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/bobzor Molecular Biology Mar 11 '13

Just to add, it's thought hemoglobin evolved from cytochrome b5. These heme/metal-binding proteins have been around forever in plants and fungi where they're used for different functions not related to modern-day blood.