How many migratory event OOA?

[djoser-xyyman]

Here is another interesting paper.


Genomic and cranial phenotype data support multiple modern human dispersals from Africa and a southern route into Asia - Hugo Reyes-Centeno


However, recent genetic studies, as well as accumulating archaeological and paleoanthropological evidence, challenge this parsimonious model. They suggest instead a “southern route” dispersal into Asia as early as the late Middle Pleistocene, followed by a separate dispersal into NORTHERN Eurasia. Here we test these competing out-of-Africa scenarios by modeling hypothetical geographical migration routes and assessing their correlation with neutral population differentiation, as measured by genetic polymorphisms and cranial shape



Africa is to consider multiple dispersals (MD) out of the continent. In an MD model, an initial dispersal between ∼50–100 ka occurs primarily along a coastal route through the southern Arabian Peninsula and is followed by a second dispersal through the Levant at ∼50 ka and into northern Eurasia (13, 14). This model proposes that extant, isolated populations in Asia could retain the biological signal of the initial, “southern route” dispersal. Such hypothetical, “relic” populations could include Australians, Melanesians, Papuans, Dravidian speakers of South Asia, and short-statured “Negrito” populations of Southeast Asia. A recent genetic study proposed that living Australians are direct descendants of the southern route dispersal, whereas Papuans, Melanesians, and Philippine Aeta “Negrito” populations also retain a signal of the southern route, but one that is obscured owing to ADMIXTURE with members of the second dispersal (8). In this model of multiple dispersals with isolation (MDI), a southern route dispersal out of Africa commences between ∼62–75 ka and is followed by a second dispersal between ∼25–38 ka. An ALTERNATIVE chronology for the MDI model posits a southern route dispersal as early as the late Middle Pleistocene ∼130 ka (MDI-MP), rather than the Late Pleistocene (MDI-LP), and is based primarily on archaeological evidence in the Arabian Peninsula (6, 15).

[djoser-xyyman]

Our findings indicate that African Pleistocene population structure may account for observed plesiomorphic genetic/phenotypic patterns in extant Australians and Melanesians. They point to an earlier out-of-Africa dispersal than previously hypothesized


We used this test for 10 populations sampled from Africa and Asia using genetic and cranial phenotype data (Table 1). We limited our phenotype analyses to the temporal bone, because it has been shown to conserve modern human population history at higher fidelity

Discussion
The test of current competing out-of-Africa models shows unambiguous support for a multiple dispersals model in which Australians, Papuans, and Melanesians remain relatively isolated after an early dispersal from Africa via a southern route. Although some degree of Holocene admixture between our sampled Indian and Australian populations has been previously proposed (17), our results are generally consistent with the view that extant Australians are descended from a relatively isolated lineage that first occupied that continent ∼50 ka (8). They differ from previous findings in that our dispersal chronology test suggests an initial African dispersal closer to the Middle–Late Pleistocene boundary. This is consistent with archaeological evidence for modern human occupation in the southern Arabian Peninsula at ∼125 ka (6, 15). This date is in intriguingly closer correspondence with the genetic divergence estimates for our sampled populations, with a calendar date of divergence between Melanesians and South Africans at ∼116 ka, for example (Table S1). No modern human fossils have been discovered in the southern Arabian Peninsula, but lithic artifacts show affinities with African assemblages, including those discovered alongside the fossil remains at Herto, Ethiopia, dated between ∼154–160 ka (2, 27). Importantly, the geological age of these specimens falls within the recent estimates for the common ancestor of all modern human populations (3, 4). This implies that an initial dispersal occurred not long after modern human origins in Africa, rather than much later, as an EE or BSD model would predict. The environmental and geographical viability for the MDI-MP model has been confirmed with a recent synthesis of available Middle– Late Pleistocene climate proxy data for Africa (28). Likewise, spatially explicit simulations developed from climate and microsatellite genetic data are in agreement with a southern route dispersal and earlier dates of Eurasian occupation than previously hypothesized (29). Moreover, it has been proposed that severe East African droughts occurring between 135–75 ka may have prompted human population fragmentation and bottlenecks (30), also possibly resulting in dispersals out of the continent. The modern human fossil series of Qafzeh and Skhul from the Levant, dated between ∼90–120 ka, could therefore correspond to this initial dispersal. Although often considered to represent a short-lived extension of African ecosystems rather than evidence of a long-range dispersal into Eurasia (31), in comparative craniometric studies the Levantine series and other early modern humans from Africa have consistently closer affinity to recent Australians than to other modern human populations (2, 32–34). Presently, clear evidence of modern human occupation eastward of the Arabian Peninsula during the early Late Pleistocene is lacking. Occupation of Australia is documented by the human paleontological record at ∼50 ka and in continental Southeast Asia at a maximum date of ∼63 ka (8, 35). Specimens before this time period are fragmentary and taxonomically ambiguous but have, in some cases, been claimed to represent anatomically modern humans (6, 7, 35–37). The MDI-MP model tested here suggests that whereas Southeast Asia may have been populated by modern humans, replacement of these descendants from subsequent migrants may obscure a southern route biological signal in extant populations of that region (6). Our dataset conforms to this hypothesis in that neither the genetic nor the cranial phenotype dataset from our sampled populations separate the Indo-European and Dravidian speakers from India, as might be expected if the latter where relic descendants of the southern route dispersal (Supporting Information, The “Negrito” Hypothesis). Instead, both Indian samples exhibit closer genetic and phenotypic affinity to the hypothetical second dispersal descendants (the Japanese, Aeta/Agta, and Central Asian populations).

[djoser-xyyman]

Presently, the favored explanation for genetic resemblance between Neanderthals and non-African modern human populations is a hypothetical admixture event in the Middle East (38). Likewise, shared polymorphisms between Denisovans and certain relic descendants of a southern route dispersal are explained by admixture in Southeast Asia (16). Identifying the presence of Neanderthal and Denisovan occupation along the southern route geographical space and within the Late Pleistocene temporal boundary is therefore crucial. The paleontological and archaeological records thus far remain elusive. An important consideration, therefore, is the persistence of population substructure ****in *****Africa (18, 38–41), which has been inferred from the human paleontological record (33, 34) and is concordant with climate fluctuations in the continent (28, 30). Population substructure implies that differential lineage assortment could be pronounced if populations in Africa remained spatially and temporally separated, affecting the subsequent diversity that is exported outside of the continent, as in an MDI-MP scenario. Genetically, polymorphisms within a parental population are randomly distributed into daughter lineages during speciation. In the recent human lineage, modern humans, Neanderthals, and Denisovans can be considered the daughter lineages of a common parental ancestor. Therefore, expression of shared genetic polymorphisms with Neanderthals and Denisovans in certain extant populations would be the consequence of biogeographical contingency and drift instead of, or in addition to, admixture with other hominins (18, 39–41). In a similar vein, expression of a plesiomorphic skeletal phenotype in extant and extinct populations has been interpreted as evidence for admixture with, or “assimilation” of, other hominin populations (42). Instead, population substructure implies that such expression reflects the retention of traits inherited from the parental population and could be more prominent in descendants of the southern route dispersal, who are chronologically closer to the parental ancestor. These findings do not imply that dispersing modern people from Africa did not interbreed with other hominin populations but suggest that, at present, other hypotheses also seem to be compatible with the biological evidence.


South Asian, southern route geographical space and a Late Pleistocene time frame— areas that have been largely understudied and where neither Neanderthal nor Denisovan occupation has been confirmed by the fossil record.


This study suggests that ancient population substructure, in addition or as an alternative to hominin interbreeding, may contribute to the observed pattern of resemblance between certain modern human populations and other hominins, ultimately generating the structure of extant modern human genetic and phenotypic diversity. Continued field work, alongside rapid advances in modern and ancient genome sequencing, will allow for greater resolution in modeling the spatial and temporal dimensions of modern human origins and dispersals.

[djoser-xyyman]

I remember about 1 year ago I had the discussion with T-Rex of ES. I speculated that based upon the geographic pattern it seemed like mtDNA-M was part of the first wave that migrated East from Africa. Later on mt-DNA-N subclades migrated North and West. This study proves me right. No fancy compute is needed. More to come.

[clydewin98]

The Melanesians are not a relic population. They came from Africa and East Asia.

See:

Indian Journal of Fundamental and Applied Life Sciences ISSN: 2231-6345
(Online) An Open Access, Online International Journal Available at www.cibtech.org/jls.htm 2014 Vol. 4 (3) July-September, pp. 694-704/Winters Research Article © Copyright 2014 | Centre for Info Bio Technology (CIBTech) 694

AFRICAN AND DRAVIDIAN ORIGINS OF THE MELANESIANS

*Dr. Clyde Winters Uthman dan Fodio Institute, Chicago, USA *Author for Correspondence

ABSTRACT The Melanesians are assumed to be a relic population of the Pacific, that probably made their way to Oceania shortly after the Out of Africa event. The toponymic, archaeological, craniometric and pan-African genomic evidence indicate that the Melanesians probably came to Oceania from Africa and Southeast (SE) Asia 4kya.


www.cibtech.org/J-LIFE-SCIENCES/PUBLICATIONS/2014/Vol-4-No-3/JLS-103-JLS-073-JUN-CLYDE-AFRICAN-MELANESIANS.pdf

[clydewin98]

In this paper I note

RESULTS
Craniometric and DNA evidence support a late Neolithic colonization of Oceania by African and
Dravidian populations. This migration went through mainland East Asia and Southeast Asia onto the
Pacific Islands.

Reyes-Centeno et al., (2014) model hypothetical geographical migration routes out of Africa (OoA).
These researchers maintain that cranial shape and genetic polymorphisms indicate Australo-Melenesian
populations as representative of isolated early population dispersal.

Although this is the view of Reyes-Centeno et al., (2014) there is no archaeological or genetic evidence
which suggest that the Melanesians represent a “relic” population.

Reyes-Centeno et al., (2014) fails to recognize that there is a craniometric difference between
Australoids/Australians, Mongoloids ( Polynesians) and Melanoids; craniometric differences that indicate
two migrations of the Black Variety: Australians and Melanesians into the Pacific. Tsuenehiko Hanihare
(2005) discussed the phenotypic variations between these populations.

The Australian aborigines and Melanesians show cranial variants and represent two distinct Black
populations. There is no denying that the Australians probably represent a “relic” population relating to an
early OoA event during the late Pleistocene, but the craniometrics, archaeological and toponymic
evidence indicate a fairly recent migration of Melanesians into Oceania (Winters, 2013).

[zarahan]

Well based on this study XYZ, does it then contradict Oppenheimer 2014
who claims a single exit? He says:

AMH left Africa via a single southern exit about 70 000 years ago and rapidly spread around the Indian Ocean towards the Antipodes, long before a small branch left a South Asian colony, earlier on the trail, to populate Europe."

In geographical terms, there is a growing consensus on a single southern dispersal of AMH extending from Africa via the mouth of the Red Sea moving around the coasts of the Indian Ocean initially to Bali, but ultimately to Melanesia and Australia in the southwest Pacific, and to the Americas on the other side (figure 1). The argument for the single exit [11,12] rather than multiple exits [13,14] is mainly based on the finding of single lineages, initially mtDNA and the Y chromosome non-recombining region (NRY), but now shown in the X chromosome and some autosomes, representing the entire non-African genetic diversity [15]. Recent claims for extra AMH exits at the Eemian interglacial [16–18] need to be viewed in this context.
--Out-of-Africa, the peopling of continents and islands: tracing uniparental gene trees Stephen Oppenheimer
--------------------------------------------------------------------


Reyes-Centeno says to the contrary:

"However, recent genetic studies, as well as accumulating archaeological and paleoanthropological evidence, challenge this parsimonious model. They suggest instead a “southern route” dispersal into Asia as early as the late Middle Pleistocene, followed by a separate dispersal into NORTHERN Eurasia. Here we test these competing out-of-Africa scenarios by modeling hypothetical geographical migration routes and assessing their correlation with neutral population differentiation, as measured by genetic polymorphisms and cranial shape.
Genomic and cranial phenotype data support multiple modern human dispersals from Africa and a southern route into Asia - Hugo Reyes-Centeno


So there is a clash of views. What's your verdict to date?
I agree with Clyde by the way that the Melenasians etc are no
so-called "relic" population.

[Tukuler al~Takruri]

Among other things do note for each
unique location population that the
corresponding genetic sub pops are
rarely the same as the cranial sub pops.

Some pops spoken in the text in
genetic terms are in fact not on
the genetic list but the cranial
one.

Eg, the Melanesian cranial sub-pops
are non-Papuany Melanesians but the
genetic sub-pops are Papuans. These
are somewhat different black peoples
though of course there are overlaps.
Papuan Highlanders are the ones with
the supposed "relic" background but no
genetic data's reported for non-New Guinea
Melanesians.


^ with reservations because I've
yet to read the full text instead
of skimming it to understand the
tabulated data and the map.


- - -

[djoser-xyyman]

My Views. The genetics studies coming out is contradicting the archeological “hypothesis” on OOA Eg there was no one OOA. There were OOA(s).

There are many examples.

For instance. Modern Southern Arabians do NOT carry WHG genetic profile but most Europeans carry some measure of WHG. This implies that WHG populations “skipped over” Arabia on their exit OOA?.

More? In that paper (cited on ES on Comorros Islanders- I recently saw Thought did a spiel on the paper) certain genetic markers found in Comorros and Australians/Melenesians are NOT found along the coastal exit route. Again implying the OOA exit is a lot more complicated and not fully understood.



Quote:

So there is a clash of views. What's your verdict to date? I agree with Clyde by the way that the Melenasians etc are no so-called "relic" population.

[djoser-xyyman]

When you read it we can talk…….


Among other things do note for each unique location population that the corresponding genetic sub pops are rarely the same as the cranial sub pops. Some pops spoken in the text in genetic terms are in fact not on the genetic list but the cranial one.

Eg, the Melanesian cranial sub-pops are non-Papuany Melanesians but the genetic sub-pops are Papuans. These are somewhat different black peoples though of course there are overlaps. Papuan Highlanders are the ones with the supposed "relic" background but no genetic data's reported for non-New Guinea Melanesians.




^ with reservations because I've yet to read the full text instead of skimming it to understand the tabulated data and the map.