For many years, we believed that Europeans descended from early farmers, who were originally in the Middle East and moved to Europe about 7,500 years ago, or from local hunter-gatherers that bred with other races. However, recent DNA analysis uncovers a third group.
Nine ancient skeletons found in Sweden, Germany, and Luxemburg were of seven hunter-gathers and one hunter who lived 8,000 years ago and one farmer who lived 7,000 years ago. Through association, the hunter-gatherers were labeled as hunter-gatherers and identified as being from the same time period. Hunter-gatherers had darker skin than farmers and typically blue eyes, while farmers had fair to pale skin tones.
The skeletal remains were dated with AMS radiocarbon dating, a method applied to organic matter based on carbon decay. AMS radiocarbon dating uses an accelerator mass spectrometer to differentiate the carbon isotopes from other atoms or molecules that have a similar mass. A danger of radiocarbon dating is that samples can be contaminated, which causes problems with the interpretation of the results. Therefore, the archaeologists used numerous approaches to search for contamination.
The team from the Harvard Medical School and Germany’s University of Tübingen noted a significant genetic transition between the era of hunter-gatherers and the era of the farmers. Thus, North Eurasians contributed to the gene pool in both Europe and North America. After overlaying the genomes with genetic codes from 2,300 present-day people living all over the world, the team concluded that the ancient North Eurasian ancestry is predominant in less than 20 percent of most Europeans’ DNA today. This ancestry is found in nearly every European group, the Caucasus, and the Near East. Northern Europeans have relatively more hunter-gather ancestry than southern Europeans who have more farmer ancestry. Most native Europeans have a mixture of genetic information from the three distinct types of ancestors. Most of the conclusions about the North Eurasian group come from DNA dating and analysis. Concerning the determination of dates, context is extremely important. Therefore, demographic history and inbreeding were accounted for during the process. The researchers focused on sex determination through Y-chromosome analysis. Other methods involved in their DNA dating were enrichment of mitochondrial DNA and shotgun sequencing, which sequences long strands of DNA.
Also, the ancient North Eurasian group explains the genetic connection between Europeans and Native Americans. Remains of ancient Siberians showed that European contributors were from the group that crossed the Bering Straight into the Americas more than 15,000 years ago. This new discovery alters our knowledge about European genetic ancestry and paints a different portrait of modern Europeans’ genetic composition.
Renfrew, Colin and Paul Bahn (2010) Archaeology Essentials. 2nd edition. Thames & Hudson, New York. Chapter 2.