Are we even? Part 3

My last post considered how we have a visceral system inside of us that, by its design, puts mechanically asymmetric pulls on our bodies. This time I want to consider the frame the viscera are packed into and transported with – the musculoskeletal system

The musculoskeletal system is the set of bones and muscles we have that lets us generate voluntary movement. It is what many people think of when they think about the human body.  This system is designed to be symmetric (at least from right to left) so there is one of each bone and muscle on each side with some individual bones in the midline. Mechanically this system usually works best if it has a neutral point that is truly in the middle. That is, it always returns to mechanical symmetry between movements. For example- to be most efficient at turning you want to be able to move to the left or right with equal ease. That means you always start a turn from the mid-point between the two. And after you finish the turn you come back to the mid-point. If you stay to the left, for instance, you will always have to do more work to turn right and it will put a twist in the entire body to support staying to the left.

Here is how the two systems vary – The musculoskeletal system works best with a neutral point that has the bones and muscles symmetric in alignment so you can move with equal ease in any direction. In contrast, the visceral system has a neutral point where the parts of the musculoskeletal system are not in mechanical symmetry.

So, here is the design balance evolution has led to in the human structure:

  • Our visceral system, which is necessary for life, pulls our body into an asymmetric shape.
  • Our musculoskeletal system, which is necessary to stay alive, works best if it can be symmetric.

How these two work out the balance is the next topic.