(Zaragoza, Monday, September 1, 2025). The necropolis of Los Castellets II, in Mequinenza, a key site of the Late Bronze Age in the northeastern Iberian Peninsula, continues to provide valuable information about the communities of the time and their funerary practices. A study recently published in Communications Biology, led by the University of Zaragoza, offers new insights into the genetic origins of the population of that period, as well as their family structures, thanks to the analysis of ancient DNA from one of the most remarkable burial mounds at this site—Tumulus 2, the only large collective grave in the necropolis, containing more than 30 individuals.
Overall, the genetic analyses indicate the absence of strict population continuity since the Middle Bronze Age and highlight the existence of genetic flow that helped shape the biological diversity of these communities. The data reveal that the individuals had a mixed origin from two different ancestral sources. One was linked to Central European populations, probably through groups from southern France, and showed a higher proportion of steppe ancestry than Middle Bronze Age individuals from the same region. The other source was more closely related to populations from the southeastern Iberian Peninsula—an aspect that deserves further research, as intra-peninsular mobility and possible connections with the Mediterranean world are not yet fully characterized.
The team has also been able to reconstruct aspects of social organization at the local level: the large funerary mound was used by an extended family, with stronger biological ties along the paternal line than the maternal one. Two-thirds of those buried were related, and the community practiced a certain degree of endogamy. These results broaden our understanding of kinship practices in the Iberian Peninsula during the Late Bronze Age.
The starting point of this research, led by Marina Bretos, predoctoral researcher affiliated with the Institute for Environmental Sciences of Aragón (IUCA – University of Zaragoza), Jesús Picazo (IUCA – University of Zaragoza), and Vanessa Villalba-Mouco, Ramón y Cajal researcher at the Institute of Evolutionary Biology (IBE-CSIC), together with an international team, was the unique character of this site: a necropolis where two different ritual practices—inhumation and cremation—coexisted. The latter has been associated in archaeological literature with the spread of the Urnfield Culture, a highly debated phenomenon regarding its causes: was it a cultural diffusion linked to population movements? Since Los Castellets is one of the very few European sites where both practices coexisted, it offers a unique source of information for studying this issue. However, ancient DNA recovery techniques have not yet overcome the challenge posed by the high temperatures of cremation for genetic preservation, which is why only inhumed individuals could be analyzed. The main focus of the study was Tumulus 2, the only large collective grave at the site (with more than 30 individuals), which combines traditional features—such as collectivity and certain megalithic reminiscences—with novel elements, including part of a funerary assemblage made up of ceramics characteristic of the Urnfield Culture.
In the same vein, researcher Marina Bretos, who conducted the genetic analyses in collaboration with the Max Planck Institute for Evolutionary Anthropology (Leipzig, Germany), points out: “The aim of the study is also to establish a comparative framework for future research, which could integrate strontium isotope analysis with genetic data to study the mobility of both cremated and non-cremated individuals, offering a more complete picture of past population dynamics.”
Thus, this study not only provides new clues about the past but also opens the way for future research to continue unraveling how ancient communities moved and mixed.