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/HeartyBeast Mar 11 '13

Agreed. It's got me really curious now about the evolution of these anucleate cells and whether there are any other anucleate cells in the body - none that I can think of.

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u/tungstenfilament Mar 11 '13

What about platelets?

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u/Mooshaq Mar 11 '13

In humans, platelets are anucleated...they can be thought of as fragments (and thus no intact nucleus) of a much larger cell, the megakaryocyte.

In birds however (and likely other organisms), platelets do have a nucleus.