BERLIN - Among the many claims made about redheads is that they are stubborn, fresh, impulsive, and awkward. They have thousands of freckles, pasty skin – not to mention "witch's genes' and most curious of all: they turn into vampires when they die. Not only that, but they also don't feel pain, and can eat as many chili peppers as they like without shedding a tear.

These sorts of comments are as common as they are generally baseless. Indeed, redheads are so rare as a ratio of the world population that the myths about them seem bound to continue piling up. Still there are differences that can be proven by science rather than hearsay.

In the U.S. and Great Britain, only about 4% of the population are natural redheads; in Germany, it's 2%; and in Asia, Africa and South America even less. Scotland is the one place on the planet with the most redheads: 14 of every 100 people are "gingers." Ireland, also known for its high number of redheads, has 10%.

So redheads are not only rare, they also stand out – and they have genetic differences that set them apart from people with other hair colors. A specific gene on chromosome 16 is responsible for hair color. The hair follicles of people with dark hair, for example, produce large quantities of eumelanin. Pheomelanin produces redheads or strawberry blondes. Nordic blondes, on the other hand, have very little of either type of melanin.

International scientists have shown that five variants of the MC1R gene lead to red hair. Another, HCL2 on chromosome 4, also appears to play a role but too little is as yet known about it. Because of the rarity of the "red gene," some scientists believe there will no longer be any redheads in the world by 2060.

Jeffrey Mogil at McGill University in Montreal has shown that mice and red-haired people with MC1R gene variant experience pain differently than dark-haired people. Mogil and other scientists have also shown that red-haired women are more sensitive to cold and heat. They are also more sensitive to a certain kind of painkiller but less sensitive to narcotics – an apparently paradoxical finding that no one to this day has been able to explain.

A team working with Lars Arendt-Nielsen of the International Association for the Study of Pain, that also conducts research at Aalborg University in Denmark, wanted to find out more about red heads' reaction to pain. They conducted research on 20, pale-skinned women with red hair, and 20 women with dark or blonde hair. They applied a cream containing chili pepper on their skin and left it for a half hour. All the subjects reacted identically. In a second round of the experiment, the researchers irritated the women's skin mechanically: and here, red heads turned out to be a lot less sensitive to the pain.

Pain and perps

Arendt-Nielsen and his team reached the conclusion that redheads are less sensitive to certain types of pain such as needle pricks or applied pressure. It seems that the pain resulting from exposure to cold or heat is processed differently by the body than pressure, pricks and scratches. Redheads are less sensitive to the latter, and more to the former.

The researchers agree that the susceptibility to pain of redheads in very complex, and that research needs to be done so that redheaded patients in pain or facing an operation can be treated optimally. Such research should also make it possible to find out how it is that a coloration gene has an impact on the way pain is experienced.

Life for redheads can be difficult in other ways, such as their susceptibility to skin cancer. And if they are criminally inclined, things get even more complicated because the presence of the MC1R gene makes it easy to identify their hair color in the DNA tests at a crime scene conducted: forensic experts can identify the perpetrator's melanin type.

Forensic scientist Manfred Kayser of Rotterdam's Erasmus University has developed a test so exact that it can tell with 80% accuracy if a perpetrator has brown or blonde hair. That goes up to 90% for those with black hair. Here again, the redheads stand out: accuracy is 100% for them.

Read the original article in German

Photo - nicolas genin