For thousands of years, people have both prized and mocked blond hair. Now, a new study shows that many can thank a tiny genetic mutation—a single letter change from an A to a G among the 3 billion letters in the book of human DNA—for their golden locks, National Geographic Daily News reports.
The mutation "is the biological mechanism that helps create that [blond] color naturally," said David Kingsley, a professor of developmental biology at Stanford University and a Howard Hughes Medical Institute investigator, who led the research. "This is a great biological example of how traits can be controlled, and what a superficial difference blond hair color really is."
Kingsley, a brunet, said the study, published today in Nature Genetics, also offers a powerful insight into the workings of the human genome. The mutation doesn't alter the protein production of any of the 20,000 genes in the human genome, he said. Instead, in people of European ancestry, it causes blond hair through a 20 percent "turn of the thermostat dial" that regulates a signaling gene in the hair follicles of the skin, according to National Geographic.