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Essays about Complex Systems, Adaptation, and Evolution, inspired by the book Complexity by M. Mitchell Waldrop

This sub-series of essays is a response to Complexity Chapter 8 Waiting For Carnot > The Growth of Complexity, starting on page 294.

1. Why does evolution seem to trend in the direction of greater complexity?
2. Does evolution have any direction? Where is it going? What will it lead to?
3. Complicated systems are not inherently better than simple ones.
4. What does "survival of the fittest" mean? What is evolutionary fitness?

Why does evolution seem to trend in the direction of greater complexity? Answer: probability.

On page 294 of Complexity is discussed the notion of a possible "new" law of evolution that should address:

"... the deceptively simple fact that evolution is constantly coming up with things that are more complicated, more sophisticated, more structured than the ones that came before. ... Learning and evolution move agents... in the direction of greater and greater complexity. Why?"

No new law is required to explain this phenomenon.

The apparent trend towards increased complexity in evolving systems is due merely to probability. It is extremely improbable that fully formed large complex structures with the capacity to survive well in an environment will arise spontaneously.

Evolving systems are built from the bottom up by the gradual accretion of parts, structures, functional subunits, that are able to survive well when they combine.

From the smallest starting building blocks, simple structures are easy to build and can occur by accident, so they appear first.

Once there are small structures that can act as first-level units, those can subsequently combine into slightly larger structures, and so on through successive levels.

More complex structures appear later than simpler ones not because nature provides an impetus in that direction, nor because they are better, nor because they are fitter. It is only because at the beginning of the process, early on, they are not possible to build. 

The natural law at work is probability. When only small building blocks are available, it is highly probable that they will combine in pairs and highly improbable that they will coalesce into large complex structures without going through the process of building the intermediate stages. 

The next page has a computer program that shows an apparent growth of complexity in "evolving strings". It starts with a population of simple units and allows them to increase or decrease in length randomly. However, since they are already starting at the lowest possible limit of complexity, their random walk can only explore new lengths in the upward direction, which creates what appears to be a trend toward greater complexity because all the newer lengths are longer than the old ones.