An international team of researchers has analyzed the ancient DNA of nearly 300 individuals from the Iberian Peninsula in more than 12,000 years in two studies published today Current biology and science, The first study looked at hunters, collectors and early farmers who lived in Iberia 13,000 to 6,000 years ago. The second part dealt with people from the region in all periods of the last 8000 years. Together, the two articles increase our knowledge of the population history of this unique region.
The Iberian Peninsula, due to its unique climate and its position on the extreme western edge of the continent, has long been considered as a runaway in the population history of Europe. During the last ice age, Iberia remained relatively warm, allowing plants and animals – and possibly humans – to retreat from the rest of Europe to continue living there. Over the past 8000 years, Iberia's geographic location, rough terrain, location on the Mediterranean coast and proximity to North Africa have made it a unique place compared to other parts of Europe in interaction with other regions. Two new studies that were published in the same time Current biology and scienceanalyze nearly 300 people who lived about 13,000 to 400 years ago to convey unprecedented clarity about the unique population history of the Iberian Peninsula.
A man and a woman who were buried side by side in the Bronze Age site of Castillejo de Bonete in Spain, had different genetic ancestors. (Luis Benítez de Lugo Enrich and José Luis Fuentes Sánchez / Oppida )
Iberian hunter-gatherers show two ancient paleolithic lines
For the paper in Current biology, Led by researchers from the Max Planck Institute for the Science of Human History, researchers analyzed eleven hunters, gatherers and Neolithic individuals from Iberia. The oldest, newly analyzed individuals are about 12,000 years old and were rescued in Balma Guilanyà in Spain.
Excavation in Balma Guilanyà. ( CEPAP-UAB)
Earlier evidence had shown that western and central Europe were dominated by hunters and gatherers after the end of the last Ice Age, whose ancestors were linked to an approximately 14,000-year-old person from Villabruna, Italy. Italy is considered a potential haven for people like Iberia during the last ice age. The lineage associated with Villabruna largely superseded its former ancestry in Western and Central Europe, referring to 19,000 to 15,000-year-old individuals associated with the so-called Magdalenian Cultural Complex.
Interestingly, the results of the current study show that both lineages were present in Iberian individuals 19,000 years ago. "We can confirm the survival of another Paleolithic line dating back to the late Ice Age in Iberia," says Wolfgang Haak of the Max Planck Institute for the Science of Human History, lead author of the study. "This confirms the role of the Iberian Peninsula as a haven during the last glacier maximum, not only for fauna and flora, but also for the population."
Prehistoric hunters and gatherers. ( CC0)
This suggests that hunters and gatherers in Iberia were by no means replaced by Villabruna-related individuals after the last Ice Age, but actually had ancestors from Magdalenian and Villabruna sources. The discovery suggests an early link between two potential refuges leading to a genetic lineage survived by later Iberian hunters and gatherers.
"The Iberian Peninsula hunters and collectors carry a mixture of two older types of genetic ancestry: one that dates back to the last glacial maximum and was once maximized in individuals attributed to the Magdalenian culture, and another that was everywhere in the world Europe is located west and central, replacing the Magdalena line in the early Holocene beyond the Iberian Peninsula, "explains Vanessa Villalba-Mouco of the Max Planck Institute for the Science of Human History, first author of the study.
The researchers hope that ongoing efforts to decipher the genetic structure of former hunter – gatherer groups across Europe will help to better understand Europe 's past and, in particular, the adoption of a Neolithic way of life by growing Middle Eastern farmers during the Last century, the Holocene was created.
Ancient DNA from individuals from the last 8,000 years helps to explain the history and prehistory of the Iberian Peninsula
The paper was published in science focuses on somewhat later periods and traces the population history of Iberia in the last 8000 years by analyzing old DNA from a large number of individuals. The study, led by Harvard Medical School and the Broad Institute, including Haak and Villalba-Mouco, analyzed 271 Iberians from the Mesolithic, Neolithic, Copper Age, Bronze Age, Iron Age and historical periods. Due to the large number of people, the team was able to draw more detailed conclusions about each period than was previously possible.
These two skeletons in La Braña, northwestern Spain, belonged to dark-haired, blue-eyed brothers who lived 8,000 years ago and were most closely related to hunters and gatherers in Central Europe. ( Julio Manuel Vida Encinas )
The researchers found that hunters and gatherers in Iberia made a subtle contribution to the genetic makeup of newly arrived peasants from the Middle East during the transition to a sedentary agricultural lifestyle. "We can see that there must have been a local mix, as the Iberian farmers also bear this double signature of the hunter-gatherer ancestors that are unique in Iberia," explains Villalba-Mouco.
Between 2500 and 2000 BC The researchers found that 40% of Iberia ancestors and nearly 100% of their Y chromosomes were replaced by people of descent from the Pontic steppe, a region in present-day Ukraine and Russia. Interestingly, the results show that "steppe ancestors" in the Iron Age had spread not only in Indo-European-speaking regions of Iberia, but also in non-Indo-European-speaking areas such as the region inhabited by the Basque Country. The researchers' analysis indicates that today's Basques are most likely to resemble a typical Iberian Iron Age population, including the immigration of steppe ancestors, but that they were not influenced by subsequent genetic contributions that influenced the remainder of Iberia , This suggests that the Basque speakers were genetically as affected as other groups by the arrival of the steppe settlements, but the language was retained in any case. Only after this time they were relatively isolated from the rest of the Iberian Peninsula.
Olentzero in Beasain. Gipuzkoa, Basque Country. (Izurutuza / CC BY SA 3.0 )
In addition, the researchers studied historical times, including times when Greek and later Roman settlements existed in Iberia. The researchers found that the lineage of the peninsula, at least in Roman times by the gene flow from North Africa and the eastern Mediterranean was changed. They found that Greek and Roman settlements were more multi-ethnic, with people from the central and eastern Mediterranean and North Africa, as well as natives, and that these interactions had lasting demographic and cultural implications.
"In addition to specific insights into Iberia, this study serves as a model for how a high-resolution, ancient DNA transect that continues in historical periods can be used to provide a detailed description of the formation of today's populations," Haak explains. "We hope that using similar strategies in the future will provide equally valuable insights in other regions of the world."
Picture above: Farmers from the Pontic steppe have drastically changed the Iberian DNA 4,500 years ago. Source: Out of the woods
The article, originally entitled " Unique diversity of the genetic history of the Iberian Peninsula evidenced by dual studies w as first published by Science Daily.
Source: Max Planck Institute for the History of Human History. "Unique diversity of the genetic history of the Iberian Peninsula evidenced by duplicate studies." ScienceDaily. ScienceDaily, March 14, 2019. www.sciencedaily.com/releases/2019/03/190314151551.htm
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