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Home , African humid period, Atlas Mountains, Chad Basin, Clarias gariepinus, Fezzan, Saharan languages

Ancient watercourses and biogeography of the explain the peopling of the

Nick A. Drakea,1, Roger M. Blenchb, Simon J. Armitagec, Charlie S. Bristowd, and Kevin H. Whitee

aDepartment of Geography, King’s College London, Strand, London WC2R 2LS, United Kingdom; bKay Williamson Educational Foundation, 8 Guest Road, Cambridge CB1 2AL, United Kingdom; cDepartment of Geography, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom; dSchool of Sciences, Birkbeck College, University of London, Malet Street, London WC1E 7HX, United Kingdom; and eDepartment of Geography, University of Reading, Whiteknights, Reading RG6 6AB, United Kingdom

Edited by Ofer Bar-Yosef, Harvard University, Cambridge, MA, and approved November 22, 2010 (received for review August 23, 2010)

Evidence increasingly suggests that sub-Saharan is at the could have been habitable during “green” periods of great- center of evolution and understanding routes of dispersal er humidity (9,10). This humid period was first suggested by “out of Africa” is thus becoming increasingly important. The Sahara Duveyrier (11) to explain the existence of the crocodiles Desert is considered by many to be an obstacle to these dispersals in isolated Saharan oases and has periodically been promoted and a Nile corridor route has been proposed to cross it. Here we since, notably by Dumont (12) who noted the trans-Saharan dis- provide evidence that the Sahara was not an effective barrier tribution of numerous aquatic species. Recent evidence and indicate how both and populated it during for this view is provided by isotopic data from a Mediterranean past humid phases. Analysis of the zoogeography of the Sahara marine core and aquatic that suggest a river corridor across shows that more animals crossed via this route than used the Nile the Sahara during marine isotope stage (MIS) 5e (13) and varia- corridor. Furthermore, many of these species are aquatic. This dis- tions in dust concentrations in a North marine core that persal was possible because during the humid period the indicates humid conditions during the last two (14). region contained a series of linked , rivers, and inland deltas The idea of the Sahara as a barrier to faunal dispersal is comprising a large interlinked waterway, channeling water and an- becoming increasingly important because of its role in the out-of- imals into and across the Sahara, thus facilitating these dispersals. Africa debate. Here we use numerous lines of evidence to eval- This system was last active in the early Holocene when many spe- uate the barrier hypothesis, and use this evidence to propose cies appear to have occupied the entire Sahara. However, species models for the peopling of the Sahara during past humid phases. that require deep water did not reach northern because of In the next section, we map the palaeohydrology of the Sahara weak hydrological connections. Human dispersals were influenced and show that during humid periods it contains an extensive in- by this distribution; Nilo-Saharan speakers hunting aquatic fauna terconnected hydrological system that animals appear to have with barbed bone points occupied the southern Sahara, while peo- used to migrate across the green Sahara. The following section ple hunting Savannah fauna with the bow and arrow spread south- compares the spatial distribution of and languages ward. The dating of lacustrine sediments show that the “green to that of the fauna and palaeohydrology to develop theories Sahara” also existed during the last (∼125 ka) and pro- of the peopling of the green Sahara during its last humid phase. vided green corridors that could have formed dispersal routes at a Finally, we evaluate dates of palaeolake sediments from the likely time for the migration of modern humans out of Africa. previous humid phase and show that it corresponds with the age of the first permanent modern human occupation of the North biogeography ∣ human migration ∣ animal migration ∣ palaeoclimate ∣ African coast and the , suggesting a crossing of the Sahara Saharan palaeohydrology at this time.

raditionally, it has been assumed that the Nile was the primary Biogeography and Palaeohydrology Tcorridor for the dispersal of hominins across the Sahara desert Reanalysis of the Saharan zoogeography (SI Appendix, Section 1 and then out of Africa (1). However, this route has proven hard to and Table S1) suggests that many animals, including water-depen- substantiate for three reasons. First, considerable research efforts dant creatures such as fish and amphibians, dispersed across the have failed to uncover evidence for its consistent use and the Sahara recently. For example, 25 North African animal species movement of its inhabitants into the Levant (2). Second, the have a spatial distribution with population centers both north and chronology of the evolution of the modern Nile drainage, which south of the Sahara and small relict populations in central re- is essential to create a functional corridor, is controversial (3, 4). gions. This distribution suggests a trans-Saharan dispersal in the Finally, although many ancient fluvial deposits have been recog- past, with subsequent local isolation of central Saharan popula- nized in the Nile , some with lithics that confirm the pre- tions during the more recent phase. If a diverse range of spe- sence of hominins, their stratigraphic relationships and ages are cies (including fish) can cross the Sahara, it is impossible to poorly understood (5). envisage the Sahara functioning as barrier to hominin dispersal. The need for a Nile migration corridor arises from the view The zoogeography of the Nile suggests that it was a much less that a belt of aridity has always separated the more humid regions effective corridor (SI Appendix, Table S1). Only nine animal spe- north and south of the Sahara, yet the evidence for this arid cies that occupy the Nile corridor today are also found both north barrier is contradictory. For example, indicates that and south of the Sahara. This paucity of Nileotic fauna highlights the Sahara has been a barrier to the dispersal of Macroscelidea

( shrews) since the late Miocene when the desert first Author contributions: N.A.D. and R.M.B. designed research; N.A.D., R.M.B., S.J.A., C.S.B., formed (6), whereas analysis of terrestrial sediments from and K.H.W. performed research; N.A.D., R.M.B., and S.J.A. analyzed data; and N.A.D. and the central Sahara demonstrates that during the Holocene humid R.M.B. wrote the paper. period an arid belt existed north of 22° (7). Furthermore, arid The authors declare no conflict of interest. taxa are found continuously through Atlantic cores This article is a PNAS Direct Submission. between 23° and 27° north for the last 250 ka suggesting a long- 1To whom correspondence should be addressed. E-mail: [email protected]. lasting Saharan arid belt at this latitude (8). In contrast, a green This article contains supporting information online at www.pnas.org/lookup/suppl/ Sahara route has been proposed whereby this currently hyperarid doi:10.1073/pnas.1012231108/-/DCSupplemental.

458–462 ∣ PNAS ∣ January 11, 2011 ∣ vol. 108 ∣ no. 2 www.pnas.org/cgi/doi/10.1073/pnas.1012231108 Downloaded by guest on September 30, 2021 the importance of a green Sahara corridor and indicates that , and Nile Basins form a single biogeographic province (20) the Nile route is, potentially, less significant. A further 13 species (Fig. 2A). The low degree of endemism indicates that these of animal are not found in the Nile corridor but are found both palaeohydrological interconnections happened relatively recently north and south of the Sahara yet not in the center (SI Appendix, (15), perhaps during the early Holocene “climatic optimum” Table S1). Although they must have dispersed across the Sahara, when the Sahara was last humid (21). whether they used the Nile or Green Sahara route cannot be de- Freshwater mollusc biogeographic provinces (22) have a simi- termined without additional evidence. lar spatial distribution to that of the fish (SI Appendix, Section 5 Fish species and molluscs are found both in oases across the and Fig. S5) suggesting that they dispersed across the Sahara Sahara and along the Nile, suggesting they crossed the Sahara using the same routes (SI Appendix, Section 2). That they have using both the Green Sahara and Nile routes. The majority of no endemic genera, and only 11 endemic species (22), again these species are thought to only disperse via water (15) (SI indicates a recent dispersal into the Sahara. In contrast, the Appendix, Section 2), thus current drainage only explains the Nile divide between amphibian biogeographic provinces (SI Appendix, populations and another mechanism needs to be established to Figs. S7 and S8) is located roughly equidistant from the head- explain the present trans-Saharan distribution. waters of the Nile, Chari, and rivers and the Moun- Mapping the palaeohydrology of the Sahara, using satellite tains (23). The latter presumably acted as refuges for these imagery and digital topographic data, yields a tenable model animals during arid periods. The contrasting spatial distribution (Fig. 1 and SI Appendix, Section 3). The Sahara was formerly of fish to amphibians is explained by the restriction of fish to riv- covered by a dense palaeoriver network with many channels con- taining very large alluvial fans where rivers divide into multiple branches in an inland area. Where these fans are located on the boundary between two river catchments, their distributary chan- nels can temporarily link adjacent river systems, thus allowing water-dependant life to transfer from one basin to the next (SI Appendix, Section 4). Five palaeofans identified in Fig. 1 link river systems in this manner. The green Sahara also contained numerous closed basins that supported some very large lakes (10, 16–19) (Fig. 1). When these lakes were full, they would have overflowed, thereby linking adjacent catchments (20). Fig. 1 shows that many fans and spillways are located in strategic positions that link waterways across the Sahara (SI Appendix, Section 4). Furthermore, tectonic activity can cause river diver- sion that transfers aquatic biota between basins, which appears to have been an important process in many northern basins (SI Appendix, Section 4). These mechanisms not only link many Saharan basins together but also connect them to large rivers with their headwaters outside the desert that can feed aquatic biota into the Sahara during humid periods. This interlinked waterway explains the observation that the fish species of the Sahara, Niger, GEOLOGY

Fig. 1. Late and early Holocene palaeohydrology of the Sahara (∼11 to 8 ka). The catchments of the megalakes that form corridors across the Fig. 2. Late Pleistocene and early Holocene palaeohydrology and biogeo- Sahara are indicated with letters A–D, while the river catchments that link graphy of the Sahara (∼11 to 8 ka). (A) Biogeographic provinces for the with many of these megalake basins to form the vast Saharan inland water- African fish species are indicated (1 Sudanian, 2 Upper Guinean, 3 Eburneo- way are indicated with letters E–I: (A) Lake Megachad, (B) Lake Megafezzan, Guinean, 4 Lower Guinean, 5 Congo, 6 Maghrebian) along with the distribu- (C) Ahnet-Mouydir Megalake, (D) the Basin of the Chotts, (E) River, tion of zillii, both recently, as indicated by the hatched area and from (F) Nile River, (G) Sahabi River, (H) Kufra River, and (I) . Numbers marking the location of Saharan refuges, and during the Holocene, as indi- indicate the location of fan, tectonic and lake outflow links between basins: cated by and . A trans-Sahara distribution is evident, both (1) Nile Basin/, (2) Chad Basin/Niger Basin, (3) Niger Basin/Senegal across the Sahara and down the Nile. (B) Distribution of Basin, (4) Niger/Basin West Ahaggar Mountains, (5) West Ahaggar Moun- amphibious both historically (∼1 ka) as shown by the hatched area and dur- tains/Ahnet-Mouydir Basin, (6) Ahnet-Mouydir Basin/Chotts Basin, (7) Chotts ing the Holocene by marking the location of older historical sightings, fossils, Basin/ Basin, (8) Fezzan Basin/Serir Tibesti, and (9) Serir Tibesti/Kufra and rock art. A distribution restricted to the River Nile and the southern- Basin. The 200-mm isohyet indicates the current limit of the Sahara Desert. central Sahara is evident.

Drake et al. PNAS ∣ January 11, 2011 ∣ vol. 108 ∣ no. 2 ∣ 459 Downloaded by guest on September 30, 2021 ers and lakes but the ability of amphibians to disperse both along suggesting the original locus of expansion. Although fragmented watercourses and overland. Consequently, during early Holocene into enclave populations today, the presence and pattern of relic climatic amelioration, Palearctic amphibian species moved south, populations in the northern desert points strongly to a much tropical species moved north, each crossing catchment divides wider distribution in the past, covering the region from the that formed insurmountable barriers to fish, allowing direct Ethio- borderland to and southwest . colonization routes and thus their meeting in the center. It has long been suggested that Nilo-Saharan languages might Although there is evidence that animals crossed the Sahara correlate with barbed bone points, the so-called “Aqualithic” relatively recently, the timing and routes taken are uncertain. (35). Fig. 3 superimposes the sites of known barbed bone points To constrain these two issues, maps of the spatial distribution on a map of current Nilo-Saharan languages, showing a remark- of the recent (∼1980) or historical ranges (∼1900) of selected able similarity in spatial distribution, and also a notable corre- North African aquatic (20, 22, 24) and (25) animal spondence with Holocene distribution of large aquatic species species, found within and north and south of the Sahara were (e.g., Fig. 2A and SI Appendix, Fig. S12). It appears that the ex- combined with maps of reported historical sightings (24, 26), pansion of aquatic resources in the Holocene made the Sahara Holocene fossils (15, 27–33), and their depictions in rock art attractive to populations with existing fishing and riverine hunting (26, 28, 34) (SI Appendix, Section 5). The evidence suggests that skills (SI Appendix, Section 6). Their ability to hunt hippopotamus many species inhabited the Sahara during the early Holocene. and crocodiles and to catch a wide variety of deepwater fish This appears to be the case for hardy fish such as Tilapia zillii species would have propelled a rapid dispersal from east to west (Fig. 2A) and gariepinus (SI Appendix, Fig. S8), for the and into the central Sahara, to judge by the numerous branches of (Crocodylus niloticus)(SI Appendix, Fig. S9), and Nilo-Saharan in the east (Fig. 3 and SI Appendix, Section 6). for savanna species such as (Giraffa camelopardalis) Their movement further north would have been restricted by (SI Appendix, Fig. S10) and African elephant (Loxadona africana) the absence of many of these species. However, the presence of (SI Appendix, Fig. S11). These distributions suggest that, during an isolated Nilo-Saharan population (the Koranje, a branch of the early Holocene, the Sahara was a savannah with riparian Songhay) and a barbed bone point in Northwest Africa near corridors linking north and south. Patches of more arid terrain the headwaters of the catchment of the Soura River, the river that in mountain rainshadows may better explain the arid pollen links the to the lakes in the Ahnet-Mouydir basin found in North Atlantic cores (8). (Fig. 1), forming a corridor from the central Sahara to Northwest Some sub-Saharan animals do not exhibit trans-Saharan spa- Africa, indicates that a few groups may have traversed the green tial distributions (Fig. 2B and SI Appendix, Figs. S12 and S13). Sahara using the most promising routes. There is direct linguistic They are found only in the southern Sahara, with a northern limit evidence that Nilo-Saharan populations exploited these aquatic near the Ennedi, Tibesti, Tasilli, and Ahoggar Mountains, repre- resources in the form of a widespread cognate for “hippo” from senting a catchment divide in the central Sahara (SI Appendix, Gumuz in , to Songhay in (SI Appendix, Table S2). Fig. S12). These species all have specialized aquatic require- SI Appendix, Table S2 shows similar forms for “crocodile,” ments, such as deep water in the case of (Lates nilo- although in this case the cognates are split between eastern and ticus) and hippopotamus (Hippopotamus amphibius) or long-term western languages. water connections for mollusc species such as Bellamya unicolor, We hypothesize that the other economic revolution that Cleopatra bulimonides Pila and Lanistes (22) (SI Appendix, occurred in the Sahara at approximately the same time was the Section 2). The fan to the west of the Ahaggar Mountains (Fig. 1, southward spread of the bow and arrow. North African hunters fan 5) provides the only hydrological connection across this would have observed the new abundance of large and unfamiliar divide to the northern Sahara, but appears to have been a barrier to specialized aquatic species, accounting for an impoverished aquatic fauna in the northern Sahara. The Peopling of the Sahara During the Holocene We hypothesize that the differences in animal resources between the northern and southern Sahara during the early Holocene influenced the way it was peopled by humans. The north–south contrast in Saharan species ranges are remarkably similar to some key lithic, bone tool, and linguistic spatial distributions, suggest- ing that the peopling of the region during the early Holocene humid phase was driven by cultural adaptations that allowed exploitation of specific fauna. The early Holocene archaeology of the Sahara is characterized by a regional distribution of specific archaeological cultures, such as those defined by barbed bone points, fishhooks, Ouna- nian arrow-points, and, more controversially, (32, 35–38). The Sahara today is largely populated by speakers of Afroasiatic languages, Berber and , with some Nilo-Saharan languages (Teda-Daza and Zaghawa) in the region of Northern Chad, and Songhay cluster languages scattered across Mali and Niger (Fig. 3). However, it is clear that this situation is recent; Berber- speaking Tuareg moved into the Central Sahara ∼ 1500 y ago and the spread of the Hassaniya Moors into Mauritania probably dates from the 15th Century (39). Before this time, the central and southern Sahara are thought to have been populated by Fig. 3. Sahara palaeohydrology overlaid with the spatial distribution of Ou- nanian and barbed bone points and Nilo-Saharan languages. The languages Nilo-Saharan speakers. The Nilo-Saharan language phylum is marked as “other” are too small to be depicted as separate colors; they are both widespread and strongly internally divided, suggesting Nyimang, Temein, Hill Nubian, Daju, Berta, and Gumuz. Note the similarity considerable antiquity (40) (Fig. 3). Its greatest diversity is in the between the distribution of barbed bone points and the distribution of spe- east, where a large number of small branches are found (Fig. 3), cies that require deep water (Fig. 2B and SI Appendix, Figs. S12 and S13).

460 ∣ www.pnas.org/cgi/doi/10.1073/pnas.1012231108 Drake et al. Downloaded by guest on September 30, 2021 land to the south, notably elephant and giraffe. In a (SI Appendix, Section 7; ref. 16) of palaeolake sediments shows dispersal inverse to that of the Nilo-Saharans, they would have that two large lakes of 1,350 and 1;730 km2 existed in this basin at been attracted southward to hunt these animals with the bow a similar time (SI Appendix, Fig. S16). The Fezzan Basin ages are and arrow. The “Ounanian” of Northern Mali, Southern , consistent with a U/Th isochron age for lake sediments from Niger, and central Egypt at ca. 10 ka is partly defined by a the basin of the Chotts (98 5 ka; ref. 18) and the Ahnet-Mouy- distinctive type of arrow point (37). These arrowheads are found dir basin [92ðþ20 − 18Þ ka; ref. 19). At this time, the Chotts basin in much of the northern Sahara (Fig. 3) and are generally consid- contained a lake with an area of 30;000 km2 while the Ahnet- ered to have spread from Northwest Africa. This view is supported Mouydir basin lake attained an area of at least 32;000 km2, by the affinity of this industry with the that also thus suggesting two green corridors across the Sahara during appears to have colonized the Sahara from the north (41). No MIS5 that could have been used by hominins to cross the Sahara Ounanian points occur in before 10 ka, suggesting (Figs. 1 and 4). Once hominins had achieved a trans-Saharan dis- the movement of a technology across the desert from north to tribution, it would have been possible to pass into the Levant via south around this time. the Mediterranean coast. Because the Levant was humid at this Our model envisages the initial Holocene repopulation of the time (44), onward dispersal would have been possible. Sahara being carried out by two separate populations practicing It is probable that increased humidity within the megalake two quite different resource exploitation strategies: (i) aquatic for- catchments is indicative of regional scale humidity and hence dis- aging using bone point and fish hook technology, and (ii) savanna persal routes may have existed throughout the desert, as appears hunting using the bow and arrow. By linking the distribution of the to have been the case during the early Holocene, rather than Nilo-Saharan language phyla to the archaeological distribution of being restricted to corridors. Other studies of Saharan fluvial aquatic- and terrestrial-adapted technologies, we explain the pat- and lacustrine sediments provide some evidence for humidity tern of human repopulation of the desert in terms of the changing in other areas. A humid corridor has recently been proposed faunal distribution, which is in turn dictated by the nature of trans- in the Sahabi palaeoriver system (13) (Fig. 4) and there are 41 Saharan hydrological linkages. other ages for 12 areas that contain humid sediments scattered throughout the Sahara that are indistinguishable from these Older Saharan Occupation and Crossings “corridor” ages. Their integration with the palaeohydrological The movement of people across the Sahara during the Holocene map provides evidence for a wider green Sahara during MIS5 as may well have been the last of several important hominin disper- sals. To demonstrate the possibility of earlier trans-Saharan well as the present interglacial (Fig. 4 and SI Appendix, Section 3). Using the Holocene biogeography and palaeohydrology of the migrations, it is necessary to determine the timing of pre-Holo- cene humid phases in the Sahara. This chronological evidence Sahara as an analogue for the MIS5 humid period, it is likely that can be obtained by dating the deposition of pre-Holocene lake an interconnected waterway would have been available for faunal sediments and demonstrating synchronous palaeohydrologic and human dispersal. This humid period corresponds very closely changes across the Sahara. MIS5 contains the most abundantly with the age of the first modern human occupation of the North dated pre-Holocene humid sediment sequences, yet only two African coast (45) and the Levant (46) by sub-Saharan popula- , two regions containing spring , and nine sepa- tions, who may have been crossing the Sahara at this time (9). rate palaeolakes have been dated to this period (SI Appendix, The occupation of the Mediterranean coast of Africa by these Sections 4 and 7), thus there are many gaps and it is not possible early modern human migrants appears to have lasted from ∼110 ∼30 to say if the entire Sahara was humid. For example, before this to ka (45), though the Levantine occupation appears ∼70 study, there was a complete lack of last MIS5 ages in the south- to have finished by ka (47). Some view the out-of-Africa dis- ernmost part of the Sahara. One way to overcome this problem is persal into the Levant as the start of the spread of modern hu- to date lacustrine episodes in the Saharan megalakes because they mans onward into Arabia and in MIS5 (48), whereas others “ ” are located within abutting catchments and these catchments span believe it to be a dead end that was followed by a later more

the desert (Fig. 1). Because the high stands indicate significantly successful dispersal of modern humans out of Africa at a later GEOLOGY increased moisture availability, fluvial systems within the megalake date: 60 ka in MIS4 (49). There is little evidence for a green catchments must be active at these times. Consequently, synchro- nous lake high stands would yield a humid corridor across the Sahara, allowing northward dispersal of hominin populations located in sub-Saharan Africa. To evaluate the timing of pre-Holocene humid phases, it is necessary to locate and date extensive sequences of lacustrine sediments in megalake basins. Fortunately, Saharan megalakes appear to preserve the required long-term lacustrine sequences (16–19, 42) despite the general assumption that such records are rare in the Sahara because of deflation of lacustrine sediments during arid periods (43). We have applied optically stimulated luminescence (OSL) dating to selected sediments (SI Appendix, Section 7) and have found evidence for synchronous humidity in the Fezzan–Chad–Chotts and Chad–Chotts–Ahnet-Moyer mega- lake corridors during MIS5 (Fig. 1). Humidity in the Chad Basin was investigated by dating Lake Megachad beach ridges (SI Appendix, Fig. S16). The Bama Ridge in northeastern forms the southwestern shoreline of the Holocene palaeolake Megachad with an area of 361;000 km2 (10). To the southwest of the Bama Ridge, we identified a succession of older beach ridges that run roughly parallel to it (SI Appendix, Fig. S16). Fig. 4. Palaeohydrology of during MIS5 with the location of OSL ages for two of these ridges at Alhajari and Kawiya give dated sites marked. The hatched area covers catchments containing large ages of 114 14 ka and 125 12 ka, respectively, suggesting palaeolakes and thus represents the minimum area which experienced megalake conditions in MIS5. In the Fezzan Basin, OSL dating considerably enhanced humidity during MIS5.

Drake et al. PNAS ∣ January 11, 2011 ∣ vol. 108 ∣ no. 2 ∣ 461 Downloaded by guest on September 30, 2021 Sahara in MIS4, so the desert is unlikely to have directly played a Green Sahara route to the North African coast by hominins and role in this postulated second dispersal, however, the modern its long-term viability are supported by archaeological evidence humans north of the Sahara could have provided the population (53–56). Stone tools from Oldowan to have been found required to drive it. Indeed, “spatially” this hypothesis is attrac- in all the megalake basins that form corridors across the Sahara, tive because the Sinai corridor out of North Africa is close to the suggesting that the region was not only periodically habitable for location of the earliest archaeological sites associated with this hominins, but that it was also regularly occupied by them. dispersal, which are found in the Levant at ∼47 ka (50). However, an alternative dispersal route for modern humans out of Africa ACKNOWLEDGMENTS. We thank the Society for Libyan Studies for funding the via the Bab el Mandab has been proposed at about this time, Fezzan Project that inspired this work and the Desert Migrations Projects that largely on genetic grounds (51), thus if this dispersal occurred, a allowed research in the Fezzan to continue. Particular thanks go to David route out of Africa via North Africa is not necessary. To further Mattingly who led these research projects and encouraged this research. complicate matters, the possibility of multiple dispersals of modern We are also grateful to Marta Lahr, Robert Foley, and Kevin MacDonald humans both into and out of Africa has recently been suggested for helpful discussions on the peopling of the Sahara and to David Blackburn (52). If these proposed migrations did indeed happen, it is feasible for his help in understanding its biogeography. Grants from the Royal Geographical Society—Institute of British Geographers Peter Fleming that these different dispersals employed different routes. Award, the National Geographic Society, Repsol/YPF S A, and the Notwithstanding the as yet unresolved issue of the timing and Great Manmade River Authority also funded aspects of this research, for route taken by modern humans out of Africa, both the use of the which they are thanked.

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