Chinese Rice Farms and "Culture"

Do rice farms select for collectivism?

An article in Nature titled People quasi-randomly assigned to farm rice are more collectivistic than people assigned to farm wheat was recently brought to my attention.

Here is the abstract:

The rice theory of culture argues that the high labor demands and interdependent irrigation networks of paddy rice farming makes cultures more collectivistic than wheat-farming cultures. Despite prior evidence, proving causality is difficult because people are not randomly assigned to farm rice. In this study, we take advantage of a unique time when the Chinese government quasi-randomly assigned people to farm rice or wheat in two state farms that are otherwise nearly identical. The rice farmers show less individualism, more loyalty/nepotism toward a friend over a stranger, and more relational thought style. These results rule out confounds in tests of the rice theory, such as temperature, latitude, and historical events. The differences suggest rice-wheat cultural differences can form in a single generation.

Nature is so “prestigious” and “scientific”, so why can’t we say “phenotype” instead of “culture”? Which “culture” are they talking about anyway? It’s not a word fit for science, because there are too many vague definitions. It’s basically the “phlogiston” of human behavioral science. More than that, our current obsession with “culture” is clearly politically motivated from the left. 100 years ago, Ronald Fisher could have given you the interpretation of the article I’m about to give you. But in the 1970s, Marxists invaded the human behavioral sciences, so now we have to talk about “culture.”

Long story short (very Chinese immigrant sounding phrase by the way), the authors use “culture” to mean phenotype and aren’t too obnoxious about interpreting this environmentally — it’s like they were waiting for someone like me to come along and give the real interpretation, but they had to get past the Nature censors.

The farming assignment happened a long time ago, so their participants are actually descendants of assignees.

This means the effect sizes they find can be explained by Darwinian selection.

The r values are reported as .18, .18, and .15 for self-inflation, loyalty/nepotism, and holistic thought. Since this should be the correlation between the standardized farming dummy variable and the standardized psychometric score, we need to multiply by the standard deviation of the farming dummy variable to get the d (standardized difference) between rice farmers and wheat farmers. The methods say that half the sample was wheat farmers, so the standard deviation is 1/2. Thus, we get d scores of .09, .09, and .075.

The breeder’s equation can be written as above. It gives the change in a population trait mean due to natural selection. h^2 is the heritability of the trait, r is the correlation between the trait and fertility, sigma_f is the standard deviation of fertility, and mu_f is the mean fertility.

We don’t know sigma_f/mu_f, but 1 is a fair approximation — it was possibly higher, but it’s around 1 today, down from the past. If we take the heritability as 50%, we get that the correlation between the traits and fertility should be .18, .18, and .15 higher on rice farms than on wheat farms. This is near the correlation between politics, IQ, and fertility today, so these are very plausible numbers.

This kind of analysis should be in the article, but it’s not, because of politics. Also because of politics, the math and knowledge used to perform this analysis is not widely known among human behavior scientists. It’s very sad! Many operate off of the flawed heuristic that effect sizes like these are “implausible” in 1 generation if the cause is biological evolution. That is objectively, mathematically incorrect! If you take anything away from this article, let it be the wrongness of that heuristic.