The Flynn Effect

Book Review: Race, Evolution, and Behavior: A Life History Perspective by J. Philippe Rushton
Rushton has a plausible theory that some human populations are more k-selected than others. He presents lots of marginal-quality evidence, but that’s no substitute for what he should be able to show if his theory is true.
Much of the book is devoted to evidence about IQs and brain sizes, but he fails to provide much of an argument for his belief that k-selected humans ought to have higher intelligence. It’s easy to imagine that it might work that way. But I can come up with an alternative based on the sexual selection theory in Geoffrey Miller’s book The Mating Mind that seems about as plausible: r-selected humans have more of their reproductive fitness determined by success at competition for mates (as opposed to k-selected humans for whom child support has a higher contribution to reproductive fitness). Since The Mating Mind presents a strong argument that human intelligence evolved largely due to such competition for mates, it is easy to imagine that r-selected humans had stronger selection for the kind of social intelligence needed to compete for mates. Note that this theory suggests the intelligence of k-selected humans might be easier to measure via standardized tests than that of r-selected humans.
Rushton’s analysis of the genetic aspects of IQ makes the usual mistake of failing to do much to control for the effects of motivation on IQ scores (see pages 249-251 of Judith Rich Harris’s book The Nurture Assumption for evidence that this matters for Rushton’s goals).
He also devotes a good deal of space to evidence such as crime rates where it’s very hard to distinguish genetic from cultural differences, and there’s no reason to think he has succeeded in controlling for culture here.
Rushton mentions a number of other traits that are more directly connected to degree of k-selection and less likely to be culturally biased. It’s disappointing that he provides little evidence of the quality of the data he uses. The twinning data seem most interesting to me, as the high twin rates of the supposedly r-selected population follow quite clearly from his theory, it’s hard to come up with alternative theories that would explain such twinning rates, and the numbers he gives look surprisingly different from random noise. But Rushton says so little about these data that I can’t have much confidence that they come from representative samples of people. (He failed to detect problems with the widely used UN data on African AIDS rates, which have recently been shown to have been strongly biased by poor sampling methods, so it’s easy to imagine that he uses equally flawed data for more obscure differences). (Aside – the book’s index is poor enough that page 214, which is where he lists most of his references for the twinning data, is not listed under the entry for twins/twinning).
Rushton occasionally produces some interesting but irrelevant tidbits, such as that Darwin “affirmed human unity” by ending the debate over whether all humanity had a common origin, or that there’s evidence that “introverts are more punctual, absent less often, and stay longer at a job”.
Edward M. Miller has a theory that is similar to but slightly more convincing than Rushton’s in a paper titled Paternal Provisioning versus Mate Seeking in Human Populations.

Book Review: The Escape from Hunger and Premature Death, 1700-2100 by Robert Fogel

This book presents good arguments that hunger was a major cause of health problems everywhere a century ago, and that the effects last long enough that even the richest countries are still suffering from problems caused by hunger. His arguments imply that experts persistently underestimate improvements in life expectancy, and even with little improvement in medical technology life expectancy will improve a good deal because people born today have much better nutrition than today’s elderly had as children.

This goes a long way toward explaining the Flynn effect (even though the book doesn’t mention Flynn or IQ). It correctly implies the biggest intelligence increase should be seen at the low end of the IQ range, unlike a number of other interesting theories I’ve come across.

Another peculiar fact that the book helps to explain is the high frequency with which the tallest presidential candidate wins. Fogel’s arguments that height has been one of the best indicators of health/wealth suggest that this is not an arbitrary criterion (although it is probably a selfish I-want-to-ally-with-a-winner strategy that may be obsolete).

The book is mostly non-idealogical, but occasionally has some good political arguments (page 42):

government transfers were incapable of solving the problems of beggary
and homelessness during the eighteenth and much of the nineteenth centuries,
because the root cause of the problems was chronic malnutrition. … At
the end of the eighteenth century British agriculture, even when supplemented
by imports, was simply not productive enough to provide more than 80 percent
of the potential labor force with enough calories to sustain regular manual
labor.

(page 106):

Readers may be surprised that I have not emphasized the extension of health insurance policies to the 15 percent of the population not currently insured. The flap over insurance has more to do with taxation than with health services. … Most proposals for extending health insurance involve taxing their wages for services they already receive.

See also Mike Linksvayer’s comments.