4-Part Evolutionary Human Brain

A half century ago, Paul MacLean introduced the idea that the hu- man brain consists of three main parts, and that the parts of our "Triune Brain" correlate to the time sequence of their evolutionary emergence: reptilian, paleo-mammalian, and neo-mammalian. Since then, scien- tists have recognized that there is a fourth and far more recently evolved mammalian structure, which is profoundly manifest in the human brain: the prefrontal cortex, or frontal lobes. Let us begin with a brief overview of each of the components of our Quadrune Brain.