Q
Why do we have different blood types?
A
Expert Answer
ABO blood types evolved through genetic mutations, likely under selective pressure from diseases. Type O is oldest; A and B arose later. Some types offer disease resistance (type O may resist malaria; type A may be more susceptible to smallpox). The evolutionary advantages aren't fully clear.
Key Insight
ABO blood types evolved through genetic mutations, likely under selective pressure from diseases.
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