Proto-Indo-Europeans were the Highlanders, who lived near the sea.

[Angela]

Ust Ishim should have had light skin then because he had large segments of Neanderthal DNA, but he had dark hair/eyes/skin. The same could be said for all of the ancient DNA so far, if they did get light skin from Neanderthals then it should be present in older samples. To the contrary we see that light skin is first found in Neolithic farmers while Mesolithic WHGs and ANEs have dark skin, althought WHGs seem to all have light eyes.

To me this implies that light skin evolved in tandem with farming in the Middle East. You forgot to take into account that Eskimos have large sections of Neanderthal DNA, as do all East Asian and American Indian groups

Studies that have specifically looked at the spread of SLC24A5 do seem to show a radiation from the general area of the Caucasus about 6-12,000 years ago, which would fit with the development of agriculture. The distribution and frequency maps likewise show it generally adhering to the migration routes taken by the first farmers. So, I think the association for this one looks pretty good, although it's not proof, of course.

I'm not so sure about SLC 42A5. All we know is that it has shown up in the far north east among hunter gatherers, and then we find it, along with more depigmentation, in EEF farmers like Otzi, and in samples in Central Europe in EEF people. A lot more study has to be done on it, I think, to try to get a handle on when and where it might have arisen. It might have occurred in multiple places and multiple times, as with many mutations, but the scientists may be able to get a handle on the most recent occurrence and the direction of its sweep.

As for eye color, we know that WHG people carried the depigmentation snp for it.

Everything I've read indicates that the scientists (and forensics people) believe that these snps have a cumulative effect. So, in Europeans, it may have been sort of like a "perfect storm" of the accumulation of all the three major depigmentation snps in one area. Of course, were they not beneficial in some way, and did positive selection not operate on them, a positive selection that the scientists are pretty confident is rather recent as these things go, then they wouldn't have swept to fixation. I don't think anyone is exactly sure what kind of positive selection was going on, but the link to agriculture and climate makes sense as one factor, I think.

There is also the possibility I've mentioned before that Mesolithic Europeans carried a completely different set of depigmentation snps of which we have no knowledge. I don't think this is very likely, however, because then there would be no reason for our modern depigmentation snps to have so obviously and relatively quickly swept to fixation. That means positive selection for a trait that wasn't present, in my opinion.

 

[LeBrok]

Regarding the Plains Indians, I'm not sure that I would call them light skinned. They're certainly not "European" fair, or even "West Asian" fair. I know older photos have a tendency to look darker than the reality, and there are the effects of constant exposure to sunlight to consider, but I would doubt that these Cheyenne have all the major European skin depigmentation variants.

.

I have to run, so I don't have much time to elaborate on your post. I think it doesn't matter if they depigmented to European level or not. It is only important if the black/brown original africans depigmented to be light enough to live as HGs in central Eurasia. And if it was done with Neanderthal help or not, regarding Paleolithic HGs. Prairie Indians might carry the answer, because they were insulated from Eurasia through all Neolithic or even longer.

 

[mihaitzateo]

Not in Alaska. The movement of black or dark brown (whatever was the initial colour) people from Africa took thousands or tens of thousands of years to progress North. It was a gradual process. The lighter they got the farther north they could get, generation after generation. If they ate a lot of fresh animal liver, like Inuit (Eskimo) do, they didn't need to get white to progress to central Europe or Syberia. Eating fresh liver could be compared to eating supplements with vitamins, or vitamin D fortified food.
It is possible to receive lucky mutations through tens of thousands of years and lighten up, so to speak. Having said that I still believe that they picked up lighter skin mutations from Neanderthals. At least initially. It was the easiest way around. However, recent research doesn't confirm Neanderthal's skin colour alleles in recent human populations. It might be due to fast (under pressure) mutating genes beyond easy comparison. I'm not sure. We know that Homo Sapiens mated with Neanderthals, so I would be surprised if first Sapiens in Europe didn't have Neanderthal's skin alleles to make them lighter.

Why are you saying such a thing?
If you have a whiter skin you produce more vitamin D from fewer sunrays?
From what I know,if we take for example Helsinki or Stockholm,the mean sunshine per year is higher than for example in London.
Because during the summer,there is a lot of sunshine,while during the winter,is very few.

 

[holderlin]

Why are you saying such a thing?
If you have a whiter skin you produce more vitamin D from fewer sunrays?
From what I know,if we take for example Helsinki or Stockholm,the mean sunshine per year is higher than for example in London.
Because during the summer,there is a lot of sunshine,while during the winter,is very few.

There's this as well. Although the averages per latitude probably hold up.

 

[holderlin]

Not in Alaska. The movement of black or dark brown (whatever was the initial colour) people from Africa took thousands or tens of thousands of years to progress North. It was a gradual process. The lighter they got the farther north they could get, generation after generation. If they ate a lot of fresh animal liver, like Inuit (Eskimo) do, they didn't need to get white to progress to central Europe or Syberia. Eating fresh liver could be compared to eating supplements with vitamins, or vitamin D fortified food.
It is possible to receive lucky mutations through tens of thousands of years and lighten up, so to speak.

I'm not convinced of the selective pressures in this model. Feel free to modify my model to black people migrating from Central America to Alaska, or whatever. They're not developing light hair, eyes, and skin in 3000 years. I don't even think 40k years is enough generations.

What's being theorized based on some data indicating recent positive selection, is that Europeans developed fair features in a 2-5k years.

Having said that I still believe that they picked up lighter skin mutations from Neanderthals. At least initially. It was the easiest way around. However, recent research doesn't confirm Neanderthal's skin colour alleles in recent human populations. It might be due to fast (under pressure) mutating genes beyond easy comparison. I'm not sure. We know that Homo Sapiens mated with Neanderthals, so I would be surprised if first Sapiens in Europe didn't have Neanderthal's skin alleles to make them lighter.

It's only because we have very few Neanderthal genomes to compare to.

 

[holderlin]

Studies that have specifically looked at the spread of SLC24A5 do seem to show a radiation from the general area of the Caucasus about 6-12,000 years ago, which would fit with the development of agriculture. The distribution and frequency maps likewise show it generally adhering to the migration routes taken by the first farmers. So, I think the association for this one looks pretty good, although it's not proof, of course.

Given this data it's almost creepy that the term "Caucasian" was coined in the 18th century.

But spreading from this region as a result of a farmer's diet doesn't make sense to me. I would imagine that if this were the case it would proceed Anatolia --> Balkans

I'm not so sure about SLC 42A5. All we know is that it has shown up in the far north east among hunter gatherers, and then we find it, along with more depigmentation, in EEF farmers like Otzi, and in samples in Central Europe in EEF people. A lot more study has to be done on it, I think, to try to get a handle on when and where it might have arisen. It might have occurred in multiple places and multiple times, as with many mutations, but the scientists may be able to get a handle on the most recent occurrence and the direction of its sweep.

The odds of this happening in mammals are astronomical.

Everything I've read indicates that the scientists (and forensics people) believe that these snps have a cumulative effect. So, in Europeans, it may have been sort of like a "perfect storm" of the accumulation of all the three major depigmentation snps in one area. Of course, were they not beneficial in some way, and did positive selection not operate on them, a positive selection that the scientists are pretty confident is rather recent as these things go, then they wouldn't have swept to fixation. I don't think anyone is exactly sure what kind of positive selection was going on, but the link to agriculture and climate makes sense as one factor, I think.


There is also the possibility I've mentioned before that Mesolithic Europeans carried a completely different set of depigmentation snps of which we have no knowledge. I don't think this is very likely, however, because then there would be no reason for our modern depigmentation snps to have so obviously and relatively quickly swept to fixation. That means positive selection for a trait that wasn't present, in my opinion.

A cumulative effect would help convince me of the possibility of the light featured European emerging so suddenly, but it's hard for me to find an adequate mechanism for the generation of these alleles in the last 10k or even 40k years.

 

[Alan]

Eskimos and prairie Indians are not dark skinned and they are hunter gatherers. Did someone looked at their pigmentation?

o

For the region they are living in, and in comparison to other population in the same latitude they are relatively dark. Of course not as dark as almost black, but more of their own Olive-brown skin tone.

 

[Angela]

Given this data it's almost creepy that the term "Caucasian" was coined in the 18th century.

But spreading from this region as a result of a farmer's diet doesn't make sense to me. I would imagine that if this were the case it would proceed Anatolia --> Balkans

The odds of this happening in mammals are astronomical.

A cumulative effect would help convince me of the possibility of the light featured European emerging so suddenly, but it's hard for me to find an adequate mechanism for the generation of these alleles in the last 10k or even 40k years.

I'm pressed for time, so I won't be able to respond at length to each of your points with the relevant citations to the appropriate papers. I would just say that none of the comments I made originated with me. They are "cribbed", I'm afraid, from the extensive literature on the subject, some of it dating back thirty or more years to the pioneering work of Cavalli-Sforza. Nor do I have the time, unfortunately, to point out once again the specific areas where I think there is still ambiguity. If you search under pigmentation on this board a number of threads and posts should turn up where I do address some of those issues.

I do have the following list of papers and commentaries in a file, and I update it periodically. You're welcome to have at it and read the papers and come to your own conclusions. This is only a representative sample of the most recent relevant papers, of course, but the papers provide cites to many others in their acknowledgment sections as well as in the body of the papers.


Norton et al, 2006, Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians:
http://mbe.oxfordjournals.org/content/24/3/710.full

Pickrell and Coop, 2009, Signals of Recent Selection in World Wide Populations:
http://genome.cshlp.org/content/19/5/826.full.p..

Ola Engelsen et al 2010, The Relationship between Ultraviolet Radiation Exposure and Vitamin D Status
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257661/

Jablonski and Chaplin 2010, Human skin pigmentation as an adaptation to UV radiation:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3024016/

Lucotte and Yuasa, 2011,
http://www.academicjournals.org/article/article1379514057_Lucotte and Yuasa pdf.pdf

Canfield and Cheng et al, 2013 Molecular Phylogeography of a Human Autosomal Skin Color Locus Under Positive Selection:
http://www.g3journal.org/content/3/11/2059.full

Sandra Wilde et al, 2014, Direct evidence for positive selection in skin, hair and eye pigmentation in Europeans during the last 5,000 years:
http://www.pnas.org/content/111/13/4832.full

This is a google book:
Human Evolutionary Biology, Michael P. Muehlenbein, Chapter on Skin Coloration
https://books.google.com/books?id=1...0CEQQ6AEwBQ#v=onepage&q=Lamason et al&f=false

Razib Khan, at Discovery Magazine has provided commentary for each of these papers and others. This is a link to the relevant archive of them (arranged in reverse chronological order:
http://www.razib.com/wordpress/?cat=566

Dienekes has also commented on some of them:
http://dienekes.blogspot.com/2013/11/europeans-and-south-asians-share-by.html
http://dienekes.blogspot.com/2014/01/slc24a5-light-skin-pigmentation-allele.html


[h=1][/h]

 

[LeBrok]

o

For the region they are living in, and in comparison to other population in the same latitude they are relatively dark. Of course not as dark as almost black, but more of their own Olive-brown skin tone.

I think that is the whole point of this exercise of mine. They are light enough to live in northern latitudes as hunter gatherers. Farmers couldn't pull this trick, and needed to get lighter. This olive tone of skin might be identical to HGs who lived in Eurasia 10k years ago.

When people who left Africa looked like this picture below, they really needed to lighten up to progress north beyond Arabia and India.

And here is hunter gatherer (Cassion Owner) from around Calgary. Same latitude as central Germany.

 

[LeBrok]

I'm not convinced of the selective pressures in this model. Feel free to modify my model to black people migrating from Central America to Alaska, or whatever. They're not developing light hair, eyes, and skin in 3000 years. I don't even think 40k years is enough generations.

That's why Neanderthal "helping hand" seems very likely to me. They lived about half a million years in Europe, long enough to adapt.

 

[Aberdeen]

That's why Neanderthal "helping hand" seems very likely to me. They lived about half a million years in Europe, long enough to adapt.

IMO, that's the only way to explain the massive difference between Sub-Saharan Africans and the people of North Africa and Arabia. I doubt that people who lived for thousands of years in hot deserts would have paler skin than people who lived under a forest canopy in a tropical rainforest during that same time period unless there was something else going on besides climate based selection. And I wonder whether the yellowish skin tone found in East Asians (who are often quite depigmented) comes from some other population, such as Denisovians.

 

[Dagne]

light skin is first found in Neolithic farmers while Mesolithic WHGs and ANEs have dark skin, althought WHGs seem to all have light eyes.

To me this implies that light skin evolved in tandem with farming in the Middle East.

Lithuanians are fairer than Mediterranean people, though having more than half of their ancestry from WHG and less than one third from EEF. It means that adaptation plays a large role, because dark skin genes are dominant over fair ones, I think.

 

[Alan]

Lithuanians are fairer than Mediterranean people, though having more than half of their ancestry from WHG and less than one third from EEF. It means that adaptation plays a large role, because dark skin genes are dominant over fair ones, I think.

WHG lived in high latitude for thousand of years but never became light skinned as it looks.
What the Lithuanian or North European case in general proves is that, *30% of Farmer DNA was enough to get the necessary light skin alleles. forget it's just some few Genes in total genome causing for light skin and every North European has at least 30% Farmer DNA. Also In comparison to WHG even South Europeans have light skin.

farmers brought the necessary genes and I agree with you adaption fulfilled the rest. A good prove for this theory is a comparison between Swedes and Russians. The former have more farmer admixture while the latter more H&G. But Swedes are on avergae lighter.

All Europeans seem to have absorbed enough farmer DNA to have the necessary light skin alleles so it doesn't really matter how much of more or less percentage of farmer DNA someone has.

 

[Angela]

I think that is the whole point of this exercise of mine. They are light enough to live in northern latitudes as hunter gatherers. Farmers couldn't pull this trick, and needed to get lighter. This olive tone of skin might be identical to HGs who lived in Eurasia 10k years ago.

When people who left Africa looked like this picture below, they really needed to lighten up to progress north beyond Arabia and India.

And here is hunter gatherer (Cassion Owner) from around Calgary. Same latitude as central Germany.

You don't think this man looks obviously admixed? He certainly does to me.

Regardless, if this theory is correct, then why is it that Loschbour and LaBrana, Mesolitic hunter gatherers from northern latitudes (one from the Low Countries, and one from near Spain) are predicted to be substantially darker than the Neolithic farmers like, say, Otzi?

There are only two ways to arrive at this conclusion, it seems to me:

l. The algorithims used every day to predict pigmentation are incorrect, even though in the real world they have around a 95% degree of accuracy. (If the snps for Loschbour and La Brana were fed into the predictors, the FBI might not be looking for someone from the Congo, but they indeed would be looking for someone who was either African-American or a dark skinned Hispanic. ) I find this one highly problematic.

2. The Paleolithic and Mesolithic hunter gatherers carried depigmentation snps of which we're completely unaware. That's a better possibility it seems to me, but that would then require an explanation for the fact that examination of our genomes shows evidence of "recent" (one paper says 11,000 to 19,000, one around 12,000, one 6,000-12,000 years ago) massive expansion of these genes. If people in northern latitudes were already depigmented, then what was the necessity for another massive expansion of depigmentation genes?

By the way, does anyone have a link to any paper that predicted light pigmentation in Neanderthals other than the Lalueza-Fox one that relied on MCIR? If that's it, I wouldn't bet the farm on that conclusion quite yet. (I don't mean the recent paper that talked about BNC2, since apparently, if I remember correctly, it doesn't affect West Eurasians, and only has to do with saturation.

 

[Angela]

WHG lived in high latitude for thousand of years but never became light skinned as it looks.
What the Lithuanian or North European case in general proves is that, *30% of Farmer DNA was enough to get thw necessary light skin alleles in the total genome. In comparison to WHG even South Europeans have lighter skin.

farmers brought the necessary genes and I agree with you adaption fulfilled the rest. A good prove for this theory is a comparison between Swedes and Russians. The former have more farmer admixture while the latter more H&G. But Swedes are on avergae lighter.

All Eeropeans seem to have absorbed enough farmer DNA to have the necessary light skin alleles so it doesn't really matter how much of more or less percentage of farmer DNA someone has.

Alan, I would only quibble that we don't as yet know the origin and trajectory of SLC45A2. I think it's the combination of, it seems, five or so major genes, and some smaller effect ones, (including the ones that affect eye color)that contribute to modern pigmentation variation. I think, for example, that the fact that some Near Easterners (and southern Europeans) have only one, or in some cases, no copies of SLC 45A2 may be responsible for the gradient we see in terms of skin pigmentation.( On the other hand, it doesn't mean that it didn't originate there. Living at a different latitude, in a different climate, would affect selection regardless of whether it originated there or not. Subsequent migrations from SSAs into more southern regions of the Middle East would also impact the pigmentation.)

All we can say is that so far the earliest ancient people in whom they've all been found were EEF farmers in Central Europe, and that the Mesolithic WHG did not have them, or at least did not have as many of them as the EEF people.

Oh, here are the values for SLC45A2 in some modern populations. (It's SLC24A5 that is fixed in Europe) Unfortunately, they didn't sample in the Near East, but they did sample in North Africa:

http://tinypic.com/view.php?pic=2w7guiu&s=6#.VIhcknvLq1g

 

[Goga]

Yamna culture = 3600 BC - 2300 BC
Maykop culture = 3700 BC - 3000 BC
Uruk period = 4000 BC - 3100 BC
Leyla-Tepe culture = 4350 BC - 4000 BC
Ubaid period = 6500 BC to 3800 BC

What does this tell us? That Leyla-Tepe is the oldest of those 'Bronze Age' civilizations and I believe that the founders of the Uruk civilization were the same as the founders of Maykop culture. I think that one part of the Leyla-Tepe folks migrated into Mesopotamia and found the Uruk civilization by replacing the Ubaid Culture, while other group went to the Northern Caucasus and found the Maykop culture which resulted into the Yamanaya culture. Since Maykop and Uruk are closely related to each other. Actually the Leyla-Tepe is the starting point of the Proto-Indo-Europeans in the Bronze Age. Leyla-Tepe/Maykop warriors most likely Indo-Europized the uncivilized Steppes folks in the Yamnaya Horizon throug the elite dominance. Something happened around this time, around 4000 BC - 3500 BC and it has something to do with J2a, R1a* and R1b...

 

[Goga]

What does this tell us? That Leyla-Tepe is the oldest of those 'Bronze Age' civilizations

Although, I don't rule out that in turn the Leyla-Tepe was heavily influenced by the (Sumerian) Ubaid Culture! But Leyla-Tepe was the rise of the proto-Indo-European cultures.

 

[Angela]

IMO, that's the only way to explain the massive difference between Sub-Saharan Africans and the people of North Africa and Arabia. I doubt that people who lived for thousands of years in hot deserts would have paler skin than people who lived under a forest canopy in a tropical rainforest during that same time period unless there was something else going on besides climate based selection. And I wonder whether the yellowish skin tone found in East Asians (who are often quite depigmented) comes from some other population, such as Denisovians.

Here is a global map of skin color reflectance. It may not be exact, but I think the general pattern is probably accurate enough for our purposes. The decreasing cline for "dark" pigmentation seems pretty gradual to me.
http://upload.wikimedia.org/wikiped...abeled_Renatto_Luschan_Skin_color_map.svg.png

For North Africans, a couple of factors might be at play, I think. We don't know much about the pigmentation of the "indigenous" inhabitants. We do know that a large Neolithic migration impacted the area. We also know that there was some movement of Arabian tribes into the area. At the same time, SSA introgression, perhaps fairly constant, but definitely important since the era of the Arab slave trade has resulted in average levels for SSA of 25%. We also know that there were large scale importations of Europeans versus another slave route. So, figuring this one out is beyond me.

Another interesting fact is that studies done on women in these areas show that many of them suffer from Vitamin D deficiencies resulting in serious health problems. It's hypothesized that the cause is the heavy veiling that they wear, particularly in the more conservative rural areas.

 

[LeBrok]

Here is a global map of skin color reflectance. It may not be exact, but I think the general pattern is probably accurate enough for our purposes. The decreasing cline for "dark" pigmentation seems pretty gradual to me.
http://upload.wikimedia.org/wikiped...abeled_Renatto_Luschan_Skin_color_map.svg.png

.

Looks like this map agrees with my observation of skin tone of prairie natives and Inuits. No it would be nice to inquire what lightening mutations they have, or lack of them.

 

[LeBrok]

IMO, that's the only way to explain the massive difference between Sub-Saharan Africans and the people of North Africa and Arabia. I doubt that people who lived for thousands of years in hot deserts would have paler skin than people who lived under a forest canopy in a tropical rainforest during that same time period unless there was something else going on besides climate based selection. And I wonder whether the yellowish skin tone found in East Asians (who are often quite depigmented) comes from some other population, such as Denisovians.

IIRC Denisovian didn't leave much genetic imprint in East Asians. There is another hominid to be found who gave bunch of East Asian traits. Perhaps the Peking man.
http://en.wikipedia.org/wiki/Peking_Man