Speaker 1: Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff,
Speaker 1: Lauren bog Obam here with a classic episode from our
Speaker 1: archives featuring former host Christian Sager. Today's topic is an
Speaker 1: excellent bit of everyday science. What determines your hair color?
Speaker 1: And why do we go gray? A brain Stuff, it's
Speaker 1: Christian Sager. Sometimes you're right in the middle of cleaning
Speaker 1: up the drain in the shower and you start pondering
Speaker 1: questions like why is my hair color different color from
Speaker 1: my mom's hair, or my neighbor's hair or my roommates
Speaker 1: disgusting soggy three ft long wolf tail drain wad? What's
Speaker 1: the real difference between blonde hair, black hair, red hair,
Speaker 1: and everything in between? Well, the main structural ingredient in
Speaker 1: human hair is a protein called keratin. It's what your
Speaker 1: hair and fingernails are made of. But also what's behind
Speaker 1: the silky sheen of wool bear claws and horse hooves. Mmmm,
Speaker 1: don't you just want to run your fingers through those hoofs?
Speaker 1: But keratin on its own is not very colorful, And
Speaker 1: if all humans had in our hair was keratin, we'd
Speaker 1: look like eighteenth century French aristocrats in powdered wigs because
Speaker 1: we'd all have the same sort of white, colorless hair.
Speaker 1: But keratin is not the only ingredient in human hair.
Speaker 1: To create natural color, you need to add pigment. This
Speaker 1: is done by cells in the skin called melana sites.
Speaker 1: These melano sites create the natural pigment known as melanin
Speaker 1: and deliver it to the cells that create the keratin
Speaker 1: for your hair, and this melanin comes into varieties you
Speaker 1: melanin and THEO melanin. You melanin is a dark pigment
Speaker 1: that gives hair a brown or black color. Pio melanin
Speaker 1: is a lighter pigment that gives hair a red, orange,
Speaker 1: or yellowish color. Both of these are present in varying degree,
Speaker 1: as a person might have had a little of each,
Speaker 1: or a lot of one and almost none of the other.
Speaker 1: So someone with black or dark brown hair probably has
Speaker 1: a lot of you melanin. A redhead has a lot
Speaker 1: of THEO melanin, and blonds, well, they don't have very
Speaker 1: much of either one. So what happens when we get
Speaker 1: older and start to go gray, Well you can probably guess.
Speaker 1: Over time, melano sites start to die off, and any
Speaker 1: new hair that grows has less pigment, so it looks
Speaker 1: gray or white. But you might be asking what determines
Speaker 1: the you melanin to feel melanin mixture to begin with?
Speaker 1: Who writes that recipe? Well, primarily it's your genes. For example,
Speaker 1: the melano corton one receptor or m C one R gene.
Speaker 1: When the protein associated with this gene is active in melanocytes,
Speaker 1: it stimulates them to make you melanin, the pigment that
Speaker 1: colors black or brown hair. When m C one r
Speaker 1: is not active in the melanocytes cells, they make mostly
Speaker 1: fio melon and instead and Hello Weasley's. But the mc
Speaker 1: one r gene is not the only genetic factor that
Speaker 1: controls hair color. Like most of your traits, hair color
Speaker 1: is actually affected by more than one genetic variable. For example,
Speaker 1: in a study in the journal Natural Genetics linked blonde
Speaker 1: hair in Northern Europeans to a genetic mutation in one
Speaker 1: single nucleotide controlling gene expression in hair follicles. They even
Speaker 1: bred mice with the same tiny mutation, and the mice
Speaker 1: had lighter colored fur than mice without the mutation. Today's
Speaker 1: episode was written by Joe McCormick and produced by Tyler Klang.
Speaker 1: The brain Stuff is production of I Heeart Radio's how
Speaker 1: Stuff Works. To hear more from Joe, check out his
Speaker 1: new podcast Invention or the old standby Stuff to Blow
Speaker 1: your Mind, of course. For more on this and lots
Speaker 1: of other hairy topics is that our home planet, how
Speaker 1: stuff Works dot com. And for more podcasts for my
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