rare, mutant gene from neanderthals

From Telegraph

General Custer was one. So was Napoleon Bonaparte. Underneath Oliver Cromwell's severe helmet was a mass of red hair. Cleopatra used henna to enhance her auburn tresses, while Christopher Columbus took ginger hair to America.

But while fiery-headed leaders, artists, poets and disc jockeys crop up with alarming regularity, evidence is emerging that red hair may be a relatively new phenomenon for mankind.

According to the most recent estimates, the first red hair sprouted just 20,000 years ago, long after the advent of modern homo sapiens and towards the end of the last great ice age.

Some have even argued that redheads such as Nicole Kidman, Charlie Dimmock, Chris Evans and Neil Kinnock could have inherited a trait originally passed on to modern man by the Neanderthals.

The secret history of redheads is one of the topics explored at the Hair Affair, a half day of talks and workshops exploring the science of hair, organised by the Royal Institution and L'Oréal and supported by The Daily Telegraph on October 25.

The redhead roll call makes for impressive reading. It includes Vincent Van Gogh, Henri Matisse, William Blake, Lord Byron, James Joyce, J K Rowling, Jean Paul Sartre, George Bernard Shaw, Bette Davis, Katharine Hepburn, Marilyn Monroe, Elizabeth I, Queen Victoria and William the Conqueror.

Despite the old folk tale that redheads are the result of interbreeding between brunettes and blonds, hair colour is actually determined by a more subtle genetic influence.

Like skin colour, hair colour comes from the pigment melanin and, in particular, two types: eumelanin, the most common form, ranges in colour from brown to black, while pheomelanin is red or yellow.

Hair and skin colour arise from the balance of these two types and the total amount of melanin produced. White skins produce less melanin than dark skins. Japanese black hair is almost entirely made of eumelanin, while Irish red hair has almost only pheomelanin.

Melanin is a good sun block, preventing damage from ultraviolet rays. The pigment is unlikely to have evolved as a protection against skin cancer (which threatens life long after reproductive age and so would be unlikely to be selected against in evolution) but might protect against burns, secondary infection and loss of fluids.

Several years ago Jonathan Rees, professor of dermatology at Edinburgh University, and colleagues discovered a gene responsible for melanin production, the melanocortin 1 receptor (MC1R).

If someone has one of about four of five variations of this gene, and if the variation is inherited from both parents, then they are likely to be red haired. If the variation has been inherited from just one parent, they have an increased chance of being red haired. What was surprising was how recently this genetic trait first appeared.

"We don't know with certainty when the first redheads walked the earth," says Prof Rees. "But we believe these changes arose in less time than we thought, maybe 20,000 to 40,000 years ago."

The red-headed gene mutation is rarely found in people of African descent. Evolutionary experts have argued that it cropped up after ancestors of white Europeans left the continent and moved northwards around 70,000 to 100,000 years ago.

"The explanations generally fall into two groups," says Prof Rees. "The first is that there may have been some advantage to having red hair and pale skin. One reason for this is that you make vitamin D in your skin and therefore you're less likely to get rickets if you have pale skin and there is not much sunlight around."

The team's analysis of the red-headed gene, however, found little evidence that red hair and pale skin were a positive trait added to mankind's genetic heritage by natural selection outside Africa.

The clue came from an analysis of codons - the sequences of DNA or RNA that provide the recipe for any one of the 20 amino acids that form the building blocks of proteins. The sequences consist of three base pairs of DNA - three "letters" of the genetic code. Two of these letters are crucial to the make-up of the amino acid. But some changes in the third base pair make little difference to the end result - the equivalent of spelling tic with a K instead of a C.

By studying the ratio of changes in this third base with the changes in the other two base pairs, it is possible to identify genetic traits that are the result of natural selection and those that have just cropped up by chance.

"With the redhead gene, you don't see any evidence for selection. The changes we see are compatible with just random change," said Prof Rees. "The gene is more important in Africa than it is in Europe. You mustn't have pale skin and bright red hair in Africa. That would make sense."

Of course, red hair is not exclusively found in pale-skinned people. In Jamaica, there are families with deep brown skin and bright red hair. On the island, the red-hair gene was brought from Europe a few hundred years ago, possibly by white sailors who fathered children there.

If the Edinburgh team are right, and the redhead gene originated only 20,000 to 40,000 years ago, it may kill off a theory that emerged last year - that the red-hair gene originated in the Neanderthals.

The idea was based on a claim that the gene was at least 100,000 years old and so may have been present before modern man left Africa. To pass into our DNA, our ancestors would have had to have interbred with Neanderthals - an unfashionable theory among the experts in human origins.