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Post by darksphere on Apr 12, 2004 9:07:59 GMT -5
I'm looking for information about basic facts regarding mainly haircolour, eyecolour and skincolour.
I allready know a deal about this but there seem to be some inconsistencies and questions unanswered that I would like to find some kind of explanation on.
these are:
1. How does suntan come about, is it possible for all people to become suntanned and does the suntan arise from production of pheomelanin or eumelanin?
2. I've heard somewhere that only one pigment is defining in regards to human hair colour but then wherein then lies the difference between eumelanin and pheomelanin? What I mean is: Are they only considered subdivisions of melanin which is then the one pigment? Or are they each pigments in their right?
3. I've read somewhere that skincolour is decided by the amount of eumelanin in the skin whereas a combination of eumelanin and pheomelanin decides the hair and eyecolour.
Is this true(thus meaning that there is no pheomelanin in the skin)?
So if you can answer these questions or can provide me with links to sites that may answer the questions then I would be grateful.
PS: Maby thus subject seems to maby have been more appropriate in the anthropology section since my questions do not relate to genetics but I have experienced that this sort of questions ussually end up concentrating on the genetic level. Hence I've posted it here in the "genetics"-section.
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Post by sbutalia on Apr 23, 2004 23:24:51 GMT -5
i really dont know enough to answer ur questions.. i have a sort of follow up one though... ever notice how even tanned caucasians are a 'different' color than tanned lets say persians... im just curious to why the colors are different if technically u could say that they are very near each other....
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domii
Full Member
Posts: 170
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Post by domii on Apr 24, 2004 3:09:26 GMT -5
^^ well Iranian are caucasians, so I guess you meant Europeans. From what I know skin colour is detrmined by the amount of melanin in it. the more melanin, the darker the skin. Iranians have more hence thier brownish skin. en.wikipedia.org/wiki/Melanin
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Post by Graeme on Apr 24, 2004 9:00:00 GMT -5
darksphere, I resisted answering your question because I thought that I have seen it before in other forums; I am suspicious, but here goes.
Melanin has two chemically distinct forms: eumelanin, the main pigment involved in skin, eye and hair colour, and phaeomelanin a minor pigment found mainly in hair, but not eyes and only in tiny amounts in skin. Eumelanin is brown and when densely packed absorbs all light producing a black effect. Phaeomelanin is a minor pigment and is red to orange in colour and found with eumelanin, but in smaller amounts and is generally masked by eumelanin. Phaeomelanin is found in hair and gives it rufous shades. Redhair is the result when eumelanin is found in tiny amounts in people with a high amounts of phaeomelanin in hair. Eumelanin is produced in melanocytes and the melanocytes can, in most people, be stimulated by UV light giving a suntan. Eumelanin is protective against the harmful effects of excessive UV light such as sunburns, excessive heat gain and cancer. Phaeomelanin has no useful properties and is incapable of being stimulated to produce more by UV light. Fleckles occur in those people with very little, but patchy deposits of eumelanin in their skin. Phaeomelanin in not present in the iris of the eye, in skin it is rarely present and skin colour is due mainly to the eumelanin concentration. Skin is a horny deposit of dead cells composed of keratin which is yellowish. Carotene contributes to skin colour especially in women, it is also yellowish and the reddish effects of blood seen through the skin. Women have on average less eumelanin in skin than men in all races. Eumelanin takes a while to be produced in newborns and increases with maturation hence the blue eyes of newborns and the blond hair of many children which later darkens.
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Post by darksphere on Apr 24, 2004 10:48:29 GMT -5
darksphere, I resisted answering your question because I thought that I have seen it before in other forums; I am suspicious, but here goes. I haven't posted this question on other boards or if I have it must have been years ago cause I don't remember. Since you mind seeing the posts on other boards I guess you're thinking of Stormfront or Skadi or some such place. I'm sure I haven't posted the question there. I would be very suspicious of the answer that people there might give. Phaeomelanin in not present in the iris of the eye, in skin it is rarely present and skin colour is due mainly to the eumelanin concentration. Thank you. That's what I really wanted to find out because I have heard diverse answers to this. The rest(besides the carotene thing) I knew but thanks for the exhausting answer anyways. I'm very interested in the way skin, eye and hair-colour fit together. Hair and eye-colour I have a rather good understanding of by now but skin-colour is hard to find out much about and it appears it is a far more complex issue than the other two. Not so surprising I guess seeing as the melanocytes in the skin are so much more reactive. In reality I don't think scientists understand the processes behind skin-colour thoroughly allthough the development has been great these last years. Phaeomelanin has no useful properties and is incapable of being stimulated to produce more by UV light. So they say. I'm not so convinced though. It's my view of nature, which i don't think does things for no reason, I guess, that prompts me to be suspicious of such a claim. Scientists would never judge a trait in an animal meaningless. Even if it didn't have what one would call survival value it would be seen as stemming from some reason. It's only in humans that scientists often say that this or that trait is just there for no particular reason. Carotene contributes to skin colour especially in women, it is also yellowish and the reddish effects of blood seen through the skin. That's interesting. I've only heard of carotene as a factor in skin-colouration in a Coon-quote(and at what you would call "a suspicious place" at that) so I figured it to be outdated. Knowing that not only melanin is involved should make it easier to understand skin-colour for me, I guess. Thanks!
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Post by darksphere on Apr 24, 2004 11:02:57 GMT -5
i really dont know enough to answer ur questions.. i have a sort of follow up one though... ever notice how even tanned caucasians are a 'different' color than tanned lets say persians... im just curious to why the colors are different if technically u could say that they are very near each other.... Yes that's one of the things that I had hoped the answer to my above questions would explain. It's a thing that just goes to show how complex the processes behind skin-colour are. I thought that maby people with a certain skin-type produced more pheomelanin than eumelanin when tanning and that could be the reason why people look different even when tanning. But according to Graeme in his post above pheomelanin cannot be stimulated by sunlight to produce more. So instead I suppose it must be the distribution of the eumelanin in the skin that different shades of tanning. Here is a chart I have found relating to skin-colour and tanning: It works with 6 types of skin. It's used by companies who produce sun-block and such rather than from independent scientific sources. So without a doubt it is very superficial.... The chart: Type 1: Always burns; never tans; sensitive ("Celtic") Type 2: Burns easily; tans minimally Type 3: Burns moderately; tans gradually to light brown (Average Caucasian) Type 4: Burns minimally; always tans well to moderately brown (Olive Skin) Type 5: Rarely burns; tans profusely to dark (Brown Skin) Type 6: Never burns; deeply pigmented, not sensitive (Black Skin)
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Post by Graeme on Apr 24, 2004 11:20:43 GMT -5
I have to tell you that I have taken an interest in phaeomelanin as redhair crops up in my family. I have dark brown hair with red undertones, I don't tan just blister turn red and flake for days, I have had skin cancer three times, basal cell, and my children are redhaired. I was born in Southern Europe and live in sunny Australia. The lack of tanning is a Keltic thing. What nature does is not always useful, adaptive or beneficial, for example, albinism, giantism, down's symdrome. Redhair with its accompanying non tanning skin in misty, cool climates allows maximum UV penetration and production of Vit D. In that case it has protective qualities, but in sunny Australia and with good diets its possession causes sunburnt, cancer proneness and premature aging.
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Post by eufrenio on Apr 24, 2004 12:53:03 GMT -5
You´d most likely have had skin cancer in your native Malta as well. Did you use to spend a lot of time outdoors with little protection, I mean just in a bathing suit?
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Post by murphee on Apr 24, 2004 13:08:27 GMT -5
I am interested in the subject also. I am Type 1, a person who cannot tan at all. My hair used to be red, but with aging, it has turned platinum/yellow-blonde. I cannot take any sun, and when I go outdoors, I wear sunblock, a hat, and plenty of clothing. An advantage of this is that I show no signs of photoaging; my skin is as smooth and unwrinkled as it was at age 20. When I was a kid in the Sixties, all the other children had deep tans in the summer and I felt like a freak.
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Post by Graeme on Apr 25, 2004 7:57:53 GMT -5
In Australia until recently the "slip, slop, slap" message of wearing hats, sunblock and UV proof clothing was not taken seriously. Australia has a high rate of skin cancer. I have lived in Australia on and off most of the time, and I was exposed to intense sunlight from childhood. The skin damage that leads to cancer takes 20 years to develop. Most Maltese people avoid the sun and consider brown skin ugly, but in Australia it is "mad dogs and Englishmen....". Also being outdoors, swimming, boating, playing sports and being close to the sea is a big thing in Australia. Sunlight in Australia is very intense and hard to avoid. Also being a Southerner it took me a long time to realise that I did not have a typical Mediterranean person's skin colour. In Australia anyone with dark hair is thought of a being dark skinned also. I thought I had a type 4 skin when actually I am type 1. Had I stayed in my native country I think I would of had a Maltese attitude to the summer sunlight and would never have been sunburnt or developed basal cell carcinoma.
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jul
Junior Member
Posts: 80
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Post by jul on May 15, 2004 4:02:34 GMT -5
When I look at the list of skintypes above i truly feel like a freak again. My mother in Law(who runs at this times a sunstudio) considered me-as the most people do-as type 1. (i do have freckles and even in summer most light skin) But it can be true because i have just two times in my life a sunburn. Once as i was a child(and my mom got confused with creames-so she uses normal creme as sunprotector) and once with twentytwo. But no sunburn no tanning happend it just do barely effect me. If i tan what takes normally a few weeks not days like most people i know, its bronze/olive beige not brown.(so odd that it look in bad light kinda greenish.) So may its some intermediate skintone between type one and 3? no clue.
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Post by darksphere on May 18, 2004 4:47:46 GMT -5
When I look at the list of skintypes above i truly feel like a freak again. My mother in Law(who runs at this times a sunstudio) considered me-as the most people do-as type 1. (i do have freckles and even in summer most light skin) But it can be true because i have just two times in my life a sunburn. So may its some intermediate skintone between type one and 3? no clue. Like I've mentioned this list of skintypes is used by beaty agencies and various companies rather than by indpendent scientists. So it's probably highly superficial... it must be, seeing as hair and eyecolour are much more complex than that and all scientists I've heard says that skincolour is more complex than both these. I also have noticed that a dark base colour does not nescessarily go with a good ability to tan just as a person with a light base colour may tan well. Of course the general picture is that people with light skin can't tan while people with darker skin can. But this isn't allways the case...
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Post by darksphere on May 18, 2004 4:56:47 GMT -5
What nature does is not always useful, adaptive or beneficial, for example, albinism, giantism, down's symdrome. I know that what nature creates isn't allways beneficial. But even when it isn't it seems to arrive because it is nescessary for something which is beneficial. Downs syndrom is surely not a beneficial trait but it is none-existant in animals. So it can be seen as a symptom of the large and extremely complex human brain which I guess must definitely be seen as a beneficial trait. So seen on a species level it is beneficient: It's much better for all in the species to have a large brain and then a few has downs syndrome rather than nobody having a large brain and thus nobody having down syndrome.
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Post by Cerdic on May 28, 2004 2:34:04 GMT -5
No mention of eye colour, so I'll give it a go.
The iris is a muscle with radial and concentric muscle fibre sheets. The variation in colour is really an illusion (much in the same way as iridescence in bird feathers, or butterfly wings), there is no variation in the brown pigment (melanin) found in the iris. The variation in colour is due to the interaction of the tranlucent muscle fibres and at what depth (from front to back) in the muscle the melanin is concentrated.
So a person with very little melanin mostly found in the rear layers of the iris will have blue eyes.
Someone with a lot of melanin, but only in the rear layers will have dark blue-violet eyes.
Someone with small amounts of melanin in the rear and middle layers will have light grey eyes.
Moderate amounts in rear and middle layers will have darker grey eyes.
Moderate amounts thoughout will have hazel eyes.
Slightly larger amounts throughout will give medium brown.
All the shades of eye colour are brought about by a combination of the amount of melanin and its distribution within the layers of muscle in the iris.
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Post by buddyrydell on May 28, 2004 21:53:17 GMT -5
How exactly is hair color inherited? I know that dark eye colors are dominant genetic traits whereas a trait such as blue eyes is recessive but crops up if the trait exists in say, the dark-eyed parent's genes, but how does hair color work? I also have heard that the reason hair darkens with age is because of the increased production of hormones during adolescence. I would greatly appreciate someone's input here, thanks!
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