Cochran's popular science book has no scientific backing or support from working scientists and peer reviewed articles. In particular, human genomics can easily refute the idea of brain functional changes in the last 10K years. Our ancestral populations that colonized EurAsia, Africa, and the Americas diverged before the 10,000 mark, and there are no discernible cognitive differences between any of these groups.
Furthermore, this is why Cochran is considered a racist; correctly so.