merrill@gigi.DEC (Rick GIGI::Merrill DECRITE) (07/20/84)
My hypothesis for the delayed reaction to sunburn is that the skin takes time to get killed thus protecting you while you HAVE to be out in the sun Working for Food to Stay Alive and doesn't bother until later when you have time to sleep (hence the survival value of the delay). The pain probably arrises from two sources: dead layers of skin shrinking and blister-type-fluid come to repair-the-damage stretching the layers. ouch!! Then yourskin fights back by tanning, freckling etc which apparently allow heat to be absorbed easier w/o burning (survival value for the dark skinned). Well then, you ask, why isn't everybody "dark"? It may be that vitamin D is produced by sun exposure (a good thing) BUT too much is bad for you (?).