A unique genetic mapping study carried out to determine the ancestry of ancient Arabs in Bahrain has revealed that the people in the region developed resistance to malaria following the appearance of agriculture around five thousand years ago.
DNA analysis of the remains of four individuals from the Tylos-period Bahrain (300 BC to 600 AD) revealed the presence of a malaria-protective genetic mutation known as G6PD Mediterranean in three samples.
The study titled ‘Ancient genomes illuminate Eastern Arabian population history and adaptation against malaria’ also revealed that Tylos-period inhabitants of Bahrain had ancestries from Anatolia, the Levant and Caucasus/Iran.
It was done by 13 researchers including Bahrain Authority for Culture and Antiquities (Baca) antiquities and museum director Dr Salman Almahari, and Mersey and West Lancashire NHS Trust specialist Dr Fatima Aloraifi.
History
“The rich population history of Bahrain, and more generally of Arabia, has been severely understudied from a genetic perspective,” said Dr Aloraifi. “Poor ancient DNA preservation in hot and humid climates prevented the direct examination of the genetic ancestry of past populations, which means no ancient samples from Arabia have been sequenced until now.
“With this study, we are able to provide the first genetic snapshot of past Arabian populations, which gives us important insights about adaptation against malaria, which was historically-endemic in the region.”
Malaria is caused by parasites that enter the body through the bite of an infected mosquito. It can cause severe health problems such as seizures, brain damage, trouble breathing, organ failure and death.
The Tylos-era began around 325BC when an expedition sent by Alexander the Great reached Bahrain. It was an era of prosperity with Greek and Persian influence.
Alexander’s death led to the establishment of the Seleucid Empire around 312BC, which dominated Anatolia, Levant, Mesopotamia and modern-day Iran.
As part of the study, researchers collected ancient human remains from archaeological collections stored at the Bahrain National Museum, exhumed from archaeological sites across the country such as A’ali Burial Mounds, Abu Saiba and Hamad Town.
They extracted DNA from 25 individuals, but only four were preserved well enough and suitable to be sequenced.
To examine the genetic affinities of the extracted DNA, the samples were compared to that of 1,301 present day West Eurasians and 117 Arabs and Levantines.
The study showed that many people in the region’s ancient populations may have enjoyed protection from malaria due to the presence of the G6PD Mediterranean mutation.
The mutation rose in frequency around five thousand years ago, coinciding with the onset of agriculture in the region, which created ideal conditions for the proliferation of malaria.
This agrees with archaeological evidence that suggested the disease was historically endemic in Eastern Arabia and proof of Tylos-period inhabitants interacting between with neighbouring regions.
Additionally, the research showed that ancient Bahrainis had a mixture of origins from ancient Levant, Iran/Caucasus and Anatolia.
It was also able to estimate the genetic makeup of modern day people in the region, with the research suggesting that Tylos-Period Bahrainis are genetically closer to present-day Levantines than to present-day Arabs.
It was found that Iraqis, Assyrians and Jewish groups from Iran, Georgia and Iraq all had ancestors from Tylos-period Bahrain, while modern-day Saudis, Emiratis and Yemenis had more East African and Natufian (modern-day Palestine and Lebanon) DNA in them.
The study was also able to predict the samples’ hair, skin and eye colours, with resulting features found to be similar to that of the present-day Middle Eastern and South Asian people.
All four samples were likely to have had brown eyes (a 99 per cent probability) with a 50-50 chance of having brown or black hair.
Two of the samples were determined to have a dark skin pigmentation (90pc probability), while the remaining two samples were uncertain, but leaning towards a lighter skin tone.
Dr Almahari highlighted the importance of such studies stating that it paved the way for future research to shed light on human population movements in Arabia and other regions with harsh climates where it is difficult to find well-preserved sources of DNA.
University of Birmingham Dubai’s Marc Haber further said that the research provided ‘an insight into progression of diseases in the region’, providing predictive capabilities for disease susceptibility, spread and treatment, thus promoting better health outcomes.”
The last case of local transmission of malaria was recorded in 1979 and Bahrain was official declared free of malaria by the World Health Organisation in 1982.
nader@gdnmedia.bh
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