martes, 11 de marzo de 2014

A Mesolithic face from Southern Europe (León)

A study conducted into the genomes of a European Mesolithic hunter -gatherer known as La Braña 1 has been published in the journal Nature. The study involved sequencing a 7,000-year-old Mesolithic skeleton discovered at the La Braña-Arintero site in León, Spain, to retrieve a complete pre-agricultural European human genome. The results further confirm that modern Iberian populations are not genetically related to these pre-farming peoples.
The Mesolithic, a transitional period that lasted from circa 11,000 to 5,000 years ago (between the Palaeolithic and Neolithic), ends with the advent of agriculture and animal husbandry and the concurrent arrival of new genetic material from the Middle East. The arrival of the Neolithic farmers, with their carbohydrate-based and domesticated animal diet, along with food-borne pathogens and the inherent  metabolic /immunological challenges can be reflected in genetic adaptations of post- Mesolithic populations.

Pre-Neolithic genetic material

The individual at the centre of the study belongs to a group prior to this influx of new genetic material.
“The biggest surprise was to discover that this individual possessed African versions in the genes that are involved in European pigmentation, indicating he had dark skin, although we can not know the exact tone,” says researcher Carles Lalueza- Fox.
“Even more surprising was the discovery that he had the genetic variants that produce blue eyes in Europeans today, resulting in a unique phenotype in a genome that is otherwise clearly northern European.”
branamanGenetic continuity in populations of central and western Eurasia
The study of the genome suggests that current populations nearest to La Braña 1 are in Northern Europe, such as Sweden and Finland. In addition, the work points out that La Braña 1 has a common ancestor with the settlers of the Upper Palaeolithic site of Mal’ta, located in Lake Baikal (Siberia), whose genome was recovered a few months ago.
Lalueza-Fox explains “These data indicates that there is genetic continuity in the populations of central and western Eurasia. In fact, these data are consistent with the archaeological remains, as in other excavations in Europe and Russia, including the site of Mal’ta, anthropomorphic figures –called Palaeolithic Venus– have been recovered and they are very similar to each other”.
La Braña-Arintero was discovered by chance in 2006 and excavated by archaeologist Julio Manuel Vidal Encinas. The cave environment, located in a cold mountainous area and 1,500 metres above sea level, contributed to the “exceptional” preservation of the DNA from two individuals found inside, who were then labelled La Braña 1 and La Braña 2.
Iñigo Olalde, lead author of the study, concludes that “the intention of the team is trying to retrieve the individual genome of the Braña 2 which is the least well preserved of the burials in the hope that they can continue to obtain information on the genetic characteristics of these early Europeans.”

Source: Past Horizons:

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