July 2, 2012
Digging For The Oldest Genetic Material In Spain
Brett Smith for redOrbit.com - Your Universe Online
Researchers from the Spanish National Research Council (CSIC) have recovered and sequenced the oldest genetic material from two individuals living in Mesolithic Spain, over 7,000 years ago.
This groundbreaking work of genetics, published in Current Biology, shows that the sequenced genomes are out-of-sync with modern day Iberians.
"These hunters-gatherers shared nomadic habits and had a common origin,” said study co-author Carles Lalueza-Fox, a biologist from the CSIC. “Despite their geographical distance, individuals from the regions corresponding to the current England, Germany, Lithuania, Poland, and Spain, shared the same mitochondrial lineage.”
The samples were recovered from the La BraÃ±a-Arintero site, located at Valdelugueros, Spain and they represent the oldest genetic material recovered since that taken from Ãtzi, the Iceman, who lived 5,300 years ago and was found on the border between Austria and Italy.
While the scientists were only able to recover 1.3 percent and 0.5 percent of the two individuals´ total genomes, they were able to completely sequence one individual´s mitochondrial DNA, a genetic first for samples of this time period. This mtDNA data was enough to determine that their ancestry could not be traced to the migration of Africans into to Iberian Peninsula that occurred during the later Neolithic and Mesolithic periods.
Scientists have speculated based on genetic evidence that major African migration occurred in waves between 20,000 and 6,200 years ago. This migration would have taken place during the last ice age that ended 10,000 years ago. During this time, the sea levels have been estimated to be almost 400 feet lower than today. With water levels this low, even the most primitive rafts would have been able to cross the Strait of Gibraltar, which measures about 9 miles across today.
Mesolithic life in Europe was highly influenced by the changing climate as the glaciers from the last ice age began to recede. The warmer temperatures and higher moisture levels provided the proper environment for the development of a more robust food supply, which the hunter-gatherers of the time likely took advantage of.
One of the notable changes in the Mesolithic was the development of microliths, or small stone tools. These tools, which were typically centimeter-long blades made from flint, from the points for spears and arrows typically used for hunting or combat.
Archeological evidence for this time period is fairly robust with several large archeological sites being located in and around Europe. One of the largest, Lenpenski Vir located in modern day Serbia, is comprised of one large settlement and ten ℠satellite´ villages. The site contains numerous sculptures and architectural structures that point to a rich social and religious life led by these early Europeans.
La BraÃ±a-Arintero site was discovered in 2006 by study co-author Juan Manuel Vidal Encinas, an archeologist from the Regional Government of Castilla y LeÃ³n. Due to its location in a cold and mountainous area, researchers said that the cave is a suitable place for the preservation of the two individuals and their DNA samples which were found inside it.
Image 2 (below): This is a reconstruction of individual BraÃ±a“1, whose skeleton was almost complete and in good condition. Credit: Alberto Tapia