"By finding the differences, we have the potential to find ways to make people with the European ancestry genes less susceptible to skin cancer," said Penn State College of Medicine's Dr Keith Cheng, professor of pathology.
Genetic mutations
While the genetics of skin colour is largely unknown, Cheng’s past research using zebrafish identified the gene in Europeans that differs from West Africans and contributes to a lighter skin colour.
Mutations in the genes SLC24A5 and SLC45A2 are largely responsible for European pigmentation, showing only single amino acid differences between Europeans and West Africans. Each version of a gene is called an allele.
While East Asians are also light skinned, these European alleles are not present, suggesting that while both groups' lighter skin colour evolved to allow for better creation of vitamin D in northern climates, they did so in a different way.
Europeans have 10 to 20 times higher rates of melanoma than Africans. However, despite also having lighter skin, East Asians have the same melanoma rates as Africans. The reason for this difference can only be explained when the gene mutations for both groups are found.
Chosen tribe
According to the scientists, in order to find the unidentified mutations they must study a population that includes a blend of original African ancestry and East Asian ancestry, with little European contribution.
The chosen tribe is the Senoi, one of three indigenous tribes from Peninsular Malaysia, believed to include an ancestry of a dark-skinned tribe called the Negrito, and a regional Mongoloid population of Indo-China, such as the Proto-Malay.
Since the skin colour of the Senoi is darker than that of Northeast Asians, researchers will be able to focus on finding the primary genetic mutation of light skin colour in Asians without seeing further skin lightening mutations.
"Skin colour has been tied to human welfare in modern history," Cheng said. "It is important for us as a species to realize that our skin colour is determined by only a small number of minute changes in our DNA -- changes that have nothing to do with the value of human beings."