Books I Liked

Chimpanzee Politics by Frans de Waal

is based on a close study, over a period of years, of a chimp colony. The chimps come across as more like dumb people than smart animals. My favorite anecdote:

While the chimps were in their indoor habitat, the experimenters buried some grapefruit in a patch of sand in their outdoor habitat. The chimps saw the experimenters go by with the grapefruit, so knew something was up.

When released outdoors, they made an apparently unsuccessful search for the grapefruit. Then it was naptime. When the rest of the chimps were asleep, one of the low status males got up, went straight to the buried graperfruit, dug them up and ate them. To me, at least, that is striking evidence not only of rational behavior but of rational thought behind the behavior.

The other interesting observation was reflected in the title. The dominant male was not always the biggest or strongest; the political struggle that determined dominance involved an elaborate pattern of shifting alliances.

The Nurture Assumption by Judith Harris:

The author argues that while children are shaped by both genetics and environment, the relevant environment for most of them is not the home but the peer group. By her account, none of the popular stories about birth order, child rearing practices, and the like as determinants of adult personality are supported by the evidence. Human beings are good at recognizing that different rules apply in different environments. The typical child can and does show one face to his parents, a different one to his peers; it is the peer group version that grows into the adult personality. One important implication is that, to influence the adult personality of your child, you should pay attention to his peer group, may want to control, insofar as you can, what it is.

Harris qualifies her claim by observing that, for some children, the family is the peer group. She gives as an example the case of a black worker with four daughters who decided that they were all going to be doctors and ended up with one doctor and three other professionals. The way he did it was by making the family the set of people with whom his daughters chiefly interacted, and with whose values they identified. That may also help explain the Polgar sisters, three girls who all ended up as chess grandmasters, one of them, Judit, the strongest female player in history, the only female chess player who was competitive with the very best male players.

I think that describes my upbringing as well. I was very much an outsider in school, seeing my family as real people and my age peers as at least mildly alien. I gather from correspondence with Judith Harris that it may have been true of her as well.

Which suggests an important point about home schooling, that it is, among other things, a way of making it more likely that your children’s parents, siblings, and a few friends will function as the effective peer group. Seen from one standpoint, that means parents trying to control their children, mold them in their own image. Seen from the other side, the choice is between the parents’ values and the values of a random collection of kids–and most parents know which they prefer.

If Harris is right — and I think it likely that she is — that raises an interesting question about the history of psychology. How could beliefs about things such as the influence of birth order and child rearing be widely held within a scientific community when there was no evidence they were true?

Part of the answer is the confusion between genetic and environmental causation. Someone confident that personality depends only on environment will interpret similarities between parent and child as due to the affect of the environment provided by the parent. To distinguish between the two alternatives you need to look at children reared by people other than their biological parents. When you do so, it turns out that the observed similarities are in large part due to genetics.

Another part of the answer has to do with the nature of statistical evidence. Suppose you believe that birth order affects personality. You get personality evidence on a bunch of people, test for correlations between personality and birth order, and find one: First born daughters are more self-confident than second and third born. You come up with a plausible explanation — the eldest child has had the experience of bossing her younger siblings around — and publish. The correlation is confirmed at the .05 level, meaning that there is no more than one chance in twenty that it could occur by chance. Another believer in the importance of birth order does a similar study. He finds no effect for first born daughters but discovers that last born sons are more optimistic than first born. He too comes up with a plausible explanation and publishes.

The process continues for many years. Occasionally someone is unable to find a correlation and, since failure is rarely interesting, abandons that project in favor of something more likely to get published. Looking at the literature, it is obvious that birth order affects personality — practically everyone agrees about that — even if the details are a matter of dispute.

Only when it occurs to someone to combine the results from many studies does it become clear what is happening. With considerably more than twenty possible relations between birth order and personality, pure chance will usually result in a significant correlation for one of them, a different one each time. Pool the data and the result vanishes.

The origin of Harris’s book makes an interesting story. It started as an article published in The Psychological Review. The article provoked a lot of mail, partly about the controversial argument, partly asking who the author was, since nobody in the field had ever heard of her.

Judith Harris had gotten a masters in psychology from Harvard and been discouraged from going further by a professor who assured her that she did not have the makings of a successful scholar. She left academia, married, helped support her family by coauthoring child development textbooks. Eventually she concluded that a good deal of what those textbooks said was not supported by the evidence. The result was the article, which received the journal’s prize for the year’s best.

The prize is named after the Harvard professor who told her that she had no future as an academic. God, Judith Harris concluded, has a sense of humor.

The Selfish Gene

A long time ago I wrote a price theory textbook and gave a copy to my favorite aunt, who I am sure never read it. She gave it to her son who gave it to his daughter who gave it to her fiancée who, I was told, entertained the family at breakfast with readings from it. That convinced me to try rewriting the textbook as a book for people who would like to learn economics for the fun of it.

My model was The Selfish Gene, the book from which I learned evolutionary biology for the fun of it.

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