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Ancient Ethiopian Man's Genome Sheds Light On African Ancestry

Oct 12, 2015 09:38 PM EDT
Mota Cave
Mota cave, pictured here, is where researchers discovered the male Ethiopian skull.
(Photo : Kathryn and John Arthur)

Scientists are constantly finding new clues that may help them solve the never-ending puzzle of human evolution. One such clue – a male skull excavated from an Ethiopian cave – recently enabled a team of researchers to successfully sequence the first full genome of an ancient African. Their critical findings suggest that current African populations have much more Eurasian ancestry than previously thought. 

"With an ancient genome, we have a direct window into the distant past. One genome from one individual can provide a picture of an entire population," Dr. Andrea Manica, senior author of the study from the University of Cambridge's Department of Zoology, said in a news release

The male skull was originally found buried face down in Mota cave, which lies in the highlands of Ethiopia. The skull was dated to be about 4,500 years old and contained well-preserved DNA. After a genetic analysis, scientists revealed key details about ancient human migration back to Africa from Western Eurasia roughly 3,000 years ago.  

When comparing the ancient Ethiopian genome to that of modern Africans, researchers found that East African populations now have as much as a quarter Eurasian ancestry; those in the far west and south of the continent still have at least five percent of their genome from Eurasian migrants. This suggests that the migration event was much larger than previously thought. 

"Roughly speaking, the wave of West Eurasian migration back into the Horn of Africa could have been as much as 30 percent of the population that already lived there – and that, to me, is mind-blowing. The question is: what got them moving all of a sudden?" Manica said in a statement

No obvious climatic changes seem to have forced West Eurasians to migrate back into Africa, the researchers noted in their study. However, the major relocation does coincide with the arrival of Near Eastern crops in East Africa. This suggests that migrants were direct descendants of – or at least very closely related to – Neolithic farmers that brought wheat and barley agriculture into West Eurasia around 7,000 years ago, and then migrated into the Horn of Africa some 4,000 years later, according to the release. 

"It's quite remarkable that, genetically-speaking, this is the same population that left the Near East several millennia previously," Eppie Jones, a geneticist at Trinity College Dublin who led the laboratory work to sequence the genome, said in the release. 

Africa is viewed as a giant melting pot, researchers noted, so being able to better understand ancient migration is a big step in understanding African ancestry as a whole. 

"The sequencing of ancient genomes is still so new, and it's changing the way we reconstruct human origins," Manica added. "These new techniques will keep evolving, enabling us to gain an ever-clearer understanding of who our earliest ancestors were." 

Manica worked alongside an international team of researchers from Trinity College Dublin, King Abdullah University of Science and Technology (KAUST), University of South Florida St. Petersburg, Ventura College, University of California Los Angeles (UCLA), University of Siena, University of Illinois, University of Oxford, Cranfield University, Theragen BiO Institute, University of Potsdam, University of York, The Genomics Institute, and the University College Dublin and the study was recently published in the journal Science.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

-Follow Samantha on Twitter @Sam_Ashley13 

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