Is white skin a Neanderthal trait?

Factual Questions
1

Subject says it all really, but just to expand a little:

It seems to me as a layman that whiteness is more likely to have evolved within the Neanderthals, who inhabited areas where white skin would be an evolutionary advantage for hundreds of thousands of years before the two species met, or perhaps even predecessor non-African species. Neanderthals would then have interbred with Sapiens, producing offspring with ever-lighter skin.

Humans have been in the Americas for over 10,000 years, perhaps 20,000, and tropical Americans aren’t even significantly black.

I suppose a start would be learning if the genes that control skin colour have been found.

I know this is a sensitive subject but I’m hoping to keep this in GQ.

2

The idea isn’t impossible, but there is no obvious evidence or reaosning behind it.

White skin itself doesn’t objectively exist. Human skin colours form a perfect spectrum from the palest to the darkest with no dividing lines of any sort. The only skin colour that forms a distinct cluster is that of the San of southern Africa. Everybody else is a mutant descendant. So if pale skin came from Neanderthals, it managed to spread across the entire globe with the exception of southern Africa. That’s not impossible, but it isn’t immediately clear that it’s consistent with a Neanderthal origin.

Then there is the problem that humans and Neanderthals only overlapped in a few places that we now of, notably in the Middle East and in Southern Russia. Neither of these are places known for inhabitants with especially pale skin. So if pale skin did come from Neanderthals, it migrated North with Sapiens and died out from the areas that Neanderthals existed. Once again, this isn’t impossible, but it’s not evidence of a Neanderthal origin either.

The next issue is that Australian Aborigines lived in environments on the same latitude as New York or Spain at the height of the last ice age and for at least 10, 000 years before. They never evolved light skin any more than tropical Americans evolved dark skin. All this doesn’t prove very much at all except that skin colour really isn’t as plastic as people often assume it, nor is it as large a survival trait as people often assume it is. There’s no doubt that it is somewhat plastic, and that it offers some survival advantage, but either plasticity or advantage is so low that it doesn’t alter in over 20, 000 years at latitude lower than those at which humans an Neanderthals predominantly overlapped. Once again, this doesn’t prove that white skin isn’t a Neanderthal trait, but it does indicate that Neanderthals didn’t need white skin to survive in Ice Age Europe.

3

Sub-Saharan Africa, you mean. Then there’s southern India and Australia.

They’re pale compared with black Africans.

Well yes. Hence my thought that white skin might have come from elsewhere. Do Australians have as much Neanderthal DNA as Europeans? Or indeed any? Wasn’t Homo Erectus the dominant hominid there before Homo Sapiens appeared? You could imagine a branch of humanity spreading from Africa Eastwards along the coast, leaving stable populations on Sri Lanka and Australia, perhaps interbreeding with Homo Erectus along the way.

Is there any evidence of this? Have Australians been tested for Neanderthal DNA?

4

No, I mean what I said: Southern Africa.

No, Indians and Australians are part of the same skin colour spectrum as Europeans.

What does that mean? Who are these “black Africans”? If you mean that they are paler than the darkest people on Earth, who happen to live in Africa, that is true. If you mean that they are paler than all people in Africa, that is clearly not true.

I don’t quite follow.

You say that the fact that Americans, who’s ancestors never interacted with Neanderthals, never evolved dark skin is indicative that White colouration comes from Neanderthals, and you also say that the fact that Australians never evolved pale skin is also indicative that White colouration comes from Neanderthals.

It seems to me that all this indicates is that skin colouration is not especially plastic or environmentally selected, and that people with pale ancestors retain pale skin, and people with dark ancestors retain dark skin regardless of environment.

We have no idea, since we have no idea how many Europeans have Neanderthal DNA, or in what proportion. For all we know Australians are genetically 99% Neanderthal and Europeans are 1%.

Nope.

That’s possible, even probable. But I can’t see that it really has much relevance to the topic of this thread.

5

Really? Both look pretty black-skinned to me.

I’m thinking of sub-Saharan Africa. From the far West coast down to the Cape.

No, I’m not saying that at all. Given that the migration point was the northern latitudes, I expect that there was interbreeding. Has there been any genetic testing done on this?

No, I’m not saying that at all. I’m noting that Australians are currently black and wondering if they have any Neanderthal DNA.

Then why are there no aboriginal whites in Africa?

I thought some testing had been done.

6

You may find this interesting:

Complete article here:

This isn’t my field of expertise (not by a long shot) but I was under the impression that white skin developed in northern Europe, where presumably where the cold weather helped select white skin related to the absorption of sunlight for vitamin D production. This seems to me to contradict your neanderthal hypothesis.

7

That’s because some of them are. That doesn’t mean that they don’t form a spectrum with other people who are not.

In that case you are incorrect. The Sanof Southern Africa are not especially darker than the Portugese, and not at all darker once you control for sun exposure.

No because there is virtually nothing to test on. We have fragments of Neanderthal DNA from a handful of individual. It is theoretically possible that you have 99% Neanderthal DNA and we would never know it no matter what tests we did.

We can establish that some people do share some genetic material with some Neanderthals. What we can’t say is how much genetic material an average modern population shares with all Neanderthals, which is what you are asking.

We don’t actually know. As you note, there are plenty of pale skinned people living in the tropical in Asia and the Americas, and the San did quite well in Tropical Africa before the Bantu explansion, so climate clearly isn’t the whole answer. In fact skin colour only maps very poorly onto climate.

At its most extreme “White” skin probably presents some evolutionary disadvantage outside of high latitudes, but that doesn’t explain its distribution. It’s probable that white skin evolved just once in North Western Europe, and there has never been any overwhelming migration that enabled it to spread the way that the Bantu expansion allowed the spread of Black skin into Southern Africa.

Some has been done, but not enough to answer your questions.

To give an analogy, imagine that we found a fragment of clay tablet from 10, 000 years ago with a picture of a bull and a word under that picture, and a picture of a cat and a word under that picture. If we compare those words to the words for “bull” and “cat” in a modern language, and “bull” is the same word and “cat” is not the same word, then we can conclude that the modern language has some heritage in the 10, 000 year old language. But we can never say how much commonality it has. For all we know, the languages could be identical with the exception of the word “cat”. Or it could be that the word “bull” is the only similarity that remains. Or it could be anywhere in between. We can never know.

That’s the situation we are in WRT Neanderthal genetics. We have fragments of DNA, and some of those fragments correspond to modern human genetics, and some do not. But we have no idea what 99.99% of Neanderthal DNA was like. For all we know the only similarity between Neanderthals and Europeans is in those sections for which we have Neanderthal material, and everything else is utterly different. And for all we know Zulus might be 99% identical to Neanderthals, with the only difference being in those regions for which we know the Neanderthal DNA doesn’t match. Or vice versa. We just don’t have near enough Neanderthal genetic material to say anything except “there is some commonality” in some individuals.

8

This bit may be of interest too:

9

Actually, the most interesting part of that is the accompanying graph of skin colourings which shows that there are black native Americans. So the answer to my query is clearly, ‘No’.

10

Actually, skin tone varies quite a bit, even among northern Canadian natives. I was at a lecture once where an aboriginal playwright discussed the detail that on some reserves, the darker-skinned tribe members are nick-named “nigger” (yes, it is meant to be as derogatory as it sounds).

OTOH, many Japanese skin tones are pretty much the same as Europeans.

As I understand it, the process is pretty straightforward. melanin production is controlled by a significant number of genes, so unlike say, eye colour, it will appear to “dilute” with cross-breeding between people of colour if those colours are different. More melanin - protection against skin cancer and other problems; less melanin, more vitamin D production where it could be needed. (One WAG -wild-assed guess - is that male pattern baldness is a similar adaption, we men get more vitamin D to stay “healthy” as our ability to hunt and gather it diminishes, while women do not need that survival trait once their fertile time is behind them).

The Australian aborigines can be about as dark as many of the sub-sahara Africans, but they didn’t just arrive in Australia 40,000 years ago from the neighbourhood of Siberia - presumably their progress was across the Middle East, etc. so they had significantly longer to adapt to tropical needs. In Australia, the majority lived unclothen in bright deserts, hence the advantage to retaining that coloration. Tropical native American Indians, OTOH, have only been there about 14,000 years and DID arrive from the arctic environs.

That’s another issue - Arabs, for example, may live in the tropics, but like mad dogs and Englishmen out in the noonday sun, they cover up quite a bit - so there is less tendency for skin colour to be a survival trait. Technology overcomes environmental pressures. OTOH, places like Florida and Australia do report higher rates of melanoma for caucasian inhabitants, I seem to recall reading.

11

But aren’t humans more than 95% genetically identical to chimpanzees? If so shouldn’t modern humans and Neanderthals also share that genetic heritage?

12

Different standards of “genetically identical”.

Humans and chimps share 95% of their genes and gene loci. Basically, the sequence that tells the human arm to grow thumb is the same as the chimpanzee gene and located in the same place on the chromosome.

IIRC humans and chimps only share about 60% of gene *alleles *and non-coding DNA. IOW, while the gene tells the arm to grow a thumb, the human version is in American English and the chimpanzee version is in British English. The instructions are the same to the point of being mutually intelligible, but the precise language varies somewhat and the punctuation is quite different. In contrast, humans share something in the order of 95% commonality in alleles and non-coding sequences. We are, of course, effectively 100% similar in terms of genes and gene loci.

13

Back to the OP, “white” is not a skin colour. Whitish flesh colour is an absence of melanin. The human genome contains multiple sites where melanin is produced. If any one of those sites fails to work, less melanin is produced. If less melanin is produced, that may or may not be a survival trait depending on environment. In some environments, only a little melanin is needed, produced on demand and eventually fading seasonally. In other environments, it has been a necessity.

Over time, mutations (bad transcription) may cause the melanin genes to stop working, one by one. This takes time, so it is not surprising if a group migrates to a new environment and could take dozens of millenia to fully adapt. I get the impression that melanoma was not a huge health problem for early man, where various diseases and other factors would generally dominate mortality rates - hence the much slower adaption rates.

But, there’s no evidence that I know that neanderthals had a monopoly on lack of melanin genes.

14

Do we know that Neanderthals had white skin? Did any skin fossilize and get preserved with color intact?

For that matter, do we know that ancient Africans had black skin?

15

I don’t think we know if Neanderthals had fur or not, far less what their skin was like.

I remember reading once that the Saami population, which absent caucasian dilution looks very east asian, is of European origin. The Saami was genetically isolated for 15 000 years or so, and missed the development of light skin/blonde hair in European populations. Its thought to be rather recent.

16

Actually, they may look the same, but they aren’t. All light skinned people of European descent have a defect in one particular gene. All light skinned people of Asian descent have a defect in a different particular gene. The implication of this is that light skin evolved completely separately and independently at least twice.

17

Can someone tell me what this means?

18

Can we see some evidence for this please, because on the face of it, it seems ridiculous.

You are telling me that the skin colour of Mohamar Ghadaffi, Mohandas Gandhi and Mao Zedong are all caused by one particular gene. Whereas the skin colour of Aristotle Onassis, Antonio Banderas and Boris Yeltsin are all caused by another particular gene. Despite the fact that the ancestors of Yeltsin and Gandhi, Banderas and Ghadaffi and Attaturk and Onassis are, respectively, more geographically close than they are to other inhabitants of the same continent?

I find that very hard to credit.

19

But it is not so far off.

Also here:

As those articles detail, certain sets of genes mutations were the raw material for paleness in European populations that are not the operative genes in other populations.

As far as Neanderthals go:

20

Sure. Here are some cites:

From here: "European Skin Turned Pale Only Recently, Gene Suggests"...Ya don't say? LOL. - Davey D's Hip Hop Political Palace

Wikipedia page on the SLC24A5 gene (yes, its Wikipedia, but there are plenty of good cites at the end of the article):

From here: http://anthropology.net/2005/12/27/the-anthropology-of-race-and-the-discovery-of-a-skin-color-gene-slc24a5/

Other articles:

http://www.msnbc.msn.com/id/10480835/
http://www.npr.org/templates/story/story.php?storyId=5055391

http://www.sciencemag.org/content/310/5755/1782.abstract?maxtoshow=%2520HITS=10%2520hits=10%2520RESULTFORMAT=%2520fulltext=Zebrafish+skin%2520searchid=1135609045223_4166%2520FIRSTINDEX=0%2520journalcode=sci

No, it’s not quite that simple. There’s more than one gene involved.