User:Jtwsaddress42/Projects/Project 4/Sections/Chapter 5/The innovations of jawed vertebrates

It appears that a second genome duplication event may have facilitated the emergence of jawed vertebrates by providing another duplicate set of genes that could be redirected to new purpose without disruption of earlier established genetic and epigenetic developmental somatic programs.

Key innovations, all of which are key components in the fight or flight system:


 * adaptive antibody-based immunity based on B and T-cells.
 * jaws, fins, proprioceptors, and the kinesthetic system.
 * myelin sheath and fast nerve conduction.
 * the myelinated sympathetic nervous system and adrenal system gradually exerting more and more control over the visceral division over evolutionary time.
 * the trigeminal system and head-sensory integration with the jaws and fins.
 * the emergence of fight or flight behavior as the sympathetic enables global coordination of somatic and visceral divisions.