Early human migration began when the pre-modern Homo erectus first migrated out of Africa
over the Levantine corridor and Horn of Africa to Eurasia about 1.8 million years ago. The
expansion of H. erectus out of Africa was followed by that of H. antecessor into Europe
around 800,000 years ago, followed by H. heidelbergensis around 600,000 years ago, who was the likely
ancestor of both Modern Humans and Neanderthals. The ancestors of the human species H. sapiens
evolved into Modern Humans around 200,000 years ago, in Africa.
Migrations out of Africa occurred some time later. Around 125,000 years ago Modern Humans
reached the Near East from where they later spread across Asia and Europe. From the Near
East, these populations spread east to South Asia by 50,000 years ago, and on to Australia
by 40,000 years ago, when for the first time H. sapiens reached territory never reached
by H. erectus. H. sapiens reached Europe around 43,000 years ago, eventually replacing the
Neanderthal population. East Asia was reached by 30,000 years ago.
The date of migration to North America is disputed; it may have taken place around 30
thousand years ago, or considerably later, around 14 thousand years ago. Colonization
of the Pacific islands of Polynesia began around 1300 BCE, and was completed by 900
CE. The ancestors of Polynesians left Taiwan around 5,200 years ago.
The study of early human migrations since the 1980s has developed significantly due
to advances in archaeogenetics.
Early humans
Early members of the Homo genus, i.e. Homo ergaster, Homo erectus and Homo heidelbergensis,
migrated from Africa during the Early Pleistocene, possibly as a result of the operation of the
Saharan pump, around 1.9 million years ago, and dispersed throughout most of the Old World,
reaching as far as Southeast Asia. The date of original dispersal beyond Africa virtually
coincides with the appearance of Homo ergaster in the fossil record, and the associated first
emergence of full bipedalism, and about half a million years after the appearance of the
Homo genus itself and the first stone tools of the Oldowan industry. Key sites for this
early migration out of Africa are Riwat in Pakistan, Ubeidiya in the Levant and Dmanisi
in the Caucasus. China was populated more than a million years
ago, as early as 1.66 Mya based on stone artifacts found in the Nihewan Basin. Stone tools found
at Xiaochangliang site were dated to 1.36 million years ago. The archaeological site
of Xihoudu in Shanxi Province is the earliest recorded use of fire by Homo erectus, which
is dated 1.27 million years ago. Southeast Asia was reached about 1.7 million
years ago. West Europe 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. Homo sapiens migrations
Homo sapiens are supposed to have appeared in East Africa around 200,000 years ago. The
oldest individuals found left their marks in the Omo remains and the Homo sapiens idaltu,
that was found at the Middle Awash site in Ethiopia.
From there they spread around the world. An exodus from Africa over the Arabian Peninsula
around 125,000 years ago brought modern humans to Eurasia, with one group rapidly settling
coastal areas around the Indian Ocean and one group migrating north to steppes of Central
Asia. Within Africa
The matrilinear most recent common ancestor shared by all living human beings, dubbed
Mitochondrial Eve, probably lived roughly 120-150 millennia ago, the time of Homo sapiens
idaltu, probably in East Africa. The broad study of African genetic diversity
headed by Dr. Sarah Tishkoff found the San people to express the greatest genetic diversity
among the 113 distinct populations sampled, making them one of 14 "ancestral population
clusters." The research also located the origin of modern human migration in south-western
Africa, near the coastal border of Namibia and Angola.
Around 100,000-80,000 years ago, three main lines of Homo sapiens diverged. Bearers of
mitochondrial haplogroup L0 / A colonized Southern Africa, bearers of haplogroup L1
/ B settled Central and West Africa, and bearers of haplogroups L2, L3, and others mtDNA remained
in East Africa. Exodus from Africa
There is some evidence for the argument that modern humans left Africa at least 125,000
years before present using two different routes: the Nile Valley heading to the Middle East,
at least into modern Israel; and a second one through the present-day Bab-el-Mandeb
Strait on the Red Sea, crossing it into the Arabian Peninsula, settling in places like
the present-day United Arab Emirates and Oman and then possibly going into the Indian Subcontinent.
Despite the fact that no human remains have yet been found in these three places, the
apparent similarities between the stone tools found at Jebel Faya, the ones from Jwalapuram
and some African ones 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 BP. 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 or survived in small numbers and
were assimilated by our major antecessors. An explanation for their extinction may be
the Toba catastrophe theory. However, some argue that its impact on human population
was not dramatic. According to the Recent African Origin theory
a small group of the L3 Haplogroup bearers living in East Africa migrated north east,
possibly searching for food or escaping adverse conditions, crossing the Red Sea about 70
millennia ago, and in the process going on to populate the rest of the world. According
to some authors, based in the fact that only descents of L3 are found outside Africa, only
a few people left Africa in a single migration to a settlement in the Arabian peninsula.
From that settlement, some others point to the possibility of several waves of expansion
close in time. South Asia and Australia
Some genetic evidence points to migrations out of Africa along two routes. However, other
studies suggest that a single migration occurred, followed by rapid northern migration of a
subset of the group. Once in West Asia, the people who remained south spread generation
by generation around the coast of Arabia and Persia until they reached India. One of the
groups that went north ventured inland and radiated to Europe, eventually displacing
the Neanderthals. They also radiated to India from Central Asia. The former group headed
along the southeast coast of Asia, reaching Australia between 55,000 and 30,000 years
ago, with most estimates placing it about 46,000 to 41,000 years ago. Some new evidence
show that the migration from Africa to Southeast Asia and Australia might occurred before 60,000
years ago. The migration routes from Africa to Southeast Asia were rather multiple and
along the way of migration, the H. sapiens interbred with other species like Neanderthals,
Denisovans and Homo erectus.
During that time, sea level was much lower and most of Maritime Southeast Asia was one
land mass known as the lost continent of Sunda. The settlers probably continued on the coastal
route southeast until they reached the series of straits between Sunda and Sahul, the continental
land mass that was made up of present-day Australia and New Guinea. The widest gaps
are on the Weber Line and are at least 90 km wide, indicating that settlers had knowledge
of seafaring skills. Archaic humans such as Homo erectus never reached Australia, although
they crossed the Lombok gap reaching as far as Flores.
If these dates are correct, Australia was populated up to 10,000 years before Europe.
This is possible because humans avoided the colder regions of the North favoring the warmer
tropical regions to which they were adapted given their African homeland. Another piece
of evidence favoring human occupation in Australia is that beginning about 46,000 years ago,
all megafauna weighing more than 100 kg became extinct. Tim Flannery and others argue new
settlers were likely to be responsible for this extinction. Many of the animals may have
been accustomed to living without predators and become docile and vulnerable to attack.
The lack of "advance" tools, however could be due to various reasons such as the fact
that they lacked the resources to make high-quality tools, that the environment they were in demanded
for different tools to survive, or with the increase in drift from their original ancestors,
this group of people could have lost their complex tool-making
While some settlers crossed into Australia, others may have continued eastwards along
the coast of Sunda eventually turning northeast to China and finally reaching Japan, leaving
a trail of coastal settlements. This coastal migration leaves its trail in the mitochondrial
haplogroups descended from haplogroup M, and in Y-chromosome haplogroup C. Thereafter,
it may have become necessary to venture inland possibly bringing modern humans into contact
with archaic humans such as H. erectus. Recent genetic studies suggest that Australia and
New Guinea were populated by one single migration from Asia as opposed to several waves,in these
single migration a population which had split from the ancestral Eurasian population, before
Asians and Europeans split each other, reach Australia and Melanesia between 62.000 and
75.000 years before present, the descendants of the earlier migration became assimilated
or replaced by the later dispersing populations from the next migration waves, with a few
exceptions that include Aboriginals Australians and other related populations like Papuans.
2 The land bridge connecting New Guinea and Australia became submerged approximately 8,000
years ago, thus isolating the populations of the two land masses.
Europe
Europe is thought to have been colonized by northwest bound migrants from Central Asia
and the Middle East. When the first anatomically modern humans entered Europe, Neanderthals
were already settled there. Debate exists whether modern human populations interbred
with Neanderthal populations, most of the evidence suggesting that it happened to a
small degree rather than complete absorption. Populations of modern man and Neanderthal
overlapped in various regions such as in Iberian peninsula and in the Middle East and that
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 sites in Arctic Russia by 40,000 years
ago. Around 20,000 BC, 10,000 years after the Neanderthal
extinction, the Last Glacial Maximum took place forcing northern hemisphere inhabitants
to migrate to several shelters until the end of this period. The resulting populations,
whether interbred with Neanderthals or not, are then presumed to have resided in those
hypothetical refuges during the LGM to ultimately reoccupy Europe where archaic historical populations
are considered their descendents. An alternate view is that modern European populations have
descended from Neolithic populations in the Middle East that have been well documented
in this area. The debate surrounding the origin of Europeans has been worded in terms of cultural
diffusion versus demic diffusion. Archeological evidence and genetic evidence strongly support
demic diffusion, that a population spread from the Middle East over the last 12,000
years. A scientific genetic concept called the Time to Most Recent Common Ancestor or
TMRCA has been used to refute the demic diffusion in favour of cultural diffusion.
Migration of the Cro-Magnons into Europe
Cro-Magnon are considered the first anatomically modern humans in Europe. They entered Eurasia
by the Arabian Peninsula around 60,000 years ago, with one group rapidly settling coastal
areas around the Indian Ocean and one group migrating north to steppes of Central Asia.
A mitochondrial DNA sequence of two Cro-Magnons from the Paglicci Cave in Italy, dated to
23,000 and 24,000 years old, identified the mtDNA as Haplogroup N, typical of the latter
group. The inland group is the founder of both North- and East Asians, Caucasoids and
large sections of the Middle East population. Migration from the Black Sea area into Europe
started some around 45,000 years ago, probably along the Danubian corridor. By 20,000 years
ago, the whole of Continental Europe, which was not covered under the Ice sheets, had
been settled. The first complete human remains that have been preserved is the mummy Ötzi,
from 3300 BC, belonging to the K1 MitDNA.
Competition with Neanderthals
The expansion is thought to have begun 45,000 years ago and may have taken up to 15,000
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
were larger and had a more robust or heavy built frame which may suggest 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 Cro-Magnons, with superior technology and language would eventually completely displace
the Neanderthals, whose last refuge was in the Iberian peninsula. After about 30,000
years ago the fossil record of the Neanderthals ends, indicating that they had become extinct.
The last known population lived around a cave system on the remote south-facing coast of
Gibraltar from 30,000 to 24,000 years ago. Proponents of the multiregional hypothesis
have long believed that Europeans were descended from Neanderthals and not from this Homo sapiens
migration. Others believed the Neanderthals had interbred with modern humans. In 1997
researchers managed to extract mitochondrial DNA from a 40,000 year old specimen of a Neanderthal.
On comparison with human DNA, its sequences differed significantly, indicating that based
on the mitochondrial DNA, modern Europeans are not descended from the Neanderthals and
that no interbreeding took place. Some scientists continue to search autosomal DNA for traces
of Neanderthal admixture. A few alleles of some autosomal genes such as the H2 allele
of the MAPT gene have been suggested, since they were only found among Europeans. In the
absence of autosomal DNA from a Neanderthal, the scientists conclude that this hypothesis
is speculative. Some archaeologists suspect that Neanderthals
and Homo sapiens were not interfertile. This is because Neanderthals and Europeans shared
the same habitat for up to 20,000 years, yet no undisputed skeletal fossils have been found
that show intermediate properties between the two species.
Current genetic evidence suggests interbreeding took place with Homo sapiens sapiens between
roughly 80,000 to 50,000 years ago in the Middle East, resulting in non-ethnic sub-Saharan
Africans having no Neanderthal DNA and Caucasians and Asians having between 1% and 4% Neanderthal
DNA. Central and Northern Asia
Mitochondrial haplogroups A, B and G originated about 50,000 years ago, and bearers subsequently
colonized Siberia, Korea and Japan, by about 35,000 years ago. Parts of these populations
migrated to North America. Americas
Paleo-Indians are agreed to have originated from Central Asia, crossing the Beringia land
bridge between eastern Siberia and present-day Alaska. Humans lived throughout the Americas
by the end of the last glacial period, or more specifically what is known as the late
glacial maximum, around 16,000 — 13,000 years before present. The 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. Dates for Paleo-Indian migration out of Beringia
are a matter of current debate. Estimates range from 40,000 to around 16,500 years ago.
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 Quaternary glaciation,
following herds of now-extinct pleistocene megafauna along ice-free corridors that stretched
between the Laurentide and Cordilleran ice sheets. Another route proposed is that, either
on foot or using primitive boats, they migrated down the Pacific coast to South America as
far as Chile. Any archaeological evidence of coastal occupation during the last Ice
Age would now have been covered by the sea level rise, up to a hundred meters since then.
See also Historical migration
Human migrations List of countries and islands by first human
settlement Middle Paleolithic
Timeline of human evolution Upper Paleolithic
References
Further reading
External links Atlas of the Human Journey - National Geographic
Journey of Mankind - Genetic Map - Bradshaw Foundation