Light skin allele of SLC24A5 gene was spread by the Indo-Europeans (R1a + R1b)

[gyms]

"Neanderthal DNA sequences are found in regions of the genome that have been linked to the regulation of skin pigmentation. The acquisition of these variants by mating with the Neanderthals may have proven to be a rapid way for humans to adapt to local conditions."

http://www.washington.edu/news/2014/01/29/neanderthal-lineages-excavated-from-modern-human-genomes/

 

[LeBrok]

"Neanderthal DNA sequences are found in regions of the genome that have been linked to the regulation of skin pigmentation. The acquisition of these variants by mating with the Neanderthals may have proven to be a rapid way for humans to adapt to local conditions."

http://www.washington.edu/news/2014/01/29/neanderthal-lineages-excavated-from-modern-human-genomes/

That's a great news, thanks gyms for posting.

Nevertheless, the Neanderthals were also a probable source for at least a few genetic variations that were adaptive for their human descendants. Neanderthal DNA sequences are found in regions of the genome that have been linked to the regulation of skin pigmentation. The acquisition of these variants by mating with the Neanderthals may have proven to be a rapid way for humans to adapt to local conditions.
“We found evidence that Neanderthal skin genes made Europeans and East Asians more evolutionarily fit,” Vernot said, “and that other Neanderthal genes were apparently incompatible with the rest of the modern human genome, and thus did not survive to present day human populations.”

NIce to be vindicated. That's what I was saying from way back, (and generally about interbreeding from a first glance at visually reconstructed Neanderthal). That mingling between these two species was the easiest and fastest way to pick up right skin colour for Sapiens coming from Africa. And that waiting for right mutation to kick in would be much more time consuming process, therefore less likely. Occam's razor wins again.

 

[Angela]

I'm not sure it's all that clear cut. These two papers are dense and difficult to absorb, so upon more readings, I may find that I'm incorrect, but I didn't see anything in the paper indicating that we have inherited any of our specific skin lightening genes from Neanderthals.

The only gene mentioned was the BCN2 gene which researchers think is somehow involved in the skin pigmentation pathways. However, they have not yet found its precise function. The best guess seems to be that it may be a precursor gene for the functioning of the color draining alleles.

Human Pigmentation Genes Under Environmental Selection:
http://genomebiology.com/2012/13/9/248#B38

The above paper also addresses many of the issues we've been discussing, including what might have triggered selection for blue eyes, advancing one theory I hadn't hear before, which is that since blue eyes absorb more light, they might have proved helpful in locations where it was continuously dark for long stretches at a time, i.e. at very northern latitudes. Also, they propose that by absorbing more light, blue eyes might have been selected for as a means of protection against things like seasonal affective disorder.

 

[Greying Wanderer]

That's a great news, thanks gyms for posting.



NIce to be vindicated. That's what I was saying from way back, (and generally about interbreeding from a first glance at visually reconstructed Neanderthal). That mingling between these two species was the easiest and fastest way to pick up right skin colour for Sapiens coming from Africa. And that waiting for right mutation to kick in would be much more time consuming process, therefore less likely. Occam's razor wins again.

Early days but logically - if Neanderthals were a long way from Sapiens - then you might think only those genes which had a dramatic advantage would be passed on - at least until an improved version was developed.

 

[Maciamo]

"Neanderthal DNA sequences are found in regions of the genome that have been linked to the regulation of skin pigmentation. The acquisition of these variants by mating with the Neanderthals may have proven to be a rapid way for humans to adapt to local conditions."

http://www.washington.edu/news/2014/01/29/neanderthal-lineages-excavated-from-modern-human-genomes/

This article doesn't mention it, but it is the BNC2 and POU2F3 genes influencing skin that were inherited from Neanderthals, not the SLC24A5 mentioned in this thread. BNC2 influences saturation of skin colour and is responsible for freckling, and is found in two thirds of Europeans. POU2F3 is involved in keratin production and is found in 70% of East Asians.

 

[Greying Wanderer]

This article doesn't mention it, but it is the BNC2 and POU2F3 genes influencing skin that were inherited from Neanderthals, not the SLC24A5 mentioned in this thread. BNC2 influences saturation of skin colour and is responsible for freckling, and is found in two thirds of Europeans. POU2F3 is involved in keratin production and is found in 70% of East Asians.

That's the critical point though. SLC24A5 is a skin lightening gene spread from the near east. I don't think there's any debate about. The question is whether the WHG like La Brana and Louschbour had already de-pigmented **before** SLC24A5 started to spread. Personally i think they had with the spread of a partial albinism based around the red hair, light eyes and freckles phentotype (MC1R) or the dark hair, light eyes and freckles phenotype (IRF4). I think the only way to explain the spread of red hair that ancient writers mention so often is if it de-pigmented the skin as well - with freckling as protection. This would also explain the decline of red hair once the improved protection of tanning came along with SLC24A5.

 

[MOESAN]

if correct the mutated SLC24A5 could have been an amazingly good thing: a lighter skin for poor sunny seasons and a possibility to tan during sunny seasons (very striking adaptability) -
by the way, the red haired light skinned freckled people can tan a bit, if irregularly, after a dangerous period of hypersensibility and burning - I think we shall discover in future other mutations upon genes which, without change radically the skin colour, can slightly modify this colour -
concerning the very black skins of subsaharian populations I 'm not sure they did not suffer other skin colour genes mutations, on the other side...

 

[kamani]

I think some people are missing that even the non-tanable pale with freckles euro types are white because of SLC24A5. Unless you're East Russian, then you just don't know whether you have SLC24A5 or the East Asian gene for paleness.

 

[Greying Wanderer]

I think some people are missing that even the non-tanable pale with freckles euro types are white because of SLC24A5. Unless you're East Russian, then you just don't know whether you have SLC24A5 or the East Asian gene for paleness.

That's just an assumption. There's no proof of that precisely because SLC24A5 is close to fixation. If Europeans already had de-pigmentation genes and then you added SLC24A5 then how would you know? You couldn't.

Europeans would have been brown once and so it would be a reasonable assumption if it wasn't for the blue eyes. What is the frequency of blue eyes and dark skin in modern populations? 0.001%? What is the supposed frequency of blue eyes among the WHG who have been tested so far - 100%.

It makes no sense unless these WHG were already de-pigmented.

 

[Greying Wanderer]

if correct the mutated SLC24A5 could have been an amazingly good thing: a lighter skin for poor sunny seasons and a possibility to tan during sunny seasons (very striking adaptability)

I agree hence fixation or close to it now but do you remember the various studies saying farmers and HGs didn't mix for a long time? When you take that as one end-point and the written records as the other that doesn't leave a lot of time for *complete* fixation and you need *complete* fixation by that time or according to the theory there would still have lots of brown euros running around during the historical period.

Alternatively euros were already de-pigmented when the farmers arrived and SLC24A5 spread because it was a better version.

 

[Maciamo]

That's just an assumption. There's no proof of that precisely because SLC24A5 is close to fixation. If Europeans already had de-pigmentation genes and then you added SLC24A5 then how would you know? You couldn't.

Europeans would have been brown once and so it would be a reasonable assumption if it wasn't for the blue eyes. What is the frequency of blue eyes and dark skin in modern populations? 0.001%? What is the supposed frequency of blue eyes among the WHG who have been tested so far - 100%.

It makes no sense unless these WHG were already de-pigmented.

Dark skinned people with blue eyes are almost inexistent in Europe, but it is still possible to find them in Pakistan, Afghanistan or India. It would be worth investigating what mutations such people carry.

 

[Maciamo]

I agree hence fixation or close to it now but do you remember the various studies saying farmers and HGs didn't mix for a long time? When you take that as one end-point and the written records as the other that doesn't leave a lot of time for *complete* fixation and you need *complete* fixation by that time or according to the theory there would still have lots of brown euros running around during the historical period.

Alternatively euros were already de-pigmented when the farmers arrived and SLC24A5 spread because it was a better version.

I disagree with those studies claiming that farmers and HGs didn't mix for a long time. Although it seems true that some hunter-gatherers survived in isolation without Near Eastern admixture, that is not the case for farmers, who did absorb some I2a1 populations. This is obvious from the high frequency of I2a1 in SE Europe and Sardinia, but we have incontrovertible proof that Neolithic farmers were already a blend of G2a and I2a in Early Neolithic France (Treilles site). If that is not enough, there are over 100 LBK mtDNA samples tested to date, and about a third of them of Mesolithic haplogroups like H1, H3, H10, H11, U4, U5 and V. The LBK sample from Stuttgart tested together with the Loschbour HG also confirm that even Early Neolithic farmers (5500 BCE is as early as it gets in Western Europe) already had a little bit of Mesolithic admixture.

Ironically, it may be the populations of Scandinavia and Finland who kept dark skin the longest in Europe, since Neolithic farmers reached them last and they have the lowest percentage of Neolithic haplogroups today. Actually it is likely that Scandinavians got white skin only from the IE invasions of the Corded Ware period.

 

[MOESAN]

Dark skinned people with blue eyes are almost inexistent in Europe, but it is still possible to find them in Pakistan, Afghanistan or India. It would be worth investigating what mutations such people carry.

I agree with several posts here: it would be very amazing, when considering the today occidental and northern populations of Europe, that a sort of depigmentation was not already occurred among Mesolithic people - but who knows?
concerning light coloured eyes in Pakistan Afghanistan or India: they are very SELDOM - and true Afghanistan population are "europoidly" skin coloured, unless tanning even if Pakistan an India are darker: - the sensible surveys about skin reflectance seems showing lighter skins among Pendjabi, Sikhs and Pathans than among "Dravidians" people of more southern places, and they are not so far from 'euopoids' - the more common skin colour mutation of Europeans is numerically dominent among them in North - so these I-E speaking populations are a mix where dominates the 'europoid' element whatever its remote origin -
crossing makes the debate more confused because, for I suppose -and it seems it would be confirmed- the number of loci implied for eye colours are less numerous than the loci for skin pigmentation ; eye colour and hair colour, even if less simple we supposed, have less intermediary positions than skin colour which is more gradual and "less absolute" - so in these regions we have a very dark skinned dark eyed dark haired population + (a) light skin dark eyes dark haired population(s) + a very light skinned light eyed light haired population from the western Steppes - the slightly lighter eyed tribes have also slightly lighter hairs (for the most in the Hindue Kush - so I am not sure we can link too quickly some light haired dark skinned people of these contacts areas of India or Pakistan to an ancient stage of evolution similar to the supposed mesolithical one in western Europe - we could have only 'metissed' individuals among whom some rare ones retained light eyes - a NEW genetic situtation NOT AN OLD one

 

[Wilhelm]

Ironically, it may be the populations of Scandinavia and Finland who kept dark skin the longest in Europe, since Neolithic farmers reached them last and they have the lowest percentage of Neolithic haplogroups today. Actually it is likely that Scandinavians got white skin only from the IE invasions of the Corded Ware period.

Doesn't make much sense, Finns have low R1a+R1b, and plus they are non-IE speakers.

 

[martiko]

Doesn't make much sense, Finns have low R1a+R1b, and plus they are non-IE speakers.

Exactly! and I saw at the Afghan or people of southern Russia eyes, hair and dark skins (except Russian european).

 

[ElHorsto]

Doesn't make much sense, Finns have low R1a+R1b, and plus they are non-IE speakers.

The ones who really lack it are the Saami, and there you are they are significantly darker in average than Finns and Scandinavians. The Saami are the most paleolithic europeans autosomally.
Finns show much autosomal IE heritage and they are very bottlenecked, don't be mislead by PCA plots who often show the mere isolation and bottleneck history.

 

[Sile]

I'm not sure it's all that clear cut. These two papers are dense and difficult to absorb, so upon more readings, I may find that I'm incorrect, but I didn't see anything in the paper indicating that we have inherited any of our specific skin lightening genes from Neanderthals.

The only gene mentioned was the BCN2 gene which researchers think is somehow involved in the skin pigmentation pathways. However, they have not yet found its precise function. The best guess seems to be that it may be a precursor gene for the functioning of the color draining alleles.

Human Pigmentation Genes Under Environmental Selection:
http://genomebiology.com/2012/13/9/248#B38

The above paper also addresses many of the issues we've been discussing, including what might have triggered selection for blue eyes, advancing one theory I hadn't hear before, which is that since blue eyes absorb more light, they might have proved helpful in locations where it was continuously dark for long stretches at a time, i.e. at very northern latitudes. Also, they propose that by absorbing more light, blue eyes might have been selected for as a means of protection against things like seasonal affective disorder.

maybe this is better

http://www.sciencedirect.com/science/article/pii/S1872497312001810

 

[Greying Wanderer]

Dark skinned people with blue eyes are almost inexistent in Europe, but it is still possible to find them in Pakistan, Afghanistan or India. It would be worth investigating what mutations such people carry.

Yes, good point.

 

[Drax]

Hello, I'm new here, I really like the Eupedia website and all the Maciamo works; I'm not fluent in english, so sorry if in my messages I do mistakes.

About the subject, for Indians peoples with light eyes, that have already proven and explained of the IE invaders/migration, so I don't think it's a valid comparaison with the curious cro-magon with brown skin and blue eyes...or maybe not.


If I trust this article from Eupedia during the Corded war (3000 BC), the IE has already exactly the same maternal lineages that the Scandinavian I1, so mtDNA haplogroups U4 and U5 (see the article about haplougroup I1, I can't posted the link).


I'm not a specialist, so sorry if I do a big mistake, but if they have similar maternal lineage already in 3000 BC, that made them technically more or less "cousin" genetically ? if during this time they has already the same mtdna haplogroups, I suppose we can say that they were already mixed way before this date ? We know blue eyes are from one single woman ancestor...so how we can be sure that not among the IE the blue eyes have appeared first (among peoples with light skins and light hairs like...today), and have passed of others cro-magnons with their wives ? The majority of cro-magnons were described, until this CM with blue eyes, like tanned, brown eyes and hairs, imho, it's not judicious to transform all of them with blue eyes just because of an indvidual case.

My second hypothesis is very simple, maybe that from CM, but it's not because you have genetically "blue eyes" genes inside you, that you are blue eyed yourself, for example today most african-american have whites ancestors, but they have rarely blue eyes, remember La Brana has just 50% to have blue eyes genetically, maybe the IE were the good "peoples", to give the possibility the blue eyes to "take place" because the IE light skins and hairs...I ask the question for the specialists...that a possibility ? To give a "dormant" gene to someone else who have a better potential for this gene ? that would be a wonderful coincidence, the light hairs and skin meet the genetically blue eyes, and they have light skins, light hairs and eyes...specially when we know that that white skin, hairs and eyes are extremely recessives.

My third hypthosis, is maybe the simple ones, because of their mtdna, both of them has blue eyes, the IE invaders improves the presences of blue eyes appearances in all the Europe but in others places in the world, that explains how a recessive traits are so present among europeans and why it's seem exclusively, at least physically, to the Europeans peoples.

Sorry if my message is confused, I'm not used to talk in forums, so I'm very sorry if I'm not clear.

Thank you Maciamo for Eupedia and all your works.

 

[LeBrok]

Welcome to Eupedia Drax. Your english is very good and your hypotheses interesting.