Lizard brain is hokum and the book is clear that there are big historical errors and biases in psychology that allowed it to be ‘discovered’ and repeatedly justified its existence. That the mind (and the body) are massively and permanently predicting and simulating reality across the whole brain is true. The reptile brain thing allows us to feel superior. It’s a misreading is evolution. It allows a number of errors to be socially allowed (that emotion is base and out of our control in particular).