Comments by "1" (@user-yt3xd2jl6d) on "What is the Origin and Reason for Blond Hair?" video.
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The EEF and the ANE already had alleles related to blonde hair, but they were not very blonde, the same happens with Yamnaya, it was not until men from the Pontic steppe mixed with EEF populations, from the Funnelbeaker and Globular Amphora culture, giving rise to the Corded Ware culture that the Blonde phenotype became dominant. When the blonde hair alleles are at frequencies less than 50%, then the phenotype is rare, it is when the phenotype is exceeded 50% that the phenotype becomes common. Funnelbeaker had high frequencies but not high enough, apparently the Men of the Steppes selected blonde-haired women, the only culture that passed through this selection was Corded Ware, then Corded Ware spread throughout Northern Europe, carrying the phenotype.
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