Lithic assemblages from the Chang Tang Region, Northern Tibet.

Lithic assemblages from the Chang Tang Region, Northern Tibet. Introduction This paper presents new evidence from surface stone toolassemblages collected by George Schaller in the Chang Tang Reserve,northern Tibet, at elevations above 4500 m asl. Eighteen separatelocalities have yielded lithic lith��ic?1?adj.Consisting of or relating to stone or rock.Adj. 1. lithic - of or containing lithium2. lithic - relating to or composed of stone; "lithic sandstone" assemblages ranging in size from a singleartefact See artifact. to as many as 158 specimens. A number of the assemblagescontain unique Upper Palaeolithic blade and bladelet technologies. Thisis perhaps surprising given that true blade technologies are rare inChinese contexts (Brantingham 1999; Gao 1999; Lin 1996; Zhang 1999).Microblade cores, blanks and tools are also found at several of theChang Tang localities. Microblade technology is common at Chinesearchaeological sites dating to the terminal Pleistocene and earlyHolocene (Elston et al. 1997; Lie 1998; Madsen et al. 1998). A widerange of stone raw materials was used in manufacturing thesetechnologies. Core reduction was intensive and many of the collectedartefacts show patterns of intensive retouch and recycling. Thecollection methods employed limit the statistical value of theseassemblages. Nevertheless, the range of lithic technologies representedand the specific characteristics of raw material utilization aresignificant for addressing questions of the nature of foragingadaptations in this hostile environment. Indeed, these surfacesassemblages from the Chang Tang are significant for understanding notonly specific aspects of East Asian prehistory prehistory,period of human evolution before writing was invented and records kept. The term was coined by Daniel Wilson in 1851. It is followed by protohistory, the period for which we have some records but must still rely largely on archaeological evidence to , but also for broaderissues concerning the range and complexity of Pleistocene forageradaptations. The Chang Tang Reserve Located in the northwestern part of the Tibetan Plateau, the ChangTang Reserve encompasses approximately 334,000 sq. km and exceeds 4500 masl in average elevation (FIGURE 1) (Schaller 1998). The Chang Tang isbounded to the north by the Kunlun Mountains and the Xinjiang UygurAutonomous Region, to the east by Qinghai province, and to the south andwest by the `northern highway', which traverses Tibet at roughly 32[degrees] N. The area is characterized by large internal-drainagebasins, saline and brackish lakes, and broad, rolling steppes broken byhills and snow-capped mountains. The Chang Tang is presently too coldand arid to support forests, but rather is dominated by cold desertgrasslands, sedges, forbs and low shrubs. Schaller & Liu (1996)divide the Chang Tang into three vegetation zones: alpine steppe steppe(stĕp), temperate grassland of Eurasia, consisting of level, generally treeless plains. It extends over the lower regions of the Danube and in a broad belt over S and SE European and Central Asian Russia, stretching E to the Altai and S to , desertsteppe and alpine meadows. Alpine steppe is dominant in the southeasternhalf of the reserve. The alpine steppe occupies elevations between 4300and 5100 m asl and is characterized by cold, windy conditions, poorsoils and 100-350 mm precipitation annually. Plant cover is sparse inthe alpine steppe zone ([is less than] 30%). Species of Stipa are thedominant plants followed by other graminoids, dwarf shrubs, herbaceous her��ba��ceous?adj.1. Relating to or characteristic of an herb as distinguished from a woody plant.2. Green and leaflike in appearance or texture. plants and a few legumes such as Astragalus astragalus/as��trag��a��lus/ (as-trag��ah-lus) talus.astrag��alar as��trag��a��lusn.See talus. . Desert steppe is dominantin the uninhabited northern areas and replaces alpine steppe between 34[degrees] 30'N and 35 [degrees] N, where a mere 50-100 mm ofprecipitation fails annually. The diversity of plant species in thedesert steppe zone is similar to the alpine steppe, though plant coveris significantly more sparse. Alpine meadows dominate the landscapewhere annual precipitation exceeds 350-400 mm. Alpine meadows are foundin areas of east Qinghai, and in Tibet along the Lhasa-Golmud highwayand as far west as Seling Co (Co = `lake'). Within the Chang Tang,alpine meadows are limited to riparian riparianadj. referring to the banks of a river or stream. (See: riparian rights) contexts along streams, seepagesand swamps. Short sedges (Kobresia spp.) and forbs are the dominantvegetation types in the apline meadow zone. [ILLUSTRATION OMITTED] These three vegetation zones provide an array of seasonallyavailable plants that support six wild and four domestic ungulate ungulateAny hoofed, herbivorous, quadruped, placental mammal in three or four orders: Artiodactyla, the even-toed ungulates (including pigs, camels, deer, and bovines); Perissodactyla, the odd-toed ungulates (including horses, tapirs, and rhinoceroses); Proboscidea species. The wild ungulates include the Tibetan antelope (chiru chiru:see antelope. ),Tibetan gazelle gazelle,name for the many species of delicate, graceful antelopes of the genus Gazella, inhabiting arid, open country. Most gazelles are found only in Africa, but several species range over N Africa and SW Asia; the Persian, or goitered, gazelle ( , Tibetan argali argalia wild sheep Ovis ammon. , blue sheep, Tibetan wild ass (kiang kiang:see ass. )and the wild yak (Schaller 1998). All but the blue sheep occur todayonly on the Tibetan Plateau, and several of these species are endangeredas a result of heavy poaching. As recently as the 1890s, there werelarge gregarious wild ungulate herds on the Plateau with the totalanimals numbering perhaps in the millions (Schaller 1998). Pastoralists currently occupy only the southern margins of theChang Tang. Areas farther to the north present extremely harshconditions for human occupation, and provide too little forage and toofew sources of fresh water for large domestic herds. While there arepresently no permanent human occupations north of Gar Co (34 [degrees]N), archaeological evidence presented here points to the presence offoraging populations in these areas perhaps into the late Pleistocene. History of archaeological research on the Tibetan Plateau Prehistoric archaeological sites have been recognized on theTibetan Plateau since the mid 1950s when the Chinese Academy of Sciences The Chinese Academy of Sciences (CAS) (Simplified Chinese: 中国科学院; Pinyin: Zhōnggu�� Kēxu��yu��n), formerly known as Academia Sinica first sent multidisciplinary research teams to investigate the geologyand palaeoenvironment of the area (An 1982; Huang 1994). Until recently,archaeological research on the Plateau has been ancillary to geological,lacustrine la��cus��trine?adj.1. Of or relating to lakes.2. Living or growing in or along the edges of lakes.[French or Italian lacustre (from Latin lacus, lake) + , glacial and palaeontological Adj. 1. palaeontological - of or relating to paleontologypaleontological studies. Extensive excavationsat the late Neolithic site of Karou (4000-5000 BP) are an exception(CPAM CPAM Caisse Primaire d'Assurance Maladie (French: health insurance)CPAM Crime Prevention Association of MichiganCPAM Certified Patient Account Manager (AAHAM)1985). In the 1980s, Chinese and international projects began toinclude archaeologists among the researchers investigating theQuaternary quaternary/qua��ter��nary/ (kwah��ter-nar?e)1. fourth in order.2. containing four elements or groups.qua��ter��nar��yadj.1. Consisting of four; in fours. of the Tibetan Plateau (An 1982; Huang 1994; Huang et al.1987). These projects have brought to light the diversity ofarchaeological sites on the Plateau and have provided tentative dates offirst occupation. Simple core and flake tools made on quartzite quartzite,usually metamorphic rock composed of firmly cemented quartz grains. Most often it is white, light gray, yellowish, or light brown, but is sometimes colored blue, green, purple, or black by included minerals. , quartz and siliceous siliceousrelating to or made of silica or a silicate. stones have been recorded from at least 10 localities (Huang 1994: table1). At the site of Xiao Qaidam (3100 m asl) in the central QaidamDepression of China's Qinghai province, simple cores and retouchedflakes were recovered from a mixed gravel-sand terrace 8-13 m above themodern salt lake. Radiocarbon dates of 33,000 [+ or -] 3300 and 35,200[+ or -] 1700 BP on ostracods and lake marls were obtained from depositsthat correlate geologically with the terrace (Huang 1994: 204). Whileradiocarbon dates on molluscs are often too old (Goodfriend & Stipp1983), these dates may still indicate human presence on the TibetanPlateau sometime prior to the last glacial maximum The Last Glacial Maximum (LGM) refers to the time of maximum extent of the ice sheets during the last glaciation (the W��rm or Wisconsin glaciation), approximately 20,000 years ago. This extreme persisted for several thousand years. (LGM LGM Last Glacial MaximumLGM Little Green Men (Astronomical: first used as the designation for pulsars)LGM Lembaga Getah Malaysia (Malay: Malaysian Rubber Board)LGM The Lone Gunmen ) approximately22-18,000 years ago. Light-duty tools and microliths also have beenrecovered from a number of localities in Qinghai and Tibet including:Sure (4500 m asl), Huo-er (4630 m asl), Zhongba (4600 m asl), Saga(4500-4900 m asl) and Ngam-ren (4300-5000 m asl) in southern Tibet; andMani Mani(mä`nē): see Manichaeism. Manior Manes or Manichaeus(born April 14, 216, southern Babylonia—died 274?, Gundeshapur) Persian founder of Manichaeism. (4920 m asl), Amugang (5200 m asl), Zuluole (4800 m asl), Xulong(4770 m asl), Duogezhai (4830 m asl) and Ge'ting (4663 m asl) innorthern Tibet (Huang 1994: table 1). These sites are thought torepresent the terminal Palaeolithic or early Neolithic, dating tosometime after glacial termination (see Elston et al. 1997; Lie 1998;Madsen et al. 1998). Developed Neolithic economies are present inlow-elevation areas of the Plateau by approximately 5000 years ago.These cultures are identified by the presence of microliths, groundstone artefacts, ceramics, and semipermanent dwellings. The site ofKarou (3100 m asl) is the best known of these Neolithic settlements (An1982; CPAM 1985). Finally, the timing of the appearance of nomadicpastoralism on the Tibetan Plateau is difficult to constrain. However,evidence from Gansu Province and Mongolia suggests that pastoralism PastoralismArcadiamountainous region of ancient Greece; legendary for pastoral innocence of people. [Gk. Hist.: NCE, 136; Rom. Lit.: Eclogues; Span. Lit. wasan outgrowth of developed Neolithic economies sometime after 5000 yearsago (Chang 1986).TABLE 1. Stone rawmaterial typesrepresented at each ofthe Chang Tanglocalities. raw materialsite chert chalcedony argillite quartziteYako Hu 11 42 104 1Lava Camp 6 13Shuang Hu 12 3 9Zhanglong He 1 3 2Zhangshui He 5 8 1Hot Spring 7 60Nyima 3 18Tianshi He 2 16 4Yibug Caka 2 15Jianggai Shan 2Dogai Coring 3 1Gar CoYibug CakaTsatsangTsatsang 1 1Margog Caka 2 2Beilai CoZhuoni CoRongmaSeling Co 1total 52 83 245 1 raw materialsite obsidian totalYako Hu 1 159Lava Camp 11 30Shuang Hu 24Zhanglong He 6Zhangshui He 14Hot Spring 67Nyima 21Tianshi He 22Yibug Caka 17Jianggai Shan 2Dogai Coring 4Gar Co 2Yibug Caka 1Tsatsang 5Tsatsang 3Margog Caka 6Beilai Co 2Zhuoni Co 6Rongma 1Seling Co 1total 12 393 Lithic assemblages from the Chang Tang Reserve Stone tool samples from 18 archaeological localities are describedand analysed in the following sections (TABLE 1). The sites werediscovered by George Schaller and colleagues in the course of systematicecological field surveys in the Chang Tang (Schaller 1998). The majorityof these sites were found in the eastern part of the Reserve, from thesouthern border north to the base of the Rola Kangri massif mas��sif?n.1. A large mountain mass or compact group of connected mountains forming an independent portion of a range.2. at 35[degrees] 15'N. The sites consist of moderate- and low-densitysurface lithic scatters and are associated with a range of topographicfeatures including freshwater stream channels, ancient lake beachlines,dry lake basins, and one mountain pass. All artefacts were surface finds, and no excavations were attemptedto establish if stratified stratified/strat��i��fied/ (strat��i-fid) formed or arranged in layers. strat��i��fiedadj.Arranged in the form of layers or strata. deposits existed. Collection procedures werenot rigorously controlled and a sample of the collected artefactsremains in Tibet. As a result, there appears to be a size bias in theartefacts represented; most of the artefacts exceed 3 cm in size. Thereis no clear bias with respect to technology, however, because Schallerand colleagues did not employ a lithic typological scheme duringcollection or splitting of the sample. This allows us to be moreconfident in discussing the range of flaked stone technologiesrepresented in high-elevation contexts on the Plateau. The assemblages recovered from the Chang Tang are technologicallydiverse. However, three broad technological groups are readily separatedfrom one another: 1 generalized core technology; 2 large blade and bladelet technology; and 3 microlithic mi��cro��lith?n. ArchaeologyA very small blade made of flaked stone and used as a tool, especially in the European Mesolithic Period.mi technology, including microblade cores and theirproducts. The retouched tool types present reflect these basic blank forms(i.e. general flakes, blades, bladelets and microblades). A wide varietyof raw materials are represented including chert chert:see flint. , chalcedony chalcedony(kălsĕd`ənē)[from Chalcedon], form of quartz the crystals of which are so minute that its crystalline structure cannot be seen except with the aid of a microscope. , obsidian,argillite ar��gil��lite?n.A metamorphic rock, intermediate between shale and slate, that does not possess true slaty cleavage.[Latin argilla, argil; see argil + -ite1. and a limited amount of quartzite (TABLE 1). At present, thesources for these raw materials are unknown. However, both extrusive ex��tru��sive?adj.1. Tending to push or thrust out.2. Tending to protrude or project.3. Derived from magma poured out or ejected at the earth's surface. Used of igneous rocks.Adj. 1. igneous and metasedimentary rocks are found in abundance on the TibetanPlateau and provide potential raw material source areas. Argillite,cherts of various colours and obsidian were used in manufacturingunstandardized cores and flakes, as well as blades, bladelets and arange of retouched tools. Only small packages of fine-grained cherts andchalcedonies were used for microblade technology. Chang Tang blade technologies One of the most interesting aspects of the materials recovered fromthe Chang Tang Reserve is the abundance of large blades, bladelets andassociated core trimming elements (TABLES 2 & 3). These productswere recovered from Yako Hu, Lava Camp, Zhangshui He, Nyima, TianshuiHe, Yibug Caka and Margog Caka. The presence of large blades in theseassemblages is surprising given that such technologies are very rare inChinese archaeological contexts. At present, only the site ofShuidonggou, Ningxia Hui Autonomous Region Ningxia Hui Autonomous Region(nĭng`shyä` hwē), autonomous region (1994 est. pop. 5,030,000), c.25,600 sq mi (66,321 sq km), N China. The capital is Yinchuan. , contains clear evidence forthe manufacture of large stone blades (Brantingham 1999; Zhang 1999).However, there are some striking differences between the bladetechnology represented at Shuidonggou and that seen in the Chang Tangassemblages. At Shuidonggou, blade production is focused onLevallois-like, flat-faced cores and hard hammer percussion (Brantingham1999). The resulting blades are very flat with large bulbs ofpercussion, facetted striking platforms, irregular margins andlength-width ratios not exceeding 4:1. In the Chang Tang, large bladesare trapezoidal or strongly convex, have flat bulbs of percussion, smalllenticular lenticular/len��tic��u��lar/ (len-tik��u-ler)1. pertaining to or shaped like a lens.2. pertaining to the lens of the eye.3. pertaining to the lenticular nucleus. or punctiform striking platforms with limited facetting, veryregular lateral margins and tend to be very elongate e��lon��gate?tr. & intr.v. e��lon��gat��ed, e��lon��gat��ing, e��lon��gatesTo make or grow longer.adj. or elongated1. Made longer; extended.2. Having more length than width; slender. (FIGURE 2). Thesefeatures are suggestive of a true prismatic blade technology utilizingeither soft hammer, or indirect percussion. Core trimming elements suchas crested blades are present both at Shuidonggou and the Chang Tanglocalities. And both contain numerous flake blades -- specimens thatmeet the metric definition of blades, but are not standardized endproducts (TABLE 2). Many of the recovered Chang Tang blades are proximalor medial fragments, displaying clear traces of intentionalsegmentation. This patterning suggests that blade and bladelet elementswere sometimes hafted as complex composite tools (see Bar-Yosef &Kuhn 1999). [ILLUSTRATION OMITTED]TABLE 2. Core types recovered from the Chang Tang localities. core type sub- pebble levallois prismatic micro- flake bladelet bladesite discoid core core coreYako Hu 1 5Shuang Hu 3Hot SpringNyimaTianshi HeJianggai Shan 1 1TsatsangZhoni Co 1total 1 1 1 10 core type indeter- flake minate micro- micro- un- narrow- broad- blade blade finished faced facedsite core core preform core coreYako Hu 3 11 1Shuang Hu 1 1Hot SpringNyimaTianshi He 2 1Jianggai ShanTsatsangZhoni Cototal 4 14 3 1 1 core typesite totalYako Hu 21Shuang Hu 5Hot Spring 2Nyima 1Tianshi He 3Jianggai Shan 2Tsatsang 1Zhoni Co 1total 36 Bladelets also comprise a large part of the Chang Tang collections.It is not clear whether blades and bladelets form two distinctivetechnological modes, or are part of a single reduction continuum.Acknowledging the statistical limitations of the collections, it isinteresting to note that the distribution of blade and bladelet widthsis unimodal Adj. 1. unimodal - having a single modestatistics - a branch of applied mathematics concerned with the collection and interpretation of quantitative data and the use of probability theory to estimate population parameters (median 15 mm) and only slightly skewed. This may suggestthat blades and bladelets are part of a technological continuum. Therecovery of a single bladelet core from Yako Hu may suggest, however,that a distinctive bladelet production strategy was used in somesituations (FIGURE 2a). This core is clearly different from the bladetechnologies characterizing the initial Upper Palaeolithic as well aslater microblade technologies in Northeast Asia (Brantingham 1999; Chen& Wang 1989). The core is sub-prismatic, displaying bladeletremovals from approximately 200 [degrees] of the core's perimeter,and the striking platform is acute and unfacetted. In contrast, initialUpper Palaeolithic blade cores are fiat, restricting reduction to asingle plane of removal, and tend to display steep, facetted strikingplatforms. Microblade cores based on pebbles and flakes tend to havecentripetally worked striking platforms angled at roughly 90 [degrees]to the percussion axis. Microblade technology comprises another important feature of thematerials recovered from the Chang Tang Reserve. Most of the examplesconsist of microblade cores in various stages of reduction (FIGURE 2).Only two microblades were recovered, both from Yako Hu. Numerousmicroblade core preparation and rejuvenation RejuvenationAesonin extreme old age, restored to youth by Medea. [Rom. Myth.: LLEI, I: 322]apples of perpetual youthby tasting the golden apples kept by Idhunn, the gods preserved their youth. [Scand. Myth. flakes, including severalsmall platform tablets, were also recovered. While it is difficult todetermine the original form of the raw material blanks from spentmicroblade cores, those discarded at an early reduction stage appear tobe based on small pebbles of chert or chalcedony (see also An 1982;Elston et al. 1997). Microblade cores based on biface blanks (Chen &Wang 1989) are not represented among the cores or core preparationdebitage The term debitage refers to the totality of waste material produced during lithic reduction and the production of chipped stone tools. This assemblage includes, but is not limited to, different kinds of lithic flakes, shatter, and production errors and rejects. , nor are there true bifaces in the collections. Utilization intensity The Chang Tang assemblages as a whole show interesting patterns ofretouch modification. While the exceptionally high frequencies ofretouch tools must be treated with caution as a result of potentialcollection biases, the ways in which tools were modified isindependently very revealing of intensive utilization histories.Contrary to expectations, many of the retouched tools found at theselocalities are not based on standardized blanks such as blades andbladelets. Rather, chunks, flake shatter, discarded cores, rejuvenationflakes, cortical flakes and other generalized pieces show secondaryretouch at nearly equal frequencies compared with blades and bladelets.Many retouched tools display more than one segment of discrete retouch.Indeed, combination tools with mixtures of retouch elements such as sidescrapers, burins and retouched notches are the single most common tooltype at most of the localities. The only uniquely specialized tool typeappears to be blades modified at the proximal end for hafting Hafting is a process by which an artifact, often bone, metal, or stone, is attached to a handle or strap. This makes the artifact more useful by allowing it to be fired (as in the case of an arrowhead), thrown (as a spear), or leveraged more effectively (as an axe or adze). (FIGURE2). Although the two specimens of this type from Margog Caka andTianshui He are broken, it is clear that they were end-hafted bladesused possibly as projectiles. Overall, retouched tools in the Chang Tangare indicative of intensive utilization of virtually everything bearinga sharp edge and high rates of recycling of artefacts through differenttasks and activities. Discussion The rigours of living at high altitudes are well known from a rangeof anthropological and other studies (see Frisancho 1993). The TibetanPlateau, with average elevations above 4500 m, would have presentedsignificant adaptive challenges to foraging populations colonizing theregion. The present climate above 5000 m is characterized by mean annualair temperatures below freezing and temperatures above 0 [degrees] Conly during June-September (Schaller 1998). Between 4000-5000 m,temperatures are higher during the summer months (6.6-15.5 [degrees] C).Areas around Lhasa may have 50-180 days annually where temperaturesexceed 10 [degrees] C, while areas of northern Tibet have fewer than 50such days (Lin & Wu 1981). Annual precipitation is primarily underthe control of the Asian monsoon and falls between June and September.However, much of this precipitation does not reach the northern portionsof the Plateau around the Chang Tang, which is generally arid tosemiarid (Lin & Wu 1981). Foraging populations in the Chang Tang would have had to contendwith chronic and acute cold exposure and persistent low wateravailability. Other challenges may have included high levels of solarradiation and high winds. Importantly, because of low overall primaryproductivity, food resources on the Plateau are concentrated in ungulatebiomass. Few of the extant plant species are appropriate for humanforagers. This leads to the expectation that subsistence strategies onthe Tibetan Plateau would have focused primarily on large game hunting. The characteristics of the Chang Tang lithic assemblages mayreflect the importance of such environmental and subsistence stresses.Settlement and mobility patterns are difficult to tease out of theavailable evidence. Many of the known sites are associated withpalaeo-hydrological features such as river channels and relict RELICT. A widow; as A B, relict of C D. lakebeaches. This patterning may be significant with respect to subsistenceorganization and tethering to available water sources. We might alsoexpect to see high mobility as one of the keys to successfulcolonization of hostile Plateau environments. The great diversity ofstone raw materials found at the Chang Tang sites may be evidence ofthis. However, the sources of these raw materials are not yet known,thus it is difficult to place boundaries on raw material transportdistances. Specific technological attributes of the Chang Tang assemblages mayalso provide clues about mobility and levels of subsistence stress. Oneof the most striking features of the assemblages is the degree ofspecialization represented by blade, bladelet and microbladetechnologies. These technologies tend to be both very efficient atgenerating usable cutting edges and predictable in terms of criticalperformance characteristics. As such, they may reflect risk reductionstrategies and, more generally, the importance of"over-designed', well-planned lithic technologies in stressfulenvironments (see Bousman 1993; Winterhalder et al. 1999). Blades andbladelets from the Chang Tang constitute a separate core reductionstrategy from microblades. Both blades and bladelets were likely used aselements in composite tools. Two blades retain traces of modificationfor use as end-hafted tools, possibly projectiles. The common occurrenceof segmented blades and bladelets may also suggest side hafting intocomplex armatures. Such technologies are well suited to specializedhunting adaptations in that they are both strong and lethal (Ellis 1997;Elston & Brantingham in press). The importance of time-stressed activities, or alternatively rawmaterial stress, may also be indicated by the extensive modification andutilization of cores, blanks and tools. The majority of nuclei, whethersimple flake, bladelet or microblade cores, were utilized until sizeconstraints, or irreparable errors prevented further effective working.Yet these nuclei were not always discarded. Rather, many spent cores, aswell as general flakes and irregular chunks, were subsequently retouchedinto hand-held tools. This is indicative of strategies aimed atsqueezing maximum utility out of available stone raw materials. Thebehavioural implication is that there were high costs associated withcasual or wasteful raw material use. Similarly, the majority of thetools show complex combinations of retouched elements, suggestingmultiple use episodes or multi-functionality. Virtually all flaked stonematerials were utilized in one form or another. There are very fewspecimens in the Chang Tang collections that can be strictly classifiedas waste by-products of core and tool production. Another critical question surrounds the absolute age of the ChangTang assemblages. On the basis of stone tool typology and a limitednumber of radiocarbon dates on lake features associated with surfacearchaeological sites, Huang (1994) believes that the earliest period ofoccupation of the Tibet Plateau dates to between 30-40,000 years ago.Contrary to some reports (e.g. Kuhle 1985), there is no evidence that acontinental-sized ice sheet capped the Tibetan Plateau during the latePleistocene (Derbyshire 1991; Lehmkuhl et al. 1998). Thus, there was nonecessary physical barrier to human colonization at this time. Heavilyablated general flake technology from the Chang Tang could be of thisage. However, there is as yet no independent confirmation of thishypothesis. Blade technology in North China, though rare, is found at sitessuch as Shuidonggou dating to between 25-30,000 years ago (Brantingham1999). As mentioned above, however, the blades and bladelets from theChang Tang are technologically quite different from those seen atShuidonggou. The chronological significance of these technologicaldifferences is unclear. Conservatively, the Chang Tang materials areprobably no older than 25,000 years. It is also possible that the ChangTang blades and bladelets were used alongside microblade technologies bythe same foraging groups. This would imply that the Chang Tang materialsdate, at most, to 15-13,000 years ago (see Elston et al. 1997; Gal 1985;Madsen 1998; but also Lie 1998). To the best of our knowledge, however,microlithic technologies in China were not used in conjunction withblade and bladelet technologies (see Lie 1998; Lin 1996; Zhang 1999). Atthe Tibetan Neolithic site of Karou (4000-5000 years ago) microbladesand simple flake tools were found in abundance, but large blade andbladelet technologies were not identified. This may indicate that theblade and microblade technologies recovered from the Chang Tang date todifferent occupation periods. Conclusion Archaeological evidence from high-elevation ([is greater than]4500m asl) environments of the Tibetan Plateau suggest that foraging groupsoccupied the region during the latter portions of the late Pleistoceneor early Holocene. Large blade and bladelet technologies reminiscent ofclassic Upper Palaeolithic adaptations elsewhere in Eurasia may bediagnostic of a late Pleistocene colonization event. The Chang Tangmicroblade technologies, on the other hand, are likely younger than15,000 years, and may date as late as 4000-5000 years ago. Regardless ofthe absolute ages of these assemblages, they point to the presence offoraging groups occupying some of the most hostile environments on theface of the planet. The limited evidence available from the Chang Tangindicates that these environmental extremes were met with flexible andsuccessful behavioural strategies involving high levels of mobility andreliance on specialized stone tool technologies. Acknowledgements. The archaeological materials discussed here werecollected during field work devoted primarily to wildlife surveys incooperation with the Tibet Forestry Department and the Tibet PlateauInstitute of Biology The Institute of Biology (IoB) is a professional body for biologists, primarily those working in the United Kingdom. Membership currently stands around 14,000. It was founded in 1950, received a Royal Charter in 1979 and holds charitable status. ; we would particularly like to thank Liu Wulin andGu Binyuan for their assistance. We also would like to thank C. VanceHaynes, Owen Davis, Jay Quade, David Madsen and two anonymous reviewersfor helpful commentary on earlier versions of this paper. Analysis ofthe archaeological materials was supported in part under a USA NationalScience Foundation Graduate Fellowship awarded to PJB PJB PJ Brown (NBA Player)PJB Pakistan Journal of BotanyPJB Pat Jordan BandPJB Premature Junctional BeatPJB Patrick Joseph Buchanan (politician). References AN, Z. 1982. Paleoliths and microliths from Shenjia and Shuanghu,northern Tibet, Current Anthropology 23: 493-9. BAR-YOSEF, 0. & S.L. 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