WEBVTT - What Determines Your Hair Color?

0:00:02.040 --> 0:00:07.840
<v Speaker 1>Welcome to brain stuff from how stuff works a brain

0:00:07.920 --> 0:00:11.360
<v Speaker 1>stuff it's Christian saga. Sometimes you're right in the middle

0:00:11.360 --> 0:00:13.560
<v Speaker 1>of cleaning up the drain in the shower and you

0:00:13.600 --> 0:00:17.280
<v Speaker 1>start pondering questions like why is my hair color different

0:00:17.280 --> 0:00:21.239
<v Speaker 1>color from my mom's hair or my neighbor's hair or

0:00:21.360 --> 0:00:26.479
<v Speaker 1>my roommates disgusting soggy three foot long wolf tail drain wad?

0:00:27.120 --> 0:00:31.240
<v Speaker 1>What's the real difference between blonde hair, black hair, red hair,

0:00:31.320 --> 0:00:35.680
<v Speaker 1>and everything in between? Well, the main structural ingredient in

0:00:35.800 --> 0:00:39.360
<v Speaker 1>human hair is a protein called keratin. It's what your

0:00:39.400 --> 0:00:43.080
<v Speaker 1>hair and fingernails are made of, but also what's behind

0:00:43.120 --> 0:00:48.920
<v Speaker 1>the silky sheen of wool bear claws and horse hooves. Mmmm.

0:00:49.200 --> 0:00:52.479
<v Speaker 1>Don't you just want to run your fingers through those hooves?

0:00:52.479 --> 0:00:55.920
<v Speaker 1>But keratin on its own is not very colorful, and

0:00:56.000 --> 0:00:59.960
<v Speaker 1>if all humans having our hair was keratin, we'd look

0:01:00.120 --> 0:01:04.480
<v Speaker 1>like eighteenth century French aristocrats in powdered wigs because we'd

0:01:04.560 --> 0:01:08.319
<v Speaker 1>all have the same sort of white, colorless hair. But

0:01:08.959 --> 0:01:12.720
<v Speaker 1>keratin is not the only ingredient in human hair. To

0:01:12.760 --> 0:01:15.920
<v Speaker 1>create natural color, you need to add pigment. This is

0:01:15.959 --> 0:01:19.119
<v Speaker 1>done by cells in the skin called melano sites. These

0:01:19.160 --> 0:01:22.560
<v Speaker 1>melano sites create the natural pigment known as melanin and

0:01:23.000 --> 0:01:25.880
<v Speaker 1>deliver it to the cells that create the keratin for

0:01:26.080 --> 0:01:30.160
<v Speaker 1>your hair, and this melanin comes into varieties you melanin

0:01:30.560 --> 0:01:34.640
<v Speaker 1>and THEO melanin. You melanin is a dark pigment that

0:01:34.720 --> 0:01:38.640
<v Speaker 1>gives hair a brown or black color. THEO melanin is

0:01:38.680 --> 0:01:41.800
<v Speaker 1>a lighter pigment that gives hair a red, orange, or

0:01:41.920 --> 0:01:45.520
<v Speaker 1>yellowish color. Both of these are present in varying degrees.

0:01:45.600 --> 0:01:48.200
<v Speaker 1>A person might have had a little of each, or

0:01:48.240 --> 0:01:50.320
<v Speaker 1>a lot of one and almost none of the other.

0:01:50.800 --> 0:01:53.960
<v Speaker 1>So someone with black or dark brown hair probably has

0:01:54.040 --> 0:01:57.160
<v Speaker 1>a lot of YOU melanin. A red head has a

0:01:57.240 --> 0:02:00.640
<v Speaker 1>lot of THEO melanin, and blonds well they don't have

0:02:00.800 --> 0:02:03.720
<v Speaker 1>very much of either one. So what happens when we

0:02:03.760 --> 0:02:07.360
<v Speaker 1>get older and start to go gray, Well you can

0:02:07.400 --> 0:02:11.120
<v Speaker 1>probably guess. Over time, melanocytes start to die off, and

0:02:11.240 --> 0:02:14.760
<v Speaker 1>any new hair that grows has less pigment, so it

0:02:14.840 --> 0:02:18.480
<v Speaker 1>looks gray or white. But you might be asking what

0:02:18.680 --> 0:02:22.560
<v Speaker 1>determines the you melanin to feel melanin mixture to begin with?

0:02:22.680 --> 0:02:26.959
<v Speaker 1>Who writes that recipe? Well, primarily it's your genes. For example,

0:02:27.240 --> 0:02:32.160
<v Speaker 1>the melano corton one receptor or m c one ur gene.

0:02:32.520 --> 0:02:36.240
<v Speaker 1>When the protein associated with this gene is active in melanocytes,

0:02:36.560 --> 0:02:39.440
<v Speaker 1>it stimulates them to make you melanin, the pigment that

0:02:39.480 --> 0:02:42.400
<v Speaker 1>colors black or brown hair. When m c one r

0:02:42.560 --> 0:02:45.400
<v Speaker 1>is not active in the melano syites cells, they make

0:02:45.520 --> 0:02:50.680
<v Speaker 1>mostly feel melanin instead and hello Weasley's. But the mc

0:02:50.919 --> 0:02:54.000
<v Speaker 1>one our gene is not the only genetic factor that

0:02:54.080 --> 0:02:57.639
<v Speaker 1>controls hair color. Like most of your traits, hair color

0:02:57.760 --> 0:03:00.760
<v Speaker 1>is actually affected by more than one gene attic variable.

0:03:01.120 --> 0:03:06.040
<v Speaker 1>For example, in a study in the journal Natural Genetics

0:03:06.240 --> 0:03:10.360
<v Speaker 1>linked blonde hair in Northern Europeans to a genetic mutation

0:03:10.480 --> 0:03:16.079
<v Speaker 1>in one single nucleotide controlling gene expression in hair follicles.

0:03:16.440 --> 0:03:20.680
<v Speaker 1>They even bred mice with the same tiny mutation, and

0:03:20.720 --> 0:03:24.560
<v Speaker 1>the mice had lighter colored fur than mice without the mutation.

0:03:30.680 --> 0:03:32.720
<v Speaker 1>Check out the brain stuff channel on YouTube, and for

0:03:32.760 --> 0:03:35.200
<v Speaker 1>more on this and thousands of other topics, visit how

0:03:35.240 --> 0:03:50.040
<v Speaker 1>stuff works dot com.