Researchers from the Johannes Gutenberg Universitaet Mainz Institute of Anthropology discovered that natural selection may have altered the human genome in the past 5,000 years.
To gather data for the study, a team of anthropologists, archaeologists, and geneticists analyzed the DNA samples from skeletons and compared them with a modern European's genome through computer simulation. Although evidences showing the role of other factors such as inheritance were not found, the researchers were able to confirm that positive selection influenced the frequency of mutation for a particular population.
Study author Sandra Wilde have noted the differences in physical appearances such as skin color, eye, and hair pigmentation. She explained that prehistoric Europeans were darker compared to modern Europeans since evolution may have preferred the darker phenotype for years. However, changes were catalyzed as humans started to transfer to northern locations 50,000 years ago.
"In Europe we find a particularly wide range of genetic variation in terms of pigmentation," member of the Palaeogenetics Group at Mainz University and co-author Dr. Karola Kirsanow told Science 2.0. "However, we did not expect to find that natural selection had been favoring lighter pigmentation over the past few thousand years."
The authors proposed several reasons for these changes. First, the mutation is a coping mechanism to the decreased supply of sunlight in a new location. According to co-author Mark Thomas from the University College London, the prehistoric Europeans were not getting enough vitamin D, so mutation gave them lighter skin in order to adapt to the changes.
Wilde is not convinced with Thomas' explanation. For her, the change in color functioned as a signal indicating if a person belongs to the same group, which influenced their selection for a partner.
Professor Joachim Burger, the senior author of the study, stated that natural selection could just be one of the factors for these physical changes. He noted that the study does not imply that the results of natural selection are still useful today.
"The characteristics handed down as a result of sexual selection can be more often explained as the result of preference on the part of individuals or groups rather than adaptation to the environment," he told Science 2.0
The study was published in the March 10 issue of Proceedings of the National Academy of Sciences.
