Cultural evolution and organic evolution are not exactly the same. Intelligent design, engineering and reverse engineering and multi-parental recombination are new phenomena, facilitating new evolutionary dynamics, much as I explained in A new Kind Of Evolution.
The relationship between organic, cultural and psychological evolution is that they are all instances of a more general Darwinian evolutionary process - based on copying with variation and selection. This idea has now been pointed out by Campbell, Cziko, Durham, Plotkin and many others. Many of the resulting differences in dynamics are due to differences in the information-storage substrates involved. For instance DNA tends to be a serial access medium which it is not easy to write to.
The reason for emphasizing the similarity between cultural and organic evolution here is because so many authors get the relationship wrong by failing to appreciate the depths of the parallels between them. The misunderstandings are numerous. We see them in the writings of Pinker, Gould and many others. I won't name more names here, but:
- Some think cultural evolution exhibits horizontal and oblique transmission, while organic evolution
is vertical. This is because they didn't properly consider organic parasites.
- Some think that cultural evolution exhibits foresight, while organic evolution is blind. This is often because they didn't properly consider the effect of brains on organic evolution - where mate choice and other effects have allowed intelligence to influence the course of evolution for hundreds of millions of years.
- Some think that cultural evolution is directional, while organic evolution is not. This is usually because they failed to appreciate the directionality of organic evolution.
- Some think that group selection works in the cultural realm - but not in the organic one. In fact kin selection applies about equally to both domains.
- Some think that cultural evolution is Lamarckian, while organic evolution is not. In reality the inheritance of acquired characteristics happens sometimes in both realms (as when a dog inherits its parents' fleas) - as does use-and-disuse (as seen with bulging muscles). However, in both realms, most inheritance is Weismannian - once you properly take within-brain evolution into account. Reverse-engineering of phenotypes does happen in the cultural realm - but is either pretty trivial (as with most imitation) or relatively rare. Also: remember that Darwin was cool with Lamarckian inheritance.
- Many express the sentiment that the human mind offers dynamics to cultural evolution that are lacking in the organic realm (deliberative selection, directed mutations, etc). They typically don't consider that the human mind itself works as an optimising system because it evolves along Darwinian lines.