A new study has found that natural selection is causing a wave of redheads.
A team of researchers from Harvard University assessed ancient DNA from nearly 16,000 people spanning more than 10,000 years in Western Eurasia, including the Middle East, the Caucasus, Europe and parts of Central Asia and North Africa.
The study found that certain genes became much more common because they likely provided some benefit or were affected by the changing environment.
According to researchers’ findings, genes linked to red hair, lighter skin tones and celiac disease are becoming increasingly common.
“Maybe having red hair was useful 4,000 years ago, or perhaps it came with a more important characteristic,” suggested the study, published in the scientific journal Nature.
The findings also suggest that natural selection has played a much larger role in shaping the modern human genome than previously thought.
The study also doubles the existing library of ancient human DNA, adding 10,016 new ancient DNA sequences and bringing the total data set to more than 22,000 individuals.
“With these new techniques and a large amount of ancient genomic data, we can now see in real time how selection has shaped biology. Instead of using simple models and assumptions to look for the scars that natural selection leaves on today’s genomes, we can let the data speak for itself,” said Ali Akbari, author of the study and senior staff scientist in the laboratory of Harvard geneticist David Reich.
Furthermore, natural selection appears to have increased the prevalence of variants associated with celiac disease and Crohn’s disease.
Evolution has also favored traits that provide resistance to leprosy and HIV, including the lower risk of bipolar disorder, alcoholism and schizophrenia.
The study also suggested that lower BMI, waist-hip ratio and lower body fat are also linked to DNA changes.
According to researchers, the study findings could also help scientists identify new genetic factors in health and disease, which could lead to revolutionary changes in medical sciences.
