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New genetics study on Ice Age populations around the Black Sea and the Northern Levant


New genetics research led by LAU professor Pierre Zalloua has confirmed the existence of isolated populations around the Black Sea and the Northern Levant during the Ice Age. Referred to as refugia, these populations lived apart from each other with no contact or inter-mixing for more than 25,000 years. "This allowed for distinct genetic signatures specific to each refugium to accumulate," the researcher explains.

New genetics study on Ice Age populations around the Black Sea and the Northern Levant
Geographic distribution of major Y chromosome haplogroups frequencies distribution in the Middle East, Arabia, North 
Africa, East Africa, and Europe from the current study and from the published data [Credit: Platt et al. 2016]
Geneticist and Dean of Graduate Studies and Research Zalloua worked together with a team made up of members from New Zealand's University of Otago, Saint Joseph University in Lebanon, and technology company IBM, to collect and study new genetic data.

"Archaeology indicates the existence of populations in certain areas, but it doesn't show that people were isolated," adds Zalloua.

New genetics study on Ice Age populations around the Black Sea and the Northern Levant
Spatial frequency distribution of haplogroups A) J*(xJ2) and B) J2 throughout the Mediterranean basin. 
Contour maps constructed using the Kriging procedure with Surfer 8.09 (Golden Software, Inc. 
http://www.goldensoftware.com/products/surfer). Black dots show location 
of analyzed populations [Credit: Platt et al. 2016]
Not only did his team confirm the existence of refugia, but they also traced their migration away from their isolation after the first ice melted some 15,000 years ago by mapping the genetic data against existing archaeological, paleontological, paleobotanical, and climate data.

Using Y-chromosome markers combined with autosomal data, they reconstructed population expansions from regional refugia in Southwest Asia. "We now know that we, in the Levant, migrated through the north around 12,000 years ago, and not directly from Africa," says Zalloua, noting that such findings enrich our understanding of our historical anthropology and of the significant impact climate plays in the way we live.

New genetics study on Ice Age populations around the Black Sea and the Northern Levant
Mean microsatellite variance distributions of haplogroups A) J*(xJ2) and B) J2 throughout the Mediterranean basin. 
Contour maps constructed using the Kriging procedure with Surfer 8.09 (Golden Software, Inc. 
http://www.goldensoftware.com/products/surfer). Black dots show location 
of analyzed populations [Credit: Platt et al. 2016]
The Ice Age forced people who had previously been hunter-gatherers moving from place to place to live in restricted areas where conditions were habitable. This led to the development of communities living in refugia.

Among the team's findings was the existence of a refugium that had not previously been known. "We not only identified the expected genetic signatures within refugia around the Black Sea and Northern Levant, but also identified a genetic signature marking a refugia in the Arabian Peninsula yet to be identified through archaeology."

New genetics study on Ice Age populations around the Black Sea and the Northern Levant
The TMRCA measurements for haplogroups show a greater age of haplogroups J *, J1, J2 in Turkey 
and the Caucasus, and a great differentiation of E1b between North Africa and Asia. The estimation 
of the divergence time of the different populations is indicated for the three haplogroups J1, J2 and
 E1b in the figure above. J1 is in a, J2 in b and E1b in c. These results confirm the TRMCA 
estimates and indicate that J1 and J2 are probably from the Caucasus  
[Credit: Platt et al. 2016]
Details of the distinct and datable expansion routes of these populations into Europe and North Africa are revealed in the study, published today in Scientific Reports. The journal article expands upon these findings with a discussion about the possible correlation between these migrations and various cultural and climatic events evident in the archaeological records of the past 15,000 years.
Such a plethora of discoveries is never anticipated, says Zalloua. "We didn't set out to say anything in particular. We plotted our data on a map together with climate and archaeological evidence and it all made sense."

Source: National News Agency - Ministry of Information Lebanese Republic [January 12, 2017]
TANN

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