Not All Blonds Share a Common Ancestor

blond hair Up until now, it was believed that blond hair developed in people who were of European ancestry, and was brought to the Solomon Islands after Europeans traveled over and had offspring with the people who lived there. A new study, however, finds that blond hair developed independently in two different parts of the world. Not all blonds share a common ancestor after all.

It is rather amazing how much genealogy related information can be learned from taking a close look at at a person’s DNA. Genealogists use it to learn about relatives and ancestors that they did not know about. Doctors can look at DNA and determine a person’s risk for certain types of diseases or if a developing baby has a particular genetically heritable disease. Scientists can use it to learn that Otzi, a man who was frozen in the ice for thousands of years, had brown eyes.

A few years ago, scientists learned that all people who have blue eyes share a common ancestor. They learned that blue eyes developed from a genetic mutation that occurred somewhere between 6,000 to 10,000 years ago. It affected the OCA2 gene in the chromosomes of humans. In short, it turns off the pigment in the eyes that causes the brown color.

It was believed that all people who have blond hair inherited genes from a common ancestor. Or, at least, an ancestor who came from Europe. In other words, it was assumed that the indigenous people of the Solomon Islands who have naturally blond hair got it from a European ancestor. It turns out that this is not so.

A study done by researchers from Stanford University collected DNA samples from several Solomon Islanders. The DNA sample was in the form of a saliva sample. There were 43 people who had blond hair and 42 people with very dark hair in the study.

The researchers looked at chromosome 9. Typically, people who have blond hair have one spot where they have thymine (or “T”). Dark haired people typically have cytosine, (or “C”) in that spot. The researchers found that the Solomon Islanders who had naturally blond hair had a mutation in chromosome 9 that causes a significant change to a gene called TYRP1. It is this mutation that has caused blond hair in the people who are native to the Solomon Islands. In other words, blond hair developed in two places on the globe independently.

Image by Moyan Brenn on Flickr

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