T's SO_GO H: Layers of the evolutionary onion.

Teresa Binstock binstoct at essex.UCHSC.edu
Thu Mar 21 16:42:21 EST 1996


In response to many e-mails to listservers and/or to me personally, 
some clarifications, via a very general sketch of "three layers" of neural 
and immunological function:

Background: My recent postings sketched/suggested an immunological basis to 
sexual- and gender-orientations and that the causal substrates may exist 
at the level of "innate immunity", even transcending (ie evolutionarily 
preceeding) major histocompatibility complex antigen-presentation genes and 
immunoglobulin genes. 

THREE LAYERS:

Layer Three: The primate visual and auditory systems and their links with 
amygdaloid, hippocampal, and other brain structures are certainly part of 
how we process sexually significant non-chemo-signal stimuli as well as 
pheromonal molecules of the olfactory and vomeronasal sort. 

Layer Two: MHC effects have been shown in human odor/scent evaluation and 
also have been documented in mating-choice preferences. Vomeronasal and 
olfactory receptors and their neural routes are within this evolutionary 
"layer".

	Comment: Item #1 seems to function regardless of sexual orientation; 
	and item #2 is studied primarily in relation to heterosexual 
	orientation, regardless of species. 

Layer One in yeast: In contrast, the yeast Saccharomyces cerevisiae (ySc) 
has a mating system with several clear sexually dimorphisms: 
a. The alpha-factor yeast produces alpha-factor pheromones and has on its 
cell surface an a-factor receptor and responds to a-factor pheromone. 
b. The a-factor yeast produces a-factor pheromones and has cell-surface 
receptors for and responds to alpha-factor pheromones. 

Layer One in humans and other mammals: ySc has neither olfactory nor 
vomeronasal nor nasal-trigeminal receptors or neural systems; and what 
seems to be an unresearched possibility is that certain kinds of 
sexually significant chemo-signaling in vertebrates occurs in tissues 
other than olfactory and vomeronasal. Three possibilities are (i) 
epidermis, (ii) respiratory epithelium, and (iii) lymphoid tissue 
anywhere within the nasal cavity. 

In my hypothesis of sexual and gender orientations, their primary 
substrate is within Layer One, thereby transcending (being more basic 
than) (i) visuals and conditionings, (ii) MHC-related filterings we 
observe as mating-type choices among heterosexual organisms regardless of 
species, and (iii) olfactory and vomeronasal processing of sexually 
significant odors and pheromones of the mammalian sort. 

***
EVOLUTIONARY QUESTIONS:



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