10% of the inhabitants of the Solomon Islands are born with a bright blond afro atop some of the darkest skin found outside Africa. For decades, the popular explanation pointed to some European ancestor mixed into the family tree. Genetics proved that theory was completely wrong.
A study published in the journal Science identified the real cause: a mutation in the TYRP1 gene, a variant that does not exist in any European genome. The genes that produce blond hair in Europe are completely different, which makes Melanesians an extraordinary example of convergent evolution: the same visible trait, generated by separate biological pathways and without any contact between populations.
The mutation is recessive, meaning both parents must carry the variant for a child to express it. Researchers estimate that it has been circulating within this population in isolation for thousands of years. Few pieces of evidence better illustrate the complexity of human genetics: the same characteristic we associate with northern Europe evolved independently in the Pacific, for reasons that science still has not fully managed to explain.
