Reverse image search shows that photo described as “Yemen protest”, without providing a link to a page using it. So it’s unclear whether it’s of protestors in Yemen, or people from elsewhere protesting about the Yemen situation.
Here’s a good link showing some faces of tribesmen from southern Arabia. Looks to be a range of skin tones.
For the record, here’s another photo from Sana’a in Yemen. In general, Yemenis, who are regarded as Arab, are quite dark.
While skin color does tend to relate to latitude (and not exactly linage) it is quite a recent development in Europe and not directly related to eye color.
Cheddar Man who was found Gough’s Cave in Cheddar Gorge, Somerset, England dates to 9100 BP and had dark skin and blue eyes.
There is a biological reason for selection of lighter shades of skin in areas without much sun, just as there is also a biological reason to select for darker skin in sunny areas (sunburn). Current general thinking does not tie that to lineage at all.
The mutations that lead to blue eyes, which actually are several variants stacked together, are just a byproduct of how “inbread” we are as a species. There is more genetic diversity in Siberia than in Europe, and more genetic diversity in Africa than the rest of the world.
I personally have green eyes, which tends to be rarer but is typically the result of not having all of the mutations that would lead to blue eyes.
Here is a story showing a recent artistic reconstruction of Chedder Man
To demonstrate the amount of inbreeding that happens within the human population.
Lets say that you can trace your ancestry to Charlemagne 42 generations ago.
He would be only one of 4,398,046,511,104 direct ancestors at that time, but obviously there weren’t 4.3 Trillion people alive back then so there was a lot of inbreeding.
It doesn’t take much bias success towards a particular group, with a fairly unlikely combination of traits to be represented at a rate that is far more common than expected. It could have been weather, chance, resistance to disease or anything that lead to blue eyes becoming more common than in other geographical areas.
Mathematically, if you have European ancestry you are a direct descendant of any European alive in ~900AD who has living descendants. And the reasons that traits without biological advantages get passed down is most likely just pure chance. It is possible that there is some localized advantage that these genes provide that just happen to result in the eye color, but really it is most likely just chance.
As I’ve already posted, this is wrong in the case of blue eyes, which show a genetic signature indicative of strong selection. The frequency of blue eyes in Europe is not due to pure chance,
Can you provide a cite that doesn’t reference papers that assumed that it co-evolved with light skin? I am looking to fight my own ignorance here, but everything I can find that makes that claim either made that outdated, incorrect assumption or claims that there is a sexual selection advantage.
Because I am failing to find open access papers, I will provide this as a “soft cite” for my position.
http://genetics.thetech.org/ask-a-geneticist/origin-blue-eyes
Note how DNA testing and examples like Chedder Man debunk option 2.
I would really appreciate any cites that can help correlate the claims, but none I have found match with what genetics has demonstrated about migrations and populations over the past few years.
Edited to add that the image in the OP covers a lot of Uralic speakers including Finland, which are more generally distant and tend to have different historical migrations (at this point in time)
Could a bottle neck have caused the concentration of blue eye genes in northern Europe?
How? Or possibly, what do you mean?
Blue eyes are concentrated in Norther Europe because the mutation causing it in Northern Europe are a late addition to human DNA and happened in lineages in, or on their way to, Northern Europe.
There’s really no need to hypothesize any bottle necks, and no other indications of any affecting blue eyes generally.
Not just holding their alcohol, light eyes have been associated with alcohol dependance as well. Eye color: A potential indicator of alcohol dependence risk in European Americans - PubMed
Perhaps bottle neck is not the right term, but I’m envisioning a situation in which blue eye mutation emerged in a family then, as a result of inbreeding, was propagated enough to spread throughout a small population. Then a catastrophe hits that wipes out most of the population. If a high proportion of survivors had blue eye genes just through random chance, couldn’t that result in a new population that is much more likely than other groups to have blue eyes?
Don’t know if this lines up with archeological evidence at all. But it would be a way for blue eyes to become pervasive without sexual selection or adaptation.
It could have been simply due to genetic drift, where each generation, some individuals purely by chance leave behind a few more descendants.
What we do know through the archaeological evidence is that the Eurocentric cultural bias that eye color, skin color and lactose tolerance arriving as a package is false.
The generally accepted thoughts today are that blue eyes arrived with hunter gatherers sometime between 12,000 to 7,000 BP. Lighter skin and lactose tolerance arrived in Europe after the Great Pyramid of Giza had been built.
This area of study is in flux as ancient DNA samples are increasing in numbers dramatically, but unless someone comes up with some amazing evidence or a testable theory that actually works, unlike the previous sexual advantage models we simply do not know. Genetic drift, adaptation or migrations (including founder effect) may be the cause but the direct cause isn’t known today.
True, but I think the bottleneck idea is pretty persuasive.
More spitballing: If the survivors of an environmental ctastrophe by chance had blue eyes and possessed traits that enabled them to survive whatever catastrophe killed everyone else (like lactose tolerance and/or extra pale skin leading to efficient vit D synthesis during a protracted period of low sun exposure), then the descendants of these well-equipped blue-eyed survivors would enjoy greater fitness than surrounding populations. They would outcompete their neighbors up until the point their traits stopped imparting an advantage (like being in lower latitude). Couldn’t something like this readily explain the apparent association between pale skin, lactose tolerance, and blue eyes? I think so.
I don’t put stock in the sexual selection theory because I don’t think horny prehistoric men would’ve rejected sex with women for something as inconsequential as eye color, especially if women were less abundant than men due to high maternal mortality). Prehistoric women discriminating against men based on minor physical traits like eye color also sounds like a stretch. Such choosiness seems like a luxury only possible when starvation, disease, tribal warfare, and exposure to the elements aren’t constant threats in your life.
This is where you edge on the difference between Philosophy and Science. While thinking about what may have happened is useful in science your claims that it must be are counter to the scientific method which is intended to prevent limitations posed by our biases.
As an example here, lactose tolerance may be a slight advantage, but without refrigeration making cheese removes that problem and produces a much more stable product. Adult lactose tolerance just isn’t needed for success at those high altitudes but may have had a slight advantage in later events but it all could have been due to chance.
Dairying societies existed for 1000’s of years without the need for that mutation in northern latitudes.
Note on why you have to be careful about these claims is documented in the history of both Eugenics and Nordicism. With the understanding I am not calling you racist, the cultural bias surrounding the belief that “Nordics” were superior because they had to live with the harder northern climate is where many of these vestigial Eurocentric theories still come from.
There is now evidence that lactase persistence arrived much later than dairying cultural practices.
I don’t think the most recent common ancestor is nearly that recent; we’re talking tens of thousands of years ago, if not hundreds of thousands for that.
My intuitions would be the same, but that is because us humans are really bad with big numbers. I was actually conservative and the most recent common ancestor of every European today was only about 600 years ago.
http://www.stat.yale.edu/~jtc5/papers/Ancestors.pdf
If you have access or want to pay for it here is a more modern cite.
Our intuitions surrounding this tend to be wrong.
Seriously, there is no need to start a lecture on the scientific method. I think it’s obvious I’m just speculating on a mechanism that could viably cause unrelated traits to become lumped together.
I also don’t know why you’re talking about cheese, as if that’s the only thing that could be consumed from a domesticated bovine. If famine is breathing down one’s back,being able to extract energy from a foraging cow could come in handy.
Dude, I’m a black woman. Don’t need you to tell me this either.
Tone is hard to convey, I was trying to explain why this idea is often rejected without evidence it happened. And why with the current state of identity politics in Europe precision is important right now. Other readers perceptions are what I was targeting, as the false ideas from this books like the following are gaining ground once again.
The it may have been a bottleneck effect, it may have been the founder effect or it may have just been genetic drift.
All three are quite possible and we don’t have information to rule any of them out right now. With the growth of Nationalism in Europe it is important to point out that there is zero evidence that we have today that makes any of these possibilities more likely than the others.
Without direct evidence, it is hard to tell.
The bottleneck effect is an extreme example of genetic drift only when a population is severely reduced. With the growing number of diverse locations of Mesolithic hunter-gatherer with blue eyes, we don’t have a reason right now to think it was a bottleneck. It may have just been pure randomness.
I mentioned cheese making because we have direct evidence of it happening way before lactase persistence existed in Europe.
Cheese making simply pre-dated adult drinking raw milk for 1000s of years in Europe.
Ok, I don’t disagree.
None of that negates the idea that an adult that can digest milk from an animal will be better off than one that can’t. Not only will they have another food source, but they will have access to nutrients that can make them more reproductively successful if they are a woman.
Cheese still contains lactose, just lower levels than milk.
The production method of hard cheeses can, and often does, eliminate lactose entirely.
