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  • - [Voiceover] In the vast timeline of humanity,

  • blue eyes are relatively new.

  • Originally, everyone was believed to have had brown eyes.

  • It wasn't until about 10,000 years ago

  • that blue eyed people started popping up everywhere.

  • It was probably creepy as (beep).

  • Today it's estimated that somewhere between

  • 20 and 40% of Europeans have blue eyes.

  • So what the heck happened?

  • Where'd all these blue eyed people come from?

  • Short answer, genetic mutation.

  • (scary music)

  • Here's a quick breakdown:

  • Eye color is determined by the amount of pigment

  • you have in your irises.

  • If you have a lot of pigment, you have brown eyes.

  • Less pigment, green or hazel.

  • And when there's little or no pigment,

  • you get blue eyes.

  • So what causes your body to produce

  • little or no pigments?

  • Genetics.

  • There are up to 16 genes involved

  • in determining eye color,

  • but the two main genes are HERC2 and OCA2.

  • Wow, those sound fun, and cool.

  • The HERC2 works as a switch to activate your OCA2 gene,

  • and the OCA2 gene activates proteins that produce pigments.

  • If either of those genes are mutated,

  • it stops the chain and pigments wont be produced.

  • I know what you're thinking,

  • how do you explain when two normal brown eyed parents

  • have a blue eyed kid?

  • See that's where it gets a little more complicated.

  • Everyone has two of each gene in their body.

  • One from their mama bear, and one from their pop.

  • So if you're daddy has one mutated OCA2 gene

  • and one working one,

  • but neither of your mom''s OCA2 genes are mutated,

  • then you'd still have brown eyes

  • because you'd inherit the working OCA2 from your mom.

  • But what if both parents have a mutated OCA2?

  • Then there's a 25% chance that you would come out

  • with those lurid baby blues.

  • A hidden mutated OCA2 gene could theoretically

  • be passed down through a family tree for generations

  • without anyone knowing.

  • Making mama and papa bear wonder whether

  • they brought home the right cub from the hospital.

  • A study at the University of Copenhagen

  • looked at the DNA of blue eyed individuals

  • and found that 99.9% of them

  • had a mutation in their OCA2 gene

  • that rendered it useless.

  • This led scientists to believe that all blue eyed people

  • may have come from one single common

  • mutant European ancestor.

  • So next time you lock eyes with another blue eyed babe,

  • be nice, because odds are, you're distant relatives.

  • Go up and hug them.

  • They wont be scared.

- [Voiceover] In the vast timeline of humanity,

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