what evolutionary advantage do we humans have with different blood types?

Question

such as type A, B, O, or AB?? why dont we just all have the same blood type?

Answer 1

This is actually one of the best known cases of something called polymorphism.

Polymorphisms can occur either because neither type has a distinct advantage or disadvantage, or when there is some advantage to variety, rather than one type or the other taking over. For example, if two blood antigens A and B confer immunity to different diseases, then something interesting happens. Diseases that attack people with the A antigen and not B, will flourish as long as there are a lot of people with blood type A. This causes an epidemic among people with A, and reduces their population of A's and increases the percentage of B's. But now that the A's are more rare, they are less succeptible to a widespread epidemic, and the next epidemic is likely to strike people with antigen B. In this way, the presence of both antigens (both blood types) makes the overall population better suited to survive an epidemic than if we all had the same antigens (same blood types).

What's interesting is that the very same ABO polymorphism (the same antigens) are also present in chimpanzees (but not as much in other primates). This indicates not only an evolutionary relationship ... a split from the branch that ended up becoming modern chimpanzees *after* this ABO polymorphism developed ... but it also shows how stable a polymorphism can be even across a split between species.

Answer 2

The blood group antigens are not there to stop or help us get compatible blood in case of need. Blood groups are proteins coating the red blood cells and other cells, which have various functions. They are indeed polymorphisms, s another answer suggested. It is well known that different blood groups offer varying defence against malaria, so this explains their prevalence in some populations and decreased percentage in others. The same with various epidemics. For instance, if an influenza epidemic were to strike, and Group AB were more resistant, due to particular proteins coating blood cells, then the percentage of AB groups would increase rapidly, and remain high in future generations for some time.

Answer 3

I'm not sure, I think O is the universal blood type meaning they can donate blood to any of the other blood types, but im not sure if its the other way around. ill ask my mother later an answer more, she is a med tech at a hospital.

Answer 4

not really sure, it is part of evolution, but type O is universal which means it can be given to other types. they just represent what type of molecules are on the blood cells.