According to a new study, during the end of the last Ice Age north European women evolved blond hair and blue eyes as a sexual advantage over their peers. They needed to stand out of the crowd in a fierce competition for males.
The end cause had been the food shortages around 10 000 - 11 000 years ago. This forced men to search for food in long, difficult hunting trips. Many of them died leading to a high ratio of surviving women to men.
An analysis of north European genes for blonde hair and blue eyes conducted by three Japanese universities has shown that the genetic mutation that resulted in blond hair happened about 11,000 years ago. Apparently, blonde hair, although started as a rare mutation, became popular and effectively attracted males. Otherwise blonde hair and blue eyes wouldn't have managed to spread.
A study by the World Health Organization previously found that natural blondes are likely to be extinct within 200 years because there aren't enough people carrying the blond gene.
Rectification: Apparently, in spite wide media coverage, the World Health Organization did not make such a study about the fate of blondes. Here is the WHO clarification:
"In response to recent media reports citing an alleged World Health Organization (WHO) study predicting the extinction of the naturally blonde hair gene, WHO wishes to clarify that it has never conducted research on this subject. Nor, to the best of its knowledge, has WHO issued a report predicting that 'natural blondes are likely to be extinct by 2202'. WHO has no knowledge of how these news reports originated but would like to stress that we have no opinion on the future existence of blondes."