R1b1 (P25) people might have been among the first people to domesticate cattle in eastern Anatolia and northern Mesopotamia/Syria during the Pre-Pottery Neolithic period. P297 branch moved north across the Caucasus to seek grazing grounds for their cattle, while the V88 branch migrated south to the Levant, then to Africa, following the Nile Valley until the Sahel, then spreading westward.
Although human Y chromosomes belonging to haplogroup R1b are quite rare in Africa, being found mainly in Asia and Europe, a group of chromosomes within the paragroup R-P25* are found concentrated in the central-western part of the African continent, where they can be detected at frequencies as high as 95%. Phylogenetic evidence and coalescence time estimates suggest that R-P25* chromosomes (or their phylogenetic ancestor) may have been carried to Africa by an Asia-to-Africa back migration in prehistoric times.
Here, we describe six new mutations that define the relationships among the African R-P25* Y chromosomes and between these African chromosomes and earlier reported R-P25 Eurasian sub-lineages. The incorporation of these new mutations into a phylogeny of the R1b haplogroup led to the identification of a new clade (R1b1a or R-V88) encompassing all the African R-P25* and about half of the few European/west Asian R-P25* chromosomes. A worldwide phylogeographic analysis of the R1b haplogroup provided strong support to the Asia-to-Africa back-migration hypothesis.
The analysis of the distribution of the R-V88 haplogroup in >1800 males from 69 African populations revealed a striking genetic contiguity between the Chadic-speaking peoples from the central Sahel and several other Afroasiatic-speaking groups from North Africa. The R-V88 coalescence time was estimated at 9200–5600 kya, in the early mid Holocene.
We suggest that R-V88 is a paternal genetic record of the proposed mid-Holocene migration of proto-Chadic Afroasiatic speakers through the Central Sahara into the Lake Chad Basin, and geomorphological evidence is consistent with this view.
A date ~8,000 YBP was estimated for the L3f3 sub-haplogroup, which is in good agreement with the supposed migration of Chadic speaking pastoralists and their linguistic differentiation from other Afro-Asiatic groups of East Africa. This is consistent with the date for V88 proposed at 9,200-5,600 years, and is also a very close match for the arrival of the Neolithic in Africa.
The only Afro-Asiatic speaking group that the Chadic speakers plot closely to is Cushitic, which will probably make Blench happy, as he claims Chadic speakers are a split-off from Cushitic speaking pastoralists. It’s fairly obvious that the male line of Chadic speakers followed a path into Africa via the Sinai, then down the West bank of the Nile and then struck out West to Lake Chad, acquiring wives as they went. The only issue is the exact date. Holocene or Neolithic? Whatever the exact date, this brings the argument for an Asian origin for Afro-Asiatic out again, as (from the DNA here) the odds are 50% that it followed the male line in from Asia.
Chadic has cognates for sheep and goats that look like they share a root with Cushitic and Egyptian, which would at least date proto Chadic to the Neolithic, making the mt DNA date of 8,000 more likely to be close to the actual date for V88 to enter Africa.
Human Y chromosome haplogroup R-V88
R1b is the most common haplogroup in Western Europe, reaching over 80% of the population in Ireland, the Scottish Highlands, western Wales, the Atlantic fringe of France, the Basque country and Catalonia. It is also common in Anatolia and around the Caucasus, in parts of Russia and in Central and South Asia.
Besides the Atlantic and North Sea coast of Europe, hotspots include the Po valley in north-central Italy (over 70%), Armenia (35%), the Bashkirs of the Urals region of Russia (50%), Turkmenistan (over 35%), the Hazara people of Afghanistan (35%), the Uyghurs of North-West China (20%) and the Newars of Nepal (11%). R1b-V88, a subclade specific to sub-Saharan Africa, is found in 60 to 95% of men in northern Cameroon.
Haplogroup R* originated in North Asia just before the Last Glacial Maximum (26,500-19,000 years ago). This haplogroup has been identified in the remains of a 24,000 year-old boy from the Altai region, in south-central Siberia. This individual belonged to a tribe of mammoth hunters that may have roamed across Siberia and parts of Europe during the Paleolithic.
Autosomally this Paleolithic population appears to have contributed mostly to the ancestry of modern Europeans and South Asians, the two regions where haplogroup R also happens to be the most common nowadays (R1b in Western Europe, R1a in Eastern Europe, Central and South Asia, and R2 in South Asia).
The oldest forms of R1b (M343, P25, L389) are found dispersed at very low frequencies from Western Europe to India, a vast region where could have roamed the nomadic R1b hunter-gatherers during the Ice Age. The three main branches of R1b1 (R1b1a, R1b1b, R1b1c) all seem to have stemmed from the Middle East.
The southern branch, R1b1c (V88), is found mostly in the Levant and Africa. The northern branch, R1b1a (P297), seems to have originated around the Caucasus, eastern Anatolia or northern Mesopotamia, then to have crossed over the Caucasus, from where they would have invaded Europe and Central Asia. R1b1b (M335) has only been found in Anatolia.
It has been hypothetised that R1b people (perhaps alongside neighbouring J2 tribes) were the first to domesticate cattle in northern Mesopotamia some 10,500 years ago. R1b tribes descended from mammoth hunters, and when mammoths went extinct, they started hunting other large game such as bisons and aurochs.
With the increase of the human population in the Fertile Crescent from the beginning of the Neolithic (starting 12,000 years ago), selective hunting and culling of herds started replacing indiscriminate killing of wild animals.
The increased involvement of humans in the life of aurochs, wild boars and goats led to their progressive taming. Cattle herders probably maintained a nomadic or semi-nomadic existence, while other people in the Fertile Crescent (presumably represented by haplogroups E1b1b, G and T) settled down to cultivate the land or keep smaller domesticates.
The analysis of bovine DNA has revealed that all the taurine cattle (Bos taurus) alive today descend from a population of only 80 aurochs. The earliest evidence of cattle domestication dates from circa 8,500 BCE in the Pre-Pottery Neolithic cultures in the Taurus Mountains.
The two oldest archaeological sites showing signs of cattle domestication are the villages of Çayönü Tepesi in southeastern Turkey and Dja’de el-Mughara in northern Iraq, two sites only 250 km away from each others. This is presumably the area from which R1b lineages started expanding – or in other words the “original homeland” of R1b.
The early R1b cattle herders would have split in at least three groups. One branch (M335) remained in Anatolia, but judging from its extreme rarity today wasn’t very successful, perhaps due to the heavy competition with other Neolithic populations in Anatolia, or to the scarcity of pastures in this mountainous environment.
A second branch migrated south to the Levant, where it became the V88 branch. Some of them searched for new lands south in Africa, first in Egypt, then colonising most of northern Africa, from the Mediterranean coast to the Sahel.
The third branch (P297), crossed the Caucasus into the vast Pontic-Caspian Steppe, which provided ideal grazing grounds for cattle. They split into two factions: R1b1a1 (M73), which went east along the Caspian Sea to Central Asia, and R1b1a2 (M269), which at first remained in the North Caucasus and the Pontic Steppe between the Dnieper and the Volga.
It is not yet clear whether M73 actually migrated across the Caucasus and reached Central Asia via Kazakhstan, or if it went south through Iran and Turkmenistan. In the latter case, M73 might not be an Indo-European branch of R1b, just like V88 and M335.
R1b-M269 (the most common form in Europe) is closely associated with the diffusion of Indo-European languages, as attested by its presence in all regions of the world where Indo-European languages were spoken in ancient times, from the Atlantic coast of Europe to the Indian subcontinent, which comprised almost all Europe (except Finland, Sardinia and Bosnia-Herzegovina), Anatolia, Armenia, European Russia, southern Siberia, many pockets around Central Asia (notably in Xinjiang, Turkmenistan, Tajikistan and Afghanistan), without forgetting Iran, Pakistan, northern India and Nepal. The history of R1b and R1a are intricately connected to each others.
Like its northern counterpart (R1b-M269), R1b-V88 is associated with the domestication of cattle in northern Mesopotamia. Both branches of R1b probably split soon after cattle were domesticated, approximately 10,500 years ago (8,500 BCE). R1b-V88 migrated south towards the Levant and Egypt.
The migration of R1b people can be followed archeologically through the presence of domesticated cattle, which appear in central Syria around 8,000-7,500 BCE (late Mureybet period), then in the Southern Levant and Egypt around 7,000-6,500 BCE (e.g. at Nabta Playa and Bir Kiseiba).
Cattle herders subsequently spread across most of northern and eastern Africa. The Sahara desert would have been more humid during the Neolithic Subpluvial period (c. 7250-3250 BCE), and would have been a vast savannah full of grass, an ideal environment for cattle herding.
Evidence of cow herding during the Neolithic has shown up at Uan Muhuggiag in central Libya around 5500 BCE, at the Capeletti Cave in northern Algeria around 4500 BCE. But the most compelling evidence that R1b people related to modern Europeans once roamed the Sahara is to be found at Tassili n’Ajjer in southern Algeria, a site famous pyroglyphs (rock art) dating from the Neolithic era. Some painting dating from around 3000 BCE depict fair-skinned and blond or auburn haired women riding on cows.
After reaching the Maghreb, R1b-V88 cattle herders could have crossed the Strait of Gibraltar to Iberia, probably accompanied by G2 farmers, J1 and T1a goat herders and native Maghreban E-M81 lineages. These Maghreban Neolithic farmers/herders could have been the ones who established the Almagra Pottery culture in Andalusia in the 6th millennium BCE.
Nowadays small percentages (1 to 4%) of R1b-V88 are found in the Levant, among the Lebanese, the Druze, and the Jews, and almost in every country in Africa north of the equator. Higher frequency in Egypt (5%), among Berbers from the Egypt-Libya border (23%), among the Sudanese Copts (15%), the Hausa people of Sudan (40%), the the Fulani people of the Sahel (54% in Niger and Cameroon), and Chadic tribes of northern Nigeria and northern Cameroon (especially among the Kirdi), where it is observed at a frequency ranging from 30% to 95% of men.
R1b-V88 would have crossed the Sahara between 9,200 and 5,600 years ago, and is most probably associated with the diffusion of Chadic languages, a branch of the Afroasiatic languages.
V88 would have migrated from Egypt to Sudan, then expanded along the Sahel until northern Cameroon and Nigeria. However, R1b-V88 is not only present among Chadic speakers, but also among Senegambian speakers (Fula-Hausa) and Semitic speakers (Berbers, Arabs).
R1b-V88 is found among the native populations of Rwanda, South Africa, Namibia, Angola, Congo, Gabon, Equatorial Guinea, Ivory Coast, Guinea-Bissau. The wide distribution of V88 in all parts of Africa, its incidence among herding tribes, and the coalescence age of the haplogroup all support a Neolithic dispersal. In any case, a later migration out of Egypt would be improbable since it would have brought haplogroups that came to Egypt during the Bronze Age, such as J1, J2, R1a or R1b-L23.
R1b is a sub-clade within the much larger Eurasian MNOPS “macro-haplogroup”, which is one of the predominant groupings of all the rest of human male lines outside of Africa, and this whole group, along indeed with all of macro-haplogroup F, is believed to have originated in Asia.
Early research focused upon Europe. In 2000 Ornella Semino and colleagues argued that R1b had been in Europe before the end of the Ice Age, and had spread north from an Iberian refuge after the Last Glacial Maximum.
Age estimates of R1b in Europe have steadily decreased in more recent studies, at least concerning the majority of R1b, with more recent studies suggesting a Neolithic age or younger. Only Morelli et al. have recently attempted to defend a Palaeolithic origin for R1b1b2.
Irrespective of STR coalescence calculations, Chikhi et al. pointed out that the timing of molecular divergences does not coincide with population splits; the TMRCA of haplogroup R1b (whether in the Palaeolithic or Neolithic) dates to its point of origin somewhere in Eurasia, and not its arrival in western Europe.
However, Michael R. Maglio argues that the closest branch of R1b is from Iberia and its small subclades found in West Asia, the Near East and Africa are examples of back migration, and not of its origin.
Barbara Arredi and colleagues were the first to point out that the distribution of R1b STR variance in Europe forms a cline from east to west, which is more consistent with an entry into Europe from Western Asia with the spread of farming.
A 2009 paper by Chiaroni et al. added to this perspective by using R1b as an example of a wave haplogroup distribution, in this case from east to west. The proposal of a southeastern origin of R1b were supported by three detailed studies based on large datasets published in 2010. These detected that the earliest subclades of R1b are found in western Asia and the most recent in western Europe.
While age estimates in these articles are all more recent than the Last Glacial Maximum, all mention the Neolithic, when farming was introduced to Europe from the Middle East as a possible candidate period.
Myres et al. (August 2010), and Cruciani et al. (August 2010) both remained undecided on the exact dating of the migration or migrations responsible for this distribution, not ruling out migrations as early as the Mesolithic or as late as Hallstatt but more probably Late Neolithic. They noted that direct evidence from ancient DNA may be needed to resolve these gene flows.
Lee et al. (May 2012) analysed the ancient DNA of human remains from the Late Neolithic Bell Beaker site of Kromsdorf, Germany identifying two males as belonging to the Y haplogroup R1b.
Analysis of ancient Y DNA from the remains of populations derived from early Neolithic settlements such as the Mediterranean Cardium and Central and North European LBK settlements have found an absence of males belonging to haplogroup R1b.
Although human Y chromosomes belonging to haplogroup R1b are quite rare in Africa, being found mainly in Asia and Europe, a group of chromosomes within the paragroup R-P25* are found concentrated in the central-western part of the African continent, where they can be detected at frequencies as high as 95%.
Phylogenetic evidence and coalescence time estimates suggest that R-P25* chromosomes (or their phylogenetic ancestor) may have been carried to Africa by an Asia-to-Africa back migration in prehistoric times.
Here, we describe six new mutations that define the relationships among the African R-P25* Y chromosomes and between these African chromosomes and earlier reported R-P25 Eurasian sub-lineages.
The incorporation of these new mutations into a phylogeny of the R1b haplogroup led to the identification of a new clade (R1b1a or R-V88) encompassing all the African R-P25* and about half of the few European/west Asian R-P25* chromosomes.
A worldwide phylogeographic analysis of the R1b haplogroup provided strong support to the Asia-to-Africa back-migration hypothesis. The analysis of the distribution of the R-V88 haplogroup in >1800 males from 69 African populations revealed a striking genetic contiguity between the Chadic-speaking peoples from the central Sahel and several other Afroasiatic-speaking groups from North Africa. The R-V88 coalescence time was estimated at 9200–5600 kya, in the early mid Holocene.
We suggest that R-V88 is a paternal genetic record of the proposed mid-Holocene migration of proto-Chadic Afroasiatic speakers through the Central Sahara into the Lake Chad Basin, and geomorphological evidence is consistent with this view.
The age of R-V88 can be younger than 4.2–8.2 ky, and could be as young as ~3-4ky in a rapidly expanding population. To determine how fast R-V88 actually grew, we must take into account its present-day demographic size (how many people in the world now possess it). The final estimate must be consistent with both the demographic size and the current Y-STR variance.
I don’t have data on R-V88 prevalence today, but it really doesn’t take a very large haplogroup in order to infer a very fast growth rate, and a Y-STR variance accumulation rate (effective rate) close to the germline one. Therefore, I am guessing that R-V88 is also one of a growing palette of haplogroups that expanded during the Bronze Age.
The maternal lineages (mtDNA) corresponding to haplogroup R1b
Haplogroup R1b is very widespread in most of Europe and across vast swathes of North Africa, the Middle East and Central Asia today. As R1b Indo-Europeans advanced from the Pontic-Caspian Steppe by marrying local women as well as Indo-European women, it is difficult to estimate what were the original mtDNA haplogroups of R1b people back in the steppes, or prior to that in the Neolithic Near East or Paleolithic Eurasia.
The most likely potential original maternal lineages of R1b tribes before they started mixing with other Near Eastern populations is the mt-haplogroups H8c, H15, J1b1a, U5 and V. Looking at deeper subclades, J1b1a and T1a1a display extremely strong correlations with the distribution of Y-haplogroup R1b.
The maternal lineages associated with the spread of R1b-V88 in Africa are mtDNA haplogroups J1b, U5 and V, and perhaps also U3 and some H subclades.
One way of determining what mt-haplogroups R1b tribes carried at the very beginning of the Neolithic, 10,000 years ago, is to compare the above haplogroups with those of African ethnic groups known to possess elevated percentages of R1b-V88.
The best studied group are the Fulani, whose mtDNA include three European-looking haplogroupss J1b1a, U5 and V making up about 15% of their total maternal lineages. These haplogroups have been identified in all four Central African countries sampled, confirming a strong correlation with haplogroup R1b.
Since African R1b-V88 and Eurasian haplogroup R1b-P297 split roughly 10,000 years ago, there is little doubt that J1b, U5 and V were three of the original maternal lineages of R1b people. Only the J1b1b subclade seems to be related to the propagation of Y-haplogroup R1b. Other J1b subclades are geographically restricted to the Near East, particularly from the Caucasus to the Arabian Peninsula.
J1b might have been the first indigenous Near Eastern lineage assimilated by R1b tribes when they moved into the region (presumably from Russia or Iran, or the Caspian Sea, which was only formed by the melting of Russian glaciers just before the Neolithic began).
If that is the case, the Paleolithic R1b people would have belonged exclusively to mtDNA U5 and V, just like the modern Sami, and like a lot of Mesolithic Europeans.
The lactase persistence allele and R1b cattle pastoralists
Lactose (milk sugar) is an essential component of breast milk consumed by infants. Its digrestion is made possible by an enzyme, called lactase, which breaks down lactose in simple sugars that can be absorbed through the intestinal walls and into the bloodstream.
In most mammals (humans included), the production of the lactase enzyme is dramatically reduced soon after weaning. As a result, older children and adults become lactose intolerant. That is true of a big part of the world population. Some people possess a genetic mutation that allows the production of lactase through adulthood. This is called lactase persistence (LP).
Lactase persistence is particularly common among Northwest Europeans, descended from the ancient Celtic and Germanic people, and in parts of Africa where cattle herding has been practiced for thousands of years.
The highest incidence for the lactase persistence alleles, known to geneticists as -13,910*T (rs4988235) and -22018*A (rs182549), are found among Scandinavian, Dutch, British, Irish and Basque people. Sub-Saharan populations with lactase persistence have different mutations, such as -14010*C, -13915*G and -13907*G.
R1b men are thought to be the first people on earth to successfully domesticate cattle and to develop a lifestyle based on cattle husbandry and herding during the Pre-Pottery Neolithic (see Neolithic section).
Looking for pasture for their cows, R1b tribes migrated from the Near East to the savannah of North Africa (which has since underwent desertification and become the Sahara) and to the Pontic Steppe in southern Russia and Ukraine. For several millennia no other human population was so depended on cattle for their survival as these R1b tribes.
It is known that most Neolithic herding societies consumed at least some animal milk and even made cheese from it (since cheese contains less lactose and is easier to digest for people who are lactose intolerant).
In most of Europe, the Middle East and South Asia, people essentially herded goats and sheep, better suited to mountainous environment of the Mediterranean basin, Anatolia and Iran. Goats and sheep could also be kept easily inside villages by sedentary cereal cultivators, while cows needed vast pastures for grazing, which were particularly scare in the Middle East.
Domesticated cattle were sometimes found in small number among other Neolithic populations, but the ones that relied almost entirely on them were the R1b tribes of the Pontic Steppe and North Africa.
To this very day, semi-nomadic pastoralists in the Sahel, such as the Fulani and the Hausa, who are descended from Neolithic R1b-V88 migrants from the Near East, still maintain primarily herds of cattle. It is among these cattle herders that selective pressure for lactase persistence would have been the strongest.
There has been speculations among geneticists and evolutionary biologists regarding the origin of the lactase persistence allele in Europeans. Over 100 ancient DNA samples have been tested from Mesolithic, Neolithic and Bronze Age Europe and Syria, and the -13910*T allele has been found only in Late Neolithic/Chalcolithic and Bronze Age individuals.
The origin of the mutation does not really matter, since it could have been present at low frequencies in the human gene pool for tens of thousands of years before it underwent postive selective pressure among cattle-herding societies.
What is certain is that individuals from Bronze Age cultures associated with the arrival of Indo-European speakers from the Pontic Steppe already possessed relatively high percentages of the LP allele.
For example the LP allele was found at a frequency of 27% among the 13 individuals from the Lichtenstein Cave in Germany, who belonged to the Urnfield culture, and was a mix of Y-haplogroups R1b, R1a and I2a2b.
Nowadays, the LP allele is roughly proportional to the percentage of R1b, and to a lower extent R1a, found in a population. In the British Isles, the Low Countries and south-west Scandinavia, where LP is the highest in the world, the combined percentage of R1a and R1b exceeds 70% of the population.
In Iberia, the highest percentage of LP is observed among the Basques, who have the highest percentage of R1b. In Italy, LP is most common in the north, like R1b. The lowest incidence of LP in Europe are found in South Italy, Greece and the Balkans, the regions that have the least R1b lineages.
R1 populations spread genes for light skin, blond hair and red hair
There is now strong evidence that both R1a and R1b people contributed to the diffusion of the A111T mutation of the SLC24A5, which explains apporximately 35% of skin tone difference between Europeans and Africans, and most variations within South Asia.
The distribution pattern of the A111T allele (rs1426654) of matches almost perfectly the spread of Indo-European R1a and R1b lineages around Europe, the Middle East, Central Asia and South Asia.
The mutation was probably passed on in the Early neolithic to other Near Eastern populations, which explains why Neolithic farmers in Europe already carried the A111T allele (e.g. Keller 2012 p.4, Lazaridis 2014 suppl. 7), although at lower frequency than modern Europeans and southern Central Asians.
The light skin allele is also found at a range of 15 to 30% in in various ethnic groups in northern sub-Saharan Africa, mostly in the Sahel and savannah zones inhabited by tribes of R1b-V88 cattle herders like the Fulani and the Hausa. This would presuppose that the A111T allele was already present among all R1b people before the Pre-Pottery Neolithic split between V88 and P297.
R1a populations have an equally high incidence of this allele as R1b populations. On the other hand, the A111T mutation was absent from the 24,000-year-old R* sample from Siberia, and is absent from most modern R2 populations in Southeast India and Southeast Asia.
Consequently, it can be safely assumed that the mutation arose among the R1* lineage during the late Upper Paleolithic, probably some time between 20,000 and 13,000 years ago.
Fair hair was another physical trait associated with the Indo-Europeans. In contrast, the genes for blue eyes were already present among Mesolithic Europeans belonging to Y-haplogroup I. The genes for blond hair are more strongly correlated with the distribution of haplogroup R1a, but those for red hair have not been found in Europe before the Bronze Age, and appear to have been spread primarily by R1b people.
Afro-Asiatic
The expansion of the Bantu-speaking people (EBSP) during the past 3000–5000 years is an event of great importance in the history of humanity. Anthropology, archaeology, linguistics and, in recent decades, genetics have been used to elucidate some of the events and processes involved. Although it is generally accepted that the EBSP has its origin in the so-called Bantu Homeland situated in the area of the border between Nigeria and the Grassfields of Cameroon, and that it followed both western and eastern routes, much less is known about the number and dates of those expansions, if more than one.
All the evidence thus far points that R1b in West Africa appears 6,000-9,000 years ago, so there’s no reason to believe R1b is original from Africa. It is far more likely that R-V88 originated in SW Asia before it was transferred to Central-West Africa. R-V88 is found in the Near East with more diversity (i.e. STR variance) than in Africa.
It seems that there was an original dispersion of E across North and West Africa that coincided with the dispersion of the Afro-Asiatic languages or probably earlier, and then another dispersion of E across Central, South and East Africa with the dispersion of the Bantu languages. Before the Bantu expansions, sub-Saharan Africa was a very different place.
Several branches of humanity’s Y DNA family tree have been proposed as having an association with the spread of Afroasiatic languages. In general, Afroasiatic speaking populations have relatively high frequencies of haplogroup E1b1b, thought to have originated in Horn of Africa, with the notable exception of Chadic speaking populations.
Christopher Ehret and Shomarka Keita have suggested that the geography of the E1b1b lineage coincides with the distribution of Afroasiatic languages.
Haplogroup R1b1a (R-V88), and specifically its sub-clade R-V69, has a very strong relationship with Chadic speaking populations, who unlike other Afroasiatic speakers have low frequencies of Haplogroup E1b1b.
The majority of R-V88 was found in northern and central Africa, in Chadic speaking populations. It is less common in neighbouring populations. The authors also found evidence of high concentration in Western Egypt and evidence that the closest related types of R1b are found in the Middle East, and to a lesser extent southern Europe.
They proposed that an Eastern Saharan origin for Chadic R1b would agree with linguistic theories such as those of Christopher Ehret, that Chadic and Berber form a related group within Afroasiatic, which originated in the area of the Sahara.
In contrast to the evidence from paternally inherited Y DNA, a recent study has shown that a branch of mitochondrial haplogroup L3 links the maternal ancestry of Chadic speakers from the Sahel with Cushitic speakers from Horn of Africa.
Other mitochondrial lineages that are associated with Afroasiatic include mitochondrial haplogroups M1 and haplogroup U6. Gonzalez et al. 2007 suggest that Afroasiatic speakers may have dispersed from Horn of Africa carrying the subclades M1a and U6a1.
According to an autosomal DNA study by Hodgson et al. (2014), the Afroasiatic languages were likely spread across Africa and the Near East by an ancestral population(s) carrying a newly identified non-African genetic component, which the researchers dub the “Ethio-Somali”.
This Ethio-Somali component is today most common among Afroasiatic-speaking populations in the Horn of Africa. It is most closely related to the Maghrebi non-African genetic component, and is believed to have diverged from all other non-African ancestries at least 23,000 years ago.
On this basis, the researchers suggest that the original Ethio-Somali carrying population(s) probably arrived in the pre-agricultural period from the Near East, having crossed over into northeastern Africa via the Sinai peninsula. The population then likely split into two branches, with one group heading westward toward the Maghreb and the other moving south into the Horn.
A related hypothesis that associates the origin of the ancestors of Afroasiatic speakers as the result of a reflux population from Southwest Asia during the Late Palaeolithic was previously put forward by Daniel McCall.
Afro-Asiatic Languages and Uniparental Genetic Markers
The westward wanderings of Cushitic pastoralists
Retracing the mtDNA haplogroups of the original R1b people
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