The researchers need to make clear that even if these SNPs have undergone selection, they do not necessarily imply intercontinental differences in phenotype or behavior. The same selective pressure may have applied to different SNPs in different populations while still yielding the same net result.
An obvious example is lactase persistence. Although Eurasian lactase persistence arose from a single individual, Arabs and East Africans developed their own genetic lactase persistence from independent origins.
The same appears to be true of red hair. Many genetic origins, same net result.
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