Gooch's dad

Spectra of leaves tied to development of primate vision

Interesting article in this month's "Photonics Spectra". They used a competitor's spectrometer, but then again, my company doesn't yet make a nice small fiber-based portable spectrometer.

I didn't realize that most other mammals, including most monkeys, only have two photopigments rather than the three that humans and other apes have. Apparently there is good reason to believe that the extra photopigment, which gives us the ability to distinguish between red and green, helps chimps pick out the best leaves to eat.

RufusAtticus

Graur's and Li's textbook, Molecular Evolution, discusses the opsins. Apes and old world monkeys are trichromatic because they have three opsin loci, one autosomal and two on the X-chromosome (a known duplication). New world monkeys (except Howler monkeys) are dichromatic because they have two opsin loci, one autosomal and one X-linked. The interesting thing is that many new world monkey species are hightly polymorphic at the X-linked locus. This causes many females to be heterozygous and thus effectively trichromatic. This polymorphism allows for reds to be distinguished from greens, and thus--it is proposed--allows the distinction of ripe fruit from background folliage.

MortalWombat

Talkorigins has an article on the evolution of color vision. One note of interest is the following:

Nic Tamzek

This is also why red-green color blindness is the most common form. Actually it's not "color blindness", it's called "anomalous trichromatic", meaning that your sensitivity to the difference between red and green is reduced. Presumably this is due to either one's red or green protein being slightly different.

(anomalous trichromatics unite!)

faust

FYI,
Due to the location of the photopigment genes on the X chromosome, and the inherent variation of them, one can infer that given two sufficiently different photopigments, with far spread optimal receptions in the middle wavelength, we could conceivably find a tetrachromat. This person would be a woman.

MortalWombat is correct in pointing out that interesting quote. It wouldn't take much.

Here's a link for an article about the first suspected tetrachromatic woman. Must be a nice way to see things

Tetrachromatic Woman

MortalWombat

Naturally. And it would give her another reason to criticize my ability to pick out a shirt that matches my pants.

Worldtraveller

From the link above:
I thought this was a (fairly) well documented phenomena. I have seen experiments where test subjects were rigged with 'glasses' that inverted the images. After 10-14 days, the brain automatically compensated by righting the image.

The kicker is, when the glasses were removed, it took the brain the same amount of time to re adjust again!

Just my $0.02

-Lane