Question

Why do humans have different types of blood group? Like some have O+,B+,B-,AB+,etc

Answer 1

The types of proteins, glycoproteins and glycolipids found (or expressed) on the surface of red blood cells define blood types. In addition, blood types, or at least the genes responsible for them, are inherited. Karl Landsteiner described the original blood types A, B and O in 1900 and doctors now recognize 23 blood group systems with hundreds of different "types." Many of the blood type antigens (and the antibodies that react with them) have been discovered as a result of transfusion incompatibilities. Some of these molecules have additional functions that are at least as important .