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