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Discussing: Hair color and genetics

Hair color and genetics

My question is fairly complicated, but I'll try to make it understandable...

With reference to hair color, how likely would it be for some of Faramir and Eowyn's children to have blond hair and some to have dark hair?

Assuming dark hair is dominant and blond hair is recessive (is that correct?), would Faramir have to have a blond recessive gene in his background for this to work? I would really like to study genetics fully so I wouldn't have to ask this, but I am hoping for a quicker answer from some of the very intelligent people here. Wink I know a little about dominant/recessive genetic diagrams and such, but not enough.

That is my main question, but I am also wondering how hair color genes work in other areas?

Is it possible for Aragorn and Arwen, both black haired, to have a brown haired child?

Are there only two genes, dark and light, and all other shades are merely variants? One of Feanor's sons had red hair, if I am not mistaken...where does red hair fit in? Is it a shade of blond? And is brown a shade of dark hair? These colors seem to be rare in Tolkien's world, but they are there, which makes me wonder how exactly they work.

How far down the genealogical line can a gene go before popping out in a descendant?

Any help with determining realistic hair color for characters would be very much appreciated!

 

 

Re: Hair color and genetics

Hi MerryK,

I'm reaching back into A.P. biology, which was about seven years ago, augmented by some quick web searching - so if someone comes along later, you may want to go with their claims instead of mine. So assuming normal modern human inheritance patterns...

With reference to hair color, how likely would it be for some of Faramir and Eowyn's children to have blond hair and some to have dark hair? Assuming dark hair is dominant and blond hair is recessive (is that correct?), would Faramir have to have a blond recessive gene in his background for this to work?

Hair colour is controlled by several genes that control what concentrations of two chemicals the body produces. The more eumelanin the darker the hair, and the more phaeomelanin the redder the hair. So...

high eumelanin, low phaeomelanin = dark brown or black hair
high eumelanin, high phaeomelanin = dark auburn hair
low eumelanin, high phaeomelanin = bright red or golden hair
low eumelanin, low phaeomelanin = fair hair ("white blond")

But like I said, it's not just one or two genes - I have heard as many as seven are involved, it's an area scientists were still debating when I last studied this stuff. Let's say for example there are five genes that control how much eumelanin is produced. My understanding is also that dark hair is dominant over fair hair, meaning that if you inherit from one parents that one of those five genes would produce eumelanin, and from the other parent that that gene wouldn't produce eumelanin, that gene would tell your body to produce eumelanin. And the more of these genes that are geared to producing eumelanin, the more that gets produced and the darker the hair.

This means two people with dark hair are more likely to have a child with dark hair, but if they both have some of those eumelanin-producing genes where the parents inherited a dominant and a recessive allele from *their* parents, the child might have light hair. It is theoretically possible for two parents with dark hair to have a blond-haired child. That happens occasionally, though not that often. Now, for the canon characters...

Eowyn is described in "The King of the Golden Hall" as:

Grave and thoughtful was her glance, as she looked on the king with cool pity in her eyes. Very fair was her face, and her long hair was like a river of gold. Slender and tall she was in her white robe girt with silver; but strong she seemed and stern as steel, a daughter of kings.


which suggests to me golden hair rather than white-blond hair, so we're talking low eumelanin and high phaeomelanin. Faramir does not have his hair colour when he's introduced in TTT, but when he and Eowyn kiss in ROTK, Tolkien writes that

a great wind rose and blew, and their hair, raven and golden, streamed out mingling in the air.


In non-caucasians there is a separate gene that controls whether a hair is black or not, but in caucasians black hair is generally from the high eum., low phaem. situation, where there is so much eumelanin that the hair is so dark it appears black. I think this is probably what is going on with Faramir. So that means you have the possibility for almost every hair colour in their children. Each child would have the greatest chance of having dark hair like Faramir, a lesser chance of having either auburn or white-blond hair, and still less chance of having golden hair like Eowyn. Again, if my understanding is correct.

One more thing to point out is the case of Morwen of Lossarnach. In UT it's said that some of the descendants of Thengel inherited dark hair from her, but the fact that Eomer and Eowyn (desc. through her daughter Theodwyn) had fair hair suggests she carried the recessive fair-hair gene as well. Which makes it possible that Faramir carried it as well (Morwen is described in UT as a kinswoman of Imrahil, and so also of Finduilas). Possible - not canonical.

Is it possible for Aragorn and Arwen, both black haired, to have a brown haired child?

Very possible - see above. I assume that in Middle-earth black hair is really just very dark brown hair, so dark it can't be distinguished from the colour black. If either of them carried a recessive allele for one of those eumelanin-producing genes to be turned off rather than on, lighter hair is possible. And remember that at least two of Arwen's grandparents had fair hair (Celeborn = silver, Galadriel = golden), so she almost certainly was carrying some recessive genes there.

Are there only two genes, dark and light, and all other shades are merely variants? One of Feanor's sons had red hair, if I am not mistaken...where does red hair fit in?

I mentioned above two chemicals, eumelanin and phaeomelanin. Phaeomelanin controls how red your hair is. if you have a lot it is auburn if you also have a lot of eumelanin, or else carrot-red or golden-blond if you have not a lot of eumelanin. Nerdanel's father I believe is described as red-haired, so it's very possible that some of their sons had the gene to produce red hair. (It's recessive, so some may have carried the gene without actually having red hair.)

Is it a shade of blond? And is brown a shade of dark hair? These colors seem to be rare in Tolkien's world, but they are there, which makes me wonder how exactly they work.

Well, modern genetics is recent, and hair colour is one of the most hotly debated. So Tolkien may not have known much about all of this! But assuming he did, red would be controlled by a different set of genes than the light/dark issue. See what I said above about this.

How far down the genealogical line can a gene go before popping out in a descendant?

Indefinitely, though with each generation there's a less chance of the gene being passed along.

Marta

 

 

Re: Hair color and genetics

Wow, Marta, that was really useful! I had a feeling that it was something like that, but you gave me some concrete evidence. I think I might dip into this more fully, but I at least have a head start. Thanks for your help!

~MerryK 

 

 

Re: Hair color and genetics

Marta's got the basics down, but a little refinement on the red pigment in hair: that is based on a single gene, so there isn't the same range of variation in pigment.  "Golden" hair--which I picture as primarily yellow, as opposed to "strawberry blonde"--doesn't have an appreciable amount of red.  Now, you might describe the striking conjunction of blond and strong red as red-gold (or flaming, or copper-colored), but that's a different pigmentation.

For people who like crunchy data, red hair, fair skin, and freckling are associated with three (out of more than 30) alleles of the MC1R (melanocortin 1 receptor) gene, which affects pigmentation in animals (including chickens) as well as humans.  It appears to be passed on as an autosomal recessive, so you have to get one of those three alleles (in some combination; this is where the variation in pigment strength comes from) from both parents to get red pigment.  A goodly number of people have red hidden underneath darker pigmentation, however, so it does pop up unexpectedly.

Cheers--

Adaneth

 

 

Re: Hair color and genetics

Thanks Adaneth! So, let me see if I have this straight...

If one parent has all three alleles (strongest red color) and the other parent has only one (lightest red color), there is a possibility of having any shade of red in the children's hair? And if only one parent has the allele, it hides because it is recessive? (I am not quite sure what autosomal recessive means.) And red can be with any other of the hair colors in various shades, but it is only when it is strong that you say someone has "red" hair? And if it is a lighter shade, it would be liked "highlights"?

Thank you for your  detailed reply! I am starting to grasp all of this at last!

~MerryK Smile

 

 

Re: Hair color and genetics

If one parent has all three alleles (strongest red color) and the other parent has only one (lightest red color), there is a possibility of having any shade of red in the children's hair? And if only one parent has the allele, it hides because it is recessive? (I am not quite sure what autosomal recessive means.)

Sorry--too much genetics-speak in that last post!  Smile  Let me translate a bit:

An allele is a variant of a gene.  We have two copies of each gene, one from each of our parents.  If you have two copies of the same allele, you're homozygous; if you have two different alleles, you're heterozygous.  So, for any gene, such as MC1R, a person has at most two of those variants, and you only get to pass one on to each offspring.

Autosomal means that the gene is not found on the chromosome pair that determines sex (XX for female or XY for male), but on one of the other 22 pairs.  This is important because it means hair color is not linked to sex in any way.

Recessive is a term used to describe an allele, and it means that the trait it produces is only expressed--you only see it--if the person is homozygous for that allele, that they have two of that allele.  The opposite is a dominant allele; this means that if you have one dominant (non-red) allele and one recessive (red) allele, you don't get red hair.  (There is also something called co-dominance, where both can be expressed--anyone with type AB blood is an example, because they have one A allele and one B allele.  For the curious, both A and B are dominant over the allele for O.  So if you have type O blood, you know you are homozygous for that allele.)

My guess is that of the three MC1R alleles that produce red hair, some produce more red pigment and some less, which would explain why some people are strawberry blonde and some flaming redheads.  I don't know which, if any, of these three red alleles might be dominant over the others, or even co-dominant; strawberry blonde might trump red-gold.  Since nobody probably knows yet, go ahead and feel free to give the children of any redheads whatever shade of red you feel aesthetically pleasing or appropriately symbolic.  Grin

Hope that makes it clearer, and not more confusing!

 

 

Re: Hair color and genetics

Thank you, thank you, thank you, Adaneth! That does make it clearer, and I'm glad I asked. Thanks to everyone who helped!  Smile

~MerryK 

 

 

Re: Hair color and genetics

But can one assume that the genes carried by Faramir and Eowyn are entirely the same as ours would be?  Faramir seems to be, physically and mentally, a Numenorean throwback, and in such people certain genes seem to me to be more fixed, like the famous dark hair and grey eyes, tallness, fair skin, and long life, ability to read the hearts of men and other possible psychic gifts, unusual stamina (especially the Dunedain of Arnor), that came into the Numenorean gene pool via elf-blood. 

 Eowyn also seems to have, physically, some Numenorean genes - she is described as resembling her grandmother Morwen in grace and height, not to mention being pale and slender. 

I think, as a fanfic writer, one doesn't necessarily have to be bound by the rules of normal human genetics, when dealing with either Faramir and Eowyn or Aragorn and Arwen, or Imrahil and his kids, etc.

Personally, in my own slightly sketched Fourth Age timeline, I have given Faramir and Eowyn three kids, semi-canonical Elboron (actually, I can't remember whether I had him blond or black-haired, but definitely grey-eyed), a black-haired grey eyed daughter named Miriel, and another daughter with blond hair and blue eyes.  I might add a fourth child, but am not sure. 

RAKSHA

 

 

Re: Hair color and genetics

I know what you mean, Raksha...I felt really awkward asking about the genetics of fictional characters. Laugh out loud

But one of the reasons that Tolkien is so wonderful, IMHO, is that his world is very realistic. Geographically, geologically, linguistically, etcetera. It seems a shame to take that wonderfully detailed world, if fantasy, and not do it justice in other areas. The more realistic a story is, the more I enjoy it. I love it when authors use herbal or medical knowledge that is relatively obscure, but accurate, because it makes the world all so much more real. So I like to return the favor and do my research if I can. But when it comes down to it, it's fantasy and that's my last excuse. Wink

~MerryK

 

 

Re: Hair color and genetics

>>certain genes seem to me to be more fixed, like the famous dark hair and grey eyes, tallness, fair skin, and long life, ability to read the hearts of men and other possible psychic gifts, unusual stamina (especially the Dunedain of Arnor), that came into the Numenorean gene pool via elf-blood.

Part of the reason for that would be marriage between relations. At some point in the history of Numenor, there was a proscription against marrying outside the line stemming from Elros (I haven't got UT at hand, but I think it's in 'The Line of Elros'). Even though we're dealing with thousands of years, the practice of intermarriage continued throughout, if not by law then by necessity: the only wife who would be suitable for a King/Steward would be one of the elite.

 

 

Re: Hair color and genetics

The Feanorian red-brown colour (it wasn't red, strictly, but brown streaked with red) is said to have been a Noldorin phenomenon, and associated with the followers of the Vala Aule. So possibly that particular shade arose simply from the mutagenic effect of hanging around a god.

 

 

Re: Hair color and genetics

So possibly that particular shade arose simply from the mutagenic effect of hanging around a god.

Laugh out loud

Maybe that's why Men shouldn't live in Valinor!

Ignoring "reality" (whatever that is) vs. following its rules is the distinction between Fantasy and Subcreation, Merry.  Have you read Tolkien's "On Fairy Stories"?

Unless you want to ignore genetics (which has no place in a premodern worldview anyway) and work from worldviews based on "blending" inheritance (which would explain why interbreeding with "lesser" folk dooms your children to inferiority in perpetuity) or the idea that every sperm contains a teeny-tiny human that just needs to be nurtured in the proper environment (which would explain why "wasting" the stuff has been discouraged by some)--or come up with your own inheritance mechanism--then Numenoreans have pretty much the same genes as ordinary folk, and so do Elves.  Now, they might have some really different alleles for a particular gene, but Tolkien himself allowed that Men and Elves were the same species.  After all, there's a 98% genetic overlap between us and chimpanzees, and the color of chickens is related to that same ol' MC1R gene.

It doesn't really matter what set of rules you choose to follow when building your world.  The important thing is for the rules to be internally consistent, or as consistent as you can make them.  And you have to respect the consequences of the rules you choose to follow.  It's usually easier to use the rules we know best and throw in a couple of curves, rather than make most of it up for yourself!

 

 

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