The largest study of the Arab genome ever conducted, reveals the most ancient of all modern Middle Eastern populations. The research also explains how modern humans may have first evolved around the world.
The Arabian Peninsula, which today includes Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates, has long been a major crossroads between the continents of Africa, Europe and Asia.
Recently, archaeological finds, fossils, and DNA have shown that analyzing the Middle East and its peoples can reveal more about how the first modern humans found their way out and migrated to Africa and around the world.
Until now, most of the genetics of the Arab population has not been studied. In the new study, researchers conducted the first large-scale analysis of Middle Eastern population genetics, examining the DNA of 6,218 adults recruited randomly from the Qatari health database, and comparing it to the DNA of people living in other regions of the world today, and DNA from ancient humans who once lived in Africa, Europe and Asia.
"This study is the first large-scale study in an Arab population," said study co-author Younes Mokrab and Head of the Medical and Population Genomics Lab at Sidra Medicine in Doha, Qatar.
The scientists found that DNA from Middle Eastern groups made significant genetic contributions to communities in Europe, South Asia and even South America, possibly due to the rise and spread of Islam around the world over the last 1,400 years, and people of Middle Eastern descent interbreeding. with that population.
"Arabic ancestry is a major ancestral component in many modern populations. This means what will be found in this region has direct implications on populations elsewhere," Mokrab said.
The new findings also suggest that the ancestral group from the Arabian Peninsula separated from early Africa about 90,000 years ago. This estimate corresponds to the time when the ancestors of Europeans and South Asians split from early Africa, thus corroborating the idea that people migrated from Africa around the world via Arabia.
"Arab lands were the main base for early migration out of Africa," Mokrab said.
Furthermore, the researchers found that the Arabian Peninsula peoples appeared to split from their European ancestors about 42,000 years ago, and the South Asian population about 32 thousand years ago.
"Previously, the Arab population was thought to be descended from a broad European population," Mokrab said.
After modern humans left Africa, they met and sometimes interbred with other now-extinct human lineages, such as the Neanderthals and Denisovans, whose ancestors left Africa long before modern humans did, and are found in Europe and Asia.
"The timeline found in our study when Arabs diverged from other populations, explains why Neanderthal DNA is much less common in Arab populations than in populations that later mixed with ancient hominins," Mokrab said.
Moreover, after comparing the modern human genome with ancient human DNA, the scientists found that a unique group of peninsula Arabs may be the most ancient of all modern Middle Eastern populations.
Members of this group may be the closest relatives of the earliest farmers and hunter-gatherers known to inhabit the ancient Middle East.
The Arab ancestral group appears to have doubled over 12,000 to 20,000 years ago. This coincided with Arab history becoming drier, and some community groups moving to more fertile areas, giving rise to settler communities, and others remaining in arid areas more conducive to a nomadic lifestyle.
The study also found high rates of inbreeding in some peninsula Arab groups dating back to ancient times, possibly due to the tribal nature of this culture which adds to barriers to intermarriage outside of tribal groups.
Researchers say inbreeding can highlight rare mutations that can increase disease risk, so this new finding could help uncover the causes of certain genetic disorders and lead to precision medicine to help diagnose and treat disease in the communities represented in this study.