The group-intelligence controversy revisited
The discussion is basically a dialogue of the deaf, with opinions splitting along familiar right-left lines. One left-leaning commentator insists that we are all members of the human race. Yes, indeed, but that does not mean that there are not aggregate differences among population groups. In a series of studies, Luigi Luca Cavalli-Sforza has shown that, based on mitochondrial and other DNA evidence, there are significant differences among population groups or pools. In this way, he has been able to construct evolutionary trees, showing how these differences arose and were confirmed.
Another common argument among the left-leaning faction is that one can measure individual intelligence but never group intelligence--between blacks and whites, women and men, and so forth. Well, if we can study differences in height and eye color on a group basis, why not do the same for intelligence? This taboo seems political, with no discernible objective basis.
Left-leaning observers often complain, with much justice, that conservatives who deny evolution and climate change are anti-science. In this matter of group intelligence, though, it is the left-leaning people who are anti-science. Both groups seem to adhere to a cafeteria approach to scientific evidence.
I confess that I have doubts about reducing the question of intelligence to g (or general intelligence). There are other aspects of intelligence, such as can-do knowledge and sensitivity to the needs of other people, that are not included under this rubric. Still, no one has been able to work out an acceptable pluralistic theory of intelligence(s) that would include all the significant variables.