"... there is the triune-brain theory from MacLean. Is anything ever done with that in evolutionary psychology, as far as you or anyone knows? ..."
I hardly ever lend books, but recently I have lent to a colleague just the very book that I think may be one example of what you are about - it's the book, "Evolutionary Psychiatry" by John Price and Stevens. As I haven't got it with me, I'm sorry I can't quote chapter & verse, but speaking from memory I believe there's a section making use of the concept of the triune brain to explain some aspects of human behaviour.
I once used this notion when treating a male personality-disordered patient as a way of starting an attempt at behaviour modification. He was quite intrigued to think that some of his more hasty automatic behaviour was a manifestation of his reptilian self!