DNA Reveals Stone Age North Africans Had Near Eastern and Sub-Saharan Ancestors
The oldest nuclear DNA ever recovered in Africa shows that people who lived in what is now Morocco 15,000 years ago were related to populations from both within and outside of the continent.
Travelers jetting from a city like Tel Aviv in Israel to Casablanca in Morocco fly about 2,320 miles during a 5-hour-long journey. Even by today's standards, the trip is lengthy.
Anthropologists over the decades have therefore thought that populations in North Africa and Western Asia were relatively isolated with little back and forth between the regions until more modern times.
Ancient DNA from 15,000-year-old members of our species from Morocco now provides evidence to the contrary. The genetic data shows that people from the two geographic areas were not only traveling long distances during the Stone Age, but also mating with each other.
"Our results show that people from Africa and the Near East had already interacted substantially at least by the early Later Stone Age," lead author Marieke van de Loosdrecht of the Max Planck Institute for the Science of Human History told Seeker.
"Although these regions are geographically far apart," she added, "this did not stop humans from migrating and interacting."
The nuclear DNA that she and her team studied is the oldest that has ever been recovered in Africa.
Nuclear DNA, contained within the nuclei of organisms, encodes for the majority of the genome. More often, mitochondrial DNA is recovered from early remains, since it tends to survive well over longer periods of time, but it provides less genetic information.
In this case, the researchers studied both types. They obtained mitochondrial DNA from seven people and genome-wide nuclear data from five individuals, all of whom were buried at a site called Grotte des Pigeons near Taforalt, Morocco.
The people were associated with the Iberomaurusian culture, known to have produced fine stone tools called microliths, which include carefully crafted blades and small bladelets used to make spears and other hafted items.
The retrieved DNA samples were fragmented and contained a lot of modifications. To reconstruct the individuals' genomic ancestry, the scientists had to overcome numerous challenges.
"We managed this using targeted in-solution capture, by which we could selectively fish out the human DNA fragments relative to the non-human environmental DNA from, for example, microbes and plants," van de Loosdrecht said.
Matching the information to known genomes, she, co-senior author Johannes Krause, and their team found two major components to the genetic heritage of the individuals.
About two-thirds of the Iberomaurusians’ DNA was related to contemporaneous populations from the Levant, the region on the eastern coast of the Mediterranean Sea north of the Arabian Peninsula and south of Turkey. It includes Israel, Jordan, Lebanon, the Palestinian Territories, and Syria.
"Our analysis shows that North Africa and the Near East, even at this early time, were part of one region without much of a genetic barrier," co-senior author Choongwon Jeong said.
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Migration routes likely existed over land and sea, co-author Abdeljalil Bouzouggar of the National Institute of Archaeology and Heritage in Rabat, told Seeker.
He explained that there is archaeological evidence for land migrations. "Both Atlantic and Mediterranean coastal routes could have been used by the Taforalt ancestors," he said.
The Levantine people who interacted with those from what is now Morocco could have been Natufians, a highly successful culture of the early Middle East.
"In addition to microlithic-backed bladelet technologies, the Natufians intensively used plants for food, made grindstones, kept dogs as pets, and buried their dead with grave goods including shells and canids (dog remains)," Bouzouggar said. "Such practices contributed a lot to the exceptional population growth and spread of the Natufians."
The other third of the Iberomaurusians' heritage comes from a previously unknown ancient population originating from Sub-Saharan Africa. The Sahara Desert is difficult to cross even today much less in ancient times, but somehow Stone Age people managed to make the trip.
While the researchers are certain that some of the ancestors of the Iberomaurusians came from this region south of the Sahara, they could find no precise genetic match with modern populations, meaning it’s possible that their heritage came from a population that no longer exists.
Bouzouggar suspects that the ancient African population that mixed into the Iberomaurusians could have been the Aterians, who were among the first to use the bow and arrow and to wear ornaments, indicative of advanced symbolic behaviors.
The researchers additionally conducted direct genetic tests for Neanderthal admixture, and sure enough, they found that the Iberomaurusians do retain Neanderthal DNA. Van de Loosdrecht explained that it "was inherited as part of their large proportion of Near Eastern ancestry."
The discovery negates prior theories that only people native to areas outside of Africa are part Neanderthal. In short, a large percentage of the world's population today is related to Neanderthals, however distantly.
Remains for some of the earliest anatomically modern humans have been unearthed in North Africa, where early technological innovations also took place.
The researchers hope to learn about ancient human populations from North Africa from a larger sample size.
"Our analyzed individuals from Taforalt are from a single, specific area and from a small window in time," van de Loosdrecht explained.
She added, "We would need a lot more ancient genomes from other areas in North Africa to be able to tell if our Taforalt individuals are good representatives for the genetic makeup of all individuals who lived in North Africa during the Later Stone Age."