New secrets of human evolution unlocked in study of ancient DNA from Europe and Near East |
Some 4,000 years ago, as ancient civilizations such as the Minoans in Crete and the Neo-Sumerian Empire in Mesopotamia were shaping cultures in Europe and the Middle East, human biology itself was evolving apace.
A groundbreaking study of ancient DNA, published last week in the prestigious journal Nature, has documented that the frequency of two DNA variants linked to celiac disease increased dramatically across populations in those regions.
Hundreds more such DNA variants were also uncovered in the study, which sheds unprecedented light on how, in the past 10,000 years, human evolution, and specifically the biology of the human body, have been shaped by natural selection. (Natural selection occurs when a version of a gene linked to a specific trait, such as a disease like celiac, but also qualities like red hair or a blood type, proves advantageous enough for survival and reproduction).
Led by scientists from Harvard University, the researchers analyzed and compared the genomes, or complete DNA sequences, of some 22,000 individuals. The data included 10,000 ancient genomes never studied before, 6,000 previously published genomes, and 6,000 modern individuals.
Previously, only 21 genetic shifts due to natural selection — as opposed to migrations, community mergers, or similar factors — were known.
“It’s so powerful to be able to watch evolution happening in action, not just to study the scars that evolution leaves on modern patterns of variation,” the study’s senior author, Harvard geneticist David Reich, told The Times of Israel in a video interview.
‘Industrializing the production of ancient DNA
Reich, who heads a lab focused on ancient DNA, biology, and disease, explained that extracting ancient DNA has only been possible for the past few years, and it took time to accumulate enough data to conduct a study on human evolution.
“The technology for getting ancient DNA out of human remains only became available beginning in 2010,” he said. “I think it’s not an understatement to say that it has had a transformative impact on our understanding of the past.”
The scientist has authored many studies on the human history of specific groups, archaeological sites, and regions, including Jews and populations in the land of Israel.
The Nature paper, which analyzed genomes from countries spanning from Iceland to Spain, Russia, Iran, and Israel, took a different approach, investigating human biology.
“Many of the people who started this field were biologists, and really thought that the most exciting thing one could do with ancient DNA would be to try to understand how our biology might have changed over time, ” he said. “However, in order to study human history, you only need one or a few samples per population, but to understand evolution, you need many samples. The data just did not exist.”
To make this type of study........