7,000-Year-Old Bones Suggest Europeans Developed Light Skin Much Later Than Previously Thought
The 7,000-year-old bones of a man discovered in Spain have upended previous theories that humans evolved light skin roughly 40,000 years ago. DNA testing of the remains, known as La Braña 1 after the location of their discovery, showed that this early European still had dark-skin genes thousands of years later than scientists predicted.
What's more, La Braña 1 also had blue eyes, suggesting that light eyes evolved before light skin. The reason for this is still unknown. "The biggest surprise was to discover that this individual possessed African versions in the genes that determine the light pigmentation of the current Europeans, which indicates that he had dark skin," said the study's co-author Carles Lalueza-Fox, of the Spanish National Research Council, in a statement. The findings were published Sunday online in the journal Nature. He adds that "we cannot know the exact shade" of his skin.
Like Us on Facebook
Lalueza-Fox said the man's genetic makeup was most similar to current inhabitants of northern Europe. In other words, if La Braña 1 were alive today, his closest relatives would be in Finland and Sweden, despite his dark skin. While much information is still speculative, the study makes the strongest case yet that the evolution of light skin had more to do with diet than with sunlight.
According to LiveScience, many scientists had assumed light-skinned humans came about soon after their migration from Africa to Europe around 40,000 years ago. Humans need vitamin D to keep bones healthy, which lighter skin can more readily synthesize from the sun's UV rays. In this way, evolution would have favored light-skin mutations in the north, where sunlight is more infrequent. But the discovery of La Braña throws this theory out the window.
Light skin still probably evolved because of humans' need for vitamin D, but now scientists involved with the new research say the pigment change was probably due to changing diets. The birth of agriculture in Europe about 8,500 years ago increased the amount of carbohydrates people ate and led to a decrease in fish and other meats high in vitamin D. Lighter skin gradually evolved as a result, the new thinking suggests. Later, Europeans also developed the ability to digest lactose; La Braña was lactose intolerant.
Still puzzling is La Braña's blue eyes. As far as scientists know, there is no practical adaptive benefit to lighter eyes. "What's the use?" asks Mark Thomas of University College London in a NewScientist report. He speculates that perhaps blue eyes were the result of "sexual selection," not natural selection. "One or both sexes preferred partners with blue eyes for some cultural reason," NewScientist writes.
© 2012 iScience Times All rights reserved. Do not reproduce without permission.