Will Wright’s demo of Spore illustrates some key concepts of complex systems, including the notion of simple rules generating complex behaviors, and also the power of recursively applied (i.e. fractal) computation at different levels. Living systems leverage these same principles.
One of the baffling aspects of living systems is the relationship of the (relatively small) genome to the seemingly infinite variation and complexity that we witness within and between species. The idea that we share 99% or so of our DNA with mice means that our differences must somehow be accounted for in the remaining 1% (roughly 7 megabytes of information).
The key insight needed to make sense of this mystery involves the aforementioned principles evidenced in the Spore universe, but it also requires the notion of real world as encoding device. By this I mean that the genome itself is not a complete, self-contained piece of code with all that is required to generate (for instance) an adult human. Rather, implicit in the genetic code is a model of the real-world environment that the code will operate in once activated (i.e. “expressed”), and this implicit model is absolutely crucial for life to have originated and continue to thrive. Imagine, for instance, if all of a sudden the laws of chemistry were altered and carbon could only form 2 bonds. Life as we know it would cease to exist; our DNA (and all DNA for that matter) relies implicitly and thoroughly on existing features of the world. And thus our DNA does not need to explicitly encode how to fold proteins since protein-folding is an automatic reaction given the structure and environment of the particular protein molecule.
This implicit encoding or reliance of the genetic code on its environment has been likened to scaffolding that is used in construction (genes being the blueprint of course). But the scaffolding analogy doesn’t do justice to the immensity of information (both in absolute terms and as a percentage of the total) that is implicitly encoded by the environment for use by the genome. Not that this is some giant happy coincidence mind you; the genome evolved in a world where physical and chemical principles pre-existed. And as lifeforms increased in complexity, each new level of organization was a pre-existing condition to be relied upon for the evolution/emergence of the next.
It is worth pointing out that by “genetic environment” I don’t just mean the environment that the whole organism finds itself in, but rather the extended and recursive environment that the genetic code will find itself in as it does its work. This includes increasing levels of complexity that are generated by, or on top of the DNA level: chromosomes, epigenetic markers, proteome, cellular structures, multicellular structures, and on up. One level begets the next, and your genetic code expects these levels to emerge in due course or it won’t function properly (or at all). Consider, for example, how useless the part of your DNA that describes brain structure would be if it were not for the encoding of how to make neurons and axons.
By grasping the significance of the extended, recursive genetic environment (ERGE?) it becomes more clear why genetic fatalism is misguided and why the nature/nurture debate misses a large portion of the action. By intervening in the expression of the genome through the ERGE to the mature human animal — for example, via early intervention in childhood — genetic “predispositions” become largely irrelevant in practice. By the same token, there’s no such thing as a purely natural or purely environmental effect: it all a matter of controlling the ERGE.