I am reading Avi Chaudhuri's Fundamentals of Sensory Perception and wondering if the information given about the somatosensory system could tell us anything about the way it evolved.
It seems (at least naively) reasonable to assume that nerves became larger and more myelinated as time went on. The types of somatosensory nerve fibre are (in order from least to most myelinated):
C < A-delta < A-beta < A-alpha
This gives an ordering on receptors of:
warm receptors < cold receptors < nociceptors < tactile mechanoreceptors < proprioceptors
My question is then: was this the order in which these receptors evolved? If not, can myelination still give us useful information about the evolutionary history of the nervous system?
P.S. Meta question: is this question better suited for the Bio or Cog Sci stack exchange? I asked it here since it seemed to be more about evolution than neurons.