it means no such thing. All it means is a type of specific antigen is either present or not present on the surface of red blood cells, persons having inherited such antigens being designated Rh+ (Rh positive) and persons lacking them, a much smaller group, being designated Rh− . it comes from the fact that rhesus monkeys also have this antigen. So do many many other creatures.

it doesn't mean we evolved from monkeys any more than us having iron in red blood cells means we evolved from them. what it probably indicates in my opinion that somewhere along the way a genetic mutation occurred that was not so detrimental that it caused the mutant to be incapable of reproduction and survival, and the trait was passed on like blue eyes, big ears or male pattern baldness

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