This saint paddies day, we want to celebrate
something besides green beer, so how about Ireland’s other famous calling card, red
heads! Today we’re digging into the chemistry of
those fiery locks and finding out that those aren’t the only thing that make redheads
unique… Chemically speaking, the thing that sets redheads
apart from the crowd is pigmentation, and in particular, pigments known as melanins. Not only does that stuff give color to your
skin, but your hair as well – more on that later. Melanin is produced by special cells called
melanocytes which make two different kinds: eumelanin which ranges from brown to black,
and pheomelanin which ranges from yellow to red. When UV light rays hit your skin, your melanocytes
increase melanin production to protect your cells. The dark color from eumelanin dissipates absorbed
radiation as heat, which stops the damaging UV from reaching your DNA where it can cause
mutations and start some forms of cancer. People from sunnier regions of the earth are
genetically predisposed to having higher quantities of eumelanin to keep them safe from the intensity
of UV. So as far as environmental factors go, is
there really that little sunlight in Ireland? Redheads have a particularly high abundance
of pheomelanin, with very little eumelanin, so what’s the deal? On the surface of melanocytes is a protein
called the melanocortin 1 receptor or MC1R for short. When activated, MC1R causes melanocytes to
specifically produce eumelanin over pheomelanin, which ultimately balances out an individual’s
ratio. Redheads are born with a genetic variant that
causes MC1R to chemically function differently on the melanocytes, resulting in less eumelanin
and more pheomelanin production. Now, these genetic variations are recessive,
which means that they can have redheaded kids only if both parents carry that MC1R mutation. In this case, neither parent has red hair,
but they’re both carriers — there is a 25% of redhead. If just one parent is a redhead and then other
is a carrier, it’s a 50/50 chance. they have pale skinned kids. What if one parent is a redhead but the other
is not a carrier? Sorry — no redheads! If both are redheads, that’s a 100% chance
of red, folks. Now about that hair, How does melanin production
affect its color? At the bulb of a hair follicle, those pigment-producing
melanocytes form protein clusters called melanosomes. These clusters become bound within the keratin
that’s produced to form hair as it grows. With an overabundance of reddish pheomelanin,
you can guess why their hair turns out red. With non-redheads, a mix of different pigments
including eumelalin make for the rainbow of hair colors. While that pale skin makes redheads susceptible
to sunburn and skin cancers like melanoma, their genetic difference may affect the way
they feel pain as well. Research has shown that redheads have a higher
sensitivity to different types of pain and a slightly greater sensitivity to cold than
others in the population. Some other small studies have suggested that
redheads might need more anesthesia during surgery. No one has pinpointed exactly why redhead
genetics results in a different sort of pain, but one finding suggests that MC1R is expressed
in the neurons of the periaqueductal grey – an ancient part of the brain that governs
some pain sensation. Genetic variants may heighten this neural
activity, giving redheads’ a different sensitivity. But most of all, redheads are a big part of
Irish heritage and for that, we here at Reactions will raise up a big green glass to MC1R proteins! Did we miss any interesting redhead claims? Post them down in the comments and we’ll
see if there’s any science to back them up. Don’t forget to give a thumbs up and subscribe
on the way out!