User:Jtwsaddress42/Projects/Project 5/Sections/Chapter 1/Alfred Sherwood Romer - The Vertebrate as a Dual Organism

The vertebrate nervous system is organized into a somatic division which is fundamentally sensorimotor in structure and dedicated to the ecology - and, a visceral division, characterized by an enteric nerve net, dedicated to the hedonic needs of the organism. The enteric nervous system (ENS) of the visceral division and its autonomic connections to the somatic division, as well as a number of subcortical structures within the somatic division, will provide the vital adaptive hedonic feedback necessary for the CNS and neocortex to form the vital perceptual categorizations and postural motor routines that are meaningful to it.

Romer expounded a vision of the vertebrate as a dual animal. Romer hypothesizes that at the origin of vertebrates these two bodyplans, which were sequentially expressed, came to be expressed simultaneously - and fused only at the hindbrain-gill slits and the sacral nerve. Originally, the only points of communication between the two "animals" was via the unmyelinated neurons of the parasympathetic nervous system. The rest of vertebrate evolution revolves around adaptions that allow the integration of these two bodyplans. Romer describes the gradual emergence of the myelinated sympathetic nervous system and its increasingly sophisticated development of control over the enteric nervous system and viscera by the somatic division as we move along the evolutionary progression of vertebrate anatomy and physiology.

