Some points I gleaned from the comments of yesterday’s post:

1. Cultural evolution can happen in cases where a super-innovation allows one culture to conquer or overwhelm all others. For example, agricultural groups were (after a long transition period) eventually able to overwhelm hunter-gatherer groups, even thought for an individual hunting-gathering was probably more enjoyable than agriculture. Likewise, industrialized societies were pretty quickly able to outcompete nonindustrialized societies, and either colonized them or forced them to industrialize in turn to keep up. Both of these seem like clear-cut examples of cultural evolution. But they only work because of a really big fitness advantage; industrial societies are on a whole other level from preindustrialized ones. It doesn’t necessarily generalize to saying that small, moderately beneficial ideas will catch on, or slightly detrimental ones be selected against.

2. Cultural evolution can happen when one group in a society outbreeds another. The Amish population has increased twenty times faster than the non-Amish American population in the past century. At a constant growth rate, it’ll be only another four hundred years or so before America is an Amish-majority nation. More seriously, some people expect something like this to happen with high-fertility-rate immigrant populations, like Latinos and Muslims. In cases of strong differential fertility rates, cultural evolution becomes a race to see if the faster-growing minority can reproduce faster than the majority can assimilate them. However, despite dire predictions of all of us being crushed under the Amish’s quaint hand-made boots, people had trouble thinking of historical examples of something like this happening. Sure, populations have replaced other populations – like the Anglo-Saxons replacing the Celts in England – but it’s tended to occur alongside military invasions.

3. Cultural evolution can happen with units smaller than Rome-sized grand civilizations. Several people brought up subcultures, like hipsters and Goths, and noted that these have “generations” on the order of a few decades, and thus could potentially undergo evolution conforming to population genetic equations in a reasonable amount of time. Because they’re larger units than just a single person, their “evolution” could select for things that bind people together, like rituals and cohesion-building symbology and so on, and be more interesting than just individual memetics. They could also spread very quickly as people rush to join the attractive ones. Okay. But subcultures like Goths seem like a very modern phenomenon, and I can’t think of ancient examples of, for example, a subculture that became popular and spread and became dominant/universal. Religions are the closest thing here, but they have lifespans measured in centuries and don’t seem to be a big improvement over waiting for the Fall of Rome.

4. Cultural evolution can occur by an accretion of things that work. For example, the first rituals might have been impromptu celebrations of specific events, but because they helped people bond, people kept doing them. But this seems to require some human intelligence to notice “Hey, we seem to be bonding better ever since we implemented that ritual, let’s keep doing it”. Without that, it collapses back to the sort of intercultural evolution where the culture is 1% better and after thousands of cultural generations lasting millennia each it outcompetes others. That makes it unsatisfying for people who want to use cultural evolution as a grounding for Chesterton’s Fence, ie “we don’t know why we do this, but we ought to keep on doing it.”

5. Cultural evolution could have occurred way way back in prehistory. There seem to be about 50,000 years of prehistory, there were many more cultures back then, and maybe cultural generations were shorter – for all anybody knows, clans could have disintegrated and reformed over the space of decades. That provides enough generation time for cultural evolution to work. Question is, can we trust anything that evolved in pre-history – when the pressing social issues of the day were things like “How do we not get eaten by bears?” – to still be relevant?

There does seem to be the potential for cultural evolution to be interesting, but I’m still not seeing it as a strong argument for preserving particular features of inherited culture absent other arguments suggesting we know why we want those things to be preserved.

[Edit: An alternative ontology]