- [voiceover] in the vasttimeline of humanity, blue eyes are relatively new. originally, everyone wasbelieved to have had brown eyes. it wasn't until about 10,000 years ago that blue eyed people startedpopping up everywhere.
laser surgery for eye color change, it was probably creepy as (beep). today it's estimatedthat somewhere between 20 and 40% of europeans have blue eyes. so what the heck happened?
where'd all these blueeyed people come from? short answer, genetic mutation. (scary music) here's a quick breakdown: eye color is determinedby the amount of pigment you have in your irises. if you have a lot ofpigment, 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 switchto activate your oca2 gene,
and the oca2 gene activatesproteins that produce pigments. if either of those genes are mutated, it stops the chain andpigments wont be produced. i know what you're thinking, how do you explain when twonormal brown eyed parents have a blue eyed kid? see that's where it getsa little more complicated. everyone has two ofeach gene in their body. one from their mama bear,and one from their pop.
so if you're daddy hasone mutated oca2 gene and one working one, but neither of your mom''soca2 genes are mutated, then you'd still have brown eyes because you'd inherit theworking oca2 from your mom. but what if both parentshave a mutated oca2? then there's a 25% chancethat you would come out with those lurid baby blues. a hidden mutated oca2gene could theoretically
be passed down through afamily tree for generations without anyone knowing. making mama and papa bear wonder whether they brought home the rightcub 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 believethat all blue eyed people may have come from one single common mutant european ancestor.
so next time you lock eyeswith another blue eyed babe, be nice, because odds are,you're distant relatives. go up and hug them. they wont be scared.
