Brain complexity evolved hierarchically, with the brainstem handling autonomic functions, the midbrain emotional processing, and the cortex cognitive thought.

“as the complexity of the organism evolved so too did that hierarchy right I mean the brainstem basically handles everything we don't have to think about ever breathing and all of those autonomic and sympathetic parasympathetic functions and then you layer on this midbrain that does everything that you said which is still kind of happening beneath consciousness and then of course there's where most of us live in our cortex where we're or where we think we live which is we're thinking these thoughts”