One other perspective on the brain and its role in emotions can be seen through seeing the brain from an evolutionary perspective. Dr Paul McLean suggests that the human brain is in fact made up of three interconnected biological computers. Each has its own special intelligence and other functions. The view of the brain from this perspective is closely related to the view of the three areas of the brain described earlier.
Throughout its evolution, the human brain has developed into an increasingly sophisticated machine. Despite that, we have retained some elements of the brains of our distant ancestors. According to this model, evolution has simply added new subbrains to the pre-existing ones. (See diagram to the right) This theory is based partly on the sequence of appearance of these layers in the development of the human embryo. It also suggests that this seqence mimics the appearance of these structures in our evolutionary history.
These are :
1. the archipallium or primitive (reptilian) brain. This includes the structures of the medulla, pons, cerebellum and the olfactory (smell) bulbs. This corresponds to the R-complex. It is responsible for self preservation and includes the mechanisms for aggression.
2. The paleopallium or intermediate (old mammalian) brain comprising the stuctures of the limbic system. It corresponds to the brain of inferior animals.
3. The neopallium also known as the superior or rational brain. It comprises the cortex and some subcortical groups. It corresponds to the brain of superior animals including the primates and humans.