A large genetics study has revealed that the gene for red hair has been actively selected for in Europe over the past 10,000 years. Scientists analysed DNA from nearly 16,000 ancient human remains and more than 6,000 living individuals, providing compelling evidence that human evolution has continued apace since the advent of agriculture.
The researchers identified 479 genetic variants favoured by natural selection, including genes linked to red hair, fair skin, susceptibility to coeliac disease, and variants that lower the chance of diabetes, baldness and rheumatoid arthritis. Previous research suggests that people with red hair and fair skin can produce vitamin D more efficiently, which may have conferred survival benefits in northern climates with low sunlight.
Dr Ali Akbari, first author of the study at Harvard University, said: 'With these new techniques and large amount of ancient genomic data, we can now watch how selection shaped biology in real time.' The study, published in Nature, used an unprecedented number of ancient DNA samples combined with sophisticated computational techniques to track evolutionary trends in West Eurasia.
The potential benefits of some selected genes appear intuitive, but others were harder to interpret. A mutation that is a major risk factor for coeliac disease appeared 4,000 years ago and has become more common since, suggesting it may have offered survival advantages despite the autoimmune risk. Similarly, an immune gene called TYK2 that raises tuberculosis risk grew in frequency between 9,000 and 3,000 years ago before declining.
The study also found negative selection for genes promoting high body-fat percentage, supporting the 'thrifty genes' hypothesis. This suggests that fat storage, once beneficial for hunter-gatherers during scarcity, became a disadvantage after agriculture provided more reliable food. Prof David Reich, senior author, said: 'This work allows us to assign place and time to forces that shaped us.'
