The peoples of Africa are characterized by regional genetic substructure and heterogeneity, depending on the respective ethno-linguistic identity, and, in part, explainable by the "multiregional evolution" of modern human lineages in various multiple regions of the African continent, as well as later admixture events, including back-migrations from Eurasia, of both highly differentiated West and East Eurasian components.[7]
Africans' genetic ancestry is largely partitioned by geography and language family, with populations belonging to the same ethno-linguistic groupings showing high genetic homogeneity and coherence. Gene flow, consistent with both short- and long-range migration events followed by extensive admixture and bottleneck events, have influenced the regional genetic makeup and demographic structure of Africans. The historical Bantu expansion had lasting impacts on the modern demographic make up of Africa, resulting in a greater genetic and linguistic homogenization.[8][9] Genetic, archeologic, and linguistic studies added extra insight into this movement: "Our results reveal a genetic continuum of Niger–Congo speaker populations across the continent and extend our current understanding of the routes, timing and extent of the Bantu migration."[10]
Overall, different African populations display genetic diversity and substructure, but can be clustered in distinct but partially overlapping groupings:[11][12][13][9][14][15]
Khoisan or 'South African hunter-gatherers' from Southern Africa represented by the Khoisan peoples; they are associated with the deepest divergence (c. 270,000 years ago) of human genetic diversity, forming a distinct cluster of their own. They subsequently diverged into a Northern and Southern subgroup, c. 30,000 years ago.[a]
'Central African hunter-gatherers' or 'Rain forest hunter-gatherers' (Pygmies) of Central Africa, represented by the Biaka and Mbuti; associated with another deep divergence (c. 220,000 years ago). They subsequently diverged into an Eastern and Western subgroup, c. 20,000 years ago.[b]
"Ancestral Eurasians" represent the ancestral population of modern Eurasians shortly before the Out-of-Africa expansion; they are inferred to have diverged from other African populations, most likely somewhere in Northeast Africa, c. 70,000 years ago.
The various Afroasiatic-speakers from Northern Africa and the Horn of Africa, are suggested to have diverged from other African groups c. 50,000 years ago, but currently insufficient data and geneflow from other groups complicate an accurate estimation of the divergence date.[16] Afroasiatic-speaking populations also display variable amounts of West Asian (primarily Natufian-like, but also Neolithic Anatolian and Iranian) admixtures from Eurasian backflow movements, with the remainder being primarily from autochthonous African genetic clusters, associated with Nilotic-like ancestry. They also display affinity for the Paleolithic North African Taforalt specimens of the Iberomaurusian culture.[c]
'Eastern African hunter-gatherers', represented by Hadza, Sandawe, Omotic-speakers, and the ancient Mota specimen; their phylogenetic relationship to other populations is not clear, but they display affinity to modern East and West African populations, and harbor Khoesan-like geneflow along a Northeast to Southwest cline, as well as later (West) Eurasian admixtures, but at lower amounts than among Afroasiatic-speakers.[d]
"Ancient East Africans" or "Ancestral West/East Africans" associated with the common ancestor of modern Niger-Congo and Nilo-Saharan-speakers originated around 28,000 years ago. They subsequently diverged at c. 18,000 years ago into the ancestors of West and West-Central African Niger-Congo and Bantu-speakers, and into the East African Nilo-Saharan/Nilotic-speakers. They represent the dominant and most widespreaded ancestry component of modern Africa, and are associated with relative recent population expansions linked to agriculture and pastoralist lifestyles. Genetic data indicates affinity for older hunter-gatherer groups in East Africa, but their exact relationship remains unclear.[11][e] There is evidence for limited geneflow (9-13%) from a human ghost lineage, referred to as 'West African foragers' with a deeper or equally deep divergence time than 'Khoisan hunter-gatherers', into modern West Africans.[17][18]
Although the validity of the Nilo-Saharan family remains controversial, the region between Chad, Sudan, and the Central African Republic is seen as a likely candidate for its homeland prior to its dispersal around 10,000–8,000 BCE.[28]
The Southern African hunter-gatherers (Khoisan) are suggested to represent the autochthonous hunter-gatherer population of southern Africa, prior to the expansion of Bantu-speakers from Western/Central Africa and East African pastoralists. Khoisan show evidence for Bantu-related admixture, ranging from nearly ~0% to up to ~87.1%.[29]
The "recent African origin of modern humans" proposes a "single origin" of Homo sapiens within Africa. Recent genetic and archeologic data suggests that Homo sapiens-subgroups originated in multiple regions of Africa, not confined to a single sub-region of origin, with the last common ancestor of all modern humans expanding from a single region absorbing or replacing various deep lineages (described as archaic ghosts). The H. sapiens ancestral to proper Eurasians most likely left Northeastern Africa between 50,000 and 100,000 years ago.[30] The "recent African origin" model proposes that all modern non-African populations descend from one or several waves of H. sapiens that left Africa 70,000-60,000 years ago.[31][32][33][34]
According to Durvasula et al. (2020), there are indications that 2% to 19% (≃6.6 to 7.0%) of the DNA of West African populations may have come from an unknown archaic hominin which split from the ancestor of humans and Neanderthals between 360 kya to 1.02 mya. However, Durvasula et al. (2020) also suggests that at least part of this archaic admixture is also present in Eurasians/non-Africans, and that the admixture event or events range from 0 to 124 ka B.P, which includes the period before the Out-of-Africa migration and prior to the African/Eurasian split (thus affecting in part the common ancestors of both Africans and Eurasians/non-Africans).[36][37][38] Chen et al. (2020) found that Africans have higher Neanderthal ancestry than previously thought. 2,504 African samples from all over Africa were analyzed and tested on Neanderthal ancestry. All African samples showed evidence for minor Neanderthal ancestry, but always at lower levels than observed in Eurasians.[39]
Significant Eurasian admixture is found in Northern Africa, and among specific ethnic groups of the Horn of Africa, Northern Sudan, the Sahel region, as well as among the Malagasy people of Madagascar. Various genome studies found evidence for multiple prehistoric back-migrations from various Eurasian populations and subsequent admixture with native groups.[41] West Eurasian-associated geneflow arrived to Northern Africa during the Paleolithic (30,000 to 15,000 years ago), followed by other pre-Neolithic and Neolithic migration events. Genetic data on the Taforalt 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.[30][15][42] Pickrell et al. (2014) indicated that Western Eurasian ancestry eventually arrived through Northeast Africa (particularly the Horn of Africa) to Southeast Africa and Southern Africa.[43]
Ramsay et al. (2018) also found evidence for significant Western Eurasian admixture in various parts of Africa, from both ancient and more recent migrations, being highest among populations from Northern Africa, and some groups of the Horn of Africa:[44]
In addition to the intrinsic diversity within the continent due to population structure and isolation, migration of Eurasian populations into Africa has emerged as a critical contributor to the genetic diversity. These migrations involved the influx of different Eurasian populations at different times and to different parts of Africa. Comprehensive characterization of the details of these migrations through genetic studies on existing populations could help to explain the strong genetic differences between some geographically neighbouring populations.
This distinctive Eurasian admixture appears to have occurred over at least three time periods with ancient admixture in central west Africa (e.g., Yoruba from Nigeria) occurring between ~7.5 and 10.5 kya, older admixture in east Africa (e.g., Ethiopia) occurring between ~2.4 and 3.2 kya and more recent admixture between ~0.15 and 1.5 kya in some east African (e.g., Kenyan) populations.
Subsequent studies based on LD decay and haplotype sharing in an extensive set of African and Eurasian populations confirmed the presence of Eurasian signatures in west, east and southern Africans. In the west, in addition to Niger-Congo speakers from The Gambia and Mali, the Mossi from Burkina Faso showed the oldest Eurasian admixture event ~7 kya. In the east, these analyses inferred Eurasian admixture within the last 4000 years in Kenya.[44]
There is no definitive agreement on when or where the original homeland of the Afroasiatic language family existed. Some have suggested that they were spread by people with largely West-Eurasian ancestry during the Neolithic Revolution, towards Northern Africa and the Horn of Africa, outgoing from the Middle East, specifically from the Levant.[45] Others argue that the first speakers of Proto-Afroasiatic were based in Northeast Africa because that region includes the majority of the diversity of the Afroasiatic language family and has very diverse groups in close geographic proximity, which is sometimes considered a telltale sign for a linguistic geographic origin.[46] A subset of the Proto-Afroasiatic population would have migrated to the Levant during the late Paleolithic, merging with local West-Eurasians and resulting in a population which would later give rise to Natufian culture, associated with the early development of agriculture and early Afroasiatic languages, or specifically pre-proto-Semitic.[47][48][page needed][49][50][51][52] In addition, Y-haplogroup sub-lineage E-M215 (also known as "E1b1b) and its derivative E-M35 are quite common among Afroasiatic speakers, and southwestern Ethiopia is a plausible source of these haplogroups.[53] Under this African model, the linguistic group and carriers of this lineage would have arisen and dispersed together from Northeast Africa in the Mesolithic, plausibly having already developed subsistence patterns of pastoralism and intensive plant usage and collection.[54][55][56][57]
The Near-Eastern agriculturalist hypothesis does not account for the domestication of plants endemic to the Horn of Africa such as teff, ensete, and Niger seed, nor does it account for the lack of evidence of intrusive agricultural populations or for the growing of wheat, barley, or sorghum in that region prior to 3000 B.C.[58] According to historian and linguist Christopher Ehret, the form of intensive plant collection practiced by the Proto-Afroasiatic population in Northeast Africa may have been a precursor to the other agricultural practices that would later independently develop in the Fertile Crescent and the Horn of Africa.[51][59][60]
Horn of Africa
While many studies conducted on Horn of Africa populations estimate a West-Eurasian admixture event around 3,000 years ago,[61][44][43][62] Hodgson et al. (2014) found a distinct West-Eurasian ancestral component among studied Afroasiatic-speaking groups in the Horn of Africa (and to a lesser extent in North Africa and West Asia), most prevalent among the ethnic Somali. This ancestral component dubbed "Ethio-Somali" is most closely related to the "Maghrebi" (peaking in Tunisians) component and is believed to have diverged from other non-African ancestries around 23,000 years ago, and migrated back to Africa prior to developing agriculture (12–23 ka) from the Near East. This population would have crossed via the Sinai Peninsula and then split into two, with one branch continuing west across North Africa and the other heading south into the Horn of Africa. The authors propose that the "Ethio-Somali" component may have been a substantial ancestral component of the Proto-Afroasiatic-speaking population. Later migration from Arabia into the HOA beginning around 3 ka would explain the origin of the Ethiosemitic languages at this time.[49] An mtDNA analysis by Gandini et al. (2016) has produced additional evidence in support of a pre-agricultural back-migration from West-Eurasia into the Horn of Africa with an estimated date of arrival into the Horn of Africa in the early Holocene, possibly as a result of obsidian exchange networks across the Red Sea.[63] Hodgson et al. also confirmed the existence of an ancestral component indigenous to the Horn of Africa - "Ethiopic" or "Omotic" (Pagani et al.) - which is most prevalent among speakers of the Omotic branch of Afroasiatic in southwestern Ethiopia.[49][61] This lineage is associated with that of a 4,500 year-old fossil (Mota) found in a cave in southwestern Ethiopia, which has high genetic affinity to modern Ethiopian groups, especially the endogamous blacksmith caste of the Omotic Aari people. Like Mota, Aari blacksmiths do not show evidence for admixture with West-Eurasians, demonstrating a degree of population continuity in this region for at least 4,500 years. In a comparative analysis of Mota's genome referencing modern populations, Gallego et al. (2016) concluded that the divergence of Omotic from other Afroasiatic languages may have resulted from the relative isolation of its speakers from external groups.[64]
In an analysis of 68 Ethiopian ethnic groups, Lopez et al. (2021) revealed that several groups belonging to the three AA classifications of Cushitic, Omotic and Semitic show high genetic similarity to each other on average. Furthermore, the Nilo-Saharan speakers in the southwest shared more recent ancestry with Bantu and Nilotics, in contrast Afro-Asiatic speakers in the northeast shared more recent ancestry with Egyptians and other West Eurasians. The data also supported widespread recent intermixing among various ethnic groups.[65]
Madagascar
Specific East Asian-related ancestry is found among the Malagasy speakers of Madagascar at a medium frequency. The presence of this East Asian-related ancestry is mostly linked to the Austronesian peoples expansion from Southeast Asia.[66][67][68][69] The peoples of Borneo were identified to resemble the East Asian voyagers, who arrived on Madagascar. East Asian ancestry among Malagasy people was estimated at a mean average of 33%, but as high as ~75% among some Highlander groups and upper caste groups.[70][71][69]
Northern Africa
Dobon et al. (2015) identified an autosomal ancestral component that is commonly found among modern Afroasiatic-speaking populations (as well as Nubians) in Northeast Africa. This Coptic component peaks among Copts in Sudan, which is differentiated by its lack of Arab influence, but shares common ancestry with the North African/Middle Eastern populations. It appears alongside a component that defines Nilo-Saharan speakers of southwestern Sudan and South Sudan.[72] Arauna et al. (2017), analyzing existing genetic data obtained from Northern African populations, such as Berbers, described them as a mosaic of North African (Taforalt), Middle Eastern, European (Early European Farmers), and Sub-Saharan African-related ancestries.[73]
Chen et al. (2020) analyzed 2,504 African samples from all over Africa, and found archaic Neanderthal ancestry, among all tested African samples at low frequency. They also identified a European-related (West-Eurasian) ancestry segment, which seems to largely correspond with the detected Neanderthal ancestry components. European-related admixture among Africans was estimated to be between ~0% to up to ~30%, with a peak among Northern Africans.[74] According to Chen et al. (2020), "These data are consistent with the hypothesis that back-migration contributed to the signal of Neanderthal ancestry in Africans. Furthermore, the data indicates that this back-migration came after the split of Europeans and East Asians, from a population related to the European lineage."[74]
There is a minor geneflow from North Africa in parts of Southern Europe, this is supported by the presence of an African-specific mitochondrial haplogroup among one of four 4,000 year old samples.[75] Multiple studies found also evidence for geneflow of African ancestry towards Eurasia, specifically Europe and the Middle East. The analysis of 40 different West-Eurasian populations found African admixture at a frequency of 0% to up to ~15%.[76][77][78][79]
Western Africa
Hollfelder et al. (2021) concluded that West African Yoruba people, which were previously used as "unadmixed reference population" for indigenous Africans, harbor minor levels of Neanderthal ancestry, which can be largely associated with back-migration of an "Ancestral European-like" source population.[7]
A genome-wide study of a Fulani community from Burkina Faso inferred two major admixture events in this group, dating to ~1800 ya, and 300 ya. The first admixture event took place between the West African ancestors of the Fula and ancestral North African nomadic groups. The second admixture event, relatively recent, inferred a source from Southwestern Europe, or suggests either an additional gene flow between the Fulani and Northern African groups, who carry admixture proportions from Europeans.[80] Sahelian populations like the Toubou also showed admixture coming from Eurasians.[81]
Southern Africa
Low levels of West Eurasian ancestry (European or Middle Eastern) are found in Khoe–Kwadi Khoesan-speakers. It could have been acquired indirectly by admixture with migrating pastoralists from East Africa. This hypothesis of gene flow from eastern to southern Africa is further supported by other genetic and archaeological data documenting the spread of pastoralism from East to South Africa.[82]
While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.[83]
Ancient DNA
Daniel Shriner (2018), using modern populations as a reference, showed that the Natufians carried 61.2% Arabian, 21.2% Northern African, 10.9% Western Asian, and a small portion of Eastern African ancestry at 6.8%, which is associated with the modern Omotic-speaking groups found in southern Ethiopia.[53]
Van de Loorsdrecht et al. (2018) found that of seven samples of Taforalts of Morocco, radiocarbon dated to between 15,100 cal BP and 13,900 cal BP, six were found to carry maternal haplogroup U6a, and one was found to carry maternal haplogroup M1b. All six males were found to carry paternal haplogroup E1b1b, and they harbored 63.5% Natufian-related ancestry and 36.5% Sub-Saharan African-related ancestry. The Sub-Saharan component is most strongly drawn out by modern West African groups such as the Yoruba and the Mende. The samples also contain an additional affinity to South, Central, and East African outgroups that cannot be explained by any known ancient or modern populations.[91] When projected onto a principal component analysis graph of African and west Eurasian populations, the Taforalt individuals form a distinct cluster in an intermediate position between modern North Africans (e.g., Berbers, Mozabites, Saharawis) and East Africans (e.g., Afars, Oromos, Somalis).[91] Jeong (2020), when comparing the Taforalt people of the Iberomaurusian culture to modern populations, found that the Taforalt's Sub-Saharan African genetic component may be best represented by modern West Africans (e.g., Yoruba).[92]
Amid the Holocene, including the Holocene Climate Optimum in 8000 BP, Africans bearing haplogroup L2 spread within West Africa and Africans bearing haplogroup L3 spread within East Africa.[93] As the largest migration since the Out of Africa migration, migration from Sub-Saharan Africa toward the North Africa occurred, by West Africans, Central Africans, and East Africans, resulting in migrations into Europe and Asia; consequently, Sub-Saharan African mitochondrial DNA was introduced into Europe and Asia.[93] During the early period of the Holocene, 50% of Sub-Saharan African mitochondrial DNA was introduced into North Africa by West Africans and the other 50% was introduced by East Africans.[93] During the modern period, a greater number of West Africans introduced Sub-Saharan African mitochondrial DNA into North Africa than East Africans.[93]
Mitochondrial haplogroups L3, M, and N are found among Sudanese peoples (e.g., Beja, Nilotics, Nuba, Nubians), who have no known interaction (e.g., history of migration/admixture) with Europeans or Asians; rather than having developed in a post-Out-of-Africa migration context, mitochondrial macrohaplogroup L3/M/N and its subsequent development into distinct mitochondrial haplogroups (e.g., Haplogroup L3, Haplogroup M, Haplogroup N) may have occurred in East Africa at a time that considerably predates the Out-of-Africa migration event of 50,000 BP.[94]
Neolithicagriculturalists, who may have resided in Northeast Africa and the Near East, may have been the source population for lactase persistence variants, including –13910*T, and may have been subsequently supplanted by later migrations of peoples.[96] The Sub-SaharanWest African Fulani, the North AfricanTuareg, and European agriculturalists, who are descendants of these Neolithic agriculturalists, share the lactase persistence variant –13910*T.[96] While shared by Fulani and Tuareg herders, compared to the Tuareg variant, the Fulani variant of –13910*T has undergone a longer period of haplotype differentiation.[96] The Fulani lactase persistence variant –13910*T may have spread, along with cattle pastoralism, between 9686 BP and 7534 BP, possibly around 8500 BP; corroborating this timeframe for the Fulani, by at least 7500 BP, there is evidence of herders engaging in the act of milking in the Central Sahara.[96]
Archaic traits found in human fossils of West Africa (e.g., Iho Eleru fossils, which dates to 13,000 BP) and Central Africa (e.g., Ishango fossils, which dates between 25,000 BP and 20,000 BP) may have developed as a result of admixture between archaic humans and modern humans or may be evidence of late-persisting early modern humans.[83] While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.[83]
Ancient DNA
As of 2017, human ancient DNA has not been found in the region of West Africa.[97] As of 2020, human ancient DNA has not been forthcoming in the region of West Africa.[92]
As a result of haplogroup D0, a basal branch of haplogroup DE, being found in three Nigerian men, it may be the case that haplogroup DE, as well as its sublineages D0 and E, originated in Africa.[99]
Fan et al. (2019) found that the Fulani people show genetic affinity to isolated Afroasiatic-speaking groups in Eastern Africa, specifically Omotic-speakers such as the Aari people. While the Fulani have nearly exclusive indigenous African ancestry (defined by West and East African ancestry), they also show traces of West-Eurasian-like admixture, supporting an ancestral homeland somewhere in North or Eastern Africa, and westwards expansion during the Neolithic, possibly caused by the arrival and expansion of West-Eurasian-related groups.[109] Fan et al. (2023) found that the Fulani, who have 50% Amhara-related and 50% Tikari-related ancestry as well as occupy regions such as West Africa, Central Africa, and the Sudan as nomadic herders, may have initially been Afroasiatic speakers that subsequently underwent language replacement and became Niger-Congo speakers.[110]
Amid the Green Sahara, the mutation for sickle cell originated in the Sahara[100] or in the northwest forest region of western Central Africa (e.g., Cameroon)[100][113] by at least 7,300 years ago,[100][113] though possibly as early as 22,000 years ago.[114][113] The ancestral sickle cell haplotype to modern haplotypes (e.g., Cameroon/Central African Republic and Benin/Senegal haplotypes) may have first arose in the ancestors of modern West Africans, bearing haplogroups E1b1a1-L485 and E1b1a1-U175 or their ancestral haplogroup E1b1a1-M4732.[100] West Africans (e.g., Yoruba and Esan of Nigeria), bearing the Benin sickle cell haplotype, may have migrated through the northeastern region of Africa into the western region of Arabia.[100] West Africans (e.g., Mende of Sierra Leone), bearing the Senegal sickle cell haplotype,[115][100] may have migrated into Mauritania (77% modern rate of occurrence) and Senegal (100%); they may also have migrated across the Sahara, into North Africa, and from North Africa, into Southern Europe, Turkey, and a region near northern Iraq and southern Turkey.[115] Some may have migrated into and introduced the Senegal and Benin sickle cell haplotypes into Basra, Iraq, where both occur equally.[115] West Africans, bearing the Benin sickle cell haplotype, may have migrated into the northern region of Iraq (69.5%), Jordan (80%), Lebanon (73%), Oman (52.1%), and Egypt (80.8%).[115]
Archaic traits found in human fossils of West Africa (e.g., Iho Eleru fossils, which dates to 13,000 BP) and Central Africa (e.g., Ishango fossils, which dates between 25,000 BP and 20,000 BP) may have developed as a result of admixture between archaic humans and modern humans or may be evidence of late-persisting early modern humans.[83] While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.[83]
In 150,000 BP, Africans (e.g., Central Africans, East Africans) bearing haplogroup L1 diverged.[93] Between 75,000 BP and 60,000 BP, Africans bearing haplogroup L3 emerged in East Africa and eventually migrated into and became present in modern West Africans, Central Africans, and non-Africans.[93] Amid the Holocene, including the Holocene Climate Optimum in 8000 BP, Africans bearing haplogroup L2 spread within West Africa and Africans bearing haplogroup L3 spread within East Africa.[93] As the largest migration since the Out of Africa migration, migration from Sub-Saharan Africa toward the North Africa occurred, by West Africans, Central Africans, and East Africans, resulting in migrations into Europe and Asia; consequently, Sub-Saharan African mitochondrial DNA was introduced into Europe and Asia.[93]
While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.[83]
Ancient DNA
Ethiopia
At Mota, in Ethiopia, an individual, estimated to date to the 5th millennium BP, carried haplogroups E1b1 and L3x2a.[136][137] The individual of Mota is genetically related to groups residing near the region of Mota, and in particular, are considerably genetically related to the Aari people, especially the blacksmith caste of that group.[138][139]
In 150,000 BP, Africans (e.g., Central Africans, East Africans) bearing haplogroup L1 diverged.[93] In 130,000 BP, Africans bearing haplogroup L5 diverged in East Africa.[93] Between 130,000 BP and 75,000 BP, behavioral modernity emerged among Southern Africans and long-term interactions between the regions of Southern Africa and Eastern Africa became established.[93] Between 75,000 BP and 60,000 BP, Africans bearing haplogroup L3 emerged in East Africa and eventually migrated into and became present in modern West Africans, Central Africans, and non-Africans.[93] Amid the Holocene, including the Holocene Climate Optimum in 8000 BP, Africans bearing haplogroup L2 spread within West Africa and Africans bearing haplogroup L3 spread within East Africa.[93] As the largest migration since the Out of Africa migration, migration from Sub-Saharan Africa toward the North Africa occurred, by West Africans, Central Africans, and East Africans, resulting in migrations into Europe and Asia; consequently, Sub-Saharan African mitochondrial DNA was introduced into Europe and Asia.[93] During the early period of the Holocene, 50% of Sub-Saharan African mitochondrial DNA was introduced into North Africa by West Africans and the other 50% was introduced by East Africans.[93] During the modern period, a greater number of West Africans introduced Sub-Saharan African mitochondrial DNA into North Africa than East Africans.[93] Between 15,000 BP and 7000 BP, 86% of Sub-Saharan African mitochondrial DNA was introduced into Southwest Asia by East Africans, largely in the region of Arabia, which constitute 50% of Sub-Saharan African mitochondrial DNA in modern Southwest Asia.[93] In the modern period, 68% of Sub-Saharan African mitochondrial DNA was introduced by East Africans and 22% was introduced by West Africans, which constitutes 50% of Sub-Saharan African mitochondrial DNA in modern Southwest Asia.[93]
While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.[83]
Ancient DNA
Three Later Stone Agehunter-gatherers carried ancient DNA similar to Khoisan-speaking hunter-gatherers.[146] Prior to the Bantu migration into the region, as evidenced by ancient DNA from Botswana, East Africanherders migrated into Southern Africa.[146] Out of four Iron Age Bantu agriculturalists of West African origin, two earlier agriculturalists carried ancient DNA similar to Tsonga and Venda peoples and the two later agriculturalists carried ancient DNA similar to Nguni people; this indicates that there were various movements of peoples in the overall Bantu migration, which resulted in increased interaction and admixing between Bantu-speaking peoples and Khoisan-speaking peoples.[146]
Various Y chromosome studies show that the San carry some of the most divergent (oldest) human Y-chromosome haplogroups. These haplogroups are specific sub-groups of haplogroups A and B, the two earliest branches on the human Y-chromosome tree.[149][150][151]
Mitochondrial DNA
In 200,000 BP, Africans (e.g., Khoisan of Southern Africa) bearing haplogroup L0 diverged from other Africans bearing haplogroup L1′6, which tend to be northward of Southern Africa.[93] Between 130,000 BP and 75,000 BP, behavioral modernity emerged among Southern Africans and long-term interactions between the regions of Southern Africa and Eastern Africa became established.[93]
Mitochondrial DNA studies also provide evidence that the San carry high frequencies of the earliest haplogroup branches in the human mitochondrial DNA tree. This DNA is inherited only from one's mother. The most divergent (oldest) mitochondrial haplogroup, L0d, has been identified at its highest frequencies in the southern African San groups.[149][152][153][154]
Autosomal DNA
Henn et al. (2011) found that the ǂKhomani San, as well as the Sandawe and Hadza peoples of Tanzania, were the most genetically diverse of any living humans studied. This high degree of genetic diversity hints at the origin of anatomically modern humans.[155][156]
Medical DNA
Among the ancient DNA from three hunter-gatherers sharing genetic similarity with San people and four Iron Age agriculturalists, their SNPs indicated that they bore variants for resistance against sleeping sickness and Plasmodium vivax.[157] In particular, two out of the four Iron Age agriculturalists bore variants for resistance against sleeping sickness and three out of the four Iron Age agriculturalists bore Duffy negative variants for resistance against malaria.[157] In contrast to the Iron Age agriculturalists, from among the San-related hunter-gatherers, a six-year-old boy may have died from schistosomiasis.[157] In Botswana, a man, who dates to 1400 BP, may have also carried the Duffy negative variant for resistance against malaria.[157]
Between 500,000 BP and 300,000 BP, anatomically modern humans may have emerged in Africa.[158] As Africans (e.g., Y-Chromosomal Adam, Mitochondrial Eve) have migrated from their places of origin in Africa to other locations in Africa, and as the time of divergence for East African, Central African, and West African lineages are similar to the time of divergence for the Southern African lineage, there is insufficient evidence to identify a specific region for the origin of humans in Africa.[83] In 100,000 BP, anatomically modern humans migrated from Africa into Eurasia.[159] Subsequently, tens of thousands of years after, the ancestors of all present-day Eurasians migrated from Africa into Eurasia and eventually became admixed with Denisovans and Neanderthals.[159]
Archaeological and fossil evidence provide support for the African origin of homo sapiens and behavioral modernity.[160] Models reflecting a pan-African origin (multiple locations of origin within Africa) and evolution of modern humans have been developed.[160] As the idea of "modern" has become increasingly problematized, research has "begun to disentangle what is meant by "modern" genetic ancestry, skeletal morphology, and behavior, recognizing these are unlikely to form a single package."[160]
In comparison to the non-African genome, the African genome features a ~25% greater number of polymorphisms,[95] or
3 to 5 times as many,[111] and genetic variants that are rare outside of Africa are found to occur at an abundant rate within Africa.[95] Most of the genetic diversity found among non-Africans is found to be, at large, a subset of genetic diversity found among Africans.[95] The genomes of Africans commonly found to undergo adaptation are regulatory DNA, and many cases of adaptation found among Africans relate to diet, physiology, and evolutionary pressures from pathogens.[95] Throughout Sub-Saharan Africa, genetic adaptation (e.g., rs334 mutation, Duffy blood group, increased rates of G6PD deficiency, sickle cell disease) to malaria has been found among Sub-Saharan Africans, which may have initially developed in 7300 BP.[95] Throughout Africa, various genetic adaptations (e.g., apolipoprotein L1 (APOL1): G1 and G2 haplotype resistance to trypanosomiasis and increased risk of kidney disease; human leukocyte antigen (HLA) genes; major histocompatibility complex (MHC)) to HIV-1, smallpox, trypanosomiasis (African sleeping sickness), and tuberculosis has been found among Africans.[95]Biomedicaltests for specific genetic variants (e.g., rs1799853 in the CYP2C9 gene), which have been approved by the U.S. Food and Drug Administration and are intended to indicate correct prescription of warfarin, has been found to be increasingly irrelevant to Africans as the variants are rare in Africa.[95] As frequency rate factors into considering and deciding variantpathogenicity and generalizable polygenic scores, modern clinical classifications of genetic variant pathogenicity are found to be inadequate due to a lack of genetic diversity in biomedical studies.[95] Fan et al (2023) recently found ~5.3 million unique genetic variants in 180 African hunter-gatherer populations, and among existing classifications for variants determined to likely be “pathogenic”, ~29% (44/154) of these “pathogenic” classified variants were found to occur frequently among the African hunter-gatherers.[95]
^The lineage leading to the Khoe-San is basal to all other human lineages with an estimated divergence time of 300–200 kya (e.g., the Ju|’Hoan with the lowest level of recent admixture diverged ~270 ± 12 kya).
^Subsequently, the Mbuti (RHG) diverged ~220 ± 10 kya from all other human lineages, forming a second basal lineage (Schlebusch et al. 2020) (fig. 1).
^First, present-day ancestry in North Africans is characterized by an autochthonous Maghrebi component related to a Paleolithic back migration to Africa from Eurasia. ... This result suggests that Iberomaurusian populations in North Africa were related to Paleolithic people in the Levant, but also that migrations of sub-Saharan African origin reached the Maghreb during the Pleistocene. ... This result is consistent with our previous finding that Cushitic ancestry formed by admixture between Nilo-Saharan and Arabian ancestries39. ... While these findings show that a Levant-Neolithic-related population made a critical contribution to the ancestry of present-day eastern Africans (Lazaridis et al., 2016), present-day Cushitic speakers such as the Somali cannot be fit simply as having Tanzania_Luxmanda_3100BP ancestry. The best fitting model for the Somali includes Tanzania_Luxmanda_3100BP ancestry, Dinka-related ancestry, and 16% ± 3% Iranian-Neolithic-related ancestry (p = 0.015). This suggests that ancestry related to the Iranian Neolithic appeared in eastern Africa after earlier gene flow related to Levant Neolithic populations, a scenario that is made more plausible by the genetic evidence of admixture of Iranian-Neolithic-related ancestry throughout the Levant by the time of the Bronze Age (Lazaridis et al., 2016) and in ancient Egypt by the Iron Age (Schuenemann et al., 2017).
^This could either suggest deep population structure with EAHG and southern hunter–gatherer groups tracing some of their ancestries to a basal central African RHG lineage (Lipson et al. 2020, 2022) or gene flow between southern African and central African foragers, as indicated by a distinct allele-sharing pattern between the !Xun/Ju|’Hoan and Mbuti (Scheinfeldt et al. 2019; Bergström et al. 2020; Schlebusch et al. 2020). ... Currently, insufficient data exist to estimate the (even older) Eastern African-Omotic divergence time.
^For the pair of Western and West-Central African ancestries, the point estimate of divergence time was 6,900 years ago. ... Western Africa ancestry is the predominant ancestry among populations from the area around Senegal and the Gambia whereas West-Central African ancestry predominates among populations from the area around Nigeria. ... Comparing two Mandenka and one Gambian to two Esan and one Yoruba, the split time was estimated to be <4,600 years ago, which is expected to be an underestimate compared to the FST-based time because of the presence of 0–11.1% West-Central African ancestry in the Western Africans and 26.7–35.0% Western African ancestry in the West-Central Africans. ... In turn, Eastern African ancestry, which is characteristic of modern Nilotes, and the common ancestor of Western and West-Central African ancestries derived from a common ancestor 18,000 years ago based on decomposition of FST or <13,800 years ago based on msmc analysis of two Dinka compared to either one Gambian and one Mandenka or two Esan. The latter time is relatively underestimated because of the presence of 22.6–26.1% Western or West-Central African ancestry in the Eastern Africans. This common ancestor probably existed in the Nile Valley. ... Currently, insufficient data exist to estimate the (even older) Eastern African-Omotic divergence time.
^Drake N, Breeze P (2016). "Climate Change and Modern Human Occupation of the Sahara from MIS 6-2". Africa from MIS 6-2. Vertebrate Paleobiology and Paleoanthropology. Africa from MIS 6-2. pp. 103–122. doi:10.1007/978-94-017-7520-5_6. ISBN978-94-017-7519-9. S2CID131383927.
^Lipson M, Ribot I, Mallick S, Rohland N, Olalde I, Adamski N, et al. (January 2020). "Ancient West African foragers in the context of African population history". Nature. 577 (7792): 665–670. Bibcode:2020Natur.577..665L. doi:10.1038/s41586-020-1929-1. ISSN1476-4687. PMC8386425. PMID31969706. The West African clade is distinguished by admixture from a deep source that can be modeled as a combination of modern human and archaic ancestry. The modern human component diverges at almost the same point as Central and southern African hunter-gatherers and is tentatively related to the deep source contributing ancestry to Mota, while the archaic component diverges close to the split between Neanderthals and modern humans (Supplementary Information section 3).
^Durvasula A, Sankararaman S (February 2020). "Recovering signals of ghost archaic introgression in African populations". Science Advances. 6 (7): eaax5097. Bibcode:2020SciA....6.5097D. doi:10.1126/sciadv.aax5097. PMC7015685. PMID32095519. "Non-African populations (Han Chinese in Beijing and Utah residents with northern and western European ancestry) also show analogous patterns in the CSFS, suggesting that a component of archaic ancestry was shared before the split of African and non-African populations...One interpretation of the recent time of introgression that we document is that archaic forms persisted in Africa until fairly recently. Alternately, the archaic population could have introgressed earlier into a modern human population, which then subsequently interbred with the ancestors of the populations that we have analyzed here. The models that we have explored here are not mutually exclusive, and it is plausible that the history of African populations includes genetic contributions from multiple divergent populations, as evidenced by the large effective population size associated with the introgressing archaic population...Given the uncertainty in our estimates of the time of introgression, we wondered whether jointly analyzing the CSFS from both the CEU (Utah residents with Northern and Western European ancestry) and YRI genomes could provide additional resolution. Under model C, we simulated introgression before and after the split between African and non-African populations and observed qualitative differences between the two models in the high-frequency–derived allele bins of the CSFS in African and non-African populations (fig. S40). Using ABC to jointly fit the high-frequency–derived allele bins of the CSFS in CEU and YRI (defined as greater than 50% frequency), we find that the lower limit on the 95% credible interval of the introgression time is older than the simulated split between CEU and YRI (2800 versus 2155 generations B.P.), indicating that at least part of the archaic lineages seen in the YRI are also shared with the CEU..."
^[1]Archived 7 December 2020 at the Wayback Machine Supplementary Materials for Recovering signals of ghost archaic introgression in African populations", section "S8.2" "We simulated data using the same priors in Section S5.2, but computed the spectrum for both YRI [West African Yoruba] and CEU [a population of European origin] . We found that the best fitting parameters were an archaic split time of 27,000 generations ago (95% HPD: 26,000-28,000), admixture fraction of 0.09 (95% HPD: 0.04-0.17), admixture time of 3,000 generations ago (95% HPD: 2,800-3,400), and an effective population size of 19,700 individuals (95% HPD: 19,300-20,200). We find that the lower bound of the admixture time is further back than the simulated split between CEU and YRI (2155 generations ago), providing some evidence in favor of a pre-Out-of-Africa event. This model suggests that many populations outside of Africa should also contain haplotypes from this introgression event, though detection is difficult because many methods use unadmixed outgroups to detect introgressed haplotypes [Browning et al., 2018, Skov et al., 2018, Durvasula and Sankararaman, 2019] (5, 53, 22). It is also possible that some of these haplotypes were lost during the Out-of-Africa bottleneck."
^Hawass Z, Ismail S, Selim A, Saleem SN, Fathalla D, Wasef S, et al. (December 2012). "Revisiting the harem conspiracy and death of Ramesses III: anthropological, forensic, radiological, and genetic study". BMJ. 345: e8268. doi:10.1136/bmj.e8268. hdl:10072/62081. PMID23247979. S2CID206896841.
^Podgorná E, et al. (November 2013). "The genetic impact of the lake chad basin population in North Africa as documented by mitochondrial diversity and internal variation of the L3e5 haplogroup". Annals of Human Genetics. 77 (6): 513–523. doi:10.1111/ahg.12040. ISSN0003-4800. OCLC6998015647. PMID25069842. S2CID24672148.
^Marcus J, et al. (2020). "Genetic history from the Middle Neolithic to present on the Mediterranean island of Sardinia". Nature Communications. 11 (939): Supplementary Material p.25. Bibcode:2020NatCo..11..939M. doi:10.1038/s41467-020-14523-6. PMC7039977. PMID32094358. Two very basal R1b-V88 (with several markers still in the ancestral state) appear in Serbian hunter-gatherers as old as 9,000 BCE, which supports a Mesolithic origin of the R1b-V88 clade in or near this broad region. The haplotype appears to have become associated with the Mediterranean Neolithic expansion … it is found in an individual buried at the Els Trocs site in the Pyrenees (modern Aragon, Spain), dated 5,178-5,066 BC and in eleven ancient Sardinians of our sample. Interestingly, markers of the R1b-V88 subclade R1b-V2197, which is at present day found in most African R1b-V88 carriers, are derived only in the Els Trocs individual and two ancient Sardinian individuals. This configuration suggests that the V88 branch first appeared in eastern Europe, mixed into Early European farmer (EEF) individuals (after putatively sex-biased admixture), and then spread with EEF to the western Mediterranean. … A west Eurasian R1b-V88 origin is further supported by a recent phylogenetic analysis that puts modern Sardinian carrier haplotypes basal to the African R1b-V88 haplotypes. The putative coalescence times between the Sardinian and African branches inferred there fall into the Neolithic Subpluvial ("green Sahara", about 7,000 to 3,000 years BCE). Previous observations of autosomal traces of Holocene admixture with Eurasians for several Chadic populations (Haber et al. 2016) provide further support for a hypothesis that at least some amounts of EEF ancestry crossed the Sahara southwards.
^Grugni V, et al. (2019). "Y-chromosome and Surname Analyses for Reconstructing Past Population Structures: The Sardinian Population as a Test Case". International Journal of Molecular Sciences. 20 (5763): 5763. doi:10.3390/ijms20225763. PMC6888588. PMID31744094. The recent and detailed reconstruction of the phylogeny of the R1b-V88 haplogroup has revealed that the rare European R1b-V88 lineages (R1b-M18 and R1b-V35) originated from the root of the phylogeny much earlier (about 12.34 kya) than the separation of the African lineages (7.85 ± 0.90 kya), thus supporting an origin of R1b-V88 outside Africa and a subsequent diffusion in sub-Saharan Africa through the Last Green Sahara period during the Middle-Holocene. Interestingly, recent studies on ancient DNA identified the most ancient R1b-V88 samples (dated 11 and 9 ky) in East Europe (Serbia and Ukraine, respectively) and more recent R1b-V88 samples (dated 7 and 6 ky) in Spain and Germany, thus supporting a European origin
^Allentoft M (2024). "Population genomics of post-glacial western Eurasia". Nature. 625 (7994): Supplementary Information, p.48. Bibcode:2024Natur.625..301A. doi:10.1038/s41586-023-06865-0. PMC10781627. PMID38200295. Newly reported samples belonging to haplogroup R1b were distributed between two distinct groups depending on whether they formed part of the major European subclade R1b1a1b (R1b-M269). Individuals placed outside this subclade were predominantly from Eastern European Mesolithic and Neolithic contexts, and formed part of rare early diverging R1b lineages. Two Ukrainian individuals belonged to a subclade of R1b1b (R1b-V88) found among present-day Central and North Africans, lending further support to an ancient Eastern European origin for this clade.
^Bozzola M, Travaglino P, Marziliano N, Meazza C, Pagani S, Grasso M, et al. (November 2009). "The shortness of Pygmies is associated with severe under-expression of the growth hormone receptor". Molecular Genetics and Metabolism. 98 (3): 310–313. doi:10.1016/j.ymgme.2009.05.009. PMID19541519.
^Schlebusch CM, Naidoo T, Soodyall H (November 2009). "SNaPshot minisequencing to resolve mitochondrial macro-haplogroups found in Africa". Electrophoresis. 30 (21): 3657–3664. doi:10.1002/elps.200900197. PMID19810027. S2CID19515426.