associated for example with texture and pigmentation patterns—in the end have almost nothing to do with natural selection.

And instead what I believe is that such differences are in essence just reflections of completely random changes in underlying genetic programs, with no systematic effects from natural selection.

Particularly among closely related species of organisms there is certainly quite a contrast between the dramatic differences often seen in features such as pigmentation patterns and the amazing constancy of other features. And most likely those features in which a great degree of constancy is seen are precisely the ones that have successfully been molded by natural selection.

But as I mentioned earlier, it is almost always those features which change most rapidly between species that show the most obvious signs of complexity. And this observation fits precisely with the idea that complexity is easy to get by randomly sampling simple programs, but is hard for natural selection to handle in any kind of systematic way.

So in the end, therefore, what I conclude is that many of the most obvious features of complexity in biological organisms arise in a sense not because of natural selection, but rather in spite of it.

No doubt it will for many people be difficult to abandon the idea that natural selection is somehow crucial to the presence of complexity in biological organisms. For traditional intuition makes one think that to get the level of complexity that one sees in biological systems must require great effort—and the long and ponderous course of evolution revealed in the fossil record seems like just the kind of process that should be involved.

But the point is that what I have discovered in this book shows that in fact if one just chooses programs at random, then it is easy to get behavior of great complexity. And it is this that I believe lies at the heart of most of the complexity that we see in nature, both in biological and non-biological systems.

Whenever natural selection is an important determining factor, I suspect that one will inevitably see many of the same simplifying features as in systems created through engineering. And only when natural selection is not crucial, therefore, will biological systems be

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From Stephen Wolfram: A New Kind of Science [citation]