Having darker or lighter skin and a certain hair colour is, in part, determined by the MC1R gene. This gene, which regulates the synthesis of melanin, is much more diverse amongst Eurasian populations than African ones. A study led by UPV/EHU researcher Santos Alonso has shown how MC1R evolved in the south of Europe. The research has been published in the journal of Molecular Biology and Evolution (MBE).
According to the research, undertaken with 1,000 individuals from different zones of Spain, two evolutionary forces appear to be acting on the MC1R gene amongst southern Europeans. On the one hand, the influence of natural selection has tended to maintain an ancestral form of the gene, also the most common in Africa; i.e. tending to eliminate mutations. On the other, one of these mutations – V60L – appears at frequencies higher than expected. This mutation is associated with fair skin and blond or red hair.
The researchers have calculated that that the appearance of this mutation about 30,000-50,000 years ago, after the exit of Homo sapiens from Africa. And this change may have been highly beneficial for adapting to the new environment, given that fair skin facilitates the synthesis of vitamin D, which becomes very necessary when ultraviolet radiation is very low, compared to Africa. “Our data reinforce this idea although it has to be investigated further, explained the Faculty of Science and Technology researcher.
Nevertheless, the mutation is simultaneously associated with a greater susceptibility for melanoma, the most dangerous type of skin cancer. “Vitamin D is necessary for growth, is very important for the correct mineralisation of bones and the development of the skeleton, while melanoma is an illness that appears in the post-reproductive phase. As regards evolution, it appears that it favours depigmentation at the cost of increased risk of melanoma in the post-reproductive phase”, explained the PhD student Saioa López, lead researcher for the article. “This is the price to pay for guaranteeing the survival of the species”.