There are countless different actions we take every day that we do so automatically we're hardly even aware of how complex they are.
Take, for example, walking. Walking takes the coordination of dozens of muscles, each of which has to contract and relax in exactly the right sequence to propel us forward and adjust for irregularities of the terrain we're navigating. To avoid falling, we need to keep our center of gravity over our base of support, which is aided by adjustments in posture and such counterbalancing movements as swinging the arms. But in order to do that we have to keep track of proprioception -- our sense of where our bodies are -- which is accomplished by a whole array of sense organs, including vision, the tactile sensors in the skin, and the semicircular canals -- the balance organs in the inner ear, which work a little like a carpenter's level.
And all of those -- the sense organs that keep track of what's going on and the muscles that use that information to contract and relax at the right times -- are linked by an astonishingly complex set of nerve relays and circuits coordinated by our brains.
All of that, just to get up and walk across the room.
The reason the topic of locomotion comes up is a paper a couple of weeks ago in Current Biology describing a single-celled protist called Euplotes eurystomus that has fourteen leg-like appendages -- and is able to walk.
The scientists studying Euplotes found that the appendages had thirty-two different configurations, which they called"gait states," and that somehow, the little creature was keeping track of which sequence of gait states allowed for the most efficient walking. It turned out that the internal scaffolding of the cell, made of hollow threads called microtubules, created cross-links from each appendage to the others. The amount of tension in the microtubules allows the organism to coordinate the movement of all fourteen appendages."The fact that Euplotes' appendages are moving from one state to another in a non-random way means this system is like a rudimentary computer," said Wallace Marshall, of the University of California - San Francisco, who co-authored the paper.