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Originally posted by Evergreen:
Current Anthropology, 51:849–883, December 2010

New Light on Human Prehistory in the Arabo Persian Gulf Oasis

Jeffrey I. Rose

The Genetics Conundrum

Genetic analyses point to a different scenario of modern human emergence than is indicated by the archaeological evidence. Some researchers working with mtDNA data envision that the initial Skhul/Qafzeh movement out of Africa was a failed expansion. They argue the first successful expansion out of Africa was associated with a genetic bottleneck release across the southern route of dispersal during MIS 3 or MIS 4 (e.g., Ambrose 1998; Macaulay et al. 2005; Quintana-Murci et al. 1999).12 To explain these genetically predicted late dates for human expansion out of Africa, in light of relatively early dates for the colonization of Sahul between 60,000 and 40,000 years ago (O’Connell and Allen 2004), researchers have suggested that the successful AMH colonists were coastally adapted groups that moved rapidly along the continental shelf rimming the Indian Ocean. This expansion is thought to have occurred during MIS 4, at which time reduced sea levels made habitable vast tracks of fertile land along the exposed coastline (Field and Lahr 2006; Field, Petraglia, and Lahr 2007; Mellars 2006; Stringer 2000).

The puzzle pieces in this scenario of a single wave of expansion out of Africa do not quite fit together; there is disagreement between archaeological, genetic, and fossil lines of evidence. The timing of the MP-UP (MSA-LSA) transition in the material record of east Africa and southwest Asia is roughly 45,000–30,000 BP and shows vastly different lithic trajectories between the two regions (Marks 1990), the mtDNA coalescence dates of the first human groups to branch from the common ancestral population is between 85,000 and 45,000 BP, and there are fossil remains of an AMH expansion out of Africa into the Levant as early as 110,000–90,000 BP. In all three cases, the predicted time spans for each demographic “event” are so different they hardly overlap. Clearly, these data sets are measuring fundamentally different things.

One problem may lie in geographic inferences associated with the human phylogenetic tree, which can, in part, be traced back to a landmark study in the late 1990s that identified mtDNA haplogroup M1 among modern populations in the Horn of Africa (Quintana-Murci et al. 1999). Geneticists recorded a high frequency of a particularly ancient human lineage—haplogroup M1—thought to be the earliest modern human branch to have split from the ancestral haplogroup L3 population. As every person living outside of Africa is derived from a branch stemming from the L3 trunk, this marker is considered representative of the common ancestral population. Thus, the discovery of haplogroup M1 in the Horn of Africa, just across the Red Sea and within sight of Arabia, suggested to scholars that the “Arabian Corridor” (i.e., Yemen, Oman, and the UAE) served as a conduit for the first populations moving out of Africa and into Asia, thereby suggesting the existence of a posited southern dispersal route during MIS 4 or MIS 3 (Field, Petraglia, and Lahr 2007; Lahr and Foley 1994, 1998; Mellars 2006; Stringer 2000).

More recent studies of subclade M1 in North Africa and the Levant have led to a different explanation for the geographic distribution of this critical genetic marker. Some researchers now propose that M1 arose in southwest Asia and moved back into Africa sometime between 45,000 and 40,000 years ago (Olivieri et al. 2006). González et al. (2007) also report the most ancient M1 lineages in North Africa and the Near East, not East Africa, suggesting an Asiatic origin for this lineage. Other analyses within the last decade examining Y chromosome DNA markers have produced additional evidence of Late Pleistocene back migrations into Africa (Altheide and Hammer 1997; Cruciani et al. 2002; Hammer et al. 1998).13 In light of these studies, it is necessary to look outside of Africa to find the region where AMH diverged from the common ancestral trunk, that is, the locus of expansion.

An additional problem with ascribing the haplogroup M expansion to the initial modern human groups leaving Africa is the timing of the M1 coalescence in east Africa versus the timing of haplogroup M coalescence elsewhere. The earliest coalescence dates indicating an mtDNA bottleneck release from the L3 ancestors are represented by the M2 subclade in India dated to BP (Metspalu et al. 2004) or BP (Thangaraj et al. 2006), while the M1 subclade in Ethiopia coalesces around BP (Quintana-Murci et al. 1999). Given these overlapping margins of error, there is no reason to presume that the founder M population originated in Eeast Africa rather than south Asia or some other place therein. In the case of subclade M2, Thangaraj et al. (2006) conclude that haplogroup M has in situ origins within South Asia.

Thus, it is significant that haplogroup M occurs in low frequencies throughout Arabia (Rídl, Edens, and Černý 2009). Among the Yemeni population in southwestern Arabia, almost every known M marker is derived from an Indian lineage unrelated to M1, leading researchers to conclude that “the available mtDNA data today [in Arabia] show no traces of the initial migration(s) out of Africa” (Rídl, Edens, and Černý 2009:76). Taking into account the mtDNA phylogenetic structure of populations in and around the Arabian Peninsula, Cabrera et al. (2009:84) write that “mitochondrial lineages carried by these colonizers were not yet ripe M and N lineages but their L3 ancestors.” In their proposed scenario, the post-MIS 4 expansion originated in Asia, not Africa, and therefore better explains the rapid human colonization along the rim of the Indian Ocean and ultimately into Australia between 60 and 40 kya.

That is not to say there are no mtDNA lineages in Arabia surviving from the Late Pleistocene. Genetic samples taken from individuals in Qatar, UAE, Oman, Socotra Island, and Yemen (Abu-Amero et al. 2007, 2008; Černý et al. 2008; Kivisild et al. 2004; Rowold et al. 2007) have yielded several highly developed mtDNA branches, indicating that some haplogroups “may coincide with or originate prior to the LGM” and “human populations, therefore, could survive during terminal Pleistocene hyperaridity” (Rídl, Edens, and Černý 2009:76).

Two particular mtDNA haplogroups provide evidence for deep genetic roots in southern Arabia: R0a and J1.14 R0a is derived from haplogroup R, one of the three major founding lineages of all modern human populations outside of Africa. The highest frequencies of R0a and its derivatives are found in Yemen (25%; Černý et al. 2008), Socotra Island (38%; Černý et al. 2009), Saudi Arabia (22%; Abu-Amero et al. 2008), and Oman (16%; Abu-Amero et al. 2007). Haplogroup R0a has an overall Middle Eastern coalescent age around 19,000 years ago and exhibits a high degree of diversity in southern Arabia, indicating that it has persisted in the region for this entire span of time. Given the hypothesis proposed in this paper, it is noteworthy that the most ancient R0a markers in Arabia are found in the UAE, with a predicted coalescence date of (Rowold et al. 2007).

Haplogroup J1 is also well represented in Arabia, with high frequencies in Saudi Arabia (37.5%), Qatar (17.8%), and Yemen (30%). Like R0a, this lineage is characterized by considerable diversity in all its main subbranches found throughout the subcontinent (J1, J1b, and J1c/J2). Of these subbranches, J1b is the most common and diverse in Arabia, with a coalescence age estimation of BP (Abu-Amero et al. 2008). While neither R0a nor J1b reaches back far enough in time to relate directly to the initial modern human expansion out of Africa, they both suggest that some Late Pleistocene groups survived the LGM and persist today within the modern Arabian gene pool.15

The archaeological and genetic evidence is not irreconcilable. The point of disagreement is simply where one places the initial coalescence from the basal trunk. If we consider that the population bottleneck release(s) branching from the common ancestral group emanated from southwest Asia, not Africa, the threads of archaeological, genetic, and fossil evidence agree. The model described in this paper proposes that the AMH population movement out of Africa during MIS 5 was not a failed wave of expansion; rather, these carriers of the mtDNA L3 marker were bivouacked (so to speak) in southwest and/or central Asian refugia, such as the Gulf Oasis, until the ameliorated conditions that set in during MIS 3 permitted subsequent range expansions. As such, it is more likely to expect several waves of expansion radiating from multiple population centers at the onset of MIS 3 rather than the single expansion scenario out of Africa.

This is in agreement with the archaeology-based model put forth by Otte et al. (2007), who argue that the locus of early modern human expansion into Europe originated between Afghanistan and the Caucasus. In his review of archaeological data from the Middle-Upper Paleolithic transitions in Europe, Asia, and Africa, Marks (2005:81) arrives at a similar conclusion: “The immediate origins of the explosion of ‘modern behavior’ seen in Europe, but not in Africa, might be found at the contact between Eastern Europe and Western Asia.”

Furthermore, the model of multiple expansions at the onset of MIS 3, due to the survival of the original MIS 5 AMH population in environmental refugia outside of Africa, is supported by analysis of modern human cranial diversity. Interregional comparison of Late Pleistocene human remains in Australia indicates that “early modern humans from the Levant either contributed directly to the ancestry of an early lineage of Autralasians, or they share a recent common ancestor with them” (Schillaci 2008:814). Examination of enamel growth increments (perikymata) on the Qafzeh specimens demonstrate that 12 of the 14 fall within the lower half of modern human variability, seven within the bottom 5% (Guatelli-Steinberg and Reid 2010). Although this study reveals a pattern not generally characteristic of modern populations, it does show a small degree of overlap between the Qafzeh humans and modern groups.16 Both of these analyses point to the possibility that Skhul/Qafzeh related populations persist outside of the Levant to this day.

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posted                      

quote:

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Originally posted by Evergreen:
Current Anthropology, 51:849–883, December 2010

New Light on Human Prehistory in the Arabo Persian Gulf Oasis

Jeffrey I. Rose

ABSTRACT:

The emerging picture of prehistoric Arabia suggests that early modern humans were able to survive periodic hyperarid oscillations by contracting into environmental refugia around the coastal margins of the peninsula. This paper reviews new paleoenvironmental, archaeological, and genetic evidence from the Arabian Peninsula and southern Iran to explore the possibility of a demographic refugium dubbed the “Gulf Oasis,” which is posited to have been a vitally significant zone for populations residing in southwest Asia during the Late Pleistocene and Early Holocene. These data are used to assess the role of this large oasis, which, before being submerged beneath the waters of the Indian Ocean, was well watered by the Tigris, Euphrates, Karun, and Wadi Batin rivers as well as subterranean aquifers flowing beneath the Arabian subcontinent. Inverse to the amount of annual precipitation falling across the interior, reduced sea levels periodically exposed large portions of the Arabo-Persian Gulf, equal at times to the size of Great Britain. Therefore, when the hinterlands were desiccated, populations could have contracted into the Gulf Oasis to exploit its freshwater springs and rivers. This dynamic relationship between environmental amelioration/desiccation and marine transgression/regression is thought to have driven demographic exchange into and out of this zone over the course of the Late Pleistocene and Early Holocene, as well as having played an important role in shaping the cultural evolution of local human populations during that interval.

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Originally posted by Evergreen:

Evergreen Writes:

It seems most probable that two types existed in the Tigres-Euphrates area by the early neolithic – a modified “Australoid” type that was spread from Australia, through India and into the vicinity of modern Iran/Iraq. There was also a semitic element that spread out of Africa and around the so-called fertile cresent during the early Holocene. A third, chariot-wielding element may have entered the region during the Bronze Age.

Further to this point, it seems that populations stretching from Senegal to Australia shared in the common M1 mtDNA lineage. These populations were Black and known as Eastern and Western Ethiopians (Blacks) by ancient Eurasians. These Black populations also seemed to have recognized their own Blackness with references to Kush/Kham/Ham/Kish evolving in relation to the emergence of chariot-wielding elements that may have entered the region during the EBA.

Further to this point, it seems that populations stretching from Senegal to Australia shared in the common M1 mtDNA lineage.

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Originally posted by Evergreen:
[QUOTE] These Black populations also seemed to have recognized their own Blackness with references to Kush/Kham/Ham/Kish evolving in relation to the emergence of chariot-wielding elements that may have entered the region during the EBA.

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Originally posted by Evergreen:
Evergreen Writes: One other area of future research is did tensions increases in SW Asia between incoming white steppe populations and the indigenous southern cradle cultures of SW Asia. Did these tensions intensify as northen cradle cultures took root and military hegemony. How did the great battles between Kush and Assyria or Aksum and Persia impact percieved phsyical differences (i.e., black versus white, zoroastriansim, etc). How did the Judahites in exile respond to this as they were assimilated and how did this impact the development of the Talmud.

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