Origin of the first civilizations of the Bronze Age in Europe

Ancient DNA analysis has revealed the origin of the earliest Bronze Age civilizations in Europe.

The first civilizations that built monumental palaces and urban centers in Europe are genetically more homogeneous than expected, according to the first sequencing of complete genomes collected from ancient archaeological sites around the Aegean Sea. The study, whose first co-author is Olga Dolgova, from the National Center for Genomic Analysis (CNAG-CRG) in Barcelona, ​​which is part of the Center for Genomic Regulation (CRG), has been published in the academic journal Cell, with the title “The genomic history of the Aegean palatial civilizations ”.

Despite marked differences in burial customs, architecture, and art, the Minoan civilization on the island of Crete, the Helladic civilization on mainland Greece, and the Cycladic civilization on the Cyclades islands in the middle of the Aegean Sea were genetically similar. during the early Bronze Age (5,000 years ago).

The findings are important because they suggest that fundamental innovations between the Neolithic to Bronze Age transition, such as the development of urban centers, the use of metals, and intensive trade, are not due solely to massive immigration from the eastern Aegean. , as it was thought, but also of the cultural continuity of the local Neolithic groups.

The study also reveals that in the Middle Bronze Age (between 4,000 and 4,600 years), individuals on the north side of the Aegean were considerably different compared to those in the early Bronze Age. These individuals shared half their lineage with people from the Pontic-Caspian steppe, a large geographic region that stretches between the Danube and Ural rivers, north of the Black Sea. These individuals were very similar to today’s Greeks.

Skeleton of one of two individuals who lived in the mid-Bronze Age and whose entire genome was reconstructed and sequenced by the Lausanne team. It comes from the archaeological site of Elati-Logkas, in northern Greece. (Photo: Ephorate of Antiquities of Kozani, Hellenic Ministry of Culture, Greece / Georgia Karamitrou-Mentessidi)

The findings suggest that waves of migration by herders from the Pontic-Caspian steppe, or populations north of the Aegean that have similar ancestry to the Pontic-Caspian steppe, shaped present-day Greece. All these possible waves of migration preceded the appearance of the first text of the Greek language. This supports the theories of Proto-Greek and the evolution of Indo-European languages ​​in Anatolia or in the Pontic-Caspian steppe region.

The international study is led by Christina Papageorgopoulou from the Thracian Democratic University and Anna-Sapfo Malaspinas from the University of Lausanne. The team took samples of well-preserved skeletal remains at various archaeological sites. They sequenced six complete genomes, four from three cultures from the Early Bronze Age and two from a Helladic culture during the Middle Bronze Age.

The research team also sequenced the mitochondrial genomes of eleven other individuals from the early Bronze Age. Whole genome sequencing provided researchers with sufficient data to perform demographic and statistical analyzes of the population histories.

The sequencing of ancient genomes is a great challenge, particularly due to the degradation of biological material and human contamination. A scientific team from CNAG-CRG overcame these limitations through the use of “machine learning” or automatic learning.

According to Oscar Lao, Head of the Population Genomics Group of the CNAG-CRG, “The quantity of samples and the quality of the DNA that we find is enormous for this type of study. We have taken advantage of this, developing sophisticated machine learning tools to overcome challenges such as low depth of coverage or damaged or contaminated debris, opening the door to the application of artificial intelligence to palaeogenomic data. “

“The implementation of deep learning in demographic inference based on ancient samples allowed us to reconstruct the ancestral relationships between ancient populations and reliably infer the volume and timing of the mass migrations that marked the cultural transition from the Neolithic to the Bronze Age. in the Aegean, ”says Olga Dolgova, postdoctoral researcher in the Population Genomics Group of the CNAG-CRG.

The Bronze Age in Eurasia was marked by fundamental changes at the social, political and economic level, visible in the appearance of the first great urban centers and monumental palaces. The increasing economic and cultural exchange that developed during this time laid the foundation for modern economic systems, including capitalism, long-distance political treaties, and a global commercial economy.

Despite its importance for understanding the rise of European civilizations and the evolution of Indo-European languages, including Spanish, the genetic origins of the peoples responsible for the transition from the Neolithic to the Bronze Age and their contribution to the current Greek population they remain controversial.

Future studies could point towards the investigation of complete genomes between the Mesolithic and Bronze Age in Armenia and the Caucasus to identify the origins of migration to the Aegean and to better integrate genomic data with existing archaeological data. (Source: CNAG-CRG)

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