A study conducted by Carles Lalueza-Fox, a researcher at the Spanish National Research Council (CSIC)’s Institute of Evolutionary Biology , in collaboration with the Centre for GeoGenetics (Denmark), says that La Braa 1, the name used to “baptize” remains of a 7,000 years old individual recovered at La Braa-Arintero site in Valdelugueros (Len, Spain) that was discovered by chance in 2006, had blue eyes and dark skin. This person from the Mesolithic Period represents the first recovered genome of an European hunter-gatherer. The research is published in Nature.
In 2012, a team of scientists, led by Dr. Lalueza-Fox recovered — for the first time in history — part of the genome of two individuals living in the Mesolithic Period, 7000 years ago. they also recovered the complete mitochondrial DNA of one of these individuals, through which they could determine that European populations from Mesolithic Period were very uniform genetically. Dr. Lauleza-Fox noted in a CSIC release that “These hunters-gatherers shared nomadic habits and had a common origin. Despite their geographical distance, individuals from the regions corresponding to the current England, Germany, Lithuania, Poland, and Spain, shared the same mitochondrial lineage.”
The DNA data, which represent the 1.34% and the 0.5% of both individuals total genome, show that they are not directly connected to current populations of the Iberian Peninsula. Iberians from the Mesolithic Period were closer to current populations of northern Europe, who could have assimilated part of the genetic legacy of these hunters-gatherers.
The Mesolithic era, a period that lasted from 10,000 to 5,000 years ago (between the Paleolithic and the Neolithic eras), ended with the advent of agriculture and livestock farming spreading from the Middle-East. The arrival of the Neolithic period, with carbohydrate-based diets and new pathogens transmitted by domesticated animals, resulted in metabolic and immunological challenges that were reflected in genetic adaptations of post-Mesolithic populations,such as the ability to digest lactose, which the La Braa individual did not have.
However Dr. Lalueza-Fox, who is also a paleogenomics researcher at Pompeu Fabra University in Spain, notes in a CSIC release that the biggest surprise was to discover that this individual possessed African versions in the genes that determine the light pigmentation of the current Europeans, which indicates that he had dark skin, although we cannot know the exact shade.
A CSIC researcher, who works at the Institute of Evolutionary Biology (a joint centre of CSIC and the University Pompeu Fabra (UPF), located in Barcelona, adds: “Even more surprising was to find that he possessed the genetic variations that produce blue eyes in current Europeans, resulting in a unique phenotype in a genome that is otherwise clearly northern European.”
Oldest Remains From Prehistory
A CSIC researcher emphasizes: “So far, we only had one genome of the European Prehistory, that of tzi [also known as the Iceman], from the Neolithic Period. His mummy, belonging to a man who lived 5300 years ago, was found in the Tyrolean Alps, on the border between Austria and Italy. La Braa-Arintero site offers a unique opportunity to obtain pre-Neolithic genomes.”
According to Dr. Lalueza-Fox, this is only a first result since the intention of the team is to recover the complete DNA of these individuals, and to compare it with that of the modern humans. A CSIC researcher notes in the release that: “The arrival of the Neolithic Period brought about a replacement of populations, and could cause genetic changes in genes associated with new infectious diseases, and in metabolic genes linked to changes in diet. Therefore, all the information extracted from this genome will be absolutely important.”
The latest CSIC release notes that the study of the genome suggests that current populations nearest to La Braa 1 are in northern Europe, such as Sweden and Finland. In addition, the work points out that La Braa 1 has a common ancestor with the settlers of the Upper Paleolithic site of Malta, located in Lake Baikal (Siberia), whose genome was recovered a few months ago. Dr. Lalueza-Fox concludes that “These data indicate that there is genetic continuity in the populations of central and western Eurasia. In fact, these data are consistent with the archeological remains, as in other excavations in Europe and Russia, including the site of Malta, anthropomorphic figures called Paleolithic Venus have been recovered and they are very similar to each other.”
DNA With Exceptional Preservation
The La Braa-Arintero site was discovered by chance in 2006 and excavated by Julio Manuel Vidal Encinas, archeologist of the Council of Castilla y Len. The cave, located in a cold mountainous area with a steady temperature and 1,500 meters below the sea level, contributed to the exceptional preservation of the DNA from two individuals found inside, and they were called La Braa 1 and La Braa 2.
According to Iigo Olalde, lead author of the study, the intention of the team is to try to recover the genome of the individual called La Braa 2, which is worse preserved, in order to keep obtaining information about the genetic characteristics of these early Europeans.
The Nature article, titled “Derived immune and ancestral pigmentation alleles in a 7,000-year-old Mesolithic European” (Nature (2014) doi:10.1038/nature12960) is co-authored by Iigo Olalde, Morten E. Allentoft, Federico Snchez-Quinto, Gabriel Santpere, Charleston W. K. Chiang, Michael DeGiorgio, Javier Prado-Martinez, Juan Antonio Rodrguez, SimonRasmussen, Javier Quilez, Oscar Ramrez,Urko M. Marigorta, Marcos Fernndez-Callejo, Mara Encina Prada, Julio Manuel Vidal Encinas, RasmusNielsen,Mihai G. Netea, John Novembre, Richard A. Sturm, PardisSabeti, Toms Marqus-Bonet, Arcadi Navarro, EskeWillerslev & Carles Lalueza-Fox of various universities and research institutions in Europe and the US. The primary authors are Iigo Olalde & Morten E. Allentoft of the Institut de Biologia Evolutiva, CSIC-UPF in Barcelona, Spain. Corresponding authors are Morten E. Allentoft, and Eske Willerslev of the Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Denmark.
The research abstract observes that ancient genomic sequences are shedding new light on the demographic impact of farmers from the Neolithic period spreading into Europe The co-authors notes that the adoption of farming, stock breeding and sedentary societies during the Neolithic may have resulted in adaptive changes in genes associated with immunity and diet. However, the limited data available from earlier hunter-gatherers precludes an understanding of the selective processes associated with this crucial transition to agriculture in recent human evolution.
Now by sequencing the approximately 7,000-year-old Mesolithic skeleton discovered at La Braa-Arintero to retrieve a complete pre-agricultural European human genome, analysis of this genome in the context of other ancient samples suggests the existence of a common ancient genomic signature across western and central Eurasia from the Upper Paleolithic to the Mesolithic. They note that the La Braa individual carries ancestral alleles in several skin pigmentation genes, suggesting that the light skin of modern Europeans was not yet ubiquitous in Mesolithic times. Moreover, they can provide evidence that a significant number of derived, putatively adaptive variants associated with pathogen resistance in modern Europeans were already present in this hunter-gatherer.
Spanish National Research Council (CSIC)
Retrato de La Braña 1./ CSIC