In the 19 sixties, a neuro scientist named paul d. Mc lean formulated a model for something called the triune brain theory. This is where we get the phrase lizard brain. It's exactly what it sounds like. The idea is that there's parts of your brain, and these are actual physical parts ofyour brain that you can see. There 's kind of like the inner nugget that is the literal lizard brain, that is liker, our least evolved form of thought. And then the layer on top of that is like our monkey brains, basically. Rachel calls it mammal brains. She talks about having like a deer in the back yard. It can kind of