An international research group has analyzed old DNA from nearly 300 individuals from the Iberian Peninsula, spanning over 12,000 years, in two studies published today in Current Biology and Science . The first study looked at hunters and early peasants living in Iberia between 13,000 and 6,000 years ago. The other looked at individuals from the region during all time periods over the past 8000 years. Together, the two essays increase our knowledge of this region's population history.
The Iberian Peninsula has long existed as an outlier in Europe's population history because of its unique climate and position on the far west side of the continent. During the last ice age, Iberia remained relatively warm, allowing plants and animals ̵
A man and a woman buried side by side at the Bronze Age Castillejo de Bonete in Spain had different genetic origins. Luis Benítez de Lugo Enrich and José Luis Fuentes Sánchez / Oppida )
Iberian hunter-collector Show two ancient paleolithic lines
For the paper in Current biology, ] led by researchers at the Max Planck Institute for Human History, researchers analyzed 11 hunter-gatherers and neolithic individuals from Iberia. The oldest newly analyzed individuals are about 12,000 years old and recovered from Balma Guilanyà in Spain.
Excavation work on site at Balma Guilanyà. CEPAP-UAB )
Previous evidence has shown that after the end of the last ice age, western and central Europe was dominated by hunter-gatherers dating back to an approximately 14,000-year-old individual from Villabruna, Italy. Italy is considered to have been a potential refuge for people during the recent Ice Age, such as Iberia. Villabruna-related relative largely replaced previous ancestry in Western Europe and Central Europe in connection with 19,000-15,000-year-old individuals in connection with the so-called Magdalenska cultural complex.
Interestingly, the results of the current study show that both lines were present in Iberian individuals dating as far as 19,000 years ago. "We can confirm the survival of an additional paleolithic lineage dating back to the late Ice Age in Iberia," said Wolfgang Haak of the Max Planck Institute for Human History Science, senior author of the study. "This confirms the role of the Iberian Peninsula as a refuge during the last Ice Age, not only for fauna and flora but also for human populations."
Prehistoric hunter-gatherer. (19659005) CC0 )
This suggests that hunter-gatherers in Iberia far from being replaced by Villabruna-related individuals after the last ice age, had actually been dating from Magdalenian and Villabruna-related sources. The discovery suggests an early link between two potential refuges, resulting in a genetic ancestry that survived in later Iberian hunters.
"The hunter-gatherers from the Iberian Peninsula carry a mixture of two older types of genetic ancestry: one that goes back to the last glacial maxim and once maximized in individuals attributed to Magdalene culture and another that is everywhere in the West. and Central Europe and had replaced the Magdalene line during the Early Holocene everywhere except the Iberian Peninsula, "Vanessa Villalba-Mouco of the Max Planck Institute for Human History Science, first author of the study, explains.
The researchers hope that ongoing efforts to decipher the genetic structure of late hunter-gatherers across Europe will help to better understand Europe's past and, in particular, the assimilation of a neolithic lifestyle that arises from expanding farmers from the Near East during Holocene.
Ancient DNA from individuals over the past 8000 years helps clarify the history and prehistory of the Iberian Peninsula
The paper published in Science focuses on somewhat later periods, and traces the Iberia population history during over the past 8000 years by analyzing old DNA from a large number of individuals. The study, led by the Harvard Medical School and Broad Institute, including Haak and Villalba-Mouco, analyzed 271 ancient Iberians from Mesolithic, Neolithic, Copper Age, Bronze Age, Iron Age, and Historical Periods. The large number of individuals allowed the team to make more detailed inferences about each time period than before.
These two skeletons in La Braña in northwestern Spain belonged to brothers with dark hair and blue eyes who lived 8,000 years ago and were most closely related to hunter-gatherers in Central Europe. (19659005) Julio Manuel Vida Encinas )
The researchers found that hunter-gatherers in Iberia during the transition to a sedentary agricultural lifestyle contributed subtly to the genetic makeup of newly arrived farmers from the Near East. "We can see that it must have been a local mix, because the Iberian peasants also carry this dual signature of the hunter-gathering uniqueness for Iberia," Villalba-Mouco explains.
Between about 2500-2000 BC the researchers observed that 40% of Iberia's ancestry and almost 100% of its Y chromosomes by humans dating from Pontic Steppe, a region of what is now Ukraine and Russia, have been replaced. Interestingly, the Iron Age results had spread the "steppe anore" not only in the Indo-European speaking regions of Iberia but also in non-Indo-European speakers, such as the region inhabited by the Basque Country. The researchers' analysis suggests that today's baskets are similar to a typical Iberian iron age population, including the influx of the "steppe anore", but were not affected by subsequent genetic contributions that affected the rest of Iberia. This suggests that Basque speakers were affected as genetically as other groups on the arrival of steppe populations, but retained their language in all circumstances. It was only after the time that they became relatively isolated genetically from the rest of the Iberian Peninsula.
Olentzero i Beasain. Gipuzkoa, Basque Country. (Izurutuza / CC BY SA 3.0 )
In addition, the researchers looked at historical periods, including times when Greek and later Roman settlements existed in Iberia. The researchers found that beginning at least during the Roman era, transformation of the peninsula of the gene flow from North Africa and the Eastern Mediterranean. They found that Greek and Roman settlements tended to be quite multi-ethnic, with individuals from the central and eastern Mediterranean and North Africa as well as the local population, and that these interactions had lasting demographic and cultural implications.
"In addition to specific insights about Iberia, this study serves as a model for how a high-resolution old DNA transect that continues for historical periods can be used to provide a detailed description of the formation of today's populations," Haak explains. "We hope that future use of similar strategies will provide equally valuable insights in other parts of the world."
Top image: Pontic Steppe farmers transformed the Iberian DNA drastically 4500 years ago. Source: Without the Forest
The article, originally titled " Unique Diversity in the Iberian Peninsula's Genetic History Revealed by Double Studies" w first published on Science Daily .
Source: Max Planck Institute for Human History Science. "The unique diversity of the Iberian peninsula's genetic history is revealed by dual studies." Science. Science Daily, March 14, 2019. www.sciencedaily.com/releases/2019/03/190314151551.htm
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