Just because a population of people is high in rh negative blood doesn’t mean they necessarily descend from a population with equal or higher frequencies of rh negative blood. It could easily be, that they come from a group or groups of people with low rh negative frequencies, but that the rh negatives of that group were the ones who decided to pack their bags, look for a better life elsewhere and wound up forming a new tribe with a higher percentage of rh negative blood.
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