Science desk
< September 2	<< Aug \| September \| Oct >>	September 4 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

September 3

Human hair color

Reading human hair color, a question popped into my head. Is black eumelanin biochemically unstable or incomplete dominance? I mean, one parent may have only black hair, and that black hair is bred true because of ancestry. Another parent may have brown hair, but carries the blonde allele; and the person may have other genes that control the amount of brown eumelanin throughout one's age. When they cross, the offspring may have some shade of brown or even blonde hair, maybe even black hair. I am not sure if the black eumelanin is actually more biochemically unstable so the brown version takes over or if there is some kind of incomplete dominance going on. 50.4.236.254 (talk) 15:32, 3 September 2017 (UTC)[reply]

What? μηδείς (talk) 16:38, 3 September 2017 (UTC)[reply]

Articles: Human hair color#Genetics and biochemistry of hair color, [1], Genetics of Blonde Hair.

Hair color is determined by the amount of eumelanin (which is dark brown) and pheomelanin (which is reddish). There are numerous examples of two brown-haired parents having red-haired offspring, which would suggest that it is determined by a recessive allele, but Neel (1943) found many offspring of two red-haired parents to have non-red hair. Reed (1952) reviewed the various hypotheses that had been proposed, including that red was recessive; that red was dominant; that red was dominant, but could be masked by brown; or that red was usually recessive but could sometimes be dominant. This report concludes that there are a large number of different MC1R (Melanocortin 1 Receptor) alleles, and other genes affecting the amount of brown pigment that plays a major role in determining hair color. Blooteuth (talk) 17:38, 3 September 2017 (UTC)[reply]

A side question: is it possible for a parent with black hair and another parent with brown hair to produce an offspring with red hair? 38.88.99.222 (talk) 08:21, 5 September 2017 (UTC)[reply]

Yes, quite common. Red hair is carried by a recessive gene. http://genetics.thetech.org/ask/ask245 Andy Dingley (talk) 10:05, 5 September 2017 (UTC)[reply]

This feature of genetics is the reason why fair skinned parents are sometimes surprised (and may receive inappropriate comments) when they give birth to a dark skinned child. 92.24.110.225 (talk) 11:49, 5 September 2017 (UTC)[reply]

No, skin colour isn't the same. Red hair is carried on one gene: MC1R (which happens to be recessive), skin colour on several genes.^[1] Although some of those genes may each exhibit similar "all or nothing" behaviour to red hair, the overall effect (and so the darkness of skin) is the composite effect of all of them. Which, by basic statistics, will thus have a more more continuum behaviour rather than the more polarised "red or not" of red hair. Of course there are outliers, but these are rare, and on average a child will have colouring midway between their parents, and largely consistent with their siblings. Although this is a complex topic and not one that can be answered in this limited space by a non specialist. Andy Dingley (talk) 18:37, 5 September 2017 (UTC)[reply]

References

^ Sturm, Richard A. (15 April 2009). "Molecular genetics of human pigmentation diversity". Human Molecular Genetics. 18 (R1): R9–R17. doi:10.1093/hmg/ddp003.

What is this plant called?

Anybody know the name? I would really like to add it to my garden!Wikigirl97 (talk) 20:35, 3 September 2017 (UTC)[reply]

Kniphofia, I think. {The poster formerly known as 87.81.230.195} 90.204.180.96 (talk) 20:44, 3 September 2017 (UTC)[reply]

I would have called it the "burning match plant". But, much like a burnt match, it looks ugly when used up (after the petals fall off), so be sure you know what you're getting into. StuRat (talk) 20:53, 3 September 2017 (UTC)[reply]

Another common name is "Red Hot Poker". Dbfirs 23:49, 3 September 2017 (UTC)[reply]

N.B. Baxter Creek Gateway Park is mentioned at Baxter Creek, so I take this to be in California. We don't presently use the image in that article. Wnt (talk) 16:08, 4 September 2017 (UTC)[reply]

[1] Sturm, Richard A. (15 April 2009). "Molecular genetics of human pigmentation diversity". Human Molecular Genetics. 18 (R1): R9–R17. doi:10.1093/hmg/ddp003.

[1]