Now we all know richly pigmented skin and dark eyes are more resistant to sunlight. So that's why people are black in Africa (no, they haven't been burned by chariots of sungods ). Ok. But what about being white, and light eyed. What is the advantage? Why not just be black as well? After all, the sun shines 12 hours a day on average in every spot of the planet, and it may be colder in europe, but being blinded by a low sun isn't all that either .

Brown eyes were first, and still blue eyes developed (even though brown eyes are dominant genes). Why?

Ask God why made this improvment.

I think it has to do with the weather and the locations. Hence the genetical differentiation. Same thing, why do asians have those «stretched» eyes or the indians red skin?

About advantage or disadvantage, I don't know. I just see it as diversity.

Ok, the vitamin D part makes sense. Still to be figured out is the light eyes then.

I knew about the dominant genes, that's what made me wonder. Because (I believe) humans started off brown eyed, and then they seem to have developed light eyes, even though brown eyes are dominant.

More sensitivity to light may be an advantage, but the sun shines everywhere just as much (on a year's average), the only difference is the angle, which is smaller in the parts with light eyes, suprisingly to me - because you get blinded by that more easily (and also the reflection on snow (where applicable) is a force to be reckoned with, as it causes snow-blindness).

Consider how many Red Haired Whites would survive, 3 months in the Äquator Area.

But why have the Whites, different hair colours (Red, Yellow/Blond, Brown and Black) and all others have only black Hairs.

Yes some Nuances but instead black, dark-brown, but not from Red to Brown or from Black  to  Blond.

Do you know, that a lot of Persians have, blue eyes and blond hair if they are children and with the progress of the adolescence they got darker and darker until they look like, a mix of Blacks and Whites.

The light factor on eyes seems strange.  If you think about it the darkest places year-round would probably be deep jungles and rainforests.  To me it seems the best explanation is isolation where genes can spring up, without re-assimilation.  Over time you get diverse areas.

The benefit may be, like Cywr wrote, that it probably made it easier for people to see in the dark during the winter. In most parts of Scandinavia we get at the most 7 hours of daylight, or less, per day at wintertime. Some parts don't get any daylight at all. So in order to be able to survive people had to learn how to see in the dark. I guess that is one possible explanation to why we have light eyes.

The winters may be darker, but that still means you get very long days in summer, and the more north and into the mountains you get, the greater the danger of snow blindness, and as lennel pointed out, rain forests etc. must be alot darker. The beams spread out like Cywr said, but I don't think that compensates this all the way. A low sun is also more annoying when you've light eyes. So maybe it is just a random genetic difference because of some degree of isolation, although I wonder why many people consider blond and blue eyes attractive (to me it seems it has some biological benefit then).

I did hear all babies are born blue eyed. But I don't think I believe that...

Originally posted by Cywr A low sun is also more annoying when you've light eyes. How do you know?

http://www.facade.com/celebrity/photo/David_Bowie.jpg - David Bowie told me

1. It is something special, what the most people do not have

2. Yes that is true, but have all babies blue eyes or only white Babies?  Because the Turks/Mongols/Tartars have as babies blue asses

The Question remains why have only the Whites, lighter Eye and Hair colour, why not Eskimos... is this because the Whites live much longer then they in the North?

yeah, that's what I figured, I can't imagine black babies being born with blue eyes (though it's not impossible).

Weren't the Eskimos (Inuit for nitpickers) up there first? Hmm nice point though, I think this is because both peoples are adapted in different ways - they're, on human scale, rather unrelated, and have both developed different features (uninfluenced by each other), to cope with the environment. So in the end they're both adapted but according to different strategies. That's my best guess..

Actually, there is still not 100% agreement among physical anthropologists about the causes for different skin pigmentation in humans

The most commonly accepted theory is the one Cywr mentioned: sunlight would dictate the skin tone by two mechanisms: light skins in sunny climates are affected by sunburns and higher frequency of skin cancer; dark skins in less sunny places would not be able to sinthetize enough precursors of Vitamin D, so to cause skin and bone illness for the lack of this latter.

Above is the famous map of human skin pigmentation collected by R. Biasutti for native populations prior to 1940.

We can certainly notice that, at least qualitatively, it seems to confirm that theory, since people with more intense pigmentation are predominantly located in the tropical/equatorial belt.

This scheme works very well for the Europe+Africa+Mid East+India Area.

It's worth to mention the fact that just above the tropics, where  sunlight dramatically changes during the year, people developped the ability to vary the skin tone by tanning. The ability to tan varies, and is particularly strong in the Mediterranean basin. Here follow some examples:

http://img9.imageshack.us/img9/7317/cucinotta-natural-2.jpg">   http://img27.imageshack.us/img27/6417/cucinotta-tanned-2.jpg">

Maria Grazia Cucinotta (Actress, Sicilian)

Carla Collado (model, Spanish)

Evelina Papantoniou (Model, Greek)

[I confide these examples helped to keep my readers attention]

In the Americas (please remember, only Native Americans/Indians/Indios are considered here, not last few centuries immigrants), a milder version of that same pattern is visible. This can be explained with the fact that Americas have been inhabited for a lot less time than the old world, and you need many many millennia for natural selection to operate.

Please consider also that the advantage or disadvantage for having or not the right skin tone for a certain environment is just marginal, so adaptation has to be rather slow.

However the Est Asia-Pacific region is quite puzzling. Most places in this area have been inhabited for very long time, and yet 1) Malaysians and Indonesians, while darker skinned than other East Asians, are not as dark as other peoples living at the same latitudes; 2) Australians aborigens are nearly as dark as Africans . . . but they are too at South! How comes they did not lose pigment? 3) most East Asians are approx. pigmented the same way, even though they live at fairly different latitudes, and certainly should have had the time to adapt.

It's certainly strange that, if extreme skin depigmentation (with the probably useless but genetically linked hair and eye blondism) is so useful to live in the North of the planet, it never diffused in Asia.

It's also peculiar that, even where blondism is common, it always co-exists with brunet and intermediate types. If it's necessary to be blond or red haired, blue or grey or green eyed, why is not everybody so?

Well, more recent studies put in evidence that, while light skin do suffer when exposed to intense light, the correlation between little light and need for depigmented skin is less strong.

For instance, the a/m inuits (eskimo) are certainly relatively dark-skinned for their environment: however, they eat a lot of fish, seals and other animal food that supply them of the necessary D vitamin.

Moreover, it has been proven that a dark-skinned person who lives in Scandinavia, while not being able to produce enough D vitamin during winter time, can produce a lot of it during summer, and since D vitamin endures for long time in the organism, the summer-produced reserve is more than enough for the whole year. That, of course, providing that that black person is exposed to sunlight for enough time during summer.

In other words, the problem of dark skins in low-sun places can be overcame by culture.

But then, where does European blondism (as well as the incipient blondism that can be found in other neighbouring populations, like North-Africans, Mid-Easterners and even Indians, as Cywr mentioned) comes from?

Well, some researchers suppose it's just a mutation (a sort of mild albinism) that, for some not well known genetic reason, is common among so-called Caucasians. 

Without check it would tend to spread since all Caucasians and near-Caucasians where blond, pale and blue-eyed; however, sunny environments keep it under control

Where the sun is not so scorching, fair and red heads have no problems (and even a mild advantage at generating D vitamin), so they spread, but always mixed with black or dark brown haired and eyed people, whom the selective pressure is not able to eliminate.

I wish I still had the link. It's much better explained.

According to the person who wrote the article mentioning this theory, Europeans were initially brown-skinned (as a matter of fact, he claims that everyone was brownish/reddish skinned). This was while they were hunter-gatherers. Then agriculture came along, and Europeans did not have the dietary source of vitamin D, so they began to have gradually whiter skin. The eskimos - according to the man - are darker than Europeans because they consume a lot of vitamin D with their food.

Go search Google. There's a better explanation

I don't believe entirely on that map. Look at Asia - according to the map all asians have equally dark skin, which is not true since there are huge variations (uighurs and mongolians are darker than the average chinese etc). Also it shows the sámi as asians (look at the Kola peninsula) and that's not true either

Not Asians then, but it's wrong anyway. There is no skin-tone difference between nordic poeple and sámi, but there is a difference between sámi and asians

And the Eurasian map ought to show more variations, according to the map tibetans and spanish poeple have the same skin tone... Well I've never seen spaniards with this skin:

http://www.talismanpress.com/images/photos/tibetans_GH.jpg - http://www.talismanpress.com/images/photos/tibetans_GH.jpg

http://wyprawy.net/img/chan2003/kirgiz.jpg -  

Well according to the map, these guys have the same skintone...

Yeah right!

I wonder how you read the map, Mangudai?

The map indicates 12-14 green in both Northern Norway and northern Algeria-Morocco

I se my map caused some rumor. Strange, since it's been very common  material among physical anthropologists for some decades. You can find it on many websites, for instance.

However, it's just a sketchy and approssimative breakdown. Please consider that each color on the map coresponds to 3 to 12 different skin shade (as defined in another old and well known table . . . have a google search and you will surely find it), to the average skin tone of a certain area (tones can differ a lot in the same area!), to untanned skin (in some populations, like Mediterraneans, skin can be even 7 or 8 tones darker when tanned!), that it ignores differences between tones due to melanine and to other pigments,like carotene (which givew yellow-reddish shades) etc.

However, if someone can find (or create!) a moe precise map, feel free to post it . . .

I found this map, wat do you think of it..?

well, for first you should better save the picture on your disk and than upload it here using the new features of this forum, since the original site does apparently not support hotlinks (I just see a big "Angeltown" icon there)

However, I went to the original page, following the link . . .  and I know that map.

Please notice it's not a map of skin tones, but of ultraviolet light at different locations.

Skin tones are just added, for comparison, in an even more skecthy way then in the map I linked, i.e. as three different areas, for dark, light and "possesing the greater potential for growing lighter or darker seasonally" -- it's the fact I mentioned in my previous posts, according to people living at intermediate latitudes are the most able to tan.

I'd say that the map you presented is intresting when seen together with the one of Biasutti I linked, since it supports the thesis acording to which in some areas skin tones reflect very closely the UV gradients, and in other ones they do it less well.