A haul of genes that underpin the diversity of human hair has emerged from a major study into our follicular foundations.
Scientists trawled through the genomes of more than 6,000 people to find versions of genes linked to straight hair, curly hair, grey hair, no hair, thick and thin beards, and glorious, arching monobrows.
The findings provide the deepest insight yet into the roots of human hair types, and pave the way for drugs that slow or prevent certain changes, such as greying, before hairs even appear on the scalp. One gene spotted by the study, known as IRF4, is the first to be linked to grey hair.
“People spend a lot of money changing their hair colour, but all of it goes on bleach or dyes,” said Kaustubh Adhikari, a geneticist on the study at University College London. “What this shows is that there is a genetic component to hair greying, and that raises the possibility of drugs that act on the hair internally, so it is already the colour you want when it comes out.”
The size of the hair-products market suggests the idea will find many fans, but not everyone is overjoyed at the prospect. “I can’t help feeling a little disappointed that the wonderful breakthroughs in genetics research are likely to be commercially exploited in the interests of hair colouring (or not),” said Mary Beard, the Cambridge classics professor who has become a champion for the act of going grey.
By connecting particular genes to distinctive hair shapes, shades and patterns, the new information is expected to help forensics specialists work up facial profiles of crime suspects based on DNA they leave behind. Should murder ever strike Sesame Street,for example, a variant of the PAX3 gene found at the scene could be good news for tufty-haired Ernie, but not for monobrowed Bert.
The story of human migration and evolution is written in hair DNA. In sub-Saharan Africa, genes favour tight, curly hair. But in east Asia, mutations have led to straighter, thicker hair. In Europe, other mutations brought wavy and straw-coloured hair. The changes mirror the different climates and the pressures of sexual selection.
Adhikari and his colleagues examined the DNA of 6,357 people from Latin America. The region is a genetic melting pot, with populations from European, Native American and sub-Saharan African ancestors. To find genes for different hair types, there can be few better places to look.
Having made detailed notes about the volunteers’ hair, including the colour and shape, and for men, the nature of their beards, eyebrows and monobrows, the scientists hunted for genes that might underpin the differences. They describe 18 in total, 10 of which appear to be new, according to a report in Nature Communications.
The gene for greying hair, IRF4, has a role in making melanin, the pigment that governs the colour of eyes, hair and skin. But the gene alone does not make hair grey, the study found.
Another gene, named PRSS53, affects the curliness of hair, while others influence balding, beard and eyebrow thickness, and the formation of a monobrow.
Adhikari said that while no single gene determines hair colour, further work in the area could help scientists understand the more complex pathway that does have an effect. “If we can elucidate that pathway, the proteins or enzymes involved could become targets for drugs that control hair colour,” he said.
David Balding, a senior author on the study at UCL, said: “It’s exciting that we are finally beginning to figure out the nuts and bolts of genetics underlying normal human variation. If that feeds into the cosmetics industry that’s just a reflection of the world we live in - it already absorbs a huge fraction of the world’s resources. It will also lead to innovations in forensics: the possibility to predict features of someone who left DNA at a crime scene. I think the new knowledge is exciting and will lead to good outcomes.”