October 12, 2007

Walk like an Egyptian!

When we move from one place to another, we use our legs. So do all other animals. Movement (locomotion, to be precise) typically involves a support phase or stance phase when we support one foot on the ground and a swing phase when we swing the leg forward. Even our internal machineries also carry molecules or organelles from one part of the cell to other, by 'walking' in this fashion, and not by rolling.

Compare this (natural movement) with that of man made things that move. How the ancient Egyptians built the Pyramid in those days, is still debated. But they probably carried those heavy stones, on logs acting as wheels. Consider locomotives for example. Vehicles run on wheels, which rotate around an axis. Nearly all machines operate by rotating motors. Why then in nature, the transportation is looked after by the process of stepping?

One explanation is that in animal kingdom, a revolving appendage would mean detachment of that appendage, due to anatomic constraints. Secondly, devising an engine that would move in a step-like manner is not easily feasible due to the inherent unsymmetrical pull on its 'limbs' due to gravity, but the 'pi' factor would let the wheel move smoothly-in a continuous fashion.

I intend to write about the movement of 'molecular motors' in a later post. In the mean time it is really worth pondering why in nature things 'walk like an Egyptian'.
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