The Origin of Blond Afros in Melanesia
Pay a visit to Melanesia’s Solomon Islands, 1800 kilometers northeast of Australia, and you’ll notice a striking contrast: about 10 per cent of the dark-skinned Islanders sport bright blond afros. Hypotheses about the origins of this golden hair have included bleaching by sun and saltwater, a diet rich in fish, and the genetic legacy of Europeans or Americans. But a new study fingers a random mutation instead, suggesting that blond hair evolved independently at least twice in human history. And other novel genes, including ones with serious health consequences, may await discovery in understudied populations.
Human hair color is a trait usually governed by many genes, but study author Sean Myles, a geneticist at Nova Scotia Agricultural College in Truro, Canada, suspected things might be simpler in the Solomon Islands because he saw 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,” says Myles.
To search for an underlying genetic blueprint, Myles and his colleagues collected saliva and hair samples from 1209 Solomon Islanders. Population genetic studies usually compare thousands of individuals, but the researchers predicted they could detect differences in a much smaller sample because of the stark contrast between the Islanders’ blond and dark locks. They 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, 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.
Source: Science Magazine