Hail Richerson & Boyd

In the last two days I read Richerson & Boyd (2004) Not By Genes Alone: How Culture Transformed Human Evolution, by two of the founders of modern cultural evolution theory. It is very good. (I’ve also been reading their classic 1985 book Culture and the Evolutionary Process.) Several datums worth noting:

Popular preteen girls of the working or lower middle class are usually the most important leaders of language evolution in American cities. …

In one study… subjects were asked their opinions on "student activism" in one of three scenarios: after hearing the opinion of somebody identified as an expert on the topic, after hearing the opinion of an expert on the Ming dynasty, and after a control condition in which they didn't hear anybody's opinion. Subjects tended to voice opinions similar to either of the two experts, and they were equally likely to adopt the opinions of experts on activism and the Ming dynasty. …

Results from several independent studies suggest that cultural transmission within the family is not very important.

They also say that maladaptive cultural evolution is behind our fertility fall: 

The evolutionary potential of culture makes possible unprecedented adaptations like our modern complex societies based on cooperation with unrelated related people, and some almost equally spectacular maladaptations, such as the collapse of fertility in these same modern societies. …

[Cultural] selective processes can often favor quite different behaviors from those favored by selection on genes. For example, beliefs and values that lead to prestige and economic success in modern societies may also reduce fertility. Such beliefs spread because the prestigious are more likely to be imitated, even though this lowers genetic fitness. …

Prestige bias can lead to an unstable, runaway process much like the one that may give rise to exaggerated characters such as peacock tails. … 

The demographic transition is at least partly caused by the increased nonparental cultural transmission associated with modernization. Modern economies require educated managers, politicians, and other kinds of professionals who typically earn high wages and achieve high status. Accordingly, competition for such roles is fierce. People who delay marriage and child rearing in order to invest time and energy in education and career advancement have an advantage in this competition. High-status people have a disproportionate influence in cultural transmission, so beliefs and values that lead to success in the professional sector will tend to spread. Because these beliefs will typically lead to lower fertility, family size will drop. …

Amish and the Hutterites … these subcultures are the exceptions that prove the rule. Despite substantial wealth, people in these societies have not gone through the demographic transition, because Anabaptist baptist customs block those same features of cultural evolution that make almost all modern societies susceptible to it.

Last fall I posted on my theory that, when parents have wealth they can invest in their kid status, a habit of copying what high status folks do reinforces the selection effect that having fewer kids makes them higher status. Richerson & Boyd’s story of prestige bias due to longer career prep makes more sense of our world today, while my story of a prestige bias among elites due to investing wealth in kids made more sense centuries ago. But plausibly this new bias was made more likely by the older one.  

Richerson & Boyd don’t seem at all interested in the future consequences of this fertility fall and its Anabaptist exceptions, or in the deeper causes if why it is being allowed to persist for so long. I try to address deeper causes in Beware Cultural Drift.