I'm sorry, I don't understand this sentence.
>From what I understand of what I've read, the only blood type originally ... in humans ... was type O. Then, gradually, due to changing ecological and climate conditions, new blood types evolved through mutation and inter-breeding.
But there is no archeological evidence for this. It is an old hypothesis -- but not established by ancient evidence, since there isn't ANY ancient evidence regarding blood types at all.
>So, I don't see the relevance or applicability of chimpanzee studies to human studies.
It is critical. See, a random mutation that causes an identical change in two separate species is highly improbable. But it can happen...rarely...probably. But two separate random mutations in three separate species, where the mutations in two of the species just happen to produce a result identical to that in the 3rd? Sorry -- the probablility is very low. Not impossible, just low. BUT! If one then discovers that all three species had a common ancestor, then suddenly the issue goes away if one asserts that the common ancestor had the different mutations and the decendent species inherited them.
Therefore, the theory of evolution backs the hypothesis that blood types A and B were present in the ancestral species of human, chimpanzees, and gorillas -- and that is why the decendent species have those blood types in varying amounts.
>The stressors that cause blood type mutation in humans were due to region, weather, and diet. Type A evolved to deal with agriculture; type B to deal with dairy. Type AB came about as the result of interbreeding between A and B.
This is just handwaving. You have provided no evidence as to what the cause the mutation would be, why it would be beneficial, etc. As far as I know, there is no evidence. What features of type A would provide benefits to agriculturalists? What benefits of B to herding?
>O hasn't changed at all.
Maybe, maybe not. It follows from your original assertion -- but where's the evidence?
See - you seem to be approaching this from a dietary perspective, and pointing out that different blood types benefit from dietary differences? This may or may not be true -- since there are OTHER genetic factors in populations that have a preponderance of particular blood types that may in fact be the important factors vis-a-vis diet, and not the blood type. Correlation, not causation, you see. But even IF the dietary hypothesis had validity -- it is not evidence for historical evolution of blood types.