In the context of the recent African origin of modern humans, the Southern Dispersal scenario (also the coastal migration or great coastal migration) refers to the early migration along the southern coast of Asia, from the Arabian Peninsula via Persia and India to Southeast Asia and Oceania.[1] Alternative names include the "southern coastal route"[2] or "rapid coastal settlement",[3][4] with later descendants of those migrations eventually colonizing the rest of Eastern Eurasia, the remainder of Oceania, and the Americas.
According to this thesis, the dispersal was possible thanks to the development of a multipurpose subsistence strategy, based on the collection of organisms, fish, crustaceans, molluscs, algae, which are part of the biotic communities of the intertidal zone, the transition ecosystem between land and sea between the upper limit of high tides and the lower limit of low tides. - In support of this hypothesis there are the remains found on an ancient Pleistocene reef, now emerged, near the locality of Abdur in Eritrea. Its rocks are the result of the compaction of marine debris about 125,000 years ago and contain fossil remains of a complex biotic community of the coast of the time: large colonies of corals, oyster shells, large clams and other bivalve molluscs, gastropods and echinoderms. A group of geologists and paleontologists found many blades and tools made of obsidian, quartz and fine volcanic stone, mixed with the remains of shells. This would prove that over 100,000 years ago human populations of Homo sapiens exploited the intertidal zone for food purposes.
The coastal route theory is primarily used to describe the initial peopling of West Asia, India, Southeast Asia, New Guinea, Australia, Near Oceania, and East Asia beginning between roughly 70,000 and 50,000 years ago.[4][5][6][7][8][9]
It is linked with the presence and dispersal of mtDNA haplogroup M and haplogroup N, as well as the specific distribution patterns of Y-DNA haplogroup F (ancestral to O, N, R, Q),[10] haplogroup C and haplogroup D, in these regions.[3][11][12]
The theory proposes that early modern humans, some of the bearers of mitochondrial haplogroup L3, arrived in the Arabian peninsula about 70,000-50,000 years ago, crossing from East Africa via the Bab-el-Mandeb strait.[4] It has been estimated that from a population of 2,000 to 5,000 individuals in Africa, only a small group, possibly as few as 150 to 1,000 people, crossed the Red Sea.[13] The group would have travelled along the coastal route around Arabia and Persia to India relatively rapidly, within a few thousand years. From India, they would have spread to Southeast Asia ("Sundaland") and Oceania ("Sahul").[6][7][9][4]
The southern route dispersal is primarily linked to the Initial Upper Paleolithic expansion of modern humans and "ascribed to a population movement with uniform genetic features and material culture" (Ancient East Eurasians), which was the major source for the peopling of the Asia–Pacific region. While certain Initial Upper Paleolithic populations represented by specimens found in Central Asia and Europe, such as the Ust'-Ishim man, Bacho Kiro cave or Oase 2, are inferred to have used inland routes, the ancestors of all modern East Eurasian populations are inferred to have used the Southern dispersal route through South Asia, where they subsequently diverged rapidly and gave rise to modern populations in Eastern Eurasia, Oceania, and the Americas.[14][15][16][17][18][19]
... The concept of a coastal migration was already envisioned in 1962 by the ...
... mitochondrial DNA variation in isolated "relict" populations in southeast Asia supports the view that there was only a single dispersal from Africa, most likely via a southern coastal route, through India and onward into southeast Asia and Australasia. There was an early offshoot, leading ultimately to the settlement of the Near East and Europe, but the main dispersal from India to Australia 65,000 years ago was rapid, most likely taking only a few thousand years. ...
... The expansion of modern humans out of Africa, following a coastal route into southern Asia, was initially thwarted by a series of large and abrupt environmental changes. A period of relatively stable climate and sea level from c. 45,000 yr bp to 40,000 yr bp supported a rapid coastal expansion of modern humans throughout much of Southeast Asia, enabling them to reach the coasts of northeast Russia and Japan by 38,000–37,000 yr bp ...
... the population of south-east Asia prior to 6000 years ago was composed largely of groups of hunter-gatherers very similar to modern Negritos ... So, both the Y-chromosome and the mtDNA paint a clear picture of a coastal leap from Africa to south-east Asia, and onward to Australia ... DNA has given us a glimpse of the voyage, which almost certainly followed a coastal route via India ...
... Haplogroup D may have accompanied another group, the Coastal Clan (haplogroup C) on the first major wave of migration out of Africa around 50,000 years ago. Taking advantage of the plentiful seaside resources, these intrepid explorers followed the coastline of Africa through the southern Arabian Peninsula, India, Sri Lanka, and Southeast Asia. Alternatively, they may have made the trek at a later time, following in the footsteps of the Coastal Clan ...
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the southern migration wave seems to have diversified into the local populations in East Asia (defined in this paper as a region including China, Japan, Korea, Mongolia, Taiwan and Southeast Asia), and the northern wave, which probably runs through the Siberian and Eurasian steppe regions and mixed with the southern wave, probably in Siberia.
Via the southern route, ancestors of current Asian populations reached Southeast Asia and a part of Oceania around 70000–50000 years ago, probably through a coastal dispersal route (Bae et al., 2017). The oldest samples providing the genetic evidence of the northern migration route come from a high-coverage genome sequence of individuals excavated from the Yana RHS site in northeastern Siberia (Figure 2), which is about 31600 years old (Sikora et al., 2019).
Population genomic studies on present-day humans7,8 have exclusively supported the southern route origin of East Asian populations.
A single major migration of modern humans into the continents of Asia and Sahul was strongly supported by earlier studies using mitochondrial DNA, the non-recombining portion of Y chromosomes, and autosomal SNP data [42–45]. Ancestral Ancient South Indians with no West Eurasian relatedness, East Asians, Onge (Andamanese hunter–gatherers) and Papuans all derive in a short evolutionary time from the eastward dispersal of an out-of-Africa population [46,47]. The HUGO (Human Genome Organization) Pan-Asian SNP consortium [44] investigated haplotype diversity within present-day Asian populations and found a strong correlation with latitude, with diversity decreasing from south to north. The correlation continues to hold when only mainland Southeast Asian and East Asian populations are considered, and is perhaps attributable to a serial founder effect [50]. These observations are consistent with the view that soon after the single eastward migration of modern humans, East Asians diverged in southern East Asia and dispersed northward across the continent.