(orchestra music)
- Sometimes you're right in the middle
of cleaning out the drain in the shower
and you start pondering questions like
why is my hair a different
color from my mom's hair
or my neighbor's hair or
my roommate's disgusting
soggy three foot long wolf tail drain wad?
What's the real difference
between blonde hair,
black hair, red hair and
everything in between?
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.
Mmm, don't you just wanna run your fingers
through those hooves?
Just me?
But keratin on its own
is not very colorful
and if all humans had
on our head was keratin,
we'd look like 18th
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
and this is done by cells in
the skin called melanocytes.
These melanocytes create
the natural pigment known
as melanin and deliver it to the cells
that create keratin for your hair.
Now this melanin comes in two varieties.
Eumelanin and pheomelanin.
Eumelanin is a dark pigment
that gives hair a brown
or black color.
Pheomelanin is a lighter
pigment that gives hair
a red, orange or yellowish color.
Both of these are present
in varying degrees.
So a person might have a little of each
or a lot of one or
almost none of the other.
So someone with black or dark brown hair
probably has a lot of
eumelanin, not to brag.
A redhead has a lot of pheomelanin
and blondes 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.
Overtime, melanocytes start to die off
and any new hair that
grow has less pigment
so it looks gray or white.
But you might be asking,
what determines the eumelanin
to pheomelanin mixture
to begin with?
Who writes that hair color recipe?
Primarily it's your genes.
For example, the melanocortin 1 receptor
or MC1R gene.
When the protein associated with this gene
is active in the melanocytes,
it stimulates them
to make eumelanin, the pigment that colors
black or brown hair.
When MC1R is not active
in the melanocyte cells,
they make mostly pheomelanin instead
and hello (mumbles).
But the MC1R gene is not
the only genetic factor
that controls hair color.
Like most of your traits, hair
color is actually effected
by more than one genetic variable.
So that's the scoop on hair color.
But hey, what's the weirdest
thing you've ever noticed
about human hair?
Let us know in the comments
and if you ever wanna learn more about
the strange science of the human body
with Brain Stuff questions like
why don't humans have tails?
Click subscribe and we'll
see you again next time.
(laughing)
I don't know.
Who writes the hair color recipe?
Not Betty Crocker.
It's your genes.
