Monday, 25 July 2011

Refuting Intelligent Design: The Game of Life and Irreducible Complexity

A long time ago I wrote a blogpost about John Conway's Game of life, which used simple set of rules to make dots on a page evolve. This zero player "game" is an excellent example of how complex systems can evolve from simplicity. All we have is a grid in which each cell has two possible states dead (shaded) or alive (empty) and four simple rules:

  1. Any live cell with fewer than two live neighbours dies, as if caused by under-population.
  2. Any live cell with two or three live neighbours lives on to the next generation.
  3. Any live cell with more than three live neighbours dies, as if by overcrowding.
  4. Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction.

 If the system is then left to evolve on it's own given certain initial conditions highly complex patterns emerge that seem almost unthinkable with such simple rules. Here's an example.

This pattern was created by humans who worked out the initial conditions using computers. But think about what would happen if you took a huge grid containing millions of squares and kept populating them randomly while allowing the system to evolve for millions of years. Although the probability of such complex patterns forming on their own is pretty low, because of the huge timescales involved, complex patterns will inevitably develop. In fact I wouldn't be surprised if some apparently lifelike systems which replicate themselves evolved. Now if someone who had absolutely no idea of the starting conditions observed this complex system and tried to work backwards he would find find himself with an outrageously complex problem. Although this person may be able to work out how the little structures in the system function and replicate he would have little or no idea about how the system came about. 

Now think about the world as it was nearly 4.5 billion years ago when our planet was in its infancy. We had a big primordial "soup" of chemicals as the "initial conditions". The laws of physics and chemistry were the rules which our "system" which is the Earth and the primordial soup of chemicals followed. Considering the fact that the laws of physics are considerably more complex than the set of four rules for John Conway's Game of Life and that atoms and molecules have a substantially larger set of possible states that alive or dead is it not conceivable that after a about a billion years--the estimated time it took for the first life forms to appear-- by some lucky coincidence very simple prokaryotic life forms had developed?

Irreducible complexity is a concept that is very commonly used by Intelligent design proponents and creationists to justify the existence of an Intelligent Designer. They claim that in it's current state, life is too complex to have evolved by chance. This is another example of the inability of our brains to intuitively grasp extremely small probabilities. "Common sense" is often misleading when we look into the world of the very small. I think the Game of life provides an excellent example of how seemingly irreducibly complex systems can arise from some initial conditions and a set of rules. We may not have the computing power to reverse engineer evolution at present but I think the day will come soon enough.

The illusion of irreducible complexity in a bacterial flagellum. The complexity of the flagellum was shown to be reducible by  Zvonimir Dogic.

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