i don't link. Just wiki.
You concentrate on the triggers and genetics.
Well again I say the facts are apparent and so the first interpretation should be the most simple.
Hair is a covering against coldness.
In our case its against wetness which in nature leads to coldness.
Yet its so patchy it follows it couldn't actually be doing much of a job or ever did.
so the conclusion must be that the body reacts to triggers that say this or that area is enduring important episodic or continious wetness.
Upon puberty this is areas of episodic sweating.
It makes sense. Its a simple concept.
I include its a over sensitivity long ago because its worthless. Then it stayed in gear .
its reasonable to conclude its from triggers within the body without knowing these atomic mechanisms. We don't know much about bodies as shown by the inability to heat a great deal.
Observation plus analysis equals likely conclusion.
Not unlikely conclusions based on evolutionary ideas.
Edited by Adminnemooseus, : Blank lines.