Dark Skin, Blond Hair: The Unique Genetics of The Solomon Islanders

Blond hair is a fairly uncommon genetic trait. Only two percent of the global population has natural blond hair and it is most prevalent among northern Europeans. However, one other place where blond hair is common is in Oceania; more specifically, in The Solomon Islands. Between five and ten percent of the dark-skinned islanders have spectacular blond hair. It seems to be especially common among children. For long it was theorised that this blond phenotype was caused by long term sun and sea exposure. Other theories claimed the blond hair was inherited from European traders and explorers over the last centuries.

In the last decade, studies have shed light on the exact reason causing the blond hair of the islanders. A study published in Science states that a specific gene is related to the blond hair of the indigenous people of The Solomon Islands. And to the surprise of the scientific community, it is not the same gene responsible for blond hair among northern Europeans. The gene in question is TYRP-1. This gene is sometimes prevalent in animals as well and causes albinism or a decrease of pigmentation in the fur. For example bears with TYRP-1 in their genome will have a lighter brown fur instead of a common dark brown. The detection of TYRP-1 in the genome of The Solomon population has baffled the scientists. It means that blond hair has evolved independently in Oceania as well as in Europe.

Where TYRP-1 comes from and how it exactly evolved among in The Solomon Islands is unknown. The gene seems to have no specific function besides the decrease of pigmentation in hair. Further studies have to be done to determine the origin of the mysterious gene. Nonetheless it gave rise to some of the most unique appearances among human beings. The scientists that discovered the TYRP-1 gene conclude that more studies among different populations in the world might shed more light on the genetic basis responsible for variations and similarities in our appearances.

The discovery is groundbreaking, even paradigm shifting some might claim. It completely changes our understanding of how phenotypes across human populations are genetically determined. As Stanford professor of genetics Carlos Bustamante states: “For instance, the genetics of skin pigmentation might be different there too — not the same as in Europe or Africa or India. We just don’t know.” In simpler language, it means that identical traits of appearance across different human populations do not have to be because of similar genes.

Sources

Kenny, Eimear E., et al. “Melanesian blond hair is caused by an amino acid change in TYRP1.” Science 336.6081 (2012): 554–554.

Stanford University School of Medicine News Centre