What Does Brown Hair And Blue Eyes Mean?

What Does Brown Hair And Blue Eyes Mean
What does it mean to have green eyes and blue eyes? – The green eyes mean that he or she has the not-brown-eye version of OCA2 and the green version of either SLC24A4 or TYR gene. Someone with this set of traits most likely has the freckle version of the TYR gene.

Is it rare to have brown hair with blue eyes?

Worldwide, brown hair and blue eyes are relatively rare. However in ethnic Europeans, this combination is common and reaches the world’s maximum in the island of Ireland in North-Western Europe. In northern France, many people also have brown hair and blue eyes (though not the majority.

What does brown and blue eyes mean?

Eyes with a higher concentration of melanin absorb more light, so less light is reflected back- resulting in a dark brown iris. With lower concentrations of melanin, less light is absorbed, so more is reflected back- resulting in a green, blue or hazel color.

What causes brown hair blue eyes?

A gene which causes people to develop freckles, dark brown hair and blue eyes has been discovered by scientists. In the study of Icelanders, researchers uncovered an intricate pathway involving the interspersed DNA sequence, or non-coding region, of a gene that is among a few dozen associated with human pigmentation traits.

It is more common to find people with ancestors from geographic locations farther from the equator, such as Iceland, who have less pigment in their skin, hair and eyes. The researchers, including scientists from the National Human Genome Research Institute (NHGRI), analysed data from a genome-wide association study (GWAS) of 2,230 Icelanders.

A GWAS compares hundreds of thousands of common differences across individuals’ DNA to see if any of those variants are associated with a known trait. “This study explains a complex molecular pathway that may also contribute insights into skin diseases, such as melanoma, which is caused by the interaction of genetic susceptibility with environmental factors,” said NHGRI Scientific Director Dan Kastner.

  • Researchers focused on the interferon regulatory factor 4 (IRF4) gene, previously associated with immunity.
  • IRF4 makes a protein that spurs production of interferons, proteins that fight off viruses or harmful bacteria.
  • The researchers noted from genomic databases that the IRF4 gene is expressed at high levels only in lymphocytes, a type of white blood cell important in the immune system, and in melanocytes, specialised skin cells that make the pigment melanin.
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The new study established an association between the IRF4 gene and the pigmentation trait. “Genome-wide association studies are uncovering many genomic variants that are associated with human traits and most of them are found in non-protein-coding regions of the genome,” said William Pavan, co-author and senior investigator, Genetic Disease Research Branch, NHGRI.

  1. The Icelandic GWAS yielded millions of variants among individuals in the study.
  2. The researchers narrowed their study to 16,280 variants located in the region around the IRF4 gene.
  3. They used an automated fine-mapping process to explore the set of variants in IRF4 in 95,085 people from Iceland.
  4. The data revealed that a variant in a non-coding, enhancer region that regulates the IRF4 gene is associated with the combined trait of sunlight sensitivity, brown hair, blue eyes and freckles.

The study was reported in the journal Cell.

What kind of eyes do guys like?

When broken down by gender, men ranked gray, blue, and green eyes as the most attractive, while women said they were most attracted to green, hazel, and gray eyes. Despite brown eyes ranking at the bottom of our perceived attraction scale, approximately 79% of the world’s population sports melanin-rich brown eyes.

Will blue eyes go extinct?

Nerdfighteria Wiki – Are Blue Eyes Endangered? Despite the apparent prevalence of the trait among swanky crooners and British spies and creepy old creatures who just hung onto the ring for too long, only about 8% of the world’s human population has blue eyes. Here in the U.S. it’s about twice that, but that’s still a lot less than it was at the turn of the twentieth century when nearly half of all Americans had the trait.

  • So what happened? Are blue-eyed humans going the way of the dodo?Well, no.
  • We cleared up that rumor about redheads going extinct; the same goes for blue eyes.
  • While the trait is becoming more rare, it’s unlikely it will disappear all together.
  • Which is crazy when you consider that 10,000 years ago blue eyes didn’t even exist.
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In fact, there’s a good chance that blue-eyed people may all share one common ancestor. Studies over the past decade have actually traced the trait to a mutation that most likely arose among brown-eyed people in a single human in the Black Sea region of southeastern Europe between 6,000 and 10,000 years ago.The mutation affected what’s known as the OCA2 gene, which helps our bodies produce melanin, the brownish pigment that gives color to our hair and eyes and skin.

  1. The mutation created kind of a dimmer switch for the pigmentation, but it didn’t affect the entire gene.
  2. Instead, it only affected the production of melanin in the iris, the ring structure around the eye that regulates how much light gets in.The bulk of the iris is a thick layer of melanin-producing cells called the stroma.

And the OCA2 mutation turns the production of melanin in the stroma way down, but the pigmentation still shows up elsewhere, like in the hair and skin and other parts of the iris. Basically, the mutation keeps the stroma from being brown.So why blue then? Well, strictly speaking, blue eyes aren’t actually blue.

Instead, in people with this mutation, the stroma is full of nearly colorless cells. And when the light strikes them, they scatter the wavelengths back out, in a process similar to what makes smoke or fog look blue when light passes through them.If there is some yellowish pigment in the stroma, then the blue light will combine with that to make green.

Throw in a little bit of brown, and you have hazel.So how did we go from having no blue-eyed people, to hundreds of millions of them in less than 10 millennia? No one’s entirely sure why the trait spread so quickly through Europe. Some scientists think the mutation could have helped prevent certain eye disorders related to long, dark northern winters.But another factors appears to be that, for whatever reason, lots of blue-eyed people simply mated with other blue-eyed people in the past, which kept the trait in circulation.

  1. Because for each of your genes, you have two different versions, called alleles, one from your father and one from your mother.
  2. If you have at least one dominant allele for a gene, that’s the trait you have.The blue eyes come from a recessive allele, which means if you inherit one allele for blue eyes and another for brown, you’re going to have brown eyes.
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But you still carry the recessive blue allele, which can be passed on. Which means that that first person that had that blue-eyed mutation didn’t have blue eyes. They had to pass that onto their children, and their children had to pass it onto their children, until eventually they came back together to make someone with two blue-eyed alleles.When both parents have blue eyes, they both have two recessive blue-eyed genes, which means their children will also have blue eyes since there’s no dominant gene to mask the recessive one.

This is how you end up with Scandinavian countries that are 95% blue-eyed, and it also explains why the percentage of blue eye-ers is dropping in much of the western world.Human populations are a lot more evenly spread throughout the world than they were 10,000 years ago, so more blue eyes are pairing up with brown eyes and producing brown-eyed offspring.I wouldn’t go so far as to call them endangered, but safe to say those blue-eyed singers and spies and Gollums will always be in the minority.

Thanks for watching this SciShow Dose. If you’d like to help us keep exploring the world, just go to to find out how you can become a supporter. And if you want to keep getting smarter with us, don’t forget to go to and subscribe. : Nerdfighteria Wiki – Are Blue Eyes Endangered?

Is brown hair blue eyes common?

How common is dark brown hair and blue eyes? – Since there are 7-8% of people worldwide with blue eyes, the percentage with blue eyes and brown hair should be somewhere in the low single digits, maybe 3-5%. |