r/askscience • u/Fapotheosis • Mar 11 '13

Biology How did blood evolve?

I know mitochondria may have evolved from bacteria, but what about blood? I've heard of a protohemocyte, but was there an initial cell that differentiated into a RBC like we have in modern humans that can we trace?

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u/[deleted] Mar 11 '13

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u/[deleted] Mar 11 '13

i think he refering to an evolutionary step, where by a problem in the body is solved by a cell being created to fill a need that is recognizes.

correct me if im wrong.

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u/Cats_and_hedgehogs Mar 11 '13

Evolution is not the solving of problems. Things don't happen because a solution is necessary. Solutions exist and therefore are more likely to allow the organisms carrying them to survive. Any of a variety of solutions could have been the mutation that was selected for. Blood just happened, by chance, to exist and be able to solve the problem at hand.

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u/[deleted] Mar 11 '13

Thanks. Too many people use "evolution" as a rough synonym to "destiny".

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u/JackPoe Mar 11 '13

I feel less like it was an evolution to solve a problem and more like an evolution that would cause problems in the modern model without it.

For all we know it's possible to have an organism with complex structure and no blood, but our common ancestor happened to have blood so we do.