1 – IQ produces many incremental ‘goods’ (morality, cooperation, adaptation, invention, cost of learning)
2 – Neoteny/Pedomorphism/Juvenilization produces lower rate and depth of maturity, more aquiline features, longer development times, and greater ‘distance’ from impulses.
3 – The balance between the male brain and the female brain produces behavioral differences. Populations vary in this distribution of biases, just as they vary in the distribution of maturity. (Climate and disease gradients largely determine this.)
4 – Asymmetric reproduction (upward reproduction) improves these conditions, and symmetric reproduction does the reverse. Hence why cities are dysgenia-factories.
5 – ‘Something wonderful happened’ either before (black sea) or when we combined horse, wheel, and bronze. But it ‘appears’ that the black sea -caspian created a rapid recursively improving gene pool. Same with yellow river. Most but west and far east were also isolated.
6 – So the answer is that when the original people moved west into poland and germany, and developed a trading civilization among the north sea baltic peoples that they already possessed a genetic and possibly cultural advantage.
7 – The roman empire destroyed celtic civilization (as they did carthaginian and east mediterranean), which appears to have been the ‘core state’ of europe – and created opportunity for the high germanics to migrate, and eventually conquer rome.
8 – Now, nordic peoples practiced a form of late marriage and manorialism for a long time, possibly ‘always’. But by 700 the people of the low countries institutionalized it, and this formalized reproductive eugenics. Bipartite manorialism is demarcated by the Hajnal Line.
9 – Beginning with the redevelopment of major trade lines, about 1000, and certainly by the establishment of the Hansa in 1200, europeans started aggressively hanging ‘troublemakers’.
10 – downward movement of middle class reproduction meant that by the late medieval/early modern period much of european population above the Hajnal line was genetically middle class. Add literacy, and redistribute the dead capital in the church hands – and magic happened.
11- So it appears that the advantage is genetic and long standing, but is amplified substantially by (a) heroic culture, and (b) culling of the underclass through systemic eugenics, starvation, war, and disease.
12 – Ergo, the underclasses were not ‘oppressed’. They were domesticated like any other animal, and the untrainable one’s ‘removed from the breeding pool’. And we have reversed those IQ gains in just 150 years.