Can redheads handle 25% more pain than brunettes?
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What do Lindsay Lohan, Ron Weasley and myself all have in common? No, we haven't all driven a magic car. We're all natural redheads. Being a redhead is an odd thing. It truly seems to be the marmite of hair colours. Some people love it to an almost disturbing degree, whereas others use it as evidence of witchcraft and burners on a stake.

Medieval Europe, I'm looking at you. It's quite confusing to be both loved and reviled. But fear not, redheads, as apparently we have a few superpowers. As the New York Times magazine reported...

Seeing as I am a redhead, I have no idea whether it's true or not, as I've never experienced anyone else's physical pain firsthand. Emotional is another story. But in the past, I have been told by people I'd need a higher dose of pain relief than non-redheads to receive the same effect.

But why? What makes redheads so special? Well, the secret is MC1R. No, that's not a classic 2000s emo band. It's the gene that makes most of us redheads in the first place.

To find out more, we spoke to Professor Geoff Mogill from McGill University in Canada. He holds the rather ominous title of Canada Research Chair in Genetics of Pain. The MC1R gene is the gene that provides the instructions for the creation of a protein known as the melanocortin-1 receptor.

And the melanocortin-1 receptor has a number of roles, but its most well-known is its involvement in producing melanin, which is the pigment that makes skin and hair turn different colors. Redheads, essentially, are those who have inherited variants of that gene such that the protein, once it's made, doesn't work.

And so melanocortin-1 doesn't do what it's supposed to do. And so instead of having brown hair like you're supposed to and somewhat darker skin, you end up having red hair and somewhat lighter skin, which is usually prone to freckling.

It's a defect. It's a mutation. Although geneticists, we don't call them mutations unless they're very rare. And these variants are not particularly rare, especially in certain parts of the world centering around the British Isles. It used to be assumed that genes only really had one function. For example, to give you blue eyes, dark skin or maybe red hair. But that isn't the case. No, it's dramatically not the case. And if you think about it for a second, it can't possibly be the case.

So genes are responsible for everything, all the traits that human beings have. Geneticists call those phenotypes. And if you think of how many genes there are versus how many phenotypes there are, you see the issue. There are only 22,000 or so genes, and those genes can make, I don't know, 40, 50, maybe 60,000 different proteins.

But how many phenotypes are there? Well, there's an infinite number of, yeah, a very, very large number, right? But there's only a finite number of genes. And what that means, if you do the math, is that every gene is ultimately involved in many, many, many, many phenotypes. It was during the search for these multifunctional genes that led Jeff and his team at McGill to make the first link between redheads and pain.

redheads of the rodent variety. My lab showed that redheaded mice were more sensitive to a particular class of opioid drugs called kappa opioid drugs.

And we found this completely by accident. We were not interested in redheads. We were not interested in redheaded mice. We were trying to find what the gene was that was responsible for how much kappa opioid analgesia mice would have. We found that certain strains had a lot and certain strains had less, and we wanted to find the gene. We eventually found the gene, and the gene happened

to be MC1R. And then we said to ourselves, hmm, we could do this same experiment in humans. And indeed, we showed that redheads were more sensitive to the drug as well. Analgesia means pain relief. So Jeff's experiments proved that redheaded mice and people needed to take a lower dose of opioids to receive the same effects of pain relief as those who took a higher dose. Bizarrely, the opposite effect was found with inhaled anesthetics.

A year later, a different group in the US headed by Edward Leem found that redheads require a higher dose of anaesthetic to knock us out. It wasn't a large study. It only included 20 people. But it confirmed anecdotal evidence from confused anaesthetists. So pain relief affects us differently. But what about this 25% pain figure?

What's going on there? Well, that's Jeff living up to his title of Chair of Genetics of Pain. They decided to see whether the MC1R variant worked as a natural inhibitor to pain too. They joined up with a team in the Netherlands to electrocute redheads. Just a bit. So in this study, we gave them electrical current to their arm. The intensity of that electrical current was slowly increased until they said, stop, I've had enough.

The non-redheads said stop when the electric current was up to 16 milliampères. And the redheads didn't say stop until it was up to 21 milliampères. So that's a difference of 5 out of 16. So yeah, about 25%. And this is where things get tricky because my lab, testing redheaded mice and redheaded people, found that redheads were less sensitive to pain. And the U.S. group

testing red-headed humans found that they were more sensitive to pain. My editor is keen for us to recreate this experiment, but unfortunately, using extra electricity is against the BBC carbon cutting policy. So it seems that redheads can withstand 25% more pain. Job done.

Not quite. A paper published around the same time found that red-headed mice were more sensitive to thermal pain. That's hot and cold temperatures. So what's going on? And why are there so many redheads in Scotland if they're more sensitive to the cold? To answer the first part, it's potentially that different types of pain elicit different responses. So you could have a more exaggerated response to one than the other.

But there's also another reason. You see, there is potentially one important difference in how the experiment was conducted. Not all redheads have the right genes. Because it turns out that the melanocortin-1 receptor accounts for about 75 or 80% of redheads, but not all.

Jeff's experiments stemmed from knowing that the MC1R variant was responsible for the differences in pain perception. So they cared more about what was on the inside. We actually looked at the genetics of our subjects to find out were they really melanocortin-1 receptor redheads. And the US group didn't. They just, you know...

Took redheads into the lab, asked them presumably, are you really a redhead? And if they said yes, they were in the study. So, according to some fairly small studies, it does seem that 75 to 80% of redheads have a 25% higher pain tolerance. But there's one final twist to the tale. Enter the secret ginger.

It turns out that some people with MC1R variants, through the additional effects of other genes, end up being blonde and not red-haired. But they too have non-functional melanocortin-1 receptors. So yeah, it's possible that there are some blondes out there that have the same pain phenotype as redheads.

Very interesting indeed. I hope I am one of the 75% of chosen redheads. Although possibly not if I need a tooth extracted. Either way, please don't use this programme as an excuse to punch your redheaded siblings or friends 25% harder. It still won't be appreciated and they might have the wrong genes.

That's all we have time for this week. Thanks again to Jeff Mogul. If you have any questions or comments, please write in to moreorless at bbc.co.uk. Goodbye.

When you have bars in the sky, onboard showers and award-winning in-flight entertainment, it's no surprise that Emirates was recently named the best airline in the world. We fly you to over 140 destinations and with partners across the globe, we connect you to another 1,700 cities across six continents. So when we say we're also the largest international airline, what we really mean is...

If you're going there, so are we. Book now on Emirates.com. Fly Emirates. Fly better. Yoga is more than just exercise. It's the spiritual practice that millions swear by.

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