Wednesday, January 18, 2006

Update 3   posted by DavidB @ 1/18/2006 07:27:00 AM

From time to time I look through my old posts to see if any of them are still worth reading. The last update was in April 2005 here.

Since then I haven't posted very often, but a few items may still be of interest.

[Added: I find that for some reason the more recent archive links don't work. I suggest that if you are interested in the topic you use the search engine on the sidebar.]

[Added later: Razib has fixed a glitch, and the links should all work now. But in some posts you may find some odd symbols. These are probably meant to be apostrophes or quotation marks. Apparently when text is cut-and-pasted from a WP program into another system these symbols may not be properly recognised.]

The most substantial items were two long posts on Measuring Genetic Diversity, here and here. Many writers on population genetics make claims about the extent of genetic diversity within or between populations (for example, Lewontin's famous claim that 85% of human diversity occurs within each racial group), but they seldom explain how diversity is measured, or discuss any problems of interpretation. My posts attempt to provide a guide to the main measures of diversity, and point out some of their strengths and weaknesses. One important point to note is that the most commonly used measures (Wright's FST and Nei's GST) treat 'between group' diversity as a residual after 'within group' diversity is subtracted from a total which cannot exceed 100%. This means that 'between group' diversity is bound to be low if 'within group' diversity is high, even if in fact the groups are extremely different from each other.

Two posts were concerned with recent game-theoretical research on 'altruistic punishment'. Punishment 'for the good of the community' is an important human social institution, but it isn't clear why anyone should take the trouble to punish others if the cost or risk exceeds the individual benefit to the punisher. In the jargon, such punishment is 'altruistic', though presumably it doesn't seem that way to the punishee. The posts are here and here. The second post takes a sceptical view of recent trends in evolutionary game theory, which in my view often start from false assumptions about what primitive societies are like. The post incorporates my own interpretation of the key features of hunter-gatherer societies, with references to the anthropological literature. In one of the posts I also remarked that explanations by means of group selection should be a last resort. As this point was questioned in some comments, I expanded on it here.

In comments on the subject of Intelligent Design someone used the tired old argument that the theory of natural selection is tautologous. Here I give seven reasons for maintaining that the theory involves empirical matters of fact, and is therefore not tautologous.

An alert reader of an old post of mine on kin selection pointed out an error, which I have corrected here.

Several posts were concerned with sociological issues that happened to catch my eye. Two posts, here and here, are concerned with social mobility. One post is about trends in the birth rate. Two posts, here and here, are about whether geographical segregation of ethnic groups in the UK is increasing or declining, which turns out to be quite a complex question.

One post, on Medieval Jewish Achievement, is my small contribution to the debate on the causes of the high level of Ashkenazi Jewish IQ. It is commonly supposed, on rather weak evidence, that Ashkenazi IQ is higher than that of other Jewish groups, lumped together inaccurately as 'Sephardim' (a term which should properly be confined to Jews of Spanish and Portuguese descent). My post points out that in the Middle Ages, and down to the 17th century, the Sephardic Jews showed great intellectual distinction, and were socially superior to the Ashkenazim.

A post on the Flynn Effect aims to establish whether James Flynn, or someone else, deserves the main credit for discovering the long-term rising trend of IQ scores in most developed countries. My conclusion is that other psychologists, such as Phillip Vernon, had from time to time remarked on the rising trend, but that Flynn does indeed deserve the main credit, as originally stated by Murray and Herrnstein when they proposed to designate the trend as the Flynn Effect.

A post on Genetics in the Movies is just a bit of fluff, but may give some harmless amusement.

A post in August on Interracial Marriage discussed reasons for and against interracial marriage (or other mating). I concluded that there are theoretical arguments on both sides, but little empirical evidence that it is important either way. I did however express caution against any large and sudden change in the gene pool, as the effects are unpredictable and would be difficult to reverse. In passing I also wondered whether the distinctive achievements of different civilisations had anything to do with distinctive combinations of genes. A later post on Genes and Civilisation considered this further, from a generally sceptical point of view. I promised a further post to look at the issue with particular reference to the history of European and Chinese science. This was rather rash, as I soon realised that I didn't know enough about Chinese science to comment on it. Since then I have tried to remedy my ignorance, by readings in Joseph Needham, G. E. R. Lloyd and others, but I can't say if I will ever get round to the promised post.