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Not really arguing anything. I'm asking if there is a rational non-meta reason to believe they do "stop at the neck" even if we throw away all the IQ/nations data.
Thanks for the reason I've missed. Are personal traits as important?
Of course there are. The standard argument is that the history of human evolution suggests that increased intelligence and favorable personality traits were strongly selected for, and traits which are strongly selected tend to reach fixation rather quickly.