Researchers of the UB take part in the reconstruction of the genomic history of the Iberian Peninsula
Researchers of the UB, members of the Prehistoric Studies and Research Seminar (SERP), have taken part in an international study that has created a genetic map of the Iberian Peninsula with a chronology covering the last 8,000 years. The study, published in the journal Science, has been co-led by researchers of the Spanish National Research Council (CSIC) in the Institute of Evolutionary Biology (IBE) and Harvard University (United States). To carry the research out, experts analysed genomes from 271 people of the Peninsula from different historical periods of time and compared them to the data collected in previous studies on 1,107 ancient and 2,862 modern individuals. Results show an unpublished image of the transformation of the Iberian population over the different historical and prehistoric periods.
Researchers of the UB, members of the Prehistoric Studies and Research Seminar (SERP), have taken part in an international study that has created a genetic map of the Iberian Peninsula with a chronology covering the last 8,000 years. The study, published in the journal Science, has been co-led by researchers of the Spanish National Research Council (CSIC) in the Institute of Evolutionary Biology (IBE) and Harvard University (United States). To carry the research out, experts analysed genomes from 271 people of the Peninsula from different historical periods of time and compared them to the data collected in previous studies on 1,107 ancient and 2,862 modern individuals. Results show an unpublished image of the transformation of the Iberian population over the different historical and prehistoric periods.
The following experts have participated in the study: SERP members Josep M. Fullola, director of the research group, Javier López Cachero, Xavier Oms, Joan Daura (Ramon y Cajal researcher and affiliated to SERP-UB), Juan Ignacio Morales (Juan de la Cierva researcher, affiliated to SERP-UB), Montserrat Sanz (Juan de la Cierva researcher, SERP-UB affiliated) and Artur Cebrià. The University of Barcelona has contributed to the study by providing the study with samples.
Male population replacement in the Bronze Age
About between 4,000 and 4,500 years ago, the arrival of groups coming from farmers from Eastern Europe to the Peninsula caused the replacement of about 40 % of the local population and almost 100 % of the male population. Progressively, during a period which could have lasted about four hundred years, the linage of the Y chromosome that were present so far in the Iberian Peninsula during the Bronze Age were almost replaced by a steppe-descendant lineage, R1b-M269. The reason why this process occurred is not clear: there is no evidence of general violence in that period and an alternative explanation would be local Iberian women preferring the newcomers in a context of social stratification. In this sense, genetic data should be together with evidence from other fields, such as archaeology and anthropology.
African contact
The distribution of the genetic current from Africa to the Peninsula is older than what researchers had thought so far. The study proves the presence of an individual from Nothern Africa who lived about 4,000 years ago in the center of the Iberian Peninsula, in the site of Camino de las Yeseras (Madrid). Also, it proves the existence of an African migrant grandson in a site in Cadiz during the same time. Both individuals had notable Sub-Saharan ancestry proportions. However, these are sporadic contacts that left a small genetic footprint in Iberian populations during the Catholitic and the Bronze Age.
Also, results show that there was Northern-African genic flow in the south-east of the Peninsula during the Punic and Roman period, before the arrival of the Muslims in the 8th Century.
Romans, Greeks, Phoenicians, Visigoths and Muslims
The analysis of the genetic map allows checking modifications in the population of the Iberian Peninsula during more recent historical periods. The results show that, at the beginning of the Middle Ages, about a quarter of Iberian ancestry had been replaced by new population flows coming from the Eastern Mediterranean (Romans, Greeks and Phoenicians). One of the examples of this phenomenon seen in the study is the Greek colony of Empúries, in the north-east of the peninsula, founded in 600 BC, and the late Roman Period. In this case, the twenty-four analysed individuals are divided into two groups with different genetic inheritance: one formed by a typical Greek ancestry and another formed by population that were genetically indistinguishable from Ibers from Ullastret.
Structure of population in Mesolithic Iberia
This study, together with another published in Current Biology, identifies for the first time the presence of a genetic structure regarding geography and time among hunter-gatherers of the Iberian Peninsula during the Mesolithic (about 8,000 years ago). In the north-east area, Mesolithic hunters who lived centuries ago before the arrival of the first farmers show a genetic similarity to hunter-gatherersʼ from Central Europe. This ancestry was not present in former hunter-gatherers from the same area nor in contemporary hunter-gatherers from the south-east area of the Iberian Peninsula during the late Mesolithic.
The study has been funded by la Caixa, FEDER-MINECO (BFU2015-64699-1118P), the National Institutes of Health (Grant GM100233), Paul G. Allen Family Foundation and the Howard Hughes Medical Institute, among other institutions.
Reference Article:
Iñigo Olalde et al. “The genomic history of the Iberian Peninsula over the past 8000 years”. Science, March, 2019. Doi: 10.1126/science.aav1444