Scientists have reported on genomic data from a 23,000-year-old individual who lived in what was probably the warmest place of Europe at the peak of the last Ice Age.
The study reported on the oldest genome to date from Cueva del Malalmuerzo in southern Spain, as well as the 7,000 to 5,000-year-old genomes of early farmers from other well-known sites, such as Cueva de Ardales, Spain.
The international team of researchers has analysed ancient human DNA from several archaeological sites in Andalucia in southern Spain.
The oldest human genome recovered from the southern tip of Spain adds an important piece of the puzzle to the genetic history of Europe, the researchers said. After an organism's death, its DNA is only preserved for a certain period of time and under favourable climatic conditions.
Extracting DNA from ancient remains from hot and dry climates is a huge challenge for researchers.
In Andalucia, in the south of present-day Spain, climatic conditions are similar to those in North Africa - however, DNA has successfully been recovered of 14,000-year-old human individuals from a cave site in Morocco.
The current study fills crucial temporal and spatial gaps, it said.
The researchers can now directly investigate the role of the southern Iberian Peninsula as a refuge for Ice Age populations and potential population contacts across the Strait of Gibraltar during the last Ice Age, when sea-levels were much lower than today, they said.
The genetic ancestry of individuals from central and southern Europe who lived before the Last Glacial Maximum, which is 24,000 to 18,000 years before today, differs from the ones who recolonised Europe afterwards.
However, the situation in western Europe has not been clear until now due to a lack of genomic data from critical time periods.
The 23,000-year-old individual from Cueva del Malalmuerzo near Granada finally adds data from the time when large parts of Europe were covered by massive ice sheets, the study said.
The study describes a direct genetic link between a 35,000-year-old individual from Belgium and the new genome from Malalmuerzo.
"Thanks to the high quality of our data we were able to detect traces of one of the first genetic lineages that settled Eurasia 45,000 years ago.
"Importantly, we found similarities with a 35,000-year-old individual from Belgium whose ancestry we can now trace further to the 23,000-year-old individual from southern Iberia," explained first author Vanessa Villalba-Mouco of the Max Planck Institute for Evolutionary Anthropology, Germany.
The individual from Cueva del Malalmuerzo not only links to earlier periods of settlement but also to the hunter-gatherers of southern and western Europe who lived long after the last Ice Age, the study said.
The individual also confirms the important role of the Iberian Peninsula as a refuge for human populations during the last Ice Age, the study said.
From there, humans migrated northwards and eastwards once the ice sheets had retreated, the study said.
"With Malalmuerzo, we managed to find the right place and the right time period to trace a Palaeolithic human group back to one of the proposed Ice Age refugia.
"It is remarkable to find such a long-lasting genetic legacy on the Iberian Peninsula, especially since this pre-Ice Age ancestry had long since disappeared in other parts of Europe," said senior author Wolfgang Haak of the Max Planck Institute for Evolutionary Anthropology.
The Iberian Peninsula plays an important role in the reconstruction of human population history.
As a geographic cul-de-sac in the southwest of Europe, it is on one hand considered a refuge during the last Ice Age with its drastic temperature fluctuations. On the other hand, it may have been one of the starting points for the recolonisation of Europe after the glacial maximum.
Previous studies have reported on the genomic profiles of 13,000 to 8,000-year-old hunter-gatherers from the Iberian Peninsula and provided evidence for the survival and continuation of a much older Palaeolithic lineage that has been replaced in other parts of Europe and is no longer detectable.