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ABO and Rh distribution by country

As with many other genetic traits, the distribution of ABO and Rh blood groups varies significantly between populations. While theories are still debated in the scientific community as to why blood types vary geographically and why they emerged in the first place, evidence suggests that the evolution of blood types may be driven by genetic selection for those types whose antigens confer resistance to particular diseases in certain regions – such as the prevalence of blood type O in malaria-endemic countries where individuals of blood type O exhibit the highest rates of survival.