The Nubian Complex in southern Arabia, 106 thousand years ago

I covered Jeffrey Rose's work most recently here. Together with his work on the Gulf Oasis, Jebel Faya, and the Skhul/Qafzeh hominids from the Levant, it now appears that modern humans were widely dispersed >100 thousand years ago in the Near East, possessing distinct lithic technologies. It is becoming increasingly impossible to reconcile this evidence with scenaria of Out-of-Africa after 70ka.

The pre-100ka Near East was seemingly teeming with modern humans; it may have been possible to dismiss these as the Out-of-Africa that failed when the Skhul/Qafzeh hominids were the only players in the game, but populations stretching from the Levant to southern Arabia did not simply vanish and were replaced after 70ka.

This leads to a conundrum:

• Either geneticists are in error when they date the L3/modern human expansion to 70 thousand years ago, or
• They are in error when they place its origin to Africa.

As I have argued before, the archaeological and genetic evidence can be reconciled if the L3/modern human expansion occurred recently Out-of-Arabia, during the super-arid conditions of MIS 4, after having establishing themselves there in the good times that preceded it.

From the paper:

The Nubian Complex is a regionally distinct Middle Stone Age (MSA) technocomplex first reported from the northern Sudan in the late 1960 s [1], [2]. Archaeological sites belonging to the Nubian Complex (Fig. 1) have since been found throughout the middle and lower Nile Valley [3]–[6], desert oases of the eastern Sahara [7], [8], and the Red Sea hills [9], [10]. Numerical ages from Nubian Complex sites (Table 1) are constrained within Marine Isotope Stage 5 (MIS 5), although temporal differences have been observed among assemblages; as such, it is divided into two phases, an early and a late Nubian Complex [5], [11].

I had previously speculated about the origin of modern humans in a wet Sahara, followed by their expansion into West Asia during MIS 5. I don't know how tenable this scenario is archaeologically, but it certainly appears to be chronologically and genetically: modern mankind coming to its own in the wet Sahara, collapsing demographically as the desert reasserted itself; finding a secondary cradle in Arabia, and expanding as the Arabian desert reasserted itself. Is this the solution: a tale of two deserts, pumping humans from Africa to the Near East pre-100ka and from the Near East to the rest of the world post-70ka?

From the paper:

The taxonomic identity of the Nubian Complex toolmakers is unknown, as no skeletal evidence has been discovered in association with any such assemblage. Although some archaic forms may have persisted in other parts of Africa at that time [79], the distribution of early anatomically modern human (AMH) remains suggest this species is the most likely candidate to have occupied northeast Africa during the Late Pleistocene. Cranial fragments of Homo sapiens found in the Omo river valley, Ethiopia (Fig. 1), represent the first appearance of AMH in East Africa ~195 ka [80]. Remains from Herto [81], Singa [82], and Mumba [83] in East Africa date to between ~160 and ~100 ka. Skeletal remains from Jebel Irhoud in Morocco show that an early form of Homo sapiens had expanded into North Africa as early as ~160 ka [84], and a modern human child discovered at Grotte des Contrebandiers in Morocco verifies the presence of AMH in North Africa by ~110 ka [85]. At the site of Taramsa Hill 1 in the lower Nile Valley, an AMH child dated to ~55 ka was found in association with a lithic industry (Taramsan) that is thought to have developed out of the late Nubian Complex [21], [86]. Despite the lack of direct evidence, given that AMH are the only species to have been found in North Africa from the late Middle Pleistocene onward, it is warranted to speculate that the Nubian Complex toolmakers were modern humans.

I have classified both Jebel Irhoud and Singa, as well as Omo II, and the Qafzeh/Skhul hominids as H. sapiens in my recent analysis of the Mounier et al. (2011) data. So, while it would be desirable to have osteological remains from the sites described in this paper, I'd say the odds are greatly in favor of them being modern humans.

Interestingly:

To some degree, the discovery of late Nubian Complex assemblages in Dhofar upholds this model. The distribution of this technocomplex in the middle and lower Nile Valley, the Horn of Africa, Yemen, and now Dhofar provides a trail of diagnostic artifacts - stone breadcrumbs - spread across the southern dispersal route out of Africa. The close similarity between African and Arabian late Nubian Complex assemblages suggests that these sites are more or less contemporaneous; they were separated for an insufficient amount of time for independently derived technological traits to develop between regions. As the late Nubian Complex at Aybut Al Auwal is dated to MIS 5c, slightly earlier than the late Nubian Complex in Africa [11], we remain open to the possibility that the late Nubian Complex originated in Arabia, and subsequently spread back into northeast Africa. Given the coarse chronological resolution in both Africa and Arabia (Table 1), however, the question of directionality cannot be adequately addressed, suffice to say there is cultural exchange across the Red Sea during MIS 5c.

Certainly the osteological evidence of modern humans in Africa (Omo and Irhoud, especially) predates that for the Near East. Also, some kind of Out-of-Africa must have taken place, since the Eurasian Y-chromosome and mtDNA phylogeny can be securely seen as a subset of the African phylogeny. Nonetheless, we don't really know when the Out-of-Africa even took place, and it could very well be that there was a first Into-Africa during MIS 5c.

Importantly:

Although southern Arabia experienced successive periods of extreme aridity after MIS 5, terrestrial archives document another increase in precipitation across the interior of Arabia during early MIS 3 [59], [104], enabling north-south demographic exchange between ~60–50 ka. South Arabian populations may have spread to the north at this time, taking with them a Nubian-derived Levallois technology based on elongated point production struck from bidirectional Levallois cores, which is notably the hallmark of the Middle-Upper Palaeolithic transition in the Levant [105], [106]. Further survey in central Arabia is required to test whether the Nubian Complex extends north of Dhofar. Until then, the fate of the Nubian Complex in Arabia must remain in question.

The puzzle is slowly filling up.

From ScienceNOW:

The problem with many of the stone tools found on the Arabian Peninsula, says New York University archaeologist Christian Tryon, is that they don't have much personality. "Stone tools are often unexciting things," he says, "like Paleolithic screwdrivers and hammers." None, he says, displayed signs of craftsmanship that could identify them definitively as the handiwork of African H. sapiens versus other hominids, such as Neandertals. None, that is, until archaeologist Jeffrey Rose of the University of Birmingham in the United Kingdom uncovered tools in Oman in 2010 with clear African connections. "This is the first time I've been convinced," says Tyron, who was not involved in the new work.

If modern humans were living in southern Arabia 106,000 years ago, the important question for human history is what happened next. Did they die out in Oman—another "failed expansion," as archaeologists describe it—or migrate north, going on to populate the globe? If the latter, it would challenge current genetic data placing global human migration out of Africa perhaps 80,000 years ago. Instead of "out of Africa," says Rose, "we could be looking at 'out of Arabia.' "

Indeed.

From the press release:

According to the authors, the evidence from Oman provides a "trail of stone breadcrumbs" left by early humans migrating across the Red Sea on their journey out of Africa. "After a decade of searching in southern Arabia for some clue that might help us understand early human expansion, at long last we've found the smoking gun of their exit from Africa," says Rose. "What makes this so exciting," he adds, "is that the answer is a scenario almost never considered."

These new findings challenge long-held assumptions about the timing and route of early human expansion out of Africa. Using a technique called Optically Stimulated Luminescence (OSL) to date one of the sites in Oman, researchers have determined that Nubian MSA toolmakers had entered Arabia by 106,000 years ago, if not earlier. This date is considerably older than geneticists have put forth for the modern human exodus from Africa, who estimate the dispersal of our species occurred between 70,000 and 40,000 years ago.

Even more surprising, all of the Nubian MSA sites were found far inland, contrary to the currently accepted theory that envisions early human groups moving along the coast of southern Arabia. "Here we have an example of the disconnect between theoretical models versus real evidence on the ground," says co-author Professor Emeritus Anthony Marks of Southern Methodist University. "The coastal expansion hypothesis looks reasonable on paper, but there is simply no archaeological evidence to back it up. Genetics predict an expansion out of Africa after 70,000 thousand years ago, yet we've seen three separate discoveries published this year with evidence for humans in Arabia thousands, if not tens of thousands of years prior to this date."

PLoS ONE 6(11): e28239. doi:10.1371/journal.pone.0028239

The Nubian Complex of Dhofar, Oman: An African Middle Stone Age Industry in Southern Arabia

Jeffrey I. Rose et al.

Despite the numerous studies proposing early human population expansions from Africa into Arabia during the Late Pleistocene, no archaeological sites have yet been discovered in Arabia that resemble a specific African industry, which would indicate demographic exchange across the Red Sea. Here we report the discovery of a buried site and more than 100 new surface scatters in the Dhofar region of Oman belonging to a regionally-specific African lithic industry - the late Nubian Complex - known previously only from the northeast and Horn of Africa during Marine Isotope Stage 5, ~128,000 to 74,000 years ago. Two optically stimulated luminescence age estimates from the open-air site of Aybut Al Auwal in Oman place the Arabian Nubian Complex at ~106,000 years ago, providing archaeological evidence for the presence of a distinct northeast African Middle Stone Age technocomplex in southern Arabia sometime in the first half of Marine Isotope Stage 5.

Link