the feeling of pain that makes us jump slightly into the air during a turn, to even the pressure building up on the legs and trunk, and in the situation I’ve been describing, a jump to the right is indicated.

A jump to the left would bring instant disaster in the form of the severance of both legs from the trunk, thus leaving nothing to separate the buttocks from the ground.

The brain never makes this mistake, of course, and this in itself is quite surprising, for the movements of the muscles of the left leg are controlled by the right side of the brain, and the movements of the right leg by the left side of the brain.

Thus, before any turn can even be contemplated, the brain has to sit down and ask itself which side of itself it has to use to move which leg.

And not only that. It has to work out which muscle to move in which foot, and I surely don’t need to tell you how complicated that can be. You’ve got real trouble if you send a message rushing down the spinal cord, addressed to the short flexor of the great toe, telling it to contract quickly, when in fact you meant to send it to gastrocnemius muscle in the calf. If you don’t fall flat on your face it will be a miracle.

Now all this simply concerns making a turn left or right.  Consider the added difficulty caused to a sailor’s brain by a rolling deck, where it’s necessary to walk with one leg higher than the other at one moment, and that same leg lower than the other at the next.  Finally, try to imagine what’s going on in  that poor brain  when a sailor walking along a rolling deck suddenly decides to make a turn.

On second thought, maybe you shouldn’t try to imagine it.  There’s only so much a human brain can take.

Today’s Thought
They wha canna walk right are sure to come to wrang,
Creep awa’, my bairnie, creep afore ye gang.
— James Ballentine, Creep Afore Ye Gang.

A cute blond entered the animal rescue center. She said to the young man behind the counter, “I want a pet.”
“Me, too,” said the man, “but the boss is awfully strict. How about we meet after work?”

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)    

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