137 human genomes from the Middle East fill gaps in human history

Date:
August 4, 2021
Source:
Cell Press
Summary:
Whole-genome sequencing efforts around the world have offered
important insights into human diversity, historical migrations,
and the relationships between people of different regions --
but scientists still don't have a complete picture because some
regions and people remain understudied. A new study helps to fill
one of these big gaps by generating more than 100 high-coverage
genome sequences from eight Middle Eastern populations using
linked-read sequencing.



FULL STORY ========================================================================== Whole-genome sequencing efforts around the world have offered
important insights into human diversity, historical migrations, and the relationships between people of different regions -- but scientists still
don't have a complete picture because some regions and people remain understudied. A new study reported in the journal Cell on August 4 helps
to fill one of these big gaps by generating more than 100 high-coverage
genome sequences from eight Middle Eastern populations using linked-read sequencing.


==========================================================================
"The Middle East is an important region to understand human history, migrations, and evolution: it is where modern humans first expanded
out of Africa, where hunter-gatherers first settled and transitioned
into farmers, where the first writing systems developed, and where the
first major known civilizations emerged," says Mohamed Almarri of the
Wellcome Sanger Institute, UK. "However, despite this importance, the
region has been historically understudied in genomic studies." In the
new study, Almarri, Marc Haber (@MarcHaber, University of Birmingham,
UK), and their colleagues sequenced 137 whole genomes from eight Middle
Eastern populations.

By generating the most comprehensive resource of human genetic variation
in the Middle East using a new sequencing technology called linked-read sequencing, the researchers were able to reconstruct the genomic history
of the region with unprecedented resolution. The researchers say that
some of the events recorded in the Middle Eastern genomes could be linked
with what's known from archeology or linguistics, such as the invention
of agriculture and the spread of Semitic languages. But other events can
only be elucidated by studying the DNA of ancient and modern people who
lived in the region.

Some of their most notable findings include the following:
* The identification of 4.8 million new gene variants that are
specific to
Middle Eastern populations that could now provide the basis for
future research.

* Genetic variants that show evidence of selection -- in other words,
mutations that spread unusually quickly -- potentially due to
adaptation to the changing environment and lifestyle.

* In the Levant, where agriculture was first developed, populations
experienced a massive growth around the transition to agriculture
that wasn't paralleled in Arabia.

* Arabian populations suffered a severe population decrease around
6,000
years ago, which coincides with the change in climate in Arabia
turning it from a green, wet region into the largest sand desert
in the world today.

* Middle Easterners descend from the same population that expanded
out of
Africa 50,000 to 60,000 years ago.

* Arabian groups have significantly lower Neanderthal ancestry
than other
Eurasians, potentially caused by excess basal Eurasian and African
ancestry in Arabians that depletes their Neanderthal ancestry
* The movement of populations during the Bronze Age potentially
spread the
Semitic languages from the Levant to Arabia and East Africa.

* An increase in the frequency of variants associated with type
2 diabetes
in some populations in the past 2,000 years, suggesting that
variants that were beneficial in the past are today associated
with diseases.

"We found 4.8 million variants that were not previously discovered in
other populations," Haber says. "Hundreds of thousands of these are common
in the region, and any of them could hold medical relevance." "Our study
fills a major gap in international genomic projects by cataloguing genetic variation in the Middle East," says Chris Tyler-Smith of the Wellcome
Sanger Institute, UK. "The millions of new variants we found in our study
will improve future medical association studies in the region. Our results explain how the genetics of Middle Easterners formed over time, providing
new insights, which complement knowledge from archeology, anthropology,
and linguistics." The researchers say they will now follow up on variants
that show evidence of selection. Through these continued studies, they
hope to further understand the biological effects of those newly found
variants while further refining the genetic history of the region.

This work was supported by the Government of Dubai -- Dubai Police GHQ,
the Wellcome Trust, and an Estonian Research Council Grant.

========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Mohamed A. Almarri, Marc Haber, Reem A. Lootah, Pille Hallast,
Saeed Al
Turki, Hilary C. Martin, Yali Xue, Chris Tyler-Smith. The
genomic history of the Middle East. Cell, 2021 DOI:
10.1016/j.cell.2021.07.013 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210804123500.htm

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