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From: berleant@ut-sally.UUCP (Dan Berleant)
Newsgroups: sci.med
Subject: Re: sex and color
Message-ID: <6283@ut-sally.UUCP>
Date: Fri, 7-Nov-86 11:52:37 EST
Article-I.D.: ut-sally.6283
Posted: Fri Nov  7 11:52:37 1986
Date-Received: Sat, 8-Nov-86 05:19:58 EST
References: <2302@bucse.bu-cs.BU.EDU>
Reply-To: berleant@sally.utexas.edu.UUCP (Dan Berleant)
Organization: U. Texas CS Dept., Austin, Texas
Lines: 24

In article <2302@bucse.bu-cs.BU.EDU> gasp@bu-cs.BU.EDU (Isaac Kohane) writes:
>Well, it seems that women can in fact see more than men.
>We ... are basically trichromatic.  That is we have three pigments
>in our retina (red green and blue).
>Now, as we all know, women have twice as much X chromosome as men do.
>Therefore, if there are multiple alleles (versions of that gene at
>that locus) for the red pigment (as is suggested by recent experiments
>in this area), then a women could have one allele on one X chromosome,
>and another allele on the second X chromosome. Each allele would have
>a different peak absorption wavelength. It might be then, that some
>women are in fact quadrichromatic. What do they see that we don't? :-)

Probably not much. Cones (the color receptor cells in the retina) 
	project to deeper areas of the brain by 'labelled lines',
	that is, the nerve from the cone codes the color
	sensitivity of the cone. Even if a woman has two
	different variations of red-sensitive cone, probably
	sensations from both would be sent along 'red' 
	nerves, and the net effect would be simply a 
	wider (less frequency-specific) curve of color
	sensitivity to red.
	
	Dan B.