The Grapevine

Europe's Genetic Ancestry: Researchers Sequence The First Genome Of An Iberian Peninsula Farmer

mediterranean
Researchers are uncovering clues to Europe's ancestry to help better understand the past. steve p2008, CC BY 2.0.

An international team of researchers is helping Europe better understand the characteristics of its past, sequencing the first complete genome of an Iberian farmer.

The efforts of this study signify the first complete genome to represent the entire ancient Mediterranean, allowing researchers to understand the genetic characteristics of people existing during the Neolithic migration in Southern Europe. The researchers also believe that this DNA sequencing can help them to understand why the hunter-gatherer way of life was neglected during this time. The study, published in the journal Molecular Biology and Evolution, was led by the Institute of Evolutionary Biology, a joint center of the Spanish National Research Council (CSIC), in collaboration with the Universitat Pompeu Fabra, and the Centre for GeoGenetics in Denmark.

About 8,000 years ago, Europe saw the first appearance of farmers, migrating from the Near East and then diverging into two different paths. One set of people migrated toward the Northern Mediterranean coastline, and developed the Impressa and Cardial traditions. The second followed the Danube River to settle into Central Europe, forming the LBK tradition. Genomes have already been sequenced for this second group constituting the LBK tradition, but up until now the complete genome of the Cardial peoples has not been fully established. The researchers attribute this to climate conditions in Southern Europe, which makes conserving genetic material more difficult.

Using a tooth from a Neolithic woman dating back to 7,400 years ago, the team working under Carles Lalueza-Fox of the Institute of Evolutionary Biology was able to sequence the complete genome. The tooth was discovered from the cardial levels of the Cova Bonica cave in Vallirana, located near Barcelona. Along with this genome, the excavation team from the University of Barcelona has found other partial genomic data from Cova de l’Or in Alicante, Cova de la Sarsa in Valenica and Almonda in Portugal.

Once sequenced, the genome helped researchers determine that these farmers must have a common ancestry population, which can most likely be traced to the first farmers who entered Europe via Anatolia.

Iñigo Olalde, the first author of the study, says that recent advances in ancient DNA extraction, along with constructing ancient genomes made this research possible, though overall, the researchers definitely found the task to be difficult.

On top of discovering that the genome indicates a homogeneous lineage, the researchers were able to decipher the appearance of these Neolithic farmers. They found that the Cardial culture had light skin, with dark eyes and dark hair, a big difference from the Mesolithic hunters of La Braña in León, whose DNA the team previously recovered in 2014. They found this group of people had the interesting combination of blue eyes and darker skin that most modern Europeans have today. Though these two groups were only 600 years and 800 kilometers apart, researchers were fascinated to find such a genetic difference. They concluded that most people currently living on the Iberian Peninsula derive some of their DNA from these people, though the Basques and Sardinians have the largest genetic connection with the farmers.

But researchers say, this genome is only the beginning. “This study is only the first step of a major project done in collaboration with David Reich at the Broad Institute that aims to create an Iberian paleogenomic transect, from the Mesolithic to the Middle Age,” Lalueza-Fox said. “So far, we have genomic data from 50 individuals and we want to reach more than 100. Being at the westernmost edge of Europe, the Iberian Peninsula is crucial to understand the final impact of population movements such as the Neolithic or the later steppe migrations that entered Europe from the East.”

Source: Olade I, Lalueza-Fox C, Schroeder H, et al. A common genetic origin for early farmers from Mediterranean Cardial and Central European LBK cultures. Molecular Biology and Evolution. 2015. 

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