What Does Blue Eyes Represent?
- Pieter Maas
Blue Eyes – While most of us are actually born with blue eyes, they change within the first few weeks of life. Consequently, many people think that blue eyes resemble a youthful appearance. It is also said that people with blue eyes have a calm and peaceful personality, and are representative of wisdom and knowledge.
What does blue eyes mean?
Whether you’re a brown-eyed girl or five-foot-two, eyes of blue, it’s what’s inside that counts. Seriously, we mean that. Your eye color has everything to do with your genetics, and if you’re blue eyed, you can probably figure out who’s a distant relative just by looking at them.
It could be said that all eyes are the same color, That’s because the pigment that gives our eyes color, melanin, is naturally brown. In fact, originally, “we all had brown eyes,” a professor from the University of Copenhagen, Hans Rudolf Litchoff Eiberg, PhD, told Science Daily, Somewhere along the way, however, someone was born with a genetic mutation, Dr.
Eiberg explains. That genetic mutation limited the amount of melanin the person’s eyes could produce, with the visual effect being that the eyes appeared blue, rather than brown. Interesting, you might be thinking, but what do blue eyes genetics have to do with me? Well, the fact that all (so-called!) blue eyes descend from a single genetic mutation means that every single person on the planet with blue eyes descended from one common ancestor.
In fact, a team of geneticists at the University of Copenhagen actually traced that mutation all the way back to a single Danish family. “By linkage analysiswe fine-mapped the blue-eye color,” Dr. Eiberg’s team reported in the journal, Human Genetics, Through that analysis, it was discovered that an identifiable group of genes had been inherited together from one single parent—the scientific word for a group of genes inherited together from a single parent is ” haplotype,” The identified haplotype was common not just among 155 blue-eyed individuals from Denmark, but also five blue-eyed individuals from Turkey, and two blue-eyed individuals from Jordan.
In addition to haplotype mapping, Dr. Eiberg’s team conducted mitochondrial DNA analysis, which looks at patterns of genetic mutation to trace maternal ancestry back hundreds of thousands of years. “Variation in the color of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes,” Dr.
- Eiberg notes.
- From this we can conclude that all blue-eyed individuals are linked to the same ancestorThey have all inherited the same switch at exactly the same spot in their DNA.” Brown-eyed individuals, by contrast, have considerable individual variation in the area of their DNA that controls melanin production.
So, are blue eyes a mutation? Yes. But is that a good thing or a bad thing? Neither, according to Dr. Eiberg. “It simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so.” What we can presume, however, is that the color of our eyes is not the only thing trait that went along with the mutation that led to that color.
higher melanoma risk more likely to be competitive lower vitiligo risk
To find out more about your own ancestry, you can try genetic testing, But be aware that you may not always be prepared for what you find out.
What are blue eyes known for?
Blog 1. Only 8 Percent of the World’s Population Has Blue Eyes If you have got blue eyes, you might just belong to one of the world’s most exclusive groups without realising it! Since blue eyes are genetically recessive, only 8 percent of the world’s population has blue eyes.
While blue eyes are significantly less common than brown eyes worldwide, they are frequently found from nationalities located near the Baltic Sea in northern Europe.2. There is No Blue Pigment in Blue Irises The colour of our eyes depends on how much melanin is present in the iris. Blue eyes get their colour the same way water and the sky get their blue colour — they scatter light so that more blue light reflects back out.
The iris is made up of two layers. For almost everyone — even people with blue eyes — the back layer (called the pigment epithelium) has brown pigment in it. The front layer of the iris (called the stroma) is made up of overlapping fibers and cells. For people with brown eyes, some of the cells also have brown pigment in them.
- If there is no pigment at all in this front layer, the fibers scatter and absorb some of the longer wavelengths of light that come in.
- More blue light gets back out and the eyes appear to be blue.3.
- Blue Eyes are More Sensitive to Light Melanin in the iris of the eye appears to help protect the back of the eye from damage caused by UV radiation and high-energy visible “blue” light from sunlight and artificial sources of these rays.
Since blue eyes contain less melanin than green, hazel or brown eyes, photophobia is more prevalent in blue eyes compared to darker coloured eyes. For these reasons, having less melanin in your irises means that you need to protect your eyes more from the sun’s UV rays.
- Therefore, it is recommended to those with blue eyes to stay out of the sun for long periods of time and try to wear protective eyewear when you are outdoors.4.
- All Blue-Eyed People May Have A Common Ancestor Originally we all had brown eyes, however, according to researchers at the University of Copenhagen, it appears that a genetic mutation in a single individual in Europe 6,000 to 10,000 years ago led to the development of blue eyes.
Therefore, we can conclude that this genetic mutation is the cause of eye colour of all blue-eyed humans alive on the planet today. What is the genetic mutation? A genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a “switch”, which “turned off” the ability to produce brown eyes.
- The OCA2 gene codes for the ‘P protein’, which is involved in the production of melanin (the pigment that determines the colour of our eyes, skin and hair).
- The “switch”, does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris – effectively “diluting” brown eyes to blue.
According to Hans Eiberg, associate professor in the Department of Cellular and Molecular Medicine from the University of Copenhagen, “From this, we can conclude that all blue-eyed individuals are linked to the same ancestor. They have all inherited the same switch at exactly the same spot in their DNA.” 5.
Blue Eyes at Birth Doesn’t Mean Blue Eyes For Life While blue eyes may be rare, they’re among the most common eye colours at birth. Since the human eye does not have its full adult amount of pigment at birth, most Caucasian babies are born with blue eyes. However, since human melanin tends to develop over time — this causes the child’s eye colour to change as more melanin is produced in the iris during early childhood.6.
People With Blue Eyes May Have a Higher Risk of Alcoholism A new study suggests that individuals with blue eyes are at a higher risk for alcohol dependency compared to those with darker eyes. Therefore, this finding adds further evidence to the idea that alcoholism has a genetic component.
A study published in American Journal of Medical Genetics, Part B: Neuropsychiatric Genetics found that European Americans with blue eyes had up to 83 percent higher odds of becoming dependent on alcohol, compared with matched controls who had darker eye colours. This research suggests that alcoholism has a genetic component linked to genetic sequences that determine eye colour, which may help explain the association.
However, at this stage, the reason for the correlation is still unknown and further research is required to fully understand this correlation in the findings.7. You Can’t Predict the Colour of Your Child’s Eyes Since it was once believed that eye colour — including blue eyes — was a simple genetic trait, many people used to believe that blue-eyed people could only have blue-eyed children.
- Before geneticists fully understood how human eye colour inheritance works, a child’s eye colour to used be used as a paternity test — based on the assumption that you could predict a child’s eye colour if you knew the colour of the parents’ eyes and perhaps the colour of the grandparents’ eyes.
- But geneticists now know that this concept is far more complicated, as eye colour is influenced by an interaction of as many as 16 different genes — not just one or two genes as once thought.
Additionally, the anatomic structure of the iris can also influence eye colour to some degree. In summary, it’s impossible to know for sure if your children will have blue eyes. Even if you and your partner both have blue eyes, that’s no guarantee your child’s eyes will also be blue.
Do blue eyes indicate intelligence?
They’re touted as being the window to the soul, but a new study says your eyes might provide a look into your personality, too. The study from the University of Queensland and the University of New South Wales, published in Current Psychology, links a person’s eye color with how agreeable that person is.
- Researchers found that those with lighter-colored (blue and green) eyes tended to be less agreeable and more competitive than their brown-eyed peers.
- Blue and green eyes were also linked to being egocentric and skeptical of others while those with brown eyes were seen as more altruistic, sympathetic and willing to help others.
The explanation for eye color serving as a benchmark for agreeableness could be cultural. “Brown eyes are more common, so it could be that there is a sense of ‘belonging’ or fitting in with those who have dark eyes,” Ramani Durvasula, Ph.D., a licensed clinical psychologist, professor of psychology and neuropsychological researcher.
“Brown eyes may also be more likely to come from cultures where a trait like agreeableness is more culturally and societally valued than in blue-eyed cultures.” “Blue eyes may seem cooler while brown eyes perhaps seem warmer. That can then be manifested by stereotypes about competition, agreeableness, etc.,” adds Durvasula.
Agreeableness isn’t the only personality trait connected to eye color. A recent survey conducted by CyberPulse, a division of Impulse Research Corporation in Los Angeles uncovered this colorful research. Brown Eyes Intelligence was the number one trait associated with brown, the most common eye color in the U.S., by 34 percent of respondents.
- Being trustworthy was second (16 percent said this) and kind (13 percent) came in as the third most likely trait of those with brown eyes.
- Other research has said brown eyed people have stronger eye contact skills, with researchers speculating this could be because they don’t anticipate being looked at as much as blue eyed people.
Blue Eyes The most common characteristic thought to be associated with blue-eyed individuals: exuding sweetness by (42 percent), with being sexy (21 percent) and kind (10 percent) rounding out the top three. Interestingly, in contrast to brown eyes, blue eyes were not associated with intelligence as only 7 percent of respondents thought of blue-eyed people as intelligent.
- Green Eyes Twenty-nine percent of participants associated green eyes with sexiness, the top characteristic thought to be related to this color.
- Green-eyes was also thought of as creative (25 percent) and a little devious (20 percent).
- Being trustworthy and shy was also linked to green-eyed people.
- No matter their color, a majority of people (60 percent) wished they could change their own hue.
The most wished for color? Green, with 27 percent of respondents saying they’d switch to green eyes if given the chance. Coming in at a close second was amethyst while 18 percent expressed the desire to have blue eyes. “While it’s not often studied, the link between eye color and personality is very interesting,” says Durvasula.
Which eye Colour is lucky?
If you’re male, aged 33 and have blue eyes, your future looks bright, according to a new poll by Casumo.com If you are blessed with brown hair or are a man called Paul, chances are you are very lucky ( Image: Getty) If you’re a male, aged 33, you’ve got brown hair, and your name is Paul, your luck could be in – literally. Researchers polled 2,000 Brits to find out the luckiest name in the country and the traditional name of Paul took top spot for men – with Rachel and Becky joint first for women.
- The age Brits feel luckiest was revealed to be 33 and 11 months, with 41 per cent of respondents saying this was the luckiest year of their lives.
- Brits also reckon the luckiest people have blue eyes ( Image: Getty) While retail is deemed the luckiest industry to work in, followed by teaching and transport ( Image: Getty) The study was conducted by online gaming site Casumo.com, whose spokesman Gregory Tatton-Brown said: “What is luck? Do people make it themselves, or are some people genuinely born luckier than others? “And can something as arbitrary as what you are named mean that you have more luck than others over the course of a lifetime?” The luckiest people in the country also tend to have light blue eyes, choose blue as their favourite colour, and have no pet – although dogs are deemed luckier than cats.
And blue is also the colour for lucky people’s cars – as the second luckiest colour behind silver, with Ford the most common car for lucky folks. Retail is the luckiest industry to work in, followed by teaching, transport and logistics, and property and construction.
And possibly due to the streets being allegedly paved with gold, London was also voted the luckiest city to live in, with Birmingham coming in second place. Men with the name Paul also have a promising future, according to the poll by Casumo.com ( Image: Getty) While London is the luckiest city to live in ( Image: Stone Sub) The most common lucky number among Brits that believe themselves to be particularly lucky was 7, with one in 20 going for the traditionally unlucky 13.
Eight in 10 of the unluckiest respondents in Britain believe that some people are naturally luckier than others. And of the respondents that rated themselves as lucky as can be, more than half had some good luck within the last week. With a third of the unluckiest saying that they’d never experienced something that could be described as a stroke of good fortune.
The top reasons for people to count themselves as lucky were being good with money, being blessed with children or being in a great relationship. And one in 10 say they survived a near death experience. On the other side of the coin, the unlucky respondents said they never seem to be in the ‘right place at the right time,’ rarely win on raffles or scratch cards, and don’t even have luck finding cash on the floor.
Gregory Tatton-Brown said: “It is interesting to see what people considered examples of luck – from finding cash on the floor to having a good education. “And most people believe that being lucky tends to make you happier, which makes sense – who wouldn’t want fortune to smile on them more often? “The games at Casumo.com contain a mixture of luck and skill – so you’ll need a bit of both if you want to be a winner.”
Why are blues eyes attractive?
Home Lifestyle People With Blue Eyes Are More Attractive, Says Science
Beauty is in the eye of the beholder, and apparently things always come up looking blue. Credit: iStock / SanneBerg It looks like Frank Sinatra had it right this entire time. And while a lot of people might not agree with this at first, there’s a new report that says people with blue eyes are more attractive than their brown-eyed counterparts.
- And yes, science does have something to do with the findings.
- Beauty is in the eye of the beholder, and apparently things always come up looking blue.
- A group of researchers at Germany’s University of Regensburg decided to do a study on which eye color is seen as more attractive: blue or brown? Researchers Martin Gründl, Sebastian Knoll, Marita Eisenmann-Klein, and Lukas Prantl asked 80 participants to rate the attractiveness of 60 women aged 15 to 65 by just looking at photos of their eyes.
And while there was no correlation found between iridal color and their rated attractiveness, the researchers did point out one thing: that the participants picked out the color blue more often as a positive aspect than other iridal colors. Also, those with large blue eyes usually have better luck in the love department: blue eyes and larger pupils often correlate with youthfulness, along with being attractive. Credit: iStock / SanneBerg In another poll by social networking site Badoo, 60 percent of men said that they thought brunettes with blue eyes were the most attractive. A third of the men found brown hair to be the most attractive; 28.6 percent said they prefer black hair.
- In addition, the same study also found that men preferred women who had green eyes over those with brown eyes.
- Yet, the majority of both men and women found blue to be the most attractive eye color over all.
- If you happen to be a green-eyed beauty though, don’t fret.
- Reports say that the green eye color is the rarest color found around the world, and it is estimated that only around 2% of the world’s population has green colored eyes.
Green eye color is a result of a mild amount of pigmentation in the eye with a golden tint. But if there is one color that happens to be even more rare than green eyes, it’s violet. Elizabeth Taylor was famous for her violet eyes, although in reality she had baby blues.
What are blue eyes better at?
Are Blue Eyes or Light Eyes More Sensitive? People with blue or light eyes tend to be more sensitive to light. This is because blue eyes, especially light blue eyes, have less pigment in the iris, making them more translucent. This can cause blue-eyed people to be more susceptible to glare and sunlight, leading to light sensitivity.
Who was the first blue-eyed human?
Behind Blue Eyes: A Look at the Genetic and Cultural Components that Propelled the Spread of Blue-Eyed Humans
- This thoroughly-researched piece is by Sarah Henry, an instructor at Delaware County Community College and tour guide at the Mütter Museum.-KI
I have blue eyes and I have always been interested in exploring my own genetic origins, but I’m not the only one interested in this genetic trait. Countless songs and poems reference people with blue eyes, whether considered a mark of beauty, a representation of sadness, or, in certain cultures, a sign of the oppressor.
- But blue eyes, so popular in art, are relatively new in human evolution, as new as the invention of writing itself.
- My interest in this subject was sparked, in part, by a unique archaeological discovery; in 2006, researchers uncovered the world’s oldest confirmed blue-eyed person, dating to approximately 7,000 years ago.
This discovery helped to confirm theories regarding the familial relationship of nearly all blue-eyed individuals. This article will exam the genetic origins of blue eyes in humans, the spread of the blue-eyed gene, and the future of this genetic trait.
- Genetics: How Do They Work? The basic explanation of eye-color works like this: a person needs only one dominant brown-eyed gene (from one parent) to be brown-eyed but needs to have two recessive blue-eyed genes (one from each parent) to be blue-eyed.
- You have probably seen this explanation accompanied by a simple Punnet square (Image 1) in your science textbooks.
However, new studies illustrate that the genetics behind eye color are not so straightforward. There are actually two separate genes that control eye color in humans. In his article, “Blue Eye Color in Humans,” Hans Eiberg writes, “Blue/Brown eye-color are known to the public as a school example of inheritance of monogenetic inheritance, however, the variation in pigment concentration and the iris suggest the eye color genetics to be far more complex as supported by recent data.” In other words, eye color is controlled not by one gene passed from parent to offspring, but by two genes working in tandem; a more complex chart would take both of these genes into consideration (Image 2).
These genes are called OCA2 and HERC2 (represented as O, o, H and h in Image 2). The simplified explanation is that the OCA2 gene controls pigment in the stroma (the tissue and blood vessels) of the iris (the colored part of the eye around the pupil) and the HERC2 gene is needed to help turn on the OCA2 gene to cause it to produce this pigment, resulting in brown eyes.
If a person has a non-functioning OCA2 gene, they will always have blue eyes, because the HERC2 gene can’t make the broken OCA2 gene work. Likewise, if a person has a HERC2 gene which doesn’t work, the OCA2 gene will “underachieve,” failing to produce enough pigment to make brown eyes, resulting in blue eyes.
These two genes aren’t directly related to each other, yet they affect each other. In this dependent relationship, both of these genes must work to give an individual brown eyes, a genetic relationship known as “epistasis.” Because of this process, it is actually possible (although rare) for two blue-eyed parents to have a brown-eyed child.
- How Do We Know All Blue-eyed People Are Related?
Homo sapiens (modern humans) emerged around 200,000 years ago in Africa, but the mutation that causes blue eyes did not appear until sometime around 10,000 years ago. In a study conducted by Professor Hans Eiberg and a team from the University of Copenhagen, researchers examined mitochondrial DNA from 155 blue-eyed subjects from Denmark, two from Jordan, five from Turkey, and 45 brown-eyed candidates, looking at the locus (specific location or position of a gene) responsible for brown or blue eyes.
The result was the discovery that more than 97% of blue-eyed people share the single H-1 haplotype (a group of genes within an organism that was inherited together from a single parent). Eiberg and his team write, “A shared haplotype among blue-eyed individuals is almost perfect and suggests the blue color phenotype is caused by a founder mutation.” This means that the vast majority of people with blue eyes share a single inherited genetic mutation, rather than each person with blue eyes possessing a unique mutation.
The study also tested seven blue-eyed Mediterranean individuals unrelated to the Danish participants as a control group. They, too, carried the H-1 haplotype. These individuals with the H-1 haplotype all inherited the same switch at the same location in their genetic coding, whereas, brown-eyed individuals have a number of variations in melanin production and DNA, with brown-eyed phenotypes being spread out between haplotypes H-5 and H-10.
- In short, almost all blue-eyed people came from a single ancestor, which is proven by the possession of the exact mutation at the same location in their genetic coding.
- That leads us back to the blue-eyed man from the article that sparked this entire investigation.
- Why is This Stone Age Body in Spain so Important? In 2006, researchers discovered a 7,000 year old body from the Stone Age in the La Brana cave system in Leon in Northern Spain (Image 4).
Genetic testing determined that this man had blue eyes. It was not in itself unusual, but what is remarkable is that he is the earliest known person with blue eyes. Far from being a fair-haired, far-skinned man that we may have expected, his genetics reveal he’s a mixture of other traits. In order to answer this question, we need to delve into Stone Age migratory patterns. According to Pickrell and Reich, there are two theories of cultural migration: Demographic Stasis vs. Demographic Change. In Demographic Stasis, inhabitants living in a particular region are the descendants of the first people to arrive in that region, meaning the people in a certain area were never integrated into or replaced by people from a second migration. Specifically, we can see this during the Neolithic (New Stone Age) Revolution, a period of time where humans began to cultivate crops, domesticate animals, and use polished stone tools. Prior to the Neolithic Revolution, almost all the world’s inhabitants subsisted primarily by hunting and gathering, but after the Neolithic Revolution, small pockets of farming emerged, first in the Fertile Crescent, China, and India and then spreading across Eurasia.
- The Neolithic Revolution occurred between 6,000-10,000 years ago, and because people were better able to procure a steady source of food, the population increased significantly.
- The technologies which emerged during this time allow archaeologists and researchers to track cultural migration from the northwestern part of the Black Sea region (where the first humans with blue eyes lived) into the rest of Europe.
A study of Armenian haplotypes determined, “.hospitable climatic conditions and the key geographic position of the Armenian Highland suggest that it may have served as a conduit for several waves of expansion of the first agriculturalists from the Near East to Europe and the North Caucasus.” People migrated out of the Caucuses (modern-day Georgia, Azerbaijan, and Armenia) and into other parts of Europe (Image 6). Another study, focusing specifically on the genetics of residents of the Iberian Peninsula (excluding the Basques), indicates a mixture of genetic traits from the Caucuses, Central Asia and North Africa, probably related to migration during the Neolithic Era.
A study of eight Bronze Age individuals dated to between 5,500 and 3,500 years ago shows an admixture between existing hunter-gatherer groups and people from later migrations, meaning people who migrated to this area began to blend into the peoples that already lived there by blending both their culture and genetics.
Why Did this Recessive Genetic Trait Survive for Thousands of Years? How did the blue-eyed gene persist if there’s no overt evolutionary advantage to possessing it? One argument would be that those original groups of people who possessed blue eyes produced offspring with other blue-eyed people in their own group, leading to a population where blue eyes were the norm.
- However, there are both objective and subjective benefits to possessing blue eyes.
- Subjectively, possessing blue eyes may just make one individual more sexually attractive to another.
- Objectively, blue eyes filter light differently than dark eyes (dark eyes, like dark skin, possess more pigment which can protect those organs from sun damage), which make them especially advantageous in the low light of Northern European winters.
Because people with light eyes are more sensitive to light, they can see better in areas that lack sufficient sunlight for large portions of the year. Conversely, while light sensitivity (photophobia) proved useful in a world prior to electricity, it actually opens blue-eyed people up to a host of medical problems including an increased risk of macular degeneration, which can ultimately lead to blindness because light eyes are worse at filtering out harmful UV light.
What is the future of blue eyes? At the turn of the 20 th century, 50 percent of people living in the United States had blue eyes. Now, however, people are more likely than ever to marry outside of their ethnic group, leading to more genetically diverse offspring and a decline in blue eyes due to the dominance of the brown-eyed genes.
Currently, in the U.S., only 17 percent of the population (1 in 6) has blue eyes and only between 5-8% of people worldwide possess the trait. (Green eyes are even more rare, but they are a topic for another article.) Even though they are new in human history, blue eyes are already on the decline.
Whether used to convey beauty, as one writer notes about the poetry of Longfellow and Romanticism, “It delighted in sentimental musings amid the ruins, in pathetic legend, in dreamy pictures of monks and harpers and knights and radiant maidens with soft blue eyes” or to convey sadness like in the Who song “Behind Blue Eyes,” where Roger Daltry sings, “No one knows what it’s like/ To be the bad man/ To be the sad man/ Behind blue eyes,” or as Kristina Richardson writes in her article regarding the perception of blue eyes in the Islamic Middle Ages, “My preliminary archival work suggests the Medieval Muslim male writers overwhelmingly accepted the characterization of blue and green eyes as unattractive and deviant,” a line of thinking fueled by the brutality of European crusaders who raped, pillaged and murdered in an attempt to reclaim the Holy Land.
Blue eyes have been a notable trait in literature across cultures for centuries. Though the future of blue eyes is unclear, nearly all living and dead blue-eyed individuals share a familial relationship through a single genetic mutation. If you have blue eyes or know someone with blue eyes, they are more than likely related to that 7,000 year old man whose remains that researchers found in a remote cave in Spain.
Sources A. Hoyhannisyan, Z. Khachatryan.M. Haber, P. Hrechdakian, et all. Different waves and directions of Neolithic migrations in the Armenian Highland. Investigative Genetics 5 (2014).B. Starr. “Eye Color.” TheTech. TheTech, 14 October 2004.B. Starr. “How Blue Eyed Parents Can Have Brown Eyed Children: Two Different Ways to Get Blue Eyes.” TheTech.F.L.
Patty. Sidelights on American Literature. “The Shadow of Longfellow.” Century Company, 1922: p.237.H. Eiberg, J. Troelsen, M. Nielsen, A. Mikkelsen, J. Mengel-From, K.W. Kjaer, L. Hansen. Blue eye color in humans may be caused by a perfectly associated founder mutation in a regulatory element located within the HERC2 gene inhibiting OCA2 expression.
- Human Genetics 123 (2008): 177-187.I.
- Lazaridis, et all.
- Ancient human genomes suggest three ancestral populations for present-day European.
- Nature 513 (18 September 2014): 409-413.K.
- Blue eyes in Islamic Middle Ages.” Medievalists.
- Medievalists, 16 February 2014.J. Bryner.
- One Common Ancestor Behind Blue Eyes.” LiveScience.
LiveScience, 31 January 2008.J.K. Pickrell and D. Reich. Toward a new history and geography of human genes informed by ancient DNA. Trends in Genetics Vol.30, No.9 (Sept 2014): 377-389.J. Mengel-From, C. Borsting, J.J. Sanchez, Hans Eiberg, Neils Morling. Human eye colours and HERC2, OCA2 and MATP.
Forensic Science International: Genetics 4 (2010): 323-328.S. Connor. “Revealed: First Ol’ Blue Eyes is 7,000 years old and was a caveman living in Spain.” IndependentUK. IndependentUK, 26 January 2014.T. Günther, C. Valdiosera, H. Malmström, I Urena, et all. Ancient genomes link early farmers from Atapuerca in Spain to modern-day Basques.
PNAS 112 (2015): 11917-11922 University of Copenhagen. “Blue-eyed humans have a single, common ancestor.” ScienceDaily. ScienceDaily, 31 January 2008. : Behind Blue Eyes: A Look at the Genetic and Cultural Components that Propelled the Spread of Blue-Eyed Humans