(Ancient genetic signals can be resurrected after lying dormant for millions of years, awaiting only the right trigger to release them.)
In the early Carboniferous there arose an organism with, for the very first time, more information in its brain than in its genes, and the brain grew more dominant over time.
The modern brain's blueprint is a story of successive accretion and specialization, which freed us from the tyranny of DNA's monopoly on total information.
The three interconnected parts of the modern brain correspond to the evolutionary emergence of reptiles, mammals and primates - especially humans - and represent a major burst forward
in overall brain development, each step adding a new function and a new layer. And since these were laid down over existing systems, the preexisting systems had to be accomodated
because making basic change deep within the fabric of life very frequently turns out to be fatal. Adding new layers while retaining the old ones allows major change consistent with survival.
Today's triune, or three part brain consists of the R-complex at its core, surrounded and surmounted by the limbic system, which is enveloped by the massive neo-cortex.
The R-complex is the most ancient part, the dinosaur component of human nature, seat of reptilian ritual and aggression, territorial and hierarchical behavior.
No carefully-weighed decisions happen here, no nuances of emotion's wrenching contradictions, just the stolid acquiescence to the dictates of its genes, no thought or action taken of its own volition.
The R-complex lies below the limbic system, which was added during the development of mammals. It generates emotions, changes of mood and states of mind and the maternal instinct found in warm-blooded animals.
Emotions can be triggered by hormonal exudations of endocrine systems such as the amygdala. Stimulating the amygdala can make a placid animal frenzied or cause a cat to cower from a mouse in abject terror.
The limbic system is the seat of subtle emotions which we think uniquely ours among the animals, but altruism may have gotten started here and love may be an invention of the mammals.
The neo-cortex is layered over the limbic system, and accounts for 85% of the brain's mass. Its frontal lobes most likely are connected with deliberation and regulation of our actions.
Transforming experience into symbolic languages is a primary function of the neo-cortex, the extrasomatic manifestation of knowledge expressed as reading, writing, speaking and mathematics.
It may control anticipation of the future and cause worry about the possibility of disaster, but in our attempts to regulate the future we produced ethics, science, legal codes and magic.
Vi's works appear widely both in print and online. She conducts Poetry Workshops and gives readings in Central New York. Her latest chapbook is "Sine Qua Non Antiques (an Arcanum of History, Geography and Treachery).
