Name: Why Do You Have Blue Eyes?
Uploaded: 2016-05-27T15:13:41.000Z
Duration: 2 min 28 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

- [Voiceover] In the vast timeline of humanity,

Originally, everyone was believed to have had brown eyes.

that blue eyed people started popping up everywhere.

Today it's estimated that somewhere between

Where'd all these blue eyed people come from?

Eye color is determined by the amount of pigment

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

but the two main genes are HERC2 and OCA2.

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

and the OCA2 gene activates proteins that produce pigments.

it stops the chain and pigments wont be produced.

how do you explain when two normal brown eyed parents

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

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

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

A hidden mutated OCA2 gene could theoretically

be passed down through a family tree for generations

they brought home the right cub from the hospital.

looked at the DNA of blue eyed individuals

This led scientists to believe that all blue eyed people

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

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

Subtitles ListPlay Video

Why Do You Have Blue Eyes?

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bear