Modern human migrations

Early human migrations are the earliest of  across continents and are believed to have begun approximately 2 million years ago with the  migration of . This initial migration was followed by other including , which lived around 500,000 years ago and was the likely ancestor of both s and s. Early hominids were said to have "crossed land bridges that were eventually covered in water" (History Alive, pub. 2004, TCI).

Within Africa,  dispersed around the time of its speciation, roughly 300,000 years ago. The paradigm suggests that the anatomically modern humans outside of Africa descend from a population of Homo sapiens migrating from  roughly 60-70,000 years ago and spreading  of Asia and to Oceania before 50,000 years ago. Modern humans spread about 40,000 years ago.

Early Eurasian Homo sapiens fossils have been found in Israel and Greece, dated to 194,000-177,000 and 210,000 years old respectively. These fossils seem to represent failed dispersal attempts by early Homo sapiens, who were likely replaced by local Neanderthal populations.

The migrating modern human populations are known to have with local varieties of archaic humans, so that contemporary human populations are descended in small part (below 10% contribution) from regional varieties of archaic humans.

After the, populations migrated  about 20,000 years ago. Northern Eurasia was peopled after 12,000 years ago, in the beginning. Arctic Canada and Greenland were reached by the expansion around 4,000 years ago. Finally, was peopled after 2,000 years ago, by the.

Early humans (before Homo sapiens)
The developed out of  ancestors after about 3 million years ago, most likely in, most likely in the area of the , where the  were found. Stone tools recently discovered at the site in China and dated to 2.12 million years ago are claimed to be the earliest known evidence of hominins outside Africa, surpassing Dmanisi in Georgia by 300,000 years.

Homo erectus
Between 3 and 2 million years ago, ' spread throughout East Africa and to ('), but not yet to West Africa. Around 1.9 million years ago,   via the  and  to. This migration has been proposed as being related to the operation of the, around 1.9 million years ago. Homo erectus dispersed throughout most of the, reaching as far as. Its distribution is traced by the lithic industry, by 1.3 million years ago extending as far north as the.

Key sites for this early migration out of Africa are in Pakistan (~2 Ma?),  in the Levant (1.5 Ma) and  in the Caucasus (1.81 ± 0.03 Ma, =0.05).

was populated as early as 1.66 Mya based on stone artifacts found in the. The archaeological site of (西侯渡) in  Province is the earliest recorded  by Homo erectus, which is dated 1.27 million years ago.

was reached about 1.7 million years ago. Western  was first populated around 1.2 million years ago.

Robert G. Bednarik has suggested that Homo erectus may have built rafts and sailed oceans, a theory that has raised some controversy.

After H. erectus
One million years after its dispersal, H. erectus was diverging into new species. H. erectus is a and was never extinct, so that its "late survival" is a matter of taxonomic convention. Late forms of H. erectus are thought to have survived until after about 0.5 million ago to 143,000 years ago at the latest, with derived forms classified as ' in Europe around 800,000 years ago and ' in Africa around 600,000 years ago. H. heidelbergensis in its turn spread across East Africa () and to Eurasia, where it gave rise to and.

H. heidelbergensis, Neanderthals and Denisovans expanded north beyond the ( 500kya,  400kya,  50 kya). It has been suggested that late Neanderthals may even have reached the boundary of the, by c. 32,000 years ago, when they were being displaced from their earlier habitats by H. sapiens, based on 2011 excavations at the site of Byzovaya in the (, 65.02°N, 57.42°W).

Other archaic human species are assumed to have spread throughout Africa by this time, although the fossil record is sparse. Their presence is assumed based on traces of with modern humans found in the genome of African populations. , discovered in South Africa in 2013 and tentatively dated to about 300,000 years ago, may represent fossil evidence of such an archaic human species.

Neanderthals spread across the Near East and Europe, while Denisovans appear to have spread across Central and East Asia and to Southeast Asia and Oceania. There is evidence that Denisovans interbred with Neanderthals in Central Asia where their habitats overlapped.

Dispersal throughout Africa
 are assumed to have emerged about 300,000 years ago based on thermoluminescence dating of artefacts and remains from, Morocco, published in 2017. Previously, the, excavated between 1967 and 1974 in , , and dated to 200,000 years ago, were long held to be the oldest known fossils of anatomically modern humans.

In July 2019, anthropologists reported the discovery of 210,000 year old remains of a H. sapiens and 170,000 year old remains of a H. neanderthalensis in in southern, more than 150,000 years older than previous H. sapiens finds in Europe.

Early modern humans expanded to Western Eurasia, Central, Western and Southern Africa from the time of their emergence. While to Eurasia appear not to have persisted, expansions to  and  resulted in the deepest temporal divergence in living human populations. Early modern human expansion in sub-Saharan Africa appears to have contributed to the end of late  industries at about 130,000 years ago, although very late coexistence of archaic and early modern humans, until as late as 12,000 years ago, has been argued for West Africa in particular.

The ancestors of the modern expanded to Southern Africa before 150,000 years ago, possibly as early as before 260,000 years ago, so that by the beginning of the  "", 130,000 years ago, there were two ancestral population clusters in Africa, bearers of  in southern Africa, ancestral to the Khoi-San, and bearers of  in central/eastern Africa, ancestral to everyone else. There was a significant back-migration of bearers of L0 towards eastern Africa between 120 and 75 kya.

Expansion to Central Africa, by the ancestors of the populations (African Pygmies) most likely took place before 130,000 years ago, and certainly before 60,000 years ago.

The situation in is difficult to interpret due to a sparsity of fossil evidence. Homo sapiens seems to have reached the western by 130 kya, while tropical West African sites associated with H. sapiens are known only from after 130 kya. Unlike elsewhere in Africa, archaic sites appear to persist until very late, down to the Holocene boundary (12 kya), pointing to the possibility of late survival of s, and late  with H. sapiens in West Africa.

Early northern Africa dispersal
Populations of H. sapiens migrated to the Levant and to Europe between 130,000 and 115,000 years ago, and possibly in earlier waves as early as 185,000 years ago. These early migrations do not appear to have led to lasting colonisation and receded by about 80,000 years ago. There is a possibility that this first wave of expansion may have reached China (or even North America) as early as 125,000 years ago, but would have died out without leaving a trace in the genome of contemporary humans.

There is some evidence that modern humans left Africa at least 125,000 years ago using two different routes: through the heading to the Middle East, at least into modern Israel (: 120,000–100,000 years ago); and a second route through the present-day  Strait on the Red Sea (at that time, with a much lower sea level and narrower extension), crossing to the Arabian Peninsula and settling in places like the present-day United Arab Emirates (125,000 years ago) and Oman (106,000 years ago), and possibly reaching the Indian Subcontinent (: 75,000 years ago). Although no human remains have yet been found in these three places, the apparent similarities between the stone tools found at, those from Jwalapuram and some from Africa suggest that their creators were all modern humans. These findings might give some support to the claim that modern humans from Africa arrived at southern China about 100,000 years ago (,, City: 100,000 years ago; and the  : controversially dated at 139,000–111,000 years ago ). Dating results of the (,, southern China) teeth, which include a right upper second molar and a left lower second molar, indicate that the molars may be as old as 126,000 years. Since these previous exits from Africa did not leave traces in the results of genetic analyses based on the Y chromosome and on MtDNA (which represent only a small part of the human genetic material), it seems that those modern humans did not survive in large numbers and were assimilated by our major antecessors. An explanation for their extinction (or small genetic imprint) may be the (74,000 years ago), though some argue it scarcely impacted human population.

An center of origin and dispersal for the mtDNA  has also been hypothesized based on the fossil record, the similar coalescence dates of L3 and its Eurasian-distributed  and  derivative clades (~71 kya), the distant location in  of the oldest subclades of M and N, and the comparable age of the paternal haplogroup. After an initial Out-of-Africa migration of early s around 125 kya, fully modern human L3-carrying females are thus proposed to have back-migrated from the maternal haplogroup's place of origin in Eurasia around 70 kya along with males bearing the paternal haplogroup, which is also proposed to have originated in Eurasia. These new Eurasian lineages are then suggested to have largely replaced the old autochthonous male and female African lineages.

Other research suggests that earlier waves of modern human migration out of Africa mostly became extinct (contributing about 2% to the ancestry only of some Oceanian peoples such as Papuans) and that instead modern Eurasians descend from a single Out-of-Africa migration occurring approximately 50,000-70,000 years ago  associated with the expansion of maternal haplogroup L3.

Coastal migration
The so-called "" of modern humans has taken place after beginning about 70,000 years ago. It is this migration wave that led to the lasting spread of modern humans throughout the world.

A small group from a population in East Africa, bearing mitochondrial haplogroup and numbering possibly fewer than 1,000 individuals, crossed the  strait at, to what is now , after around 75,000 years ago. A recent review has also shown support for the northern route through Sinai/Israel/Syria (Levant). Their descendants spread along the around  and  to the  before 55,000 years ago. The coastal migration between roughly 70,000 and 50,000 years ago is associated with mitochondrial haplogroups and, both derivative of L3.

A fragment of a jawbone with eight teeth found at, Israel, has been dated to around 185,000 years ago. Layers dating from between 250,000 and 140,000 years ago in the same cave contained tools of the type which could put the date of the first migration even earlier if the tools can be associated with the modern human jawbone finds.

Along the way H. sapiens interbred with Neanderthals and Denisovans, with Denisovan DNA making 0.2% of mainland Asian and Native American DNA.

Oceania
Migrations continued along the Asian coast to Southeast Asia and Oceania, colonising before 50,000 years ago. By reaching Australia, H. sapiens for the first time expanded its habitat beyond that of H. erectus. Denisovan ancestry is shared by Melanesians,, and smaller scattered groups of people in Southeast Asia, such as the , a people in the , suggesting the interbreeding took place in Eastern Asia where the Denisovans lived. Denisovans may have crossed the, with serving as their last. Homo erectus had crossed the Lombok gap reaching as far as Flores, but never made it to Australia.

During this time sea level was much lower and most of formed one land mass known as. Migration continued Southeast on the to the s between Sunda and, the continental land mass of present-day Australia and. The gaps on the are up to 90 km wide, so the migration to Australia and New Guinea would have required seafaring skills. Migration also continued along the coast eventually turning northeast to and finally reaching  before turning inland. This is evidenced by the pattern of descended from, and in.

Sequencing of one Aboriginal genome from an old hair sample in Western Australia, revealed that the individual was descended from people who migrated into East Asia between 62,000 and 75,000 years ago. This supports the theory of a single migration into Australia and New Guinea before the arrival of Modern Asians (between 25,000 and 38,000 years ago) and their later migration into North America. This migration is believed to have happened around 50,000 years ago, before Australia and New Guinea were separated by rising sea levels approximately 8,000 years ago. This is supported by a date of 50,000–60,000 years ago for the oldest evidence of settlement in Australia, around 40,000 years ago for the oldest human remains, the earliest humans artifacts which are at least 65,000 years old and the extinction of the by humans between 46,000 and 15,000 years ago argued by Tim Flannery, which is similar to what happened in the Americas. The continued use of stone age tools in Australia has been much debated.

Dispersal throughout Eurasia
The population brought to by  appears to have remained there for some time, during roughly 60,000 to 50,000 years ago, before spreading further throughout Eurasia. This dispersal of early humans, at the beginning of the, gave rise to the major population groups of the and the.

Towards the West, Upper Paleolithic populations associated with mitochondrial haplogroup and its derivatives, spread throughout Asia and Europe, with a back-migration of  to North Africa and the Horn of Africa several millennia ago.

Presence is certain after 40,000 years ago, possibly as early as 43,000 years ago, rapidly replacing the Neanderthal population. Contemporary Europeans have, but it seems likely that substantial interbreeding with Neanderthals ceased before 47,000 years ago, i.e. took place before modern humans entered Europe.

There is evidence from that modern humans have passed through at least one, in which genome diversity was drastically reduced. has proposed that humans spread from a geographically restricted area about 100,000 years ago, the passage through the geographic bottleneck and then with a dramatic growth amongst geographically dispersed populations about 50,000 years ago, beginning first in Africa and thence spreading elsewhere. Climatological and geological evidence suggests evidence for the bottleneck. The explosion of, the largest volcanic eruption of the , may have created a 1,000 year cold period, potentially reducing human populations to a few tropical refugia. It has been estimated that as few as 15,000 humans survived. In such circumstances genetic drift and may have been maximised. The greater diversity amongst African genomes may be reflect the extent of African refugia during the Toba incident. However, a recent review highlights that the single-source hypothesis of non-African populations is less consistent with ancient DNA analysis than multiple sources with genetic mixing across Eurasia.

Europe
The recent expansion of reached Europe around 40,000 years ago from Central Asia and the Middle East, as a result of cultural adaption to big game hunting of sub-glacial steppe fauna. were present both in the Middle East and in Europe, and the arriving populations of anatomically modern humans (also known as "" or ) to a limited degree. Populations of modern humans and Neanderthal overlapped in various regions such as the Iberian peninsula and the Middle East. Interbreeding may have contributed Neanderthal genes to palaeolithic and ultimately modern Eurasians and Oceanians.

An important difference between Europe and other parts of the inhabited world was the northern latitude. Archaeological evidence suggests humans, whether Neanderthal or Cro-Magnon, reached by 40,000 years ago.

Cro-Magnon are considered the first anatomically modern humans in Europe. They entered by the  (near present-day  and eastern ) around 50,000 years ago, with one group rapidly settling coastal areas around the  and another migrating north to the steppes of. Modern human remains dating to 43–45,000 years ago have been discovered in Italy and Britain, as well as in the European Russian Arctic from 40,000 years ago.

Humans colonised the environment west of the Urals, hunting reindeer especially, but were faced with adaptive challenges; winter temperatures averaged from −20 to −30 °C with fuel and shelter scarce. They travelled on foot and relied on hunting highly mobile herds for food. These challenges were overcome through technological innovations: tailored clothing from the pelts of fur-bearing animals; construction of shelters with hearths using bones as fuel; and digging “ice cellars” into the permafrost to store meat and bones.

A sequence of two Cro-Magnons from the  in Italy, dated to 23,000 and 24,000 years old (Paglicci 52 and 12), identified the  as, typical of the latter group.

The expansion of modern human population is thought to have begun 45,000 years ago, and it may have taken 15,000–20,000 years for Europe to be colonized.

During this time, the Neanderthals were slowly being displaced. Because it took so long for Europe to be occupied, it appears that humans and Neanderthals may have been constantly competing for territory. The Neanderthals had larger brains, and were larger overall, with a more robust or heavily built frame, which suggests that they were physically stronger than modern Homo sapiens. Having lived in Europe for 200,000 years, they would have been better adapted to the cold weather. The anatomically modern humans known as the, with widespread trade networks, superior technology and bodies likely better suited to running, would eventually completely displace the Neanderthals, whose last refuge was in the. After about 25,000 years ago the fossil record of the Neanderthals ends, indicating extinction. The last known population lived around a cave system on the remote south-facing coast of from 30,000 to 24,000 years ago.

From the extent of linkage disequilibrium, it was estimated that the last Neanderthal gene flow into early ancestors of Europeans occurred 47,000–65,000 years. In conjunction with archaeological and fossil evidence, interbreeding is thought to have occurred somewhere in Western Eurasia, possibly the Middle East. Studies show a higher Neanderthal admixture in East Asians than in Europeans. North African groups share a similar excess of derived alleles with Neanderthals as non-African populations, whereas Sub-Saharan African groups are the only modern human populations with no substantial Neanderthal admixture. The Neanderthal-linked haplotype B006 of the dystrophin gene has also been found among nomad pastoralist groups in the Sahel and Horn of Africa, who are associated with northern populations. Consequently, the presence of this B006 haplotype on the northern and northeastern perimeter of Sub-Saharan Africa is attributed to gene flow from a non-African point of origin.

East and North Asia
"", an individual who lived in China c. 40,000 years ago, showed substantial Neanderthal admixture. A 2017 study of the ancient DNA of Tianyuan Man found that the individual is related to modern Asian and Native American populations. A 2013 study found of 18 genes within the chromosome 3p21.31 region (HYAL region) of East Asians. The introgressive haplotypes were positively selected in only East Asian populations, rising steadily from 45,000 years ago until a sudden increase of growth rate around 5,000 to 3,500 years ago. They occur at very high frequencies among East Asian populations in contrast to other Eurasian populations (e.g. European and South Asian populations). The findings also suggests that this Neanderthal introgression occurred within the ancestral population shared by East Asians and Native Americans.

A 2016 study presented an analysis of the population genetics of the people of northern Japan as key to the reconstruction of the early peopling of East Asia. The Ainu were found to represent a more basal branch than the modern farming populations of East Asia, suggesting an ancient (pre-Neolithic) connection with northeast Siberians. A 2013 study associated several phenotypical traits associated with Mongoloids with a single mutation of the gene, dated to c. 35,000 years ago.

Mitochondrial haplogroups, and  originated about 50,000 years ago, and bearers subsequently colonized ,  and , by about 35,000 years ago. Parts of these populations migrated to North America during the.

Eurasia
Around 20,000 years ago, approximately 5,000 years after the Neanderthal extinction, the forced northern hemisphere inhabitants to migrate to several   until the end of this period. The resulting populations are presumed to have resided in such refuges during the LGM to ultimately reoccupy Europe, where archaic historical populations are considered their descendants. The composition of European populations was later altered by further migrations, notably the expansion from the Middle East, and still later the  population movements associated with. A Paleolithic site on the Yana River, Siberia, at 71°N, lies well above the Arctic Circle and dates to 27,000 radiocarbon years before present, during glacial times. This site shows that people adapted to this harsh, high-latitude, Late Pleistocene environment much earlier than previously thought.

Americas
s originated from, crossing the between eastern Siberia and present-day Alaska. Humans lived throughout the Americas by the end of the, or more specifically what is known as the , no earlier than 23,000 years before present. Details of Paleo-Indian migration to and throughout the American continent, including the dates and the routes traveled, are subject to ongoing research and discussion.

The routes of migration are also debated. The traditional theory is that these early migrants moved when sea levels were significantly lowered due to the, following herds of now-extinct  along ice-free corridors that stretched between the  and  ice sheets. Another route proposed is that, either on foot or using, they migrated down the Pacific coast to as far as. Any archaeological evidence of coastal occupation during the last Ice Age would now have been covered by the, up to a hundred metres since then. The recent finding of indigenous n genetic markers in Amazonia supports the coastal route hypothesis.

Holocene migrations
The is taken to begin 12,000 years ago, after the end of the. During the, beginning about 9,000 years ago, human populations which had been geographically confined to began to migrate. By this time, most parts of the globe had been settled by H. sapiens; however, large areas that had been covered by were now re-populated.

This period sees the transition from the to the  stage throughout the. The Neolithic subsequently gives way to the in  cultures and the gradual emergence of the  in the  and  beginning around 4,000 years ago.

Large-scale migrations of the Mesolithic to Neolithic era are thought to have given rise to the pre-modern distribution of the world's major such as the, , ,  ,  or  phyla. The speculative postulates the derivation of the major language families of Eurasia (excluding Sino-Tibetan) from a single proto-languages spoken at the beginning of the Holocene period.

Eurasia
Evidence published in 2014 from genome analysis of ancient human remains suggests that the modern native populations of Europe largely descend from three distinct lineages: "", derivative of the Cro-Magnon population of Europe,  introduced to Europe from the Near East during the  and which expanded to Europe in the context of the.

The has been placed in either Africa or Asia.

Sub-Saharan Africa
The are thought to be derived from an earlier undifferentiated  unity by the 3rd millennium BCE. The development of the Proto-Nilotes as a group may have been connected with their domestication of. The Eastern Sudanic unity must have been considerably earlier still, perhaps around the 5th millennium BCE (while the proposed unity would date to the  about 15kya). The original locus of the early Nilotic speakers was presumably east of the Nile in what is now. The Proto-Nilotes of the 3rd millennium BCE were, while their neighbors, the Proto- peoples, were mostly agriculturalists.

The phylum is thought to have emerged around 6,000 years ago in West or Central Africa. Its expansion may have been associated with the expansion of Sahel agriculture in the African Neolithic period, following the desiccation of the Sahara in. The has spread the  to Central, Eastern and Southern Africa, partly replacing the indigenous populations of these regions. Beginning about 3,000 years ago, it reached South Africa about 1,700 years ago.

Pacific
The were  populated between c. 1600 BCE and 1000 CE. The people, who got their name from the archaeological site in Lapita,, where their characteristic pottery was first discovered, were an Austronesian-speaking people who settled in Near Oceania (notably the Bismarck Archipelago in Papua New Guinea, and the Solomon Islands) around 1500 BCE, where some intermingling  with the existing Papuan population took place. Acquiring long distance voyaging skills, they ventured into 'Remote Oceania', probably settling Vanuatu and New Caledonia around 1200 BCE, then Fiji, Samoa and Tonga. By the beginning of the 1st millennium BCE, this western part of Polynesia was a loose web of thriving populations settled on the islands' coasts and living off the sea. By 0 CE was completely colonized; tropical eastern Polynesia, including Tahiti, was probably settled by 700 CE. The last region of to be reached was, probably by 1300 CE.

Caribbean
The was one of the last places in the Americas that were settled by humans. The oldest remains are known from the Greater Antilles (Cuba and Hispaniola) dating between 4000–3500 BCE, and comparisons between tool-technologies suggest that these peoples moved across the Yucatán Channel from Central America. All evidence suggests that later migrants from 2000 BCE and onwards originated from South America, via the Orinoco region. The descendants of these migrants include the ancestors of the and  (Island Carib) peoples.

Arctic
The last region to be permanently settled by human migrations is the.

The earliest inhabitants of North America's central and eastern Arctic are referred to as the (AST) and existed c. 2500 BCE. AST consisted of several cultures, including the  and  culture.

The are the descendants of the, which emerged from western Alaska around AD 1000 and  the Dorset culture.