So today we're going to do something a little bit
different.
We have a special guest, and we're
going to talk about a fascinating interplay
between your genes and your environment-- freckles.
So my name's Alex Dainis, and I'm a genetics PhD student.
And my name is Trina Espinosa, a.k.a.
MsBeautyphile, and I like to talk about the science
behind beauty.
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I have freckles.
And I don't, which is a total bummer,
because right now, freckles are totally trending in beauty.
While trends of earlier decades favored covering up
those freckles with heavy makeup,
more recent beauty trends are encouraging
us to play our freckles, which are
thought to be more youthful and natural in appearance.
Earlier this year, I saw lots of beauty tutorials
that use eyeliner to dot a few extras across your face.
Or Instagram hashtags that showed serious beauty devotees
going as far as having freckles tattooed across their face.
So that has me posing the question,
what is a freckle, Alex?
Yeah, so people use the word freckle
to refer to two different things.
So the first are ephelides.
So these are the freckles we generally think of in children.
They're small reddish-brown freckles
that appear in the spring and summer on your face, back,
and arms.
So areas that are exposed to the sun.
But sometimes people also use the word "freckle"
to refer to lentigines.
So these are darker spots that appear with age,
that don't really change with the seasons,
and that occur after years of sun damage.
OK.
So those are like age spots.
Yeah.
So today, when we talk about the word "freckle"
we're going to talk about ephelides.
But I think, before we do that, we
need to put some freckles on our face!
Totally!
OK, ready?
Here we go.
Yeah.
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What do you think?
So let's talk about what makes a real freckle?
A real freckle is caused by melanin.
That is a pigment that gives hair and skin its color.
A freckle forms on the skin when a cell called
a melanocyte overproduces melanin in response
to UV radiation from the sun.
The melanin is packaged into melanosomes,
and melanocytes inject them into skin cells
as they migrate towards the upper layers of skin.
When this happens in a concentrated area,
it is called a freckle.
But not everybody has them.
So is that a genetics thing?
It is.
So some people are more prone to getting freckles than others.
And this can totally be traced back to your genetics,
meaning that it can also be inherited and passed down
through families.
OK.
So while there are genes that make
you more susceptible to getting freckles,
you also need that UVA light exposure
to actually have them happen.
This is why we think about them in the spring and summer, when
kids are outside playing in the sun.
Exactly.
It's the environment and your genetics
that creates a freckle.
So how did researchers first figure out
that this is a genetic trait?
So I found this insane experiment from 1982,
that I'd like to put into the category of "crazy things that
college students will do for science".
I think I've done some of those.
Yeah, me too.
So the researchers took 18 18-to-23 year olds,
and they split them up into two groups of known frecklers
and known non-frecklers.
Hm.
How did they make that determination?
So the known freckles all had visible spots on them
at the time, and a childhood history of freckling.
And the known non-frecklers had neither of those things.
So the researchers took these two groups, and the exposed
areas of their lower back-- which is generally
protected from the sun and has few freckles--
to intense amounts of UV light.
Yikes!
That sounds scary!
Yeah, it is scary.
And I would totally not have wanted
to be a subject in this study.
[LAUGHTER]
But what they found was that all of the known frecklers
actually had freckles appear after this exposure,
and none of the known non-frecklers did.
I see.
So they figured out that there was probably
a genetic component to this.
You had to be susceptible to it before the UV exposure
to actually get freckles.
Let's cut to the nitty gritty.
What genes are associated with freckling?
I hear there's like five.
Yeah, so there are about five genes
that have been associated with freckling at this point.
But the most well-studied, and probably the most impactful,
is a gene called MC1R, which codes
for a receptor on the surface of your melanocytes, those cells
that make the melanin pigment.
So it's the MC1R that determines the type of melanin
that our melanocytes make, whether that's the eumelanin--
the brown black pigment--
or pheomelanin-- the reddish pigment?
Exactly.
Hm.
And so, when we think about our genes,
we have two copies of every gene-- one from our mother,
and one from our father.
And these copies that we inherit can come in different versions,
or alleles.
So this variation in the MC1R gene
can determine whether or not it gives you
these darker pigments or lighter pigments,
and these alleles have been associated with everything
from red hair and pale skin, to freckles.
So while we can buy temporary or permanent freckle tattoos that
make us look more youthful and-- (BLOWS KISS) -- sunkissed,
our real freckles are determined by our genes,
which are given to us by our parents.
Or whether or not we slather on sunscreen
before we hit the pool.
Exactly.
Thank you so much for answering all my freckle questions, Alex.
Well, thank you so much for being here.
But now I think it's time that we take off of these freckles,
with--
my summer water.
What?
But what is my summer water?
I'll tell you if you head on over to my channel.
The link is right up here.
You can also go over and subscribe
to MsBeautyphile's channel by clicking here,
and subscribe to mine by clicking here.
And as always, a huge shout out to my Patreon patrons
for making fun videos like this possible.
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