Contrary to popular belief, redheads originated in Central Asia rather than Scandinavia, Scotland, or Ireland. Their colour is caused by a mutation in the MC1R gene, which causes pale skin, freckles, and red hair instead of the sun-protective, skin-darkening eumelanin. This mutation has been found only in people with European ancestry, so if you're a redhead you must have Irish blood. The first evidence of people with red hair living in what is now Ireland was in 1887, when several skeletons were excavated from a cave near Galway called the Yellow Man's Cave. The bones were radiocarbon dated to between 1240 and 1180 BC, making them some of the earliest evidence of human habitation in Ireland. The people who lived here were of British origin, not Irish, but they may have adopted some Native American customs. In any case, they had red hair like everyone else at that time. People with red hair are more likely than others to have Irish blood. In fact, up to 80% of all redheads are born with Irish parents. The other 20% are the result of inheritance from both parents, or one parent with a new mutation. Either way, it means that if you're a redhead you must have Irish blood.