Evolutionary Anthropology 21:113–125 (2012) ARTICLE The Prehistory of the Arabian Peninsula: Deserts, Dispersals, and Demography HUW S. GROUCUTT AND MICHAEL D. PETRAGLIA As a geographic connection between Africa and the rest of Eurasia, the Ara- the research potential of the region, bian Peninsula occupies a central position in elucidating hominin evolution and as do increasingly detailed environ- dispersals. Arabia has been characterized by extreme environmental fluctuation mental records. in the Quaternary, with profound evolutionary and demographic consequences. Early western explorers of Arabia Despite the importance of the region, Arabia remains understudied. Recent recognized stone tools, often in asso- 4 years, however, have seen major developments in environmental studies and ar- ciation with ancient lake beds. These early findings were followed by the cheology, revealing that the region contains important records that should play a 5 significant role in future paleoanthropological narratives.1–3 The emerging picture discoveries of archeologists, which of Arabia suggests that numerous dispersals of hominin populations into the significantly advanced from the 1970s region occurred. Populations subsequently followed autochthonous trajectories, onward, with large-scale surveys such as the Comprehensive Survey of the creating a distinctive regional archeological record. Debates continue on the re- Kingdom (1976-1981) in Saudi Ara- spective roles of regional hominin extinctions and population continuity, with the bia.6,7 Analogous developments took latter suggesting adaptation to arid conditions. place in southern Arabia.8–11 Over the last decade, systematic surveys and interdisciplinary excavations have desert has certainly played a role in greatly increased our understanding There exists a striking imbalance 2,3,12–14 between the clear importance of Ara- the lack of serious research. In some of prehistoric Arabia, as have developments in paleoenvironmental bia and what is actually known cases, cultural and political issues 15–17 about the region. The incorrect per- have hampered research, as, for studies. Research is now extend- ception of Arabia as an unchanging example, in contemporary Yemen. ing to the coastal waters around Ara- bia18 and to the use of remote sensing Numerous archeological surveys 19 have been conducted but, until techniques. recently, these have been unsyste- In the paleoanthropological litera- Huw Groucutt is a doctoral candidate matic. Most prehistoric sites consist ture, the Arabian Peninsula often at the School of Archaeology, University serves as a useful blank on the map of Oxford. His research focuses on the of lithic scatters from surface con- Middle Paleolithic of Arabia and Late texts. As a result, knowledge of Ara- in which to draw hypothetical and Pleistocene hominin dispersals. He has rather abstract dispersal arrows. This recently conducted excavations in Saudi bian prehistory often comes from sites potentially, but not necessarily, has particularly reflected patterns of Arabia and is undertaking a comparative 20,21 analysis of lithic technology in Africa and representing multiple phases of occu- global genetic variation. In such Southwestern Asia. Email: huw.groucutt@ models, the specific paleoenviron- rlaha.ox.ac.uk pation, which lack absolute dates Michael Petraglia is Professor of Human and paleoenvironmental information. mental and biogeographical charac- Evolution and Prehistory, Senior Research Attribution to cultural phases has teristics of Arabia have little role, yet Fellow, and Co-Director of Centre for typically reflected typological analy- it is precisely such contexts that are Asian Archaeology, Art & Culture, School of Archaeology, University of Oxford. He ses of biased collections. The absence critical to defining patterns of homi- is also a Senior Research Fellow, Linacre of a pre-Holocene hominin fossil re- nin dispersal and adaptation. As College (Oxford), and a member of the cord in Arabia precludes definitive genetic studies of Arabian popula- Human Origins Program, Smithsonian Institution. Email: michael.petraglia@rla identification of the manufacturers tions have increased in scale, they 22–25 ha.ox.ac.uk of the widespread lithic industries. reveal a complex pattern. Such These problems must be recognized studies show that modern Arabian and used to guide future research. populations are mostly derived from Key words: Arabia; paleoenvironments; Nevertheless, the Arabian record Western Asia, reflecting dispersals Paleolithic; lithic technology; hominins constitutes an important and under- since the Last Glacial Maximum studied dataset. The recent discovery (LGM). In some areas, however, VC 2012 Wiley Periodicals, Inc. of stratified archeological sites in there are relatively high levels of DOI 10.1002/evan.21308 Published online in Wiley Online Library Saudi Arabia, Yemen, Oman, and the ‘‘African’’ lineages, which have gener- (wileyonlinelibrary.com). United Arab Emirates demonstrates ally been attributed to historical 114 Groucutt and Petraglia ARTICLE Figure 1. Geography of the Arabian Peninsula. The locations of Pleistocene fossil localities and key sites for paleoenvironmental recon- struction are shown; note the southern and coastal concentration of the latter. Black lines depict major paleorivers.28 (Basemap cour- tesy of NASA’s Earth Observatory.) [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] processes such as slavery.26,27 long, and an interior with numerous bridge since the Miocene,33 but Genetic evidence, then, is poorly paleorivers and paleolakes (Fig. 1). during times of low sea level the gap placed to elucidate the position of Understanding the variable topogra- would have been significantly Arabia in the dispersal of hominin phy, ecology, and geography of Ara- reduced. However, Arabia was con- populations. Likewise, the extinction bia is therefore a necessary back- cordantly arid during these times. of regional populations means they ground to elucidate changes in homi- Consequently, some have stressed the will not be represented in contempo- nin demography.28,29 temporal lag between environmental rary genetic structure. In this situa- To the north of Arabia there are no amelioration and sea level rise2; tion, archeology, in the context of fundamental barriers to hominin dis- others emphasize the hypothesis of a paleoenvironmental fluctuation, persal, given favorable paleoenviron- 34 offers a key way to elucidate the dis- significant role for ‘‘coastal oases.’’ mental conditions. The Sinai persal of hominin populations into Modern observers are familiar with Peninsula offered a connection to Arabia and their subsequent evolu- the dry side of Arabia, most iconi- Africa.30 On the eastern edge of Ara- tionary and cultural trajectories. cally demonstrated by the Rub’ al bia, the Persian Gulf today is a shal- Khali, which, at 600,000 km2, low sea but, for most of the Pleisto- forms the world’s largest sandy de- cene, was a large river valley, leading sert. In the east, the Wahiba Sands GEOGRAPHY AND CLIMATE some to suggest that it formed an im- area is of importance, having been 31 The vast size of Arabia, at more portant population refugia. The pos- well studied in paleoenvironmental than 3 million km2, suggests that sibility of hominins crossing the Bab terms.35,36 Contemporary Arabia, hominin evolutionary processes have al Mandab has been much debated.32 however, has some areas, such as the been complex and regionally vari- Today the Red Sea here is less than 30 Asir-Yemen highlands and Oman’s able. The land mass consists of a km wide with small islands, meaning Dhofar, that receive considerably range of topographical and environ- that the maximum single water cross- more precipitation, The landscape of mental settings, including highlands, ing is less than 18 km. Isotopic studies Arabia reveals numerous signs of lowlands, a coastline some 7,000 km suggest that there has not been a land more humid conditions in the past. ARTICLE Groucutt and Petraglia 115 Vast paleoriver systems cut across been particularly wet, with extensive periods also included short dry the Peninsula, most starting in the speleothem, calcrete, and lake forma- phases. Recent studies in Saudi Ara- western highlands and extending tion.13,17,43 A pronounced deteriora- bia and the United Arab Emirates east to the Persian Gulf (Fig. 1). For tion occurred with MIS 4; however, demonstrate a short-lived wet phase instance, the now dry Wadi al Batin few records are known for this pe- at 55 ka.39,54 Another short pluvial drained a large area of northern riod, so we are dealing primarily period occurred 14 ka, not long af- Saudi Arabia and left a huge alluvial with an absence of evidence (for ter the LGM.55,56 fan around modern Kuwait, some example, of speleothem formation). Much progress has been made in 300 m deep and covering 190 by 130 MIS 3 has been labeled the ‘‘debated elucidating paleoenvironmental 15 km.28 Such paleorivers can clearly be pluvial.’’ Many radiocarbon dates change in Arabia, but many ques- seen in satellite images.37 Paleolakes had suggested a prolonged humid tions remain. A key question con- 44,45 of various sizes are found across Ara- period 30-25 ka, but this is not cerns the relative contributions of bia, from the relatively small to the the two weather systems. This has vast, such as the 2,000 km2 implications with regard to the open- Mudawwara paleolake on the border ing of dispersal routes. Within inter- 13,38,39 of Saudi