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From: debray@sbcs.UUCP (Saumya Debray)
Newsgroups: net.cooks,net.flame
Subject: dark skins near equator
Message-ID: <111@sbcs.UUCP>
Date: Fri, 30-Nov-84 14:30:09 EST
Article-I.D.: sbcs.111
Posted: Fri Nov 30 14:30:09 1984
Date-Received: Tue, 4-Dec-84 08:23:05 EST
References: <2559@dartvax.UUCP> <642@watdcsu.UUCP> <1245@utah-gr.UUCP> <2804@ucbcad.UUCP>
Organization: Computer Science Dept, SUNY@Stony Brook
Lines: 17
Xref: watmath net.cooks:3189 net.flame:7064

> What I've always wondered is why the closer to the equator people live, the
> darker their skin tends to be. It seems that in the interests of
> maintainting a reasonable body temperature, it should be just the opposite.
> 

Melanin (the dark pigment you refer to) blocks out ultraviolet radiation:
because the amount of atmosphere sunlight has to travel through is lesser
nearer the equator, less UV is absorbed by the atmosphere and more of it
reaches the surface.
-- 
Saumya Debray, 	SUNY at Stony Brook

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