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Gender Differences July 28, 2008

Posted by federalist in Human Markets, Social Politics.
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Mainstream Media continue to butcher this important fact of life: Sample variances of just about any measure of behavior, ability, or disability are higher for men than for women. This means that regardless of whether men or women are on average innately better at something, the best (and worst) in a large population are probably almost all men.

(It’s worth noting that apparently only the Wall Street Journal got this fact right in the recent reporting on this subject.)

Addendum: There is one non-reproductive ability exclusive to females, which is quite fascinating: Tetrachromatic vision. Because the genes for red and green rods are carried on the X chromosome, and because there is at least one known mutation for these receptors that changes their spectral sensitivity curves (and which leads to color-deficiency if inherited by a male), it is possible (though rare) for a female to have four distinct color receptors instead of the usual three, which in theory would allow such a “tetrachromat” to distinguish colors that appear identical to regular humans. Research on human tetrachromats seems to be sorely lacking at present, but in the course of checking out the state of the art I came across some other fascinating notes.

For one thing, apparently regular humans are actually tetrachromats: We have a fourth photoreceptor tuned to the near ultraviolet spectrum, but our natural ocular lenses absorb that wavelength so only people who have had their lenses replaced with artificial ones can enjoy ultraviolet vision. (This means that a natural tetrachromat with artificial lenses would in theory possess pentachromatic vision!) One unresolved question in current research is how effectively the visual cortex can exploit these extra color sensors. Given the evidence for neural plasticity one suspects that they would be fully utilized. But you don’t have to find a natural tetrachromat to test that: An amusing patent proposes eyeglasses that spectrally shift the image presented to one eye, which in principle allows a regular trichromat to distinguish colors as if he were a hexachromat. Of course this is nothing compared to the vision king of the animal world: The Mantis Shrimp has sixteen distinct photoreceptors and is also sensitive to both linear and circular polarization of light!

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