1
00:00:01,920 --> 00:00:07,080
Speaker 1: Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff,

2
00:00:07,120 --> 00:00:09,480
Speaker 1: Lauren bog Obam here with a classic episode from our

3
00:00:09,560 --> 00:00:13,480
Speaker 1: archives featuring former host Christian Sager. Today's topic is an

4
00:00:13,480 --> 00:00:17,160
Speaker 1: excellent bit of everyday science. What determines your hair color?

5
00:00:17,360 --> 00:00:22,840
Speaker 1: And why do we go gray? A brain Stuff, it's

6
00:00:22,880 --> 00:00:26,400
Speaker 1: Christian Sager. Sometimes you're right in the middle of cleaning

7
00:00:26,480 --> 00:00:28,840
Speaker 1: up the drain in the shower and you start pondering

8
00:00:28,920 --> 00:00:32,320
Speaker 1: questions like why is my hair color different color from

9
00:00:32,320 --> 00:00:36,760
Speaker 1: my mom's hair, or my neighbor's hair or my roommates

10
00:00:36,840 --> 00:00:41,920
Speaker 1: disgusting soggy three ft long wolf tail drain wad? What's

11
00:00:41,960 --> 00:00:45,760
Speaker 1: the real difference between blonde hair, black hair, red hair,

12
00:00:45,800 --> 00:00:50,159
Speaker 1: and everything in between? Well, the main structural ingredient in

13
00:00:50,280 --> 00:00:53,880
Speaker 1: human hair is a protein called keratin. It's what your

14
00:00:53,880 --> 00:00:57,600
Speaker 1: hair and fingernails are made of. But also what's behind

15
00:00:57,640 --> 00:01:03,480
Speaker 1: the silky sheen of wool bear claws and horse hooves. Mmmm,

16
00:01:03,680 --> 00:01:06,600
Speaker 1: don't you just want to run your fingers through those hoofs?

17
00:01:07,000 --> 00:01:10,440
Speaker 1: But keratin on its own is not very colorful, And

18
00:01:10,520 --> 00:01:14,240
Speaker 1: if all humans had in our hair was keratin, we'd

19
00:01:14,280 --> 00:01:18,720
Speaker 1: look like eighteenth century French aristocrats in powdered wigs because

20
00:01:18,760 --> 00:01:22,240
Speaker 1: we'd all have the same sort of white, colorless hair.

21
00:01:22,720 --> 00:01:26,840
Speaker 1: But keratin is not the only ingredient in human hair.

22
00:01:27,120 --> 00:01:30,280
Speaker 1: To create natural color, you need to add pigment. This

23
00:01:30,360 --> 00:01:33,160
Speaker 1: is done by cells in the skin called melana sites.

24
00:01:33,319 --> 00:01:36,840
Speaker 1: These melano sites create the natural pigment known as melanin

25
00:01:37,000 --> 00:01:40,120
Speaker 1: and deliver it to the cells that create the keratin

26
00:01:40,280 --> 00:01:44,000
Speaker 1: for your hair, and this melanin comes into varieties you

27
00:01:44,200 --> 00:01:48,960
Speaker 1: melanin and THEO melanin. You melanin is a dark pigment

28
00:01:49,040 --> 00:01:52,920
Speaker 1: that gives hair a brown or black color. Pio melanin

29
00:01:53,080 --> 00:01:56,080
Speaker 1: is a lighter pigment that gives hair a red, orange,

30
00:01:56,200 --> 00:01:59,920
Speaker 1: or yellowish color. Both of these are present in varying degree,

31
00:02:00,040 --> 00:02:02,280
Speaker 1: as a person might have had a little of each,

32
00:02:02,600 --> 00:02:04,800
Speaker 1: or a lot of one and almost none of the other.

33
00:02:05,280 --> 00:02:08,480
Speaker 1: So someone with black or dark brown hair probably has

34
00:02:08,520 --> 00:02:11,960
Speaker 1: a lot of you melanin. A redhead has a lot

35
00:02:12,120 --> 00:02:15,440
Speaker 1: of THEO melanin, and blonds, well, they don't have very

36
00:02:15,560 --> 00:02:18,480
Speaker 1: much of either one. So what happens when we get

37
00:02:18,520 --> 00:02:22,720
Speaker 1: older and start to go gray, Well you can probably guess.

38
00:02:22,800 --> 00:02:26,000
Speaker 1: Over time, melano sites start to die off, and any

39
00:02:26,120 --> 00:02:29,600
Speaker 1: new hair that grows has less pigment, so it looks

40
00:02:29,639 --> 00:02:33,720
Speaker 1: gray or white. But you might be asking what determines

41
00:02:33,880 --> 00:02:37,040
Speaker 1: the you melanin to feel melanin mixture to begin with?

42
00:02:37,160 --> 00:02:41,440
Speaker 1: Who writes that recipe? Well, primarily it's your genes. For example,

43
00:02:41,720 --> 00:02:46,640
Speaker 1: the melano corton one receptor or m C one R gene.

44
00:02:47,000 --> 00:02:50,720
Speaker 1: When the protein associated with this gene is active in melanocytes,

45
00:02:51,040 --> 00:02:53,920
Speaker 1: it stimulates them to make you melanin, the pigment that

46
00:02:53,960 --> 00:02:56,920
Speaker 1: colors black or brown hair. When m C one r

47
00:02:57,040 --> 00:03:00,440
Speaker 1: is not active in the melanocytes cells, they make mostly

48
00:03:00,800 --> 00:03:05,200
Speaker 1: fio melon and instead and Hello Weasley's. But the mc

49
00:03:05,440 --> 00:03:08,520
Speaker 1: one r gene is not the only genetic factor that

50
00:03:08,560 --> 00:03:12,120
Speaker 1: controls hair color. Like most of your traits, hair color

51
00:03:12,240 --> 00:03:16,239
Speaker 1: is actually affected by more than one genetic variable. For example,

52
00:03:16,600 --> 00:03:21,520
Speaker 1: in a study in the journal Natural Genetics linked blonde

53
00:03:21,520 --> 00:03:25,600
Speaker 1: hair in Northern Europeans to a genetic mutation in one

54
00:03:26,160 --> 00:03:31,679
Speaker 1: single nucleotide controlling gene expression in hair follicles. They even

55
00:03:31,800 --> 00:03:35,560
Speaker 1: bred mice with the same tiny mutation, and the mice

56
00:03:35,600 --> 00:03:43,360
Speaker 1: had lighter colored fur than mice without the mutation. Today's

57
00:03:43,400 --> 00:03:46,000
Speaker 1: episode was written by Joe McCormick and produced by Tyler Klang.

58
00:03:46,360 --> 00:03:48,240
Speaker 1: The brain Stuff is production of I Heeart Radio's how

59
00:03:48,240 --> 00:03:50,400
Speaker 1: Stuff Works. To hear more from Joe, check out his

60
00:03:50,440 --> 00:03:53,200
Speaker 1: new podcast Invention or the old standby Stuff to Blow

61
00:03:53,240 --> 00:03:55,240
Speaker 1: your Mind, of course. For more on this and lots

62
00:03:55,280 --> 00:03:57,440
Speaker 1: of other hairy topics is that our home planet, how

63
00:03:57,440 --> 00:03:59,960
Speaker 1: stuff Works dot com. And for more podcasts for my

64
00:04:00,080 --> 00:04:02,680
Speaker 1: heart Radio, visit the i Heart Radio app, Apple Podcasts,

65
00:04:02,760 --> 00:04:15,480
Speaker 1: or wherever you listen to your favorite shows. H