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scarabic t1_izd8pr8 wrote

Reply to comment by bruceleroy99 in Have living things always had an immune system? How did they survive / evolve to deal with diseases, and how does that compare to modern immune systems? by bruceleroy99

The same answer goes all the way down really. There’s not a single chemical process or pathway anywhere in your entire metabolism that wasn’t invented in bacteria before multicellular life came about. Even photosynthesis originated in bacteria, long before there were plants.

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