Comments on: Date http://www.explainxkcd.com/2009/09/09/date/ Thu, 09 Feb 2012 23:36:29 -0500 http://wordpress.org/?v=2.8.4 hourly 1 By: Janice http://www.explainxkcd.com/2009/09/09/date/comment-page-1/#comment-5007 Janice Fri, 22 Apr 2011 12:22:52 +0000 http://explainxkcd.com/?p=118#comment-5007 Actually, according to the March 2007 Discover magazine, eye color is determined by the interaction of at least 3 genes, despite the simple Punnett squares we did in high school biology. I suppose you could do a Punnett square for the known genes on eye color, but a Punnett square for at least 3 genes is no longer very simple, not to mention the difficulty in being confident which variants of each gene each parent had. http://discovermagazine.com/2007/mar/eye-color-explained/?searchterm=Hair%20color Actually, according to the March 2007 Discover magazine, eye color is determined by the interaction of at least 3 genes, despite the simple Punnett squares we did in high school biology. I suppose you could do a Punnett square for the known genes on eye color, but a Punnett square for at least 3 genes is no longer very simple, not to mention the difficulty in being confident which variants of each gene each parent had.
http://discovermagazine.com/2007/mar/eye-color-explained/?searchterm=Hair%20color

]]> By: Zoz http://www.explainxkcd.com/2009/09/09/date/comment-page-1/#comment-4193 Zoz Thu, 17 Feb 2011 04:14:28 +0000 http://explainxkcd.com/?p=118#comment-4193 i think one point is missing: if both his parents are colorblind, that means he is also colorblind (he got an X from the mother whose alleles are both recessive). If he's colorblind, he wouldn't be able to see that his child's hair is red and the eyes are green. This in itself makes their entire conversation obsolete. Punnett squares give only the probability of a child having a specific phenotype but one thing is for certain: the child will be 100% of a nerd. i think one point is missing: if both his parents are colorblind, that means he is also colorblind (he got an X from the mother whose alleles are both recessive). If he’s colorblind, he wouldn’t be able to see that his child’s hair is red and the eyes are green. This in itself makes their entire conversation obsolete. Punnett squares give only the probability of a child having a specific phenotype but one thing is for certain: the child will be 100% of a nerd.

]]> By: JaniceOly http://www.explainxkcd.com/2009/09/09/date/comment-page-1/#comment-3086 JaniceOly Wed, 15 Dec 2010 08:33:53 +0000 http://explainxkcd.com/?p=118#comment-3086 Leapfrogging off of Jon, I found a fascinating article about both colorblindness and the possibility of tetrachromacy: http://www.rmki.kfki.hu/~lukacs/TETRACH.htm Jon, I am curious about the situation you describe. It seems to be different from the 3 types of tetrachromacy listed in the article, none of which seem likely to me to have the results in the offspring that Jon was indicating. According to this article, the genes producing the red pigment and the green pigment are on the X chromosome, so defects in either of those can be overcome by a female (or XXY male) who has normal genes on the other X chromosome. The gene producing the blue pigment is on chromosome 7, so a male could also be a carrier of blue-yellow colorblindness - this type of colorblindness is naturally less common. This article describes one type of tetrachromacy as occurring when someone has one normal gene for a pigment, but the other gene that would have been for that pigment detects a significantly different wavelength, between the wavelengths detected by typical human cones. The case studies described are fascinating to me. Leapfrogging off of Jon, I found a fascinating article about both colorblindness and the possibility of tetrachromacy:
http://www.rmki.kfki.hu/~lukacs/TETRACH.htm

Jon, I am curious about the situation you describe. It seems to be different from the 3 types of tetrachromacy listed in the article, none of which seem likely to me to have the results in the offspring that Jon was indicating.

According to this article, the genes producing the red pigment and the green pigment are on the X chromosome, so defects in either of those can be overcome by a female (or XXY male) who has normal genes on the other X chromosome.
The gene producing the blue pigment is on chromosome 7, so a male could also be a carrier of blue-yellow colorblindness – this type of colorblindness is naturally less common.

This article describes one type of tetrachromacy as occurring when someone has one normal gene for a pigment, but the other gene that would have been for that pigment detects a significantly different wavelength, between the wavelengths detected by typical human cones. The case studies described are fascinating to me.

]]> By: Jon http://www.explainxkcd.com/2009/09/09/date/comment-page-1/#comment-1910 Jon Sat, 07 Aug 2010 12:18:28 +0000 http://explainxkcd.com/?p=118#comment-1910 Actually, if a woman is a carrier for two different types of colorblindness (red-green and purple-yellow, iirc), then her eyes will actually produce a fourth pigment and allow her to see a broader range of colors than most of us can. Her sons would all be colorblind, and her daughters could be colorblind, normal sighted carriers of colorblindness, or have the superior color vision of their mother. Actually, if a woman is a carrier for two different types of colorblindness (red-green and purple-yellow, iirc), then her eyes will actually produce a fourth pigment and allow her to see a broader range of colors than most of us can. Her sons would all be colorblind, and her daughters could be colorblind, normal sighted carriers of colorblindness, or have the superior color vision of their mother.

]]> By: Josh Rotella http://www.explainxkcd.com/2009/09/09/date/comment-page-1/#comment-1196 Josh Rotella Thu, 17 Dec 2009 02:03:31 +0000 http://explainxkcd.com/?p=118#comment-1196 Also worth noting that they're evidently postulating/hoping for a trifecta (or quadfecta), where their red-haired, green-eyed daughter will have red-green colorblindness and be unable to recognize a difference in hue between two of her major defining characteristics. Messing with the kids' heads seems to be a popular theme. Also worth noting that they’re evidently postulating/hoping for a trifecta (or quadfecta), where their red-haired, green-eyed daughter will have red-green colorblindness and be unable to recognize a difference in hue between two of her major defining characteristics. Messing with the kids’ heads seems to be a popular theme.

]]> By: M http://www.explainxkcd.com/2009/09/09/date/comment-page-1/#comment-761 M Thu, 15 Oct 2009 02:41:25 +0000 http://explainxkcd.com/?p=118#comment-761 Slight correction/clarification: A daughter would definitely be at least a carrier. If the mother is colorblind, the daughter will definitely be colorblind. If the mother is a carrier, she has a 50% chance of being colorblind. Of course, a son can only inherit colorblindness from his mother. Slight correction/clarification:
A daughter would definitely be at least a carrier. If the mother is colorblind, the daughter will definitely be colorblind. If the mother is a carrier, she has a 50% chance of being colorblind. Of course, a son can only inherit colorblindness from his mother.

]]> By: woodstock http://www.explainxkcd.com/2009/09/09/date/comment-page-1/#comment-39 woodstock Wed, 09 Sep 2009 13:55:36 +0000 http://explainxkcd.com/?p=118#comment-39 And I didn't not know that colorblindness was carried on the X chromosome. Learn something new every day. And I didn’t not know that colorblindness was carried on the X chromosome. Learn something new every day.

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