Genetic selectivity discovered amongst Eurasians over the last 8,000 thousand years as a response to adaptive needs

These genes are related to diet, as agents permitting to digest milk in adulthood, as well as to the immune response and pigmentation.

Some of them have a biomedical interest because they are associated, for example, with vitamin deficiency and coeliac disease.

Researchers have analyzed 230 ancient genomes, including 15 from the Cueva de El Mirador site at Atapuerca

Josep Maria Vergès, Marina Lozano and Eudald Carbonell, all IPHES members, are among the authors of this research.

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A multidisciplinary research team headed by David Reich (Broad Institute, Harvard), Ron Pinhasi (University College Dublin) and Wolfgang Haak (Max Planck Institute), with the participation of two Spanish research institutes, the Instituto de Biología Evolutiva (CSIC-UPF) and the Institut Català de Paleoecologia Humana i Evolució Social (IPHES-URV), have recovered genetic information from numerous European prehistoric human remains, in order to determine which genetic variants have been selected over thousands of years in response to various adaptive challenges. The samples include, for the first time, genomes from Neolithic Anatolia (Turkey), dated to 8,000 years ago, belonging to populations at the origin of the first European farmers. The results are published today in the journal Nature, in the paper entitled “Genome-wide patterns of selection in 230 ancient Eurasians”.

The researchers, among whom IPHES staff members Josep Maria Vergès, Marina Lozano and Eudald Carbonell, observed how some genetic variations have been favoured by natural selection through time and space. These genetic variations increased in frequency over millennia, reaching in some cases 100% among current Europeans. These genes are involved in the adaptive processes that have shaped the genomes of European populations and that have allowed them to survive. Genes include the persistence of the enzyme lactase, which allows digesting milk in adulthood and appears in Europe only 4,000 years ago, immunity genes that respond to past epidemics, and pigmentation genes. The latter include mutations involved in the current light-skinned Europeans (which were absent in the Mesolithic hunter-gatherers like the Man from La Braña en León, Spain) as well as the blue eye color (which was prevalent in the Mesolithic and seems to have been advantageous in Northern Europe). Some of the selected genes have a biomedical interest and have been linked, for example, with vitamin deficiencies and celiac disease. The emergence of new mutations in these genes is due to the adoption of agriculture from the Neolithic diet.

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The El Mirador site has been excavated since 1999 under the direction of Josep Maria Vergès

Height

In addition, researchers have been able to test complex traits which depend on hundreds of genes, such as height, which has been negatively selected in Iberian populations. In this part of the study, the DNA samples of fifteen individuals from the Copper Age of El Mirador Cave (Sierra de Atapuerca), dated between 4,800 and 4,200 years ago, have played an important role. The El Mirador site has been excavated since 1999 under the direction of Josep Maria Vergès.

This data adds new information to the recent publication of seven genomes from the El Portalón site, also, in Atapuerca, within a comparable time-range.

According to Josep Maria Vergès, researcher at IPHES, “the obtained data is essential to understanding the role of cultural adaptation in the genetic makeup of European populations in recent Prehistory”.

Carles Lalueza-Fox, researcher from Instituto de Biología Evolutiva (CSIC-UPF) who participated in this study, notes that “this is the first step to understanding how human populations evolved in the recent past. In the future, the analysis of older samples should reveal minor episodes of selection on a regional level”.

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