On the rate of cultural evolution

One of the myths about cultural evolution is to do with its speed. It is often claimed that cultural evolution is faster than biological [sic] evolution. This claim may - or may not be correct. However, almost all of the proponents of the idea are using very bad accounting techniques to prove their claims.

A good example comes from a recent paper by Charles Perreault titled: The Pace of Cultural Evolution.

This compares rates of cultural evolution and biological [sic] evolution - and finds that cultural evolution is faster. However, the article makes two very wrong assumptions:

It compares cultural evolution with evolution rates in wild animals. Animal populations have much longer generation times than some biological systems - sich as bacteria and viruses. Memes are a lot like bacteria and viruses in that they reproduce rapidly and can spread from host to host. Wild animals are not an appropriate point of comparison for memes - their lifespans are too long.

Charles Perreault anticipates this objection - to some extent - by going on to argue that the effect is independent of generation times. However for cultural evolution he compares to the generation time of the host humans, writing:

the amount of cultural change observed per generation time (20 years) is significantly faster than what we would expect from biological evolution for a species with the same generation time as humans

Well, duh. Cultural change is the result of rapidly-reproducing memes, not slowly-reproducing humans. Mixing these two up is a fundamental mistake. The generation time in cultural evolution is the time for meme reproduction. The generation time in organic evolution is the time taken for gene reproduction in germ-line cells. Neither is 20 years - even in humans - unless you are confining your attention to sexual reproduction.

Meme reproduction rates can be very rapid - especially when you take intracrainial memetics into account. Since much meme reproduction occurs inside minds, large numbers of variations can be explored in a short period of time.

I'm afraid I think that the kind of analysis in this paper is completely hopeless - since it is based on a faulty understanding of the nature of cultural evolution.

Looking at the skyscrapers, microchips and space travel that have arisen in a remarkably short space of time as a result of cultural evolution, there may be something to the case that it is - in some sense - faster than DNA-based evolution. However, dud accounting doesn't help make the case for this, it just piles confusion onto the issue.

Update 2013-11-23: Charles Perreault now has a 2013 video titled: "The pace of cultural evolution".