How Europeans evolved white skin

Most of us think of Europe as the ancestral home of white people. But a new study shows that pale skin, as well as other traits such as tallness and the ability to digest milk as adults, arrived in most of the continent relatively recently. The work, presented here last week at the 84th annual meeting of the American Association of Physical Anthropologists, offers dramatic evidence of recent evolution in Europe and shows that most modern Europeans don’t look much like those of 8000 years ago.

The origins of Europeans have come into sharp focus in the past year as researchers have sequenced the genomes of ancient populations, rather than only a few individuals. By comparing key parts of the DNA across the genomes of 83 ancient individuals from archaeological sites throughout Europe, the international team of researchers reported earlier this year that Europeans today are a mix of the blending of at least three ancient populations of hunter-gatherers and farmers who moved into Europe in separate migrations over the past 8000 years. The study revealed that a massive migration of Yamnaya herders from the steppes north of the Black Sea may have brought Indo-European languages to Europe about 4500 years ago.
Now, a new study from the same team drills down further into that remarkable data to search for genes that were under strong natural selection—including traits so favorable that they spread rapidly throughout Europe in the past 8000 years. By comparing the ancient European genomes with those of recent ones from the 1000 Genomes Project, population geneticist Iain Mathieson, a postdoc in the Harvard University lab of population geneticist David Reich, found five genes associated with changes in diet and skin pigmentation that underwent strong natural selection.

First, the scientists confirmed an earlier report that the hunter-gatherers in Europe could not digest the sugars in milk 8000 years ago, according to a poster. They also noted an interesting twist: The first farmers also couldn’t digest milk. The farmers who came from the Near East about 7800 years ago and the Yamnaya pastoralists who came from the steppes 4800 years ago lacked the version of the LCT gene that allows adults to digest sugars in milk. It wasn’t until about 4300 years ago that lactose tolerance swept through Europe.

When it comes to skin color, the team found a patchwork of evolution in different places, and three separate genes that produce light skin, telling a complex story for how European’s skin evolved to be much lighter during the past 8000 years. The modern humans who came out of Africa to originally settle Europe about 40,000 years are presumed to have had dark skin, which is advantageous in sunny latitudes. And the new data confirm that about 8500 years ago, early hunter-gatherers in Spain, Luxembourg, and Hungary also had darker skin: They lacked versions of two genes—SLC24A5 and SLC45A2—that lead to depigmentation and, therefore, pale skin in Europeans today.

But in the far north—where low light levels would favor pale skin—the team found a different picture in hunter-gatherers: Seven people from the 7700-year-old Motala archaeological site in southern Sweden had both light skin gene variants, SLC24A5 and SLC45A2. They also had a third gene, HERC2/OCA2, which causes blue eyes and may also contribute to light skin and blond hair. Thus ancient hunter-gatherers of the far north were already pale and blue-eyed, but those of central and southern Europe had darker skin.
Then, the first farmers from the Near East arrived in Europe; they carried both genes for light skin. As they interbred with the indigenous hunter-gatherers, one of their light-skin genes swept through Europe, so that central and southern Europeans also began to have lighter skin. The other gene variant, SLC45A2, was at low levels until about 5800 years ago when it swept up to high frequency.

The team also tracked complex traits, such as height, which are the result of the interaction of many genes. They found that selection strongly favored several gene variants for tallness in northern and central Europeans, starting 8000 years ago, with a boost coming from the Yamnaya migration, starting 4800 years ago. The Yamnaya have the greatest genetic potential for being tall of any of the populations, which is consistent with measurements of their ancient skeletons. In contrast, selection favored shorter people in Italy and Spain starting 8000 years ago, according to the paper now posted on the bioRxiv preprint server. Spaniards, in particular, shrank in stature 6000 years ago, perhaps as a result of adapting to colder temperatures and a poor diet.

Surprisingly, the team found no immune genes under intense selection, which is counter to hypotheses that diseases would have increased after the development of agriculture.
The paper doesn’t specify why these genes might have been under such strong selection. But the likely explanation for the pigmentation genes is to maximize vitamin D synthesis, said paleoanthropologist Nina Jablonski of Pennsylvania State University (Penn State), University Park, as she looked at the poster’s results at the meeting. People living in northern latitudes often don’t get enough UV to synthesize vitamin D in their skin so natural selection has favored two genetic solutions to that problem—evolving pale skin that absorbs UV more efficiently or favoring lactose tolerance to be able to digest the sugars and vitamin D naturally found in milk. “What we thought was a fairly simple picture of the emergence of depigmented skin in Europe is an exciting patchwork of selection as populations disperse into northern latitudes,” Jablonski says. “This data is fun because it shows how much recent evolution has taken place.”

Anthropological geneticist George Perry, also of Penn State, notes that the work reveals how an individual’s genetic potential is shaped by their diet and adaptation to their habitat. “We’re getting a much more detailed picture now of how selection works.”



http://news.sciencemag.org/archaeology/2015/04/how-europeans-evolved-white-skin

I always wondered whether we started off as black, living in Africa, and a piece of African land broke off and drifted to colder climes over hundreds of years and thats why we became paler?

After all, we go dark in the sun....black people don't ever go white...?

eddie wrote:I always wondered whether we started off as black, living in Africa, and a piece of African land broke off and drifted to colder climes over hundreds of years and thats why we became paler?

After all, we go dark in the sun....black people don't ever go white...?

It all depends on UV levels Eddie

Brasidas wrote:

eddie wrote:I always wondered whether we started off as black, living in Africa, and a piece of African land broke off and drifted to colder climes over hundreds of years and thats why we became paler?

After all, we go dark in the sun....black people don't ever go white...?

It all depends on UV levels Eddie

Yes but it is a possibility don't you think Didge?

eddie wrote:

Brasidas wrote:


It all depends on UV levels Eddie

Yes but it is a possibility don't you think Didge?

Dark skinned people just like we do have their skin lighten in winter for example, so anything is possible over time, we people who are classed as white are testimony to this very fact that it has already happened where UV levels have helped change and lighten our skin.

Catch you tomorrow Eddie

Brasidas wrote:

eddie wrote:

Brasidas wrote:


It all depends on UV levels Eddie

Yes but it is a possibility don't you think Didge?

Dark skinned people just like we do have their skin lighten in winter for example, so anything is possible over time, we people who are classed as white are testimony to this very fact that it has already happened where UV levels have helped change and lighten our skin.

Catch you tomorrow Eddie

Laters didge x

eddie wrote:I always wondered whether we started off as black, living in Africa, and a piece of African land broke off and drifted to colder climes over hundreds of years and thats why we became paler?

After all, we go dark in the sun....black people don't ever go white...?

Skin pigmentation in human beings evolved primarily to regulate the amount of ultraviolet radiation penetrating the skin the single most important substance is the pigment melanin

Did you guys not get this in biology at school ?

What is more interesting than peoples "colour" is the DNA traits that affect what foods individuals can eat

the part about milk i already knew about some people can and some can`t drink it
i can .....about 6 pints a day :-)

korban dallas wrote:

eddie wrote:I always wondered whether we started off as black, living in Africa, and a piece of African land broke off and drifted to colder climes over hundreds of years and thats why we became paler?

After all, we go dark in the sun....black people don't ever go white...?

Skin pigmentation in human beings evolved primarily to regulate the amount of ultraviolet radiation penetrating the skin the single most important substance is the pigment melanin

Did you guys not get this in biology at school ?

Hence why I said what I said?

eddie wrote:

korban dallas wrote:
Skin pigmentation in human beings evolved primarily to regulate the amount of ultraviolet radiation penetrating the skin the single most important substance is the pigment melanin

Did you guys not get this in biology at school ?

Hence why I said what I said?

indeed you did i was agreeing with you a with a bit more technical explanation.

and although i realise this may be a bit pedantic colder climate is not the trigger its the UV exposure hence why Inuit and Eskimos have darker skin

The Toubou people of north Africa:



... were discovered to have actually migrated back into Africa from around Yemen in their early history. It's quite possible that their ancestors had darker skin in Africa, became lighter skinned after generations in the Middle East, and then re-evolved black skin when they returned to Africa.

Ben_Reilly wrote:The Toubou people of north Africa:



... were discovered to have actually migrated back into Africa from around Yemen in their early history. It's quite possible that their ancestors had darker skin in Africa, became lighter skinned after generations in the Middle East, and then re-evolved black skin when they returned to Africa.

Beautiful picture Ben of beautiful women.

Excellent

Ben_Reilly wrote:The Toubou people of north Africa:



... were discovered to have actually migrated back into Africa from around Yemen in their early history. It's quite possible that their ancestors had darker skin in Africa, became lighter skinned after generations in the Middle East, and then re-evolved black skin when they returned to Africa.

that actually makes a lot of sense
because the African black gene is a dominate gene
while the Aboriginal black gene is regressive.
thus it makes sense that the aboriginal one is older and until the last 200 years unchanged (due to isolation)
while the African one is Dominate because it is newer and developed over both the original black gene and the fair gene,
the fairer gene is regressive to the African gene but dominate over the Aboriginal gene so it makes sense that it is the 'middle age' gene
The fairer gene can probably be broken down further into various Eurasian and American localised genes

korban dallas wrote:

eddie wrote:

korban dallas wrote:
Skin pigmentation in human beings evolved primarily to regulate the amount of ultraviolet radiation penetrating the skin the single most important substance is the pigment melanin

Did you guys not get this in biology at school ?

Hence why I said what I said?

indeed you did i was agreeing with you a with a bit more technical explanation.

and although i realise this may be a bit pedantic colder climate is not the trigger its the UV exposure hence why Inuit and Eskimos have darker skin  

Ah ok I got you lol

You know I worked this colour of skin thing out when I was really quite young. I alwahs assumed Jesus was black too

eddie wrote:You know I worked this colour of skin thing out when I was really quite young. I alwahs assumed Jesus was black too

well one thing is for sure he wasn`t white

korban dallas wrote:

eddie wrote:You know I worked this colour of skin thing out when I was really quite young. I alwahs assumed Jesus was black too

well one thing is for sure he wasn`t white

Only according to Hollywood films lol

I agree with the Vitamin D thing. If you live in a climate which has less UV light, you would need lighter skin. I wonder if studies have been done re Vitamin D deficiency in darker people living in northern Europe. Of course, these days people can take supplements, so it might not be very useful.