> The arrival of mitochondria is kind of a red herring by comparison, in my view; we know cellular endosymbiosis has happened a bunch of times so it's not speci

> The arrival of mitochondria is kind of a red herring by comparison, in my view; we know cellular endosymbiosis has happened a bunch of times so it's not special. On the contrary! In billions of years of evolution it happened only very few times (successful), and only once really successfully. It is a rare event.