Scientists believe that the “ginger gene,” or “V6OL allele,” showed up 50,000 years ago after humans left Africa for colder climates. This gene made human skin lighter, as they were exposed to less vitamin D from the sun.
Scientists reported their discovery in a 2013 study after studying the gene evolution of 1,000 people from Spain.
The percentage of people with red hair on the island of Ireland is estimated to be around 10-15%. However, it's worth noting that this figure is based on self-reported data and can vary depending on how red hair is defined and measured.
In total, there are 20 million people in the United Kingdom and Ireland with the gene that can cause red hair and this study shows that this remains a dominant gene in southern Europeans today.
However, this paler skin also brought health risks, such as melanoma, the deadliest form of cancer, but the study’s author Doctor Saioa Lopez says this is not necessarily due to the redhead gene itself.
He told the Daily Mail in 2013, “As a consequence of depigmentation there has been a collateral damage consequence to health.
“This can be reconciled if we assume that melanoma is typically a post-reproductive disease, and consequently should have little effect on the individual’s genetic contribution to the next generation.”
According to a 2018 report by the Irish Cancer Society, over 80% of skin cancer cases in Ireland are diagnosed in people with fair skin. This suggests that a significant proportion of the population has fair or pale skin. It's worth noting, however, that skin color is a complex trait that is influenced by a variety of genetic and environmental factors, and it is not always easy to categorize people into neat categories based on their skin tone.
The study followed on the results of a ScotlandsDNA project in 2012 which found that the Celt's flaming red hair can be put down to the weather. The experts believe that the gloomy climate in Scotland has seen a deliberate genetic adaptation. Essentially this means that red hair helps to take advantage of sunny days and allows the body to absorb more vitamin D.
* Originally published in 2013, updated in April 2013.