We think of blond hair as a primarily European trait, but around the world there are people who have blond hair scattered throughout the population. Geneticists have gone to trying to solve this riddle, by studying these different populations. Is it a European influence that makes them blond? And if not, are their genes still the same?
The most common blonds in the world are ones that come in a bottle. The second most common are the ones who come from Europe. Over there, a gene in the region of SLC24A4 and KITLG gives us blond hair instead of brown, and green eyes instead of blue eyes. Or, maybe they do. So far genetic blondness has mostly been studied in those of European ancestry. A new study changes that — by looking at blonds all the way over in the Solomon Islands in the South Pacific. There seem to be a fair amount of genetic blonds in the islands; between five and ten percent of the population. A team from Stanford University wanted to find out why.
There was the possibility that the Solomon Islanders, while far removed from Europe, had genetically crossed over with Europeans over the years. Some genes just have a knack for spreading in the right conditions. If the genetic twist for blondness had originated in the Islands, though, researchers wanted to know if it was the same twist that gave some Europeans their light hair. Is there one or two genes for blondness?
Using light-meter readings to quantify hair-color, scientists took height, weight, blood pressure, and saliva samples of forty-two dark-haired and forty-three blond islanders. They were not hopeful when they began analyzing genetic samples, since the confusing mix of genes that make up pigmentation usually result in inconclusive or weak results unless thousands of people participate. To their delight, however, a strong result came in right away, and they could narrow down the blondinating as coming from one gene: TYRP1. TYRP1 encodes an enzyme which has been shown to affect pigmentation in both mice and human tests. It has not, however, been shown to cause blondness in European populations. Solomon Island blonds popped up out of native genetics, and not outside influences.
And that, in turn, means that there's more than one kind of blond in the world.
Top Image: Nevit Dilmen
Second Image: Graham Crumb