Uriah

It can be true that much of the variation in IQ *within* populations is due to genetic differences, without such differences explaining diffs in mean IQ *between* populations

Indeed, all the available evidence supports idea that most diffs in IQ between diff populations (or in same pop'n over time) are due to environmental/cultural factors (nutrition, healthcare, education, habits of abstract thought)

IQ is under such strong stabilising selection and involves such a dynamic spectrum of genetic variants that it would require huge, sustained selective forces to have driven real group diffs