The term ''Eurasian backflow'', or ''Eurasian back-migrations'', has been used to describe several pre-Neolithic and

Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...

migration events of humans from western

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

back to

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. ''

Homo sapiens Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

'' had left Africa about 70-50,000 years ago, and between 30,000-15,000 years ago migrated back from the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

into

Northern Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...

. About 3,000 years ago, or already earlier between 6,000-5,000 years ago, farmers from

Anatolia Anatolia (), also known as Asia Minor, is a peninsula in West Asia that makes up the majority of the land area of Turkey. It is the westernmost protrusion of Asia and is geographically bounded by the Mediterranean Sea to the south, the Aegean ...

and the

Near East The Near East () is a transcontinental region around the Eastern Mediterranean encompassing the historical Fertile Crescent, the Levant, Anatolia, Egypt, Mesopotamia, and coastal areas of the Arabian Peninsula. The term was invented in the 20th ...

migrated into the

Horn of Africa The Horn of Africa (HoA), also known as the Somali Peninsula, is a large peninsula and geopolitical region in East Africa.Robert Stock, ''Africa South of the Sahara, Second Edition: A Geographical Interpretation'', (The Guilford Press; 2004), ...

. Signs of this migration can be found in the genomes of contemporary peoples from all over

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

. Moreover, analysis has also recognized that some of the Eurasian ancestry in

Northeast Africa Northeast Africa, or Northeastern Africa, or Northern East Africa as it was known in the past, encompasses the countries of Africa situated in and around the Red Sea. The region is intermediate between North Africa and East Africa, and encompasses ...

could possibly pre-date agriculture, from around ~12-23 ka. Next to Eastern Africa, significant Eurasian ancestry is found in Northern Africa, and among specific ethnic groups of the Horn of Africa, Northern Sudan, the

Sahel The Sahel region (; ), or Sahelian acacia savanna, is a Biogeography, biogeographical region in Africa. It is the Ecotone, transition zone between the more humid Sudanian savannas to its south and the drier Sahara to the north. The Sahel has a ...

region, as well as among the

Malagasy people The Malagasy ( or ) are a group of Austronesian-speaking ethnic groups indigenous to the island country of Madagascar, formed through generations of interaction between Austronesians originally from southern Borneo and Bantus from Southeast ...

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. Various genome studies found also evidence for multiple pre-historic back-migrations from various

n populations and subsequent admixture with native groups. West-Eurasian geneflow arrived to Northern Africa during the Paleolithic, followed by other

migration events. Genetic data on the

Taforalt Taforalt, or Grotte des Pigeons, is a cave in the province of Berkane, Aït Iznasen region, Morocco, possibly the oldest cemetery in North Africa. It contained at least 34 Iberomaurusian adolescent and adult human skeletons, as well as young ...

samples "demonstrated that Northern Africa received significant amounts of gene-flow from Eurasia predating the Holocene and development of farming practices". Medieval geneflow events, such as the Arab expansion also left traces in various African populations, but with Neolithization having a much larger demographic impact than Arabization. Map of major prefarming population stratification across the African continent

Map of major prefarming population stratification across the African continent

The people migrating back to Africa were closely related to the Neolithic farmers who had brought agriculture from the Near East to Europe about 7,000 years ago. This population is also closely related to present-day

Sardinians Sardinians or Sards are an Italians, Italian ethno-linguistic group and a nation indigenous to Sardinia, an island in the western Mediterranean Sea, Mediterranean which is administratively an Regions of Italy#Autonomous regions with special st ...

, although studies have made distinctions between the population that brought farming into Europe and

Maghreb The Maghreb (; ), also known as the Arab Maghreb () and Northwest Africa, is the western part of the Arab world. The region comprises western and central North Africa, including Algeria, Libya, Mauritania, Morocco, and Tunisia. The Maghreb al ...

, and the Levantine related groups that spread southward into East Africa. A study from 2020 inferred two sources for the spread of Eurasian admixture in Northeastern Africa, with one associated with pastoralism. The initial phase involved groups originating from the Levant and North Africa that gave rise to the Pastoral Neolithic. Further research has shown that the back-migration into the region was a complex process, identifying multiple origins for the Eurasian component in Northeast African groups today. A report in November 2015 on a 4,500-year-old Ethiopian genome had originally overestimated the genetic influence of the Eurasian backflow, claiming that signs of the migration could be found in genomes all over Africa. This mistaken claim was based on a data-processing error and was corrected in February 2016. The West Asian admixture was only predominant in the populations of the Horn of Africa, in particular Ethiopian highlanders, and less relevant or absent in the genetic makeup of West and Central Africans. In addition to intrinsic diversity within the continent borne by population structure and isolation, influxes of Eurasian populations into Africa has been seen as a critical contributor to the existing genetic diversity.

Neanderthal admixture and Eurasian ancestry

An investigation in 2012 discovered that unlike most sub-Saharan Africans, North Africans have similar levels of Neanderthal DNA to South Europeans and West Asians, which is pre-Neolithic in origin, rather than via any recent admixture, as the Neanderthal's genetic signals were higher in populations with an autochthonous 'back-to-Africa' genomic component that arrived 12,000 years ago. These Neanderthal genomic traces do not mark a division between Africans and non-Africans, but rather a division between sub-Saharan Africans and the rest of the modern human groups, including those from North Africa. In 2016, researchers recognized that the

Neanderthal Neanderthals ( ; ''Homo neanderthalensis'' or sometimes ''H. sapiens neanderthalensis'') are an extinction, extinct group of archaic humans who inhabited Europe and Western and Central Asia during the Middle Pleistocene, Middle to Late Plei ...

ancestry in African populations, strongly corresponds with the levels of Western Eurasian ancestry. The geneticists elaborated that: "Neanderthal ancestry is not expected in Africa, yet today many Africans carry Neanderthal-derived alleles. The plot shows that the Neanderthal ancestry proportion in Africans is correlated with gene flow from Eurasians. For example, knowing that today Eurasians carry ~2% of Neanderthal ancestry, we observed that East Africans (Ethiopians) had ~1% Neanderthal ancestry and ~50% Eurasian ancestry. Correspondingly, Near Easterners showed a decline in Neanderthal ancestry proportional to their levels of African ancestry." Human dispersals within and into Africa

Chen, Lu's publication found back-migrations contributed to the signal of Neanderthal ancestry in Africans. Data indicated that back-migrations giving Neanderthal sequences came after the split of Europeans and East Asians, from populations related to the European lineage. The overlap of this ancestral European ancestry and Neanderthal segments was highly significant.

Average Eurasian frequencies in African populations

References

{{reflist Prehistoric migrations

Neanderthal admixture and Eurasian ancestry

Average Eurasian frequencies in African populations

See also

References