Early human migrations

The earliest humans developed out of australopithecine ancestors about 3 million years ago, most likely in the area of the Kenyan Rift Valley, where the oldest known stone tools have been found.

[11][12] The archaeological site of Xihoudu (西侯渡) in Shanxi province is the earliest recorded use of fire by Homo erectus, which is dated 1.27 million years ago.

H. heidelbergensis, Neanderthals and Denisovans expanded north beyond the 50th parallel (Eartham Pit, Boxgrove 500kya, Swanscombe Heritage Park 400kya, Denisova Cave 50 kya).

It has been suggested that late Neanderthals may even have reached the boundary of the Arctic, 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 Urals (Komi Republic, 65°01′N 57°25′E / 65.02°N 57.42°E / 65.02; 57.42).

[5][18][19][20] Homo naledi, 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.

Homo sapiens are believed to have emerged in Africa about 300,000 years ago, based in part on thermoluminescence dating of artifacts and remains from Jebel Irhoud, Morocco, published in 2017.

[22] There is a possibility that this first wave of expansion may have reached China (or even North America[dubious – discuss][46]) as early as 125,000 years ago, but would have died out without leaving a trace in the genome of contemporary humans.

[57][58] Since these previous exits from Africa did not leave traces in the results of genetic analyses based on the Y chromosome and on MtDNA, it seems that those modern humans did not survive in large numbers and were assimilated by our major antecessors.

A small group from a population in East Africa, bearing mitochondrial haplogroup L3 and numbering possibly fewer than 1,000 individuals,[63][64] crossed the Red Sea strait at Bab-el-Mandeb, to what is now Yemen, after around 75,000 years ago.

Migration continued Southeast on the coastal route to the straits between Sunda and Sahul, the continental land mass of present-day Australia and New Guinea.

The explosion of Toba, the largest volcanic eruption of the Quaternary, may have created a 1,000 year cold period, potentially reducing human populations to a few tropical refugia.

[89] 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.

[22] The recent expansion of anatomically modern humans 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.

They entered Eurasia by the Zagros Mountains (near present-day Iran and eastern Turkey) around 50,000 years ago, with one group rapidly settling coastal areas around the Indian Ocean and another migrating north to the steppes of Central Asia.

[91][96] Humans colonised the environment west of the Urals, hunting reindeer especially,[97] but were faced with adaptive challenges; winter temperatures averaged from −20 to −30 °C (−4 to −22 °F) with fuel and shelter scarce.

[97][98] However, from recent research it is believed that the ecological crisis resulting from the eruption in c. 38,000 BCE of the super-volcano in the Phlegrean Fields near Naples, which left much of eastern Europe covered in ash, wiped out both the last Neanderthal and the first Homo Sapiens populations of the early Upper Paleolithic.

The anatomically modern humans known as the Cro-Magnons, 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 Iberian Peninsula.

[107] 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 BP.

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.

The ESEA lineage trifurcated from an earlier East-Eurasian or "eastern non-African" (ENA) meta-population, which also contributed to the formation of Ancient Ancestral South Indians (AASI) as well as to Australasians.

[128][129][130][131] The traditional theory is that these early migrants moved when sea levels were significantly lowered due to the Quaternary glaciation,[124][127] following herds of now-extinct pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets.

[134] The recent finding of indigenous Australasian genetic markers in Amazonia supports that a coastal route and subsequent isolation did occur with some migrants.

The Neolithic subsequently gives way to the Bronze Age in Old World cultures and the gradual emergence of the historical record in the Near East and China 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 language families such as the Niger-Congo, Nilo-Saharan, Afro-Asiatic, Uralic, Sino-Tibetan or Indo-European phyla.

The speculative Nostratic theory postulates the derivation of the major language families of Eurasia (excluding Sino-Tibetan) from a single proto-language spoken at the beginning of the Holocene period.

[143] Some evidence (including a 2016 study by Busby et al.) suggests admixture from ancient and recent migrations from Eurasia into parts of Sub-Saharan Africa.

During a period of around 1,500 years, they gradually lost the technology for pottery (likely due to the lack of clay deposits in the islands), replacing it with carved wooden and bamboo containers.

Austronesians remain the dominant ethnolinguistic group of the islands of the Indo-Pacific, and were the first to establish a maritime trade network reaching as far west as East Africa and the Arabian Peninsula.

They assimilated earlier Pleistocene to early Holocene human overland migrations through Sundaland like the Papuans and the Negritos in Island Southeast Asia.

The oldest remains are known from the Greater Antilles (Cuba and Hispaniola) dating between 4000 and 3500 BCE, and comparisons between tool-technologies suggest that these peoples moved across the Yucatán Channel from Central America.