Richard Lynn is back with more speculation about the origin of racial IQ differences. I will not dwell on his data, which should be taken with a heavy grain of salt. Rather, I will deal with his suggestions that racial IQ differences have something to do with cold winters during human evolution.
Lynn's speculations implicitly assume that IQ differences are of deep evolutionary origin. In other words, he assumes that Caucasoid-Mongoloid-Negroid aptitudes, as well as subracial cognitive distinctions (e.g., between Northcentral Europeans and Southeastern Europeans and Arctic vs. Far Eastern Mongoloids) date to the prehistoric period and accompanied racial differentiation.
Of course, this assumption is entirely unfounded. Indeed, increasingly, we are realizing that recent human evolutionary change, in post-Neolithic times was rapid, and the characteristics of populations were not already fixed (as the evolutionary psychologists hold) at the onset of the Neolithic, when racial differentiation was already in place.
But, the real problem is that there are only about 100 years of IQ data for some human populations and data of good quality (e.g., measured with culture-fair instruments) are at most 1-2 generations old. At the same time, it has been amply demonstrated that human IQ has been rising rapidly in several human populations even over the short time span for which IQ data exist, the so-called Flynn effect.
We thus know that (a) IQ is volatile, and can change rapidly, and (b) we have data that spans only perhaps 2% of human history.
The combination of these two factors renders any extrapolations from recent IQ data into the Stone Age or even a few centuries ago entirely unusable and untrustworthy. A good analogy would be someone's attempt to estimate the price of the IBM stock in 1935 by taking into account its value in the last year.
Richard Lynn must be commended for collecting and compiling such a volume of IQ data, but it's time to move beyond an early-20th century statistical understanding of human cognitive differences based on the reification of g and tackle the really hard problems of (a) figuring out whether individual racial ancestry predicts IQ, and (b) identifying some of the genes contributing to intelligence.
As I explain here, I see little hope of (b) occurring to any significant degree any time soon, but determining the racial (ancestral) contribution to IQ is wholly feasible. Let's hope that the race/IQ enthusiasts take up the challenge.