Africa is a continent that lags behind Asia, Europe and the Americas when it comes to DNA tracing of human fossils, with the hot, humid climate making scientific work all the more difficult. However, a team of researchers has, for the first time, successfully sequenced the first full genome from a 4,500-year-old African skeleton.
It’s a landmark discovery because, up until now, African skeletons had been rendered fairly unusable, with richer scientific rewards on offer pretty much anywhere else.
In the recent past, researchers have sequenced genomes from Neandertals in Europe (a 38,000-year-old fossil in Croatia, for example), prehistoric herders in Asia and Paleoindians in the Americas.
Due to the belief that climate played too detrimental a role in DNA preservation, scientists have eschewed Africa and, instead, fled to colder areas like Siberia, where far more of the skeletal remains are salvageable.
Now, according to a report published in Science, the “Mota” genome reveals the DNA of a skeleton found in the Mota caves (thus the name), which shows that the man, alive 4,500 years ago, had brown eyes, dark skin and three gene variants associated with adaptation to high altitudes.
The skeleton was discovered by US anthropologists John and Kathryn Arthur a few years ago, with DNA surviving in its ear.
Population geneticist Andrea Manica and graduate student Marcos Gallego Llorente then stepped in to start working on the DNA that had actually survived in the skeleton’s earbone.
“We have the complete blueprint, every single gene, every single bit of information that made this individual that lived 4,500 years ago in Ethiopia,” said Manica.
Comparing the genome to populations all over Europe, Asia and Africa, it was established that today’s Ari tribe, living in the area where the skeleton was found, was the closest match. But Mota lacks around 4-7pc of the Ari DNA, which got the scientists wondering, ‘Where did this difference originate?’.
By looking at the disparity, they established that it comes from modern Sardinians and a prehistoric farmer who lived in Germany.
Manica suggests that both the European farmers and living Africans inherited this DNA from the same source – a population in the Middle East, perhaps Anatolia or Mesopotamia.
Historically, it was known that these Middle Easterners migrated into Europe and Asia, becoming some of the earliest known farmers in the former.
Now, though, it is clear that they headed into Africa, too, because so many farmers carry this strain of DNA. “Every single population for which we have data in Africa has a sizeable component of Eurasian ancestry,” said Manica on the BBC.
“The extent of this backflow was much greater than previously reported, reaching all the way to Central, West and Southern Africa, affecting even populations such as Yoruba and Mbuti, previously thought to be relatively unadmixed, who harbour 6-7pc Eurasian ancestry,” reads the study.
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