Life Science

Inuits live in very cold climates, why do they have dark skin?

- asks Anonymous

June 18, 2007
An Alaskan Inuk. [CREDIT: CULTUREBY.COM]
An Alaskan Inuk. [CREDIT: CULTUREBY.COM]

Despite the frigid, ice covered landscape of Northern Canada and Alaska, the Inuits remain warm beneath parkas of animal hide. Warm and…tan. Despite barely seeing the light of day, the native people’s skin retains a bronze glow.

Even in the early 20th century, scientists were trying to understand and map skin color. Felix Von Luschan, a doctor and anthropologist, created a Human Skin Colour Distribution containing 36 different color tiles to characterize skin tones. The further a person’s ancestors are from the equator, the fairer the person’s skin should be, according to his scale.

More recently, Penn State anthropologists Nina Jablonski and George Chaplin wrote in a 2000 edition of Science that there is a correlation between the skin color in people residing in an area for more than 500 years and their exposure to ultraviolet light. They even came up with an equation that determined the pigments of a population based on sun exposure and length of time spent living in an area. But neither their nor Von Luschan’s research answered the question of an Inuk’s bronze complexion without exposure to a great deal of sun.

Jablonski and Chaplin were onto something though, when they realized that the body’s interaction with UV rays from the sun, was tied together with skin tone. Skin color is determined genetically. Genes tell the body how much of the two types of melanin, the pigment that helps to determine the skin color, to produce. Pheomelanin causes reddish yellow pigments, and eumelanin gives deep brown coloring. But skin tone is not all genetic: more melanin is produced when you are out in the sun. Sunlight exposure causes the optic nerve to signal the pituitary glad to release more melanin. Thus, you tan.

Ultraviolet, or UV rays, from the sun are responsible for activating the melanin. As melanin levels rise and our body’s natural pigment darkens, protection against the sun’s rays increases. Too much UV exposure can deplete vitamin B folate –used by the cells to create DNA. On a smaller scale, the rays can also cause painful sunburns, with too much exposure leading to cancer.

However, UV rays aren’t all bad for us: they naturally convert cholesterol into Vitamin D, which is crucial in protecting the body against certain cancers, heart disease, diabetes, and mental illnesses.

When the ancestors of modern man separated from apes, they were covered in hair. Little UV light reached their skin and as a result, anthropologists believe they were fair skinned. As modern humans evolved however, their body hair became finer and thinner, leaving their skin more exposed to the equatorial sun. To adapt, thier bodies produced more melanin to protect them from damaging UV rays. Increased melanin made their skin become darker.

As early humans started migrating north into Europe and east into Asia, they were exposed to different amounts of sun. Those who went north found their dark skin worked against them–preventing them from absorbing enough sunlight to create vitamin D. To adapt, these humans started producing less melanin.

But Inuits vitamin D intake wasn’t dependent upon the sun. They get all that they need from their diet, heavy on types of fatty fish that are naturally rich in vitamin D. The plentiful amounts of the vitamin kept them from developing less melanin. In fact, before milk was fortified with D, people living outside of Northern Canada and Alaska loaded their diets with fishy products, such as cod liver oil, to get their daily supplement. So despite their chilly climate and lack of sun exposure, it’s the Inuit diet that has kept them in their natural glow.

Editor’s note: The content of this story has been changed based on a readers comment about the plural and singular usage of the word Inuit. Where ‘Inuit’ was originally referencing a single person, the world has been changed to Inuk.

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Discussion

74 Comments

Tyler says:

This is absolutely absurd. Vitamin D cannot and will not change genetic coding. It does not explain the Russian pigment or European pigment predominantly white colored. Furthermore, it does not explain why thousands of years have passed and yet these Eskimos who supposedly migrated to a cooler climate to get away from the sun are still dark skinned. If this were true and the exposure to the sun and vitamin D changed our genetic coding then these cultures today would be the palest humans alive due to their lack of sun exposure. Yes they eat fish and get vitamin D that way but not near enough what the sun provides. This is so dumb its laughable.

Fingal says:

I wouldn’t exactly call Eskimo skin ‘dark’ y’know. Colored sure, but not heavy in melanin.

trsystr says:

Tyler you didn’t read the whole thing, it doesn’t say anything like that

Von Dif says:

Forgive the typos, I was tying with my tablet. Here’s a rewrite:

Sometimes we should just learn to admit we are wrong or lack understanding. It seems like we want to have answers so bad that we create explanations that makes no sense but call it fact because “science” . It’s okay to admit that we don’t truly understand why some people are darker than others because let’s be honest, the Inuits shouldn’t be so melanin rich in that climate. They should have been just like the Europeans.

deriuqer says:

Just use google images and look up Inuit people. At least from what I can see is that on average Inuit people have about as dark skin as people from southern Canada, when you are talking about skin tone alone. Of course there are also Inuit people who have very light skin and very dark skin too. Historically Inuit people have a lot of connections to Yupik people, and people from Siberia, Russia. And were pretty different from Mexicans, and people from some parts of US and Canada. But are often times lumped together because they are from the same continent. Many people there have darker skin because their family had lived in a warm climate for many generations. In Inuit people, if you go back, there might have even been some connections to Turkic people and central Asia.

Even if the dark skin alleles were more prevalent in the Inuit population, it wouldn’t necessarily say that much. It takes over the course of thousands of years to completely change the skin color of a population, Inuit people came from the ancient Thule people, and before that their ancestors could have came from almost anywhere honestly. The only reason why no northern populations have very dark skin is mostly just a coincidence.

Skin color is a incomplete dominant trait. Which is when the trait is partially dominant and is expressed intermediately. If 1% a population in Siberia has the gene for dark skin, one in every 100 people would be born with a tan looking, medium skin tone. The chance of having two heterogeneous parents with a medium skin tone would be one in every 10,000. 1/4 of their children would have light skin, 1/2 would be born with medium skin, and 1/4 would be born with very dark skin. Dark skin is usually something you would not see in some populations, but the alleles are still there.

deriuqer says:

There are populations in Indonesia, the Pacific, and northern India, Myanmar, Nepal, and southwestern China that have high frequencies of both light skin and dark skin alleles. Often times a person might have very light skin but someone else in their family is homozygous for very dark skin. And this is not due to “admixture”.

Dale says:

This article seems to conflates cold temperature of the Arctic climate with sun exposure. Are there significantly fewer sunny days a year in the Arctic, bearing in mind the light months? Inuits are prodigious hunters, wouldn’t tan skin be a massive advantage when spending consecutive hours outside hunting? If it’s easy to get sunburn in from an afternoon of skiing, just imagine spending all day out in the bright tundra with no chance of shade or apres-ski refreshments other than seal blubber. No thanks.

Alex says:

The author should explicitly state that Vitamin D (really a hormone) enables the feedback pathway. Since the Inuits ate a diet rich in Hormone D the feedback mechanism did not kick in to lighten skin as much (transition factors as tribe moved North).

Sidra Ahmed says:

Theory 1:
Europeans became lighter skinned to absorb more sunlight for Vitamin D synthesis.

Fact:
The Inuit live in the same environment as Northern Europeans.

Expectation:
The Inuit should have the same color has Northern Europeans.

Fact:
The Inuit are darker than Northern Europeans.

————–

Yes, there is a discrepancy between our expectations and the actual fact. However, the actual theory proposed (that Inuit get Vitamin D from diet, and therefore did not become lighter) seems rather ridiculous. Norwegians have always eaten fatty fish (full of Vitamin D), yet they are still very pale. Perhaps the initial theory of whiteness as a Vitamin D adaptation needs to be revisited. There may be additional variables influencing the evolution of lighter skin.

James says:

This is a great example of selection and evolution. If a dark skinned population moved to the frigid north, we would expect evolution to favor the selection of lighter skin over time. Such that, given 500-1000 years, the population should be lighter on average. The selection may be on synthesis of vitamin D, as we know dark skinned populations become Rickets-prone without UV light to synthesize Vitamin D and calcium. Now if one population already has a source of vitamin D, through their diet, then there is no need for evolution to favor lighter skin. It will not be a selective pressure, so they maintain their original pigmentation levels despite hundreds of years in UV-limited region.

jhutter37 says:

The natural selection for pigment in skin has always fascinated me. My guess would simply be that natural selection didn’t have enough time to reduce the melanin in the inuit. Assuming the Americas were peopled 15k-30k years ago, it could be the case that they simply weren’t in that habitat long enough, like the native Europeans who were in their native habitat around 70k-100k years ago.

Gina Chicksi says:

First off, I am Inuit but that does not make me en expert. Here are some things I know though:
Most ‘modern’ Inuit people have only been in the region for a thousand years or less, descendants of the Thule from Alaska. Yes, the traditional diet does include vitamin D from animal sources. There is lots of sunlight in the summer, but there are so many bugs that skin has to be pretty covered up anyway. However, in winter although the daylight hours are short the sun gets reflected up again by the snow, leading to increased exposure on that small portion of skin that is not covered. More melanin could help to have less skin damage.
Also something that hasn’t been stated in this article or the comments is that pretty much all North American indigenous people have dark skin when compared to Europeans. The ancestors of the Inuit people did come from inland and further south originally. My guess is that we have darker skin simply because it’s a passed down trait with no evolutionary reason to have lighter skin.

You’re so cool! I don’t think I’ve truly read through something like
this before. So wonderful to discover someone with a few
original thoughts on this subject. Seriously..

thank you for starting this up. This web site is something
that’s needed on the web, someone with a little originality!

Don Davey says:

i have pondered this question for most of my 75 + years and never yet been satisfied with the present answers.

JILL Friedman says:

Inuits are not dark. They are not black or dark brown like sub-Saharan Africans. They are much lighter, tan or tannish and much of that tan is from the sun.
Keep in mind that much of Europe was densely forested, unlike the arctic areas which are open to the sun, and the snow reflects the sun. And summer can be very sunny with little shade.
Evolution happens through random mutation. Populations in similar environments won’t be exactly the same, but there are patterns. There is a general corellation of latitude and pigmentation.

Inuit Indians are the same color as some groups of people in Sub Saharan as the Bushman,and they have similar eyes and Mongolian chinese Asian features. They have brownish medium yellow and light brown skin. When Matthew Henson and Perry reached the Pole the Inuit loved him because of his color. They called him brother and cousin. They originated from darkskinned races.

Brian Peterson says:

Just to clear up a misconception – several comments seem to indicate that sunlight somehow caused a change in skin color. It seems reasonable darker skin is an ancestral trait retained from the native further south (as Gina implied). In the small amount of time, selection hasn’t been strong enough to confer a significant advantage for extremely pale skin, potentially due in part to consumption of vit. D rich foods.

During summer, there is plenty of UV exposure glaring as light reflects off of the snow, so dark skin can be an advantage here.

Also, there is the concept of genetic drift to consider – if immigration is fairly recent, there might be some amount of random chance in the alleles that migrated north. This, coupled with weak selection gives the Inuits darker skin on average than the Europeans -> Danes/Swedes -> Celts, but lighter than Africans.

Is everything explained by an dietary source of Vitamin D? No, but couple that with a host of other factors and it seems reasonable that there is some contribution.

Brian Peterson says:

I meant to add “caused a change in skin color on the DNA level”, since we know that sunlight can cause skin tanning.

Crosby Beene says:

Ricardo is correct regarding the color of the Inuit Indians. Martin Frobisher, an English explorer, made three voyages, in 1576, 1577, and 1578, into the subarctic ice of Bafflin Island, mainly exploring the inlet that has since been named Frobisher Bay in his honor. The most vivid description of Frobisher’s three voyages are from the hand of one of his captains, George Best, in an account published in 1578, over 440 years ago. Best’s description of their color was likened to the color of a ripe olive. This certainly is a definitive eyewitness color description of the Inuit Indians, hence, the indigenous people who they encountered were black. In fact, George Best goes on to reject the premise of climate as a cause of skin color.

Bubes says:

So white people never consumed fish? How do you explain dark skinned south Africans and dark south Americans not very far from Antarctica? It’s freezing there!!!

sarah says:

The notion that a seafood diet plays into this is absurd when you consider the high seafood intake (thus dietary Vit D) of many very light skinned people (British Isles, Scandinavia, etc.). Curiosity brought me to this article, but the readers’ comments were much more helpful than the nonsense in the article. I don’t see any citations, so clearly this is not scholarly research–and seems like poor journalism as well.

Lee Loxleigh says:

This article, although interesting, shows that what science is trying to tell us, is in itself unscientific. When you read the article it clearly states, that skin colour becomes darker the hotter the climate, in layman’s terms. And that Inuits have retained said color from eating a rich vitamin D diet. Fair enough, until you start to think about it logically.
So logically speaking, Scandinavians equally have a fish diet. And are, well… White. Also it does not answer the question of, after 500 years plus, of white Europeans living in hotter climates, why have they not naturally become darker over this period of time. Europeans still have European white babies, still have little to no natural protection from skin cancer, and the list could go on. It also doesn’t address other dark skinned people that also are indigenous to very cold northern regions, and unlike the Inuits have a diet with far less vitamin D.
All in all the math, theory and science does not add up. Very good if you wish to teach the masses simplistic science, but sometimes you get more respect by saying that you just don’t know.

James Nicholls says:

I think the reasons could be that white people evolved in caves whereas the Inuit people didn’t use caves and were still exposed to significant sunlight during the daytime. In a cave there wouldn’t have been any daylight at all and ancient Europeans during the Ice Age would’ve of course used caves to congregate and hide from wild predators and to also help keep warm. Also it’s possible the Inuit people’s ancestors came from East Asia right after the end of the last Ice Age, this is another theory which may explain why the Inuit people look so East Asian in appearance.

Joe says:

seems like cap

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