Can girls be color blind?

I once heard it was IMPOSSIBLE for a girl to be color blind.


Peace,

Not as common in females than males, but not impossible.

I have my own little theory about evolutionary reasons for gender difference in the incidence, and severity of colorblindness.

Males were the hunters. Big critters are big critters regardless of color. What mattered to hunters was movement.

Females gathered food stuffs of plant origins, while tending the small people. It was VERY important to be able to see the nuances in plants so you didn't end up picking something that would poison the whole clan. Good to know the good berries from the bad ones.

What nuances in plants that related to females seeing color?

Thanks. :)

what I have learned about human history. If our female ancestors didn't notice color variance between the good plants and the ones that were toxic, most of them would have died off.

I feel no need to back up my pet theories with links. They evolved WAY before the internet did ;) Deductive reasoning is out of style now? Who knew?

I am just wondering what the color differences are between good plants and toxic plants. What is the difference? :)

You just gotta be able to see details to do accurate plant identification. Little things can mean a lot ;)

Or is it just variations between light green and dark green? I'm totally ignorant on this subject. :)

No, one just needs to be able to see the details of plants to be able to identify them. Like, Oog told me this berry from the plant with the pale, blue green tint to the leaves is BAD, even though it looks like the berry from the plant with the yellow green leaves, which is good.

What I am saying is one needs to be able to see the plant well, in order to identify/recall it. There is no magic color formula as to which color is toxic and which isn't. But color is one of the ways to identify if the plant is a this or a that. To be able to remember the plant, one must first be able to see it well. Some red berries will kill and some will cure. Best to be able to SEE all the charactistics of the PLANTS to tell the difference. Color helps with detail.

Mastadons, on the other hand, were generally the same shape and color, and very rarely toxic :evilgrin:

Gads, I hope you are just pulling my leg and not really thinking one color plant is yummy and the other will rot your tummy ;)

However, I disagree with your concept that men only hunted "big" animals and did not need to see color. Ain't you ever had no rabbit stew? ;)

One of the three cone pigment genes happens to be on the X chromosome. Since men only have one X, there is no exrtra X to make up for any problems if a guy has a mutation on that gene.

Are you saying that women have more than one X gene? How and why did that happen?

I appreciate your knowledge and input. :)

it is the 7th largest human chromosome and has hundreds of genes. Originally there was two types of X chromosomes, one with the SRY gene induring male development in the embryo and one without that gene. then, for various reasons dealing with selfish genes the version of the X with SRY slimmed down into the little runt of a chromosome that the Y is today. eventually a mutation will attach the Y to another chromosme, which becomes the new X and the cycle begins again.

But it is unusual......

The trait is carried on the X chromosome....

So if a woman has that particular chromosome on one of hers, then she is a carrier....

If she gives that X to her son, then he is colorblind...

If by chance she receives a tainted X chromosome from both her mom and her dad, then she is color-blind.

Making any sense to you?

:shrug:

but not impossible. I myself have what's called "shade deficiency". Found that out when I was going through my Army physical. I have no problem telling the difference between red and green or any other color but when I'm shown different shades of the same color they all look the same to me. That's why I always wore blue jeans and tee shirts growing up. If I tried to dress up all the colors would clash.

and can only happen when there are both genes presence - which girls don't have (in guys, the "Y" is shorter than the "X" gene).

You'll find there are a host of other conditions very rare in girls like hemophilia. WOmen are the carriers

colorblindness.....

here're some links:

http://www.abc.net.au/science/news/stories/s1168851.htm

---- Quote from the article ----

Verelli and co-author Assistant Professor Sarah Tishkoff, from the
University of Maryland, said that the X chromosomes could have two types
of opsin, one perceiving shades of true red, the other shades within the
red-orange range.

Men have one X chromosome and one Y chromosome, so they only have one of
the two types of red-detecting opsin.

The limit, and possible problems with amino acid exchanges, sometimes
result in colour blindness, which now affects 8% of all men.

Women can possess both opsin pigments because they have two X
chromosomes.

According to Tishkoff and Verrelli, the 40% of women who have both
pigments have superior colour perception for reds, and possibly other
colours.

*****

---- Quotes from the article ----

What the researchers were finding when they actually looked at the
structure of the eye is that many women—perhaps over fifty
percent—possessed a fourth photopigment.

<snip>

Four-pigment females perceived significantly more bands of color than
both three-pigment males and females. Further, three-pigment males and
females are statistically indistinguishable, suggesting that the result
is not due to some cultural difference between men and women.

receptors - the structure that results in color blindness.]

http://scienceblogs.com/cognitivedaily/2005/09/do_women_perceive_color_differ.php

It is carried by an X chromosome. When the gene for color sight is defective in the X chromosome of men, there is no functioning color-sight gene in the Y chromosome to make up for it. That is why it is mostly men who get it. Still, if BOTH X chromosomes in women have the defect, then the woman will be color blind. For this to happen, the mother has to be a carrier AND the daughter has to draw the gene that has the defect, not the one that does not. Also, the father has to be color blind. There is a lady in our office that is color blind and it is pretty rare.