According to a study published online in Genome Research, individuals migrated between African and Europe as far back as 11,000 years ago. Although migrations between these two continents have been well-documented during time periods, such as the Roman Empire, the Arab conquest, and the slave trade, this is the first time researchers have found genetic evidence for prehistoric gene flow.

In order to track back human evolution and ancestry, researchers examined the DNA sequence of the mitochondria. Mitochondria provide the energy a cell requires and also hold genetic information that is separate from the rest of the genome in the nucleus.

Although genetic information in the nuclear genome is a combination passed on from both mother and father, mitochondria DNA (mtDNA) is only passed to a child directly from the mother.

However, over extensive periods, small alterations in the mtDNA sequence have occurred in various populations. These alterations can be used by geneticists as markers that suggest the movements and migrations of our ancestors, and categorize them into specific “haplogroups.”

In order to unravel the history of genetic links between Africa and Europe, the researchers conducted the largest examination to date of complete mtDNA genomes in the haplogroup L (a lineage of sub-Saharan African origin).

After comparing the mtDNA genomes from different parts of Europe with mitochondria genomes from around the world, the team gained new insight as to when sub-Saharan lineages first appeared in Europe.

Although 65% of European haplogroup L lineages appeared in more recent times, Dr. Antonio Salas of the University of Santiago de Compostela and senior author of the study said:

“It was very surprising to find that more than 35 percent of the sub-Saharan lineages in Europe arrived during a period that ranged from more than 11,000 years ago to the Roman Empire times.”

According to the researchers, these contacts probably linked the two continents not only through North Africa, but directly by coastal routes as well. However, the scientists are still unsure as to why there was genetic flow between the two continents in prehistoric times. One theory is that some bidirectional flow was promoted when the last glaciation forced some Europeans to move south until the glacier receded and they were able to move back up north.

Salas believes that findings from the study will also help people who wish to learn more about their own ancestry. He explained:

“There is a growing interest in direct-to-consumer genetic testing, including those aimed to serve a public interested in reconstructing their ancestry. Studies like the one presented here will help to unravel inferences made in these studies.”

Written by Grace Rattue