You know, redheads take a lot crap, not only do they fall prey to nicknames like
Big Red, Rusty and Daywalker, they also carry a rich history of misunderstanding on
their frequently freckled shoulders.
In Greek mythology it was said that red heads turn into vampires when they die.
Egyptians particularly enjoyed burning ginger virgins. And a number of alchemist
spells called for the fat of a flame-haired man. If that weren't enough,
in recent years there been headlines suggesting that redheads will actually go extinct
within this century. A lot of the ignorance surrounding red-headedness
probably has to do with the fact that although they aren't very rare, redheads
aren't very common either.
Though certain countries like Ireland and Scotland seem to be hosting
perpetual Weasley family reunions,
gingers only make up about 1 to 2 percent of the world population and they don't
have red hair because they stole hellfire or were conceived during
menstruation or bitten by a werewolf as a baby. They get their coppery hue the same
way we all get our coloration: from mellanin. Hair color is a genetic trait
associated with the melanocortin one receptor, or MC1R gene. We all have it
nestled on our chromosome 16 but your red-headed friends possess a mutated
version of it. This gene gives instructions for making protein
receptors located on our melanocytes, the special cells that produce melanin.
Melanin is what gives our eyes, hair, and skin their distinct hue and it comes in
two varieties:
eumelanin and pheomelanin. A person producing mostly eumelanin will
have darker hair and skin that tans easily and is better protected from the
sun's UV radiation
but if you're brewing mostly pheomalinin then you're gonna have reddish or blonde hair,
fair skin that burns easily because it's not naturally protected from the sun.
That's why fair folk have an increased risk of skin cancer.
It's that MC1R gene that dictates what kind of melanin you get.
If the gene is activated,
you'll end up with more eumelanin and will be darker complected.
If those receptors don't trigger,
your cells pump out the fair pheomelanin. We're not exactly sure just how
far back the trait goes, but scientists recently extracted a version of the
ginger gene from the remains of
two Neanderthals indicating that at least some of them
were redheads. However the gene was a variant. Not the one present in modern
humans, indicating the mutation evolved independently from human red-headedness in
an example of convergent evolution. Now you may be wondering why
both humans and Neanderthal genes would perpetuate a skin type so prone to sunburns.
Well, it has to do in part with geography. People from equatorial regions usually
have darker hair and skin to better protect them from the sun's radiation.
Whereas fair skin and hair
is more prevalent in northern areas with lower levels of sunlight. The farther you move
from the equator, the more that selective pressure for darker pigmentation lessens
and the mutant MC1R genes are not selected against
so they can spread throughout a population. And then, hello Scotland.
The successful spread of this mutation may be because fair skin is better at generating vitamin D
which could have actually given flame hairs an evolutionary advantage in the
perpetually cloudy North. But you may have also heard that gingers are kinda babies when it
comes to pain
and I hate to say it but there's some truth to that. A couple of studies funded by the
National Institutes of Health
found that redheads are actually more sensitive to thermal pain, or excessive
heat and cold,
and that they actually required, on average, nearly 20 percent higher doses
of anaesthetic than their dark-haired counterparts. And researchers aren't entirely
sure what's going on here, but one hypothesis connects
pain tolerance to that tricksy MC1R gene.
Since the gene is responsible for the receptors of pigment-producing hormones,
they may also interact with similar molecules like endorphins,
our body's natural painkillers. And finally, what about that great
imminent ginger extinction? That, I can tell you, is bogus.
Yes, the mutation is a recessive trait meaning that both parents have to carry
the allele or gene variant for it
to produce a red-haired offspring. But that still means that even if say, four
percent of the population actually has red hair, perhaps thirty percent still
carry that gene
keeping the potential for ginger generations alive and not just in the UK.
So rest assured gingers are gonna be passing along their genes and supporting
the sunscreen industry
for a very long time. Thank you for watching this SciShow dose and a big thanks to
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