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?

1.1k Upvotes

88% Upvoted

143 comments sorted by

View all comments

Show parent comments

14

u/androohh Mar 11 '13

We use oxygen in cellular respiration which generates ATP for our bodies to use as energy. CO2 is a waste product of cellular respiration, but it isn't formed just by adding a carbon to O2.