Dark skinned, blond-haired indigenous people on the Solomon Islands have a gene that is unique to the South Pacific nation and was not picked up from interbreeding with Europeans, scientists said.Outsiders have long presumed the unusually fair-haired Melanesians were a result of long-ago liaisons with European traders, while locals often attributed their golden locks to a diet rich in fish or the constant exposure to the Sun.
But the reason why some five to 10 per cent of the islanders are blond comes down to simple genetics - a gene called TYRP1 that natives of the Solomon Islands possess but Europeans do not", said the study in the US journal, Science.
"So the human characteristic of blond hair arose independently in equatorial Oceania. That's quite unexpected and fascinating," said lead author Eimear Kenny, a postdoctoral scholar at Stanford University in California.
Researchers gained the trust of a local chief and collected data from 1000 people, including hair and skin colour assessments, blood pressure, height and weight and saliva samples for DNA.
The lab analysis on samples from 43 blond and 42 dark-haired natives began in September 2010 and "within a week, we had our initial result", said Mr Kenny.
"It was such a striking signal pointing to a single gene - a result you could hang your hat on. That rarely happens in science."
The idea to study the genetics of the population came from co-author Sean Myles, a former Stanford postdoctoral scholar who is now an assistant professor at the Nova Scotia Agricultural College, after a trip there in 2004.
"They have this very dark skin and bright blond hair. It was mind-blowing," said Mr Myles.
"As a geneticist on the beach watching the kids playing, you count up the frequency of kids with blond hair, and say, 'Wow, it's five to 10 per cent'."
Co-author Carlos Bustamante, professor of genetics at Stanford, said the study gives good cause for more research on the genomes of rarely studied populations.
"Since most studies in human genetics only include participants of European descent, we may be getting a very biased view of which genes and mutations influence the traits we investigate," Prof Bustamante said.
Nic Timpson from the Medical Research Council Centre for Causal Analyses in Translational Epidemiology at the University of Bristol was a co-author on the report.