WEBVTT - BrainStuff Classics: What Determines Your Hair Color?

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<v Speaker 1>Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff,

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<v Speaker 1>Lauren bog Obam here with a classic episode from our

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<v Speaker 1>archives featuring former host Christian Sager. Today's topic is an

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<v Speaker 1>excellent bit of everyday science. What determines your hair color?

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<v Speaker 1>And why do we go gray? A brain Stuff, it's

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<v Speaker 1>Christian Sager. Sometimes you're right in the middle of cleaning

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<v Speaker 1>up the drain in the shower and you start pondering

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<v Speaker 1>questions like why is my hair color different color from

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<v Speaker 1>my mom's hair, or my neighbor's hair or my roommates

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<v Speaker 1>disgusting soggy three ft long wolf tail drain wad? What's

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<v Speaker 1>the real difference between blonde hair, black hair, red hair,

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<v Speaker 1>and everything in between? Well, the main structural ingredient in

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<v Speaker 1>human hair is a protein called keratin. It's what your

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<v Speaker 1>hair and fingernails are made of. But also what's behind

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<v Speaker 1>the silky sheen of wool bear claws and horse hooves. Mmmm,

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<v Speaker 1>don't you just want to run your fingers through those hoofs?

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<v Speaker 1>But keratin on its own is not very colorful, And

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<v Speaker 1>if all humans had in our hair was keratin, we'd

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<v Speaker 1>look like eighteenth century French aristocrats in powdered wigs because

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<v Speaker 1>we'd all have the same sort of white, colorless hair.

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<v Speaker 1>But keratin is not the only ingredient in human hair.

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<v Speaker 1>To create natural color, you need to add pigment. This

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<v Speaker 1>is done by cells in the skin called melana sites.

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<v Speaker 1>These melano sites create the natural pigment known as melanin

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<v Speaker 1>and deliver it to the cells that create the keratin

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<v Speaker 1>for your hair, and this melanin comes into varieties you

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<v Speaker 1>melanin and THEO melanin. You melanin is a dark pigment

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<v Speaker 1>that gives hair a brown or black color. Pio melanin

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<v Speaker 1>is a lighter pigment that gives hair a red, orange,

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<v Speaker 1>or yellowish color. Both of these are present in varying degree,

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<v Speaker 1>as a person might have had a little of each,

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<v Speaker 1>or a lot of one and almost none of the other.

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<v Speaker 1>So someone with black or dark brown hair probably has

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<v Speaker 1>a lot of you melanin. A redhead has a lot

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<v Speaker 1>of THEO melanin, and blonds, well, they don't have very

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<v Speaker 1>much of either one. So what happens when we get

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<v Speaker 1>older and start to go gray, Well you can probably guess.

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<v Speaker 1>Over time, melano sites start to die off, and any

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<v Speaker 1>new hair that grows has less pigment, so it looks

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<v Speaker 1>gray or white. But you might be asking what determines

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<v Speaker 1>the you melanin to feel melanin mixture to begin with?

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<v Speaker 1>Who writes that recipe? Well, primarily it's your genes. For example,

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<v Speaker 1>the melano corton one receptor or m C one R gene.

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<v Speaker 1>When the protein associated with this gene is active in melanocytes,

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<v Speaker 1>it stimulates them to make you melanin, the pigment that

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<v Speaker 1>colors black or brown hair. When m C one r

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<v Speaker 1>is not active in the melanocytes cells, they make mostly

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<v Speaker 1>fio melon and instead and Hello Weasley's. But the mc

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<v Speaker 1>one r gene is not the only genetic factor that

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<v Speaker 1>controls hair color. Like most of your traits, hair color

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<v Speaker 1>is actually affected by more than one genetic variable. For example,

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<v Speaker 1>in a study in the journal Natural Genetics linked blonde

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<v Speaker 1>hair in Northern Europeans to a genetic mutation in one

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<v Speaker 1>single nucleotide controlling gene expression in hair follicles. They even

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<v Speaker 1>bred mice with the same tiny mutation, and the mice

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<v Speaker 1>had lighter colored fur than mice without the mutation. Today's

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<v Speaker 1>episode was written by Joe McCormick and produced by Tyler Klang.

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<v Speaker 1>The brain Stuff is production of I Heeart Radio's how

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<v Speaker 1>Stuff Works. To hear more from Joe, check out his

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<v Speaker 1>new podcast Invention or the old standby Stuff to Blow

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<v Speaker 1>your Mind, of course. For more on this and lots

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<v Speaker 1>of other hairy topics is that our home planet, how

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<v Speaker 1>stuff Works dot com. And for more podcasts for my

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<v Speaker 1>heart Radio, visit the i Heart Radio app, Apple Podcasts,

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<v Speaker 1>or wherever you listen to your favorite shows. H