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Speaker 1: Welcome to brain stuff from how stuff works a brain

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Speaker 1: stuff it's Christian saga. Sometimes you're right in the middle

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Speaker 1: of cleaning up the drain in the shower and you

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Speaker 1: start pondering questions like why is my hair color different

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Speaker 1: color from my mom's hair or my neighbor's hair or

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Speaker 1: my roommates disgusting soggy three foot long wolf tail drain wad?

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Speaker 1: What's the real difference between blonde hair, black hair, red hair,

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Speaker 1: and everything in between? Well, the main structural ingredient in

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Speaker 1: human hair is a protein called keratin. It's what your

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Speaker 1: hair and fingernails are made of, but also what's behind

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Speaker 1: the silky sheen of wool bear claws and horse hooves. Mmmm.

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Speaker 1: Don't you just want to run your fingers through those hooves?

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Speaker 1: But keratin on its own is not very colorful, and

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Speaker 1: if all humans having our hair was keratin, we'd look

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Speaker 1: like eighteenth century French aristocrats in powdered wigs because we'd

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Speaker 1: all have the same sort of white, colorless hair. But

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Speaker 1: keratin is not the only ingredient in human hair. To

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Speaker 1: create natural color, you need to add pigment. This is

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Speaker 1: done by cells in the skin called melano sites. These

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Speaker 1: melano sites create the natural pigment known as melanin and

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Speaker 1: deliver it to the cells that create the keratin for

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Speaker 1: your hair, and this melanin comes into varieties you melanin

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Speaker 1: and THEO melanin. You melanin is a dark pigment that

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Speaker 1: gives hair a brown or black color. THEO melanin is

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Speaker 1: a lighter pigment that gives hair a red, orange, or

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Speaker 1: yellowish color. Both of these are present in varying degrees.

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Speaker 1: A person might have had a little of each, or

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Speaker 1: a lot of one and almost none of the other.

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Speaker 1: So someone with black or dark brown hair probably has

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Speaker 1: a lot of YOU melanin. A red head has a

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Speaker 1: lot of THEO melanin, and blonds well they don't have

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Speaker 1: very much of either one. So what happens when we

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Speaker 1: get older and start to go gray, Well you can

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Speaker 1: probably guess. Over time, melanocytes start to die off, and

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Speaker 1: any new hair that grows has less pigment, so it

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Speaker 1: looks gray or white. But you might be asking what

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Speaker 1: determines the you melanin to feel melanin mixture to begin with?

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

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Speaker 1: the melano corton one receptor or m c one ur gene.

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Speaker 1: When the protein associated with this gene is active in melanocytes,

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Speaker 1: it stimulates them to make you melanin, the pigment that

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Speaker 1: colors black or brown hair. When m c one r

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Speaker 1: is not active in the melano syites cells, they make

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Speaker 1: mostly feel melanin instead and hello Weasley's. But the mc

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Speaker 1: one our gene is not the only genetic factor that

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Speaker 1: controls hair color. Like most of your traits, hair color

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Speaker 1: is actually affected by more than one gene attic variable.

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Speaker 1: For example, in a study in the journal Natural Genetics

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Speaker 1: linked blonde hair in Northern Europeans to a genetic mutation

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Speaker 1: in one single nucleotide controlling gene expression in hair follicles.

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Speaker 1: They even bred mice with the same tiny mutation, and

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Speaker 1: the mice had lighter colored fur than mice without the mutation.

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Speaker 1: Check out the brain stuff channel on YouTube, and for

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Speaker 1: more on this and thousands of other topics, visit how

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Speaker 1: stuff works dot com.