Previously I wrote about "The Others: How Animals Made Us Human" by Dr. Paul Shepard. Dr. Shepard wrote a number of books, and maybe I'll review them all. MOL!
In "Thinking Animals: Animals and the Development of Human Intelligence," Dr. Shepard briefly discusses the neurotransmitters. Prey animals are hypervigilant, always watching and waiting for some unknown something to startle them into flight. Predators' neurochemistry, however, mandates focus: moving slowly, with patience and determination, toward the object of their attention. What kind of animal can display both kinds of attention? It must require a wild mood swing to instantly change a creeping hunter into someone who is running at top speed from a predator. It is a huge shift from one neurochemical pathway to a completely different pathway, releasing a neurotransmitter and simultaneously inhibiting another. The ability to switch contexts was an important factor in human evolution. It totally explains their mood swings and inconsistant behavior.
No matter how much our humans have evolved both psychologically and culturally, the old systems are still wired in and still affect then. Humanity is not a separate act of creation.
"Except possibly his soul, man prizes his mind above all else. His mind is a product of its ecology -- the same ecology. Nothing that evolves persists unless sustained by those same creative forces. Like a ball at the top of a fountain, the human head pivots on its animal backbone, the mind a turning knot of thought and dream on the end of a liquid spear of living animals."
-- Paul Shepard, "Thinking Animals"