A new genetic line in blond hair has been discovered in an unlikely place - among the people of Melanesia in the Solomon Islands and Fiji.

The magazine Science reports today that scientists now realise that blond hair evolved independently at least twice in human history.

Around 10 per cent of Solomon Islanders had the blond gene, said study author Sean Myles, a geneticist at Nova Scotia Agricultural College in Truro, Canada.

Strikingly there was almost no variation in shades of blond hair.

"It looked pretty obvious to me that it was a real binary trait. You either had blond hair or you didn't," Myles told Science.

After testing 1209 Solomon Islanders scientists compared the entire genetic makeup of 43 blond and 42 dark-haired islanders.

The two groups, they found, had different versions of a crucial gene, TYRP1, one that coded for a protein involved in pigmentation. Switching one "letter" of genetic code - replacing a "C" with a "T" - meant the difference between dark hair and blond hair. A similar mutation creates blond mice by reducing the melanin content in their fur.

The gene was recessive, which meant that blonds inherited it from both parents.

Myles said the results help deconstruct a Eurocentric view of the world in thinking about where blond hair originated. He hoped the paper will draw attention to the bigger issue of other novel genes that scientists may be missing by concentrating on the genomes of Europeans.

"If you can find a gene for blond hair that exists in Melanesia and nowhere else," Myles says, "then there's no reason why those sorts of genes don't exist all over the world in under represented populations, and affect not only hair pigmentation, but also disease-related traits."

The study refuted the possibility that blonde hair was introduced by colonial Europeans, said Carlos Bustamante, a geneticist at Stanford University School of Medicine in Stanford, California, and a senior co-author on the study.

"Blonde hair has clearly evolved twice," he said.

Bustamante said the genetics behind blond hair in Europe were distinct from those leading to flaxen locks in the South Pacific.

"Before this everybody would have thought blond hair evolved once in humans," said Bustamante.

"This tells us we can't really assume that even these common mutations are common across different human populations. Non-European populations are critical to study to find mutations that may be underlying the vast phenotypic variation of humans."

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