Researchers analyse the genetic changes that took place in the Iberian Peninsula 4,200 years ago

By 19 noviembre, 2021Arts and Humanities

The third millennium BC brought significant changes for European populations. A study published in Science Advances, led by the Max-Planck Institute for Evolutionary Anthropology with the collaboration of researchers from Valencia University and Alicante University, documents the arrival of the genetic ancestors of today’s human beings in the Iberian Peninsula, with the rise of Argaric culture, around 4,200 years ago.

La Bastida fortified settlement in Murcia, SpainC. Salazar, from Valencia University and who took part in the research explains that “each new archaeogenetic study reinforces the idea that prehistoric populations were much more dynamic than was traditionally believed”, says Domingo C. Salazar García. “The societies that in the present we mentally frame in a simple way as Copper or Bronze were probably much more diverse and complex than we can imagine,” says the Valencian doctor and historian, who has been working in the studied sites for years.

The third millennium BC was a very dynamic period in prehistory in Europe and Western Asia, characterised by large-scale social and political changes: In the Iberian Peninsula, the Copper Age was in full force around 4,500 years ago, with significant demographic growth as attested by a large variety of settlement and fortifications, monumental funerary structures and large settlements of over 100 hectares. For yet unclear reasons, in the second half of the millennium there was a loss of population and settlements were abandoned.

In the southeast of the Iberian Peninsula, around 2,200 BC, there emerged one of the most noteworthy archaeological entities of the European Bronze Age: Argaric culture, one of the first state-wide societies in Europe. This society identifies with its large plants on mountains, distinctive ceramics, specialised weapons and bronze, silver and gold artifacts, together with funerary rituals that took place within the city, with burials and habitats together in the same space.

A new study has explored the relationship between the large-scale demographic changes and the main societal and political changes of the third and second millennium BC, by analysing the genomes of 136 individuals who lived between 3,000 and 1,500 BC (96 of the Bronze Age of Argaric culture and other contemporary societies, 34 from the Copper Age and 6 from the Late Bronze Age). Including the genomes published from the Iberian Peninsula, this new study encompasses data from almost 300 prehistoric individuals.

“Even though we knew that the so-called steppe descent, which spread across Europe in the third millennium BC, ended up reaching the north of the Iberian Peninsula around 2,400 BC, we were surprised to find that all the prehistoric individuals from the Argaric era had part of this descent, whereas individuals from the Copper Age did not,” says Max Planck researcher Wolfgang Haak, principal author and researcher of the study.

The genomic data reveal some of the processes the underlie this genetic change. Whereas most of the genome shows that individuals from the Bronze Age are a mix of descent from the local population of the Copper Age and a smaller part from Europe, the lineage of the chromosome inherited from the patrilineal linkage show a complete change connected to the steppe descent movement that is also visible in other areas of Europe.

Social implications

The genetic change may have been caused by several factors and not only by the migration of groups from the north and centre of the Iberian Peninsula. It probably contributed to the climactic deterioration that affected the Western Mediterranean around 2,200 BC. Another of these factors may have been pandemics, such as an early form of the plague, which has been verified to have taken place in other regions of Europe around that time.

“It makes sense to think that the people who lived in those periods of time interacted with people from other cultures and places, although the type of interaction is not fully clear with genetic analyses. Were they violent interactions? Commercial? Cultural? To answer this, we must study the archaeological records”, says Salazar García.

In this sense, although the archaeological records of Argaric culture shows a clear break from the traditions of the previous Copper Age, this does not happen in the Valencian region. “Until recently, we assumed that during the Copper Age, Valencian burials were defined by the ritual of group burials inside natural caves, whereas, since the Bronze Age, its number decreased drastically and they were located inside a small number of towns. However, this study shows that the cave ritual lasted longer,” says Gabriel García Atiénzar, researcher at Alicante University.

Article

Vanessa Villalba-Mouco et al. «Genomic transformation and social organization during the Copper Age-Bronze Age transition in southern Iberia». Science Advances 17 Nov 2021. Vol 7, Issue 47. DOI: https://www.science.org/doi/10.1126/sciadv.abi7038