Journal of Archaeological Science (2000) 27, 1085–1113 doi:10.1006/jasc.2000.0597, available online at http://www.idealibrary.com on
Archaeology, Palaeoenvironment, and Chronology of the Tsodilo Hills White Paintings Rock Shelter, Northwest Kalahari Desert, Botswana
L. H. Robbins and M. L. Murphy
Department of Anthropology, Michigan State University, East Lansing, MI 48824, U.S.A.
G. A. Brook
Department of Geography, University of Georgia, Athens, GA 36082, U.S.A.
A. H. Ivester
Department of Geosciences, State University of West Georgia, Carrollton, GA 30118, U.S.A.
A. C. Campbell
P.O. Box 306, Crocodile Pools, Gaborone, Botswana
R. G. Klein
Department of Anthropology, Stanford University, Stanford, CA 94305-2145, U.S.A.
R. G. Milo
Department of Geography, Economics, and Anthropology, Chicago State University, 9501 South King Drive, Chicago, IL 60629, U.S.A.
K. M. Stewart
Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario, Canada
W. S. Downey
Department of Physics, University of Botswana, Private Bag 0022, Gaborone, Botswana
N. J. Stevens
Department of Anthropology, SUNY, Stony Brook, NY 11794-4364, U.S.A.
(Received 3 February 2000, revised manuscript accepted 6 June 2000)
Excavations conducted at the White Paintings Rock Shelter (WPS) have uncovered 7 m of deposits ranging in age from the historic period to at least 100,000 years at the base. Eleven stratigraphic units are described in relation to palaeoenvironmental conditions inferred from sediments and other data. These units contain seven major divisions in
1085 0305–4403/00/111085+29 $35.00/0 2000 Academic Press 1086 L. H. Robbins et al.
the cultural sequence highlighted by a lengthy record of Later and Middle Stone Age deposits. A wide variety of mammals as well as other animals were found in the upper 3 m. Numerous fish bones, wetland mammals and barbed bone points make this site especially interesting because of its desert location. The highest frequencies of fish bones are found between c. 80/90–130 cm (Upper Fish deposits) and between 210–280 cm below the surface (Lower Fish deposits). Most of the barbed bone points were recovered in the Upper Fish deposits. The Lower Fish deposits contain extinct Equus capensis and a microlithic industry as well as some bone points. A large blade industry is found beneath the Lower Fish deposits. This blade industry shows continuity with the underlying Middle Stone Age. 2000 Academic Press
Keywords: TSODILO, KALAHARI, PALAEOENVIRONMENT, FISH EXPLOITATION, BARBED BONE POINTS, OSTRICH EGGSHELL, LATER AND MIDDLE STONE AGE.
Introduction Murphy, 1999; Robbins et al., 1996a, 1996b, 1998a). The WPS, with an overhang of approximately 6 m, is he White Paintings Rock Shelter (WPS) is the most prominent natural shelter at Tsodilo. There located in the Tsodilo Hills to the west of the are three main hills at Tsodilo known as Male, Female, Okavango River in the Kalahari Desert of and Child, and the shelter is situated at the base of Tnorthwest Botswana (Figure 1). Tsodilo is well known Male Hill within one km of a Zhu San village that was for its wealth of rock art, Early Iron Age (EIA) recently abandoned. villages, rock shelters, and caves containing Later Excavations at the site have uncovered the longest Stone Age (LSA) and Middle Stone Age (MSA) archaeological sequence yet documented for a single deposits and prehistoric specularite mines (Campbell locality in the Kalahari extending from about 60/70 et al., 1994; Denbow & Wilmsen, 1986; Robbins, 1990; years ago, through much of the LSA and into the MSA. The entire sequence is estimated to have spanned approximately 100,000 years. In all, 7 m of deposits were excavated resulting in the recovery of ZIM • over 100,000 archaeological specimens. The shelter Tsodilo BABW Hills proved to be especially interesting because of the long Okavango E record of fish exploitation and the first finds of barbed N bone points in southern Africa which are similar to
BOTSWANA those found far to the north, in East Africa (Robbins et al., 1994; Yellen, 1998). This paper presents an Gaborone overview of the archaeological sequence, fauna, NAMIBIA • Child Hill paleoenvironmental information and dating. SOUTH AFRICA 0 200 km The White Paintings The shelter takes its name from the numerous (about 98) white paintings on the wall. A small sample of the white pigment from WPS has been identified as calcrete Female Hill which is readily available in the nearby area (D. Sibley, pers. comm.). While there are also a few red paintings it should be noted that red paintings are actually much more abundant at Tsodilo as a whole in relation to the Divuyu total number of paintings and the number of painted • sites that have been documented (Campbell et al., 1994). Moreover, some sites at Tsodilo contain white • Nqoma paintings that have been superimposed on red paint- ings, indicating that white paintings are more recent White Paintings Shelter (Campbell et al., 1994). The white paintings on the shelter wall include Male Hill one elephant, three possible snakes, one mythological Zhu Village• animal (perhaps an ostrich?), one goat, seven mounted horses, one indeterminate species, 47 geometrics (in- cluding six that resemble the letter ‘‘m’’), 35 humans, including seven on horseback, one wagon and one Kilometers possible wagon wheel (Figure 2). Human figures fre- Figure 1. The locations of the principal sites mentioned in the text. quently have their hands on their hips. The most Tsodilo Hills White Paintings Rock Shelter 1087
Figure 2. Sample paintings on the wall of White Paintings Shelter. prominent painting is of a large male elephant with its were subdivided into the following groups: humans— tail, penis and trunk projecting straight out. hands free, one or both hands on hips, leading an Paintings of horses and riders reveal that some of the animal, riding an animal, human+grid; animals— shelter artwork could not be older than the mid 1800s snake, elephant, horse-like; circles—single, bifurcated, since that is when horses would have first been seen in with interior grid; designs—non-circular grid, resem- the general area. Moreover, local Zhu San traditions bling letter m, indeterminate. Additional variables suggest that a Khoe group, known as the N/aekhwe, included the following brightness categories: scarcely had formerly lived at Tsodilo and that the N/aekhwe visible, faded, distinct and bright. Statistical analysis were responsible for the white paintings. A relatively revealed that there was no relationship between recent age for some of the white paintings at this the types of images and the brightness categories shelter is consistent with evidence from other sites in (R. Lovell, pers. comm.). A chi-square of 15·4421 with central and southern Africa where there are similar df=15 indicates that the relationships are essentially white paintings (Prins & Hall, 1994). However, as random. However, a regression equation revealed that suggested below, some of the paintings could be earlier there is a relationship between the degree of brightness than the historic period. of the paintings and height above the surface of the The majority of the white paintings are concentrated ground. The most faded paintings were closest to the within an 8 m area along the shelter wall. In 1989, ground while brightness increased with height above copies of most of these paintings (N=67) were sketched the floor (2=19·8). This difference may be due to by two artists, S. and M. Hartland-Rowe, and infor- differential weathering, perhaps resulting from more mation was recorded regarding the position on the wall intense heat near the ground and blowing sand. Alter- and the relative degree of brightness. Height of the natively, the faded paintings found closer to the paintings ranges from 30 to 160 cm above the surface. ground may be older and were possibly done at a time The 67 recorded paintings were coded into four when the ground surface was somewhat lower than it is major image categories including humans, animals, at present. Several worn pieces of white calcrete, found circles and other designs. Subsequently, these images buried in the deposits, also suggest that some of the 1088 L. H. Robbins et al.
Year Squares Depth cm
1989 1–4 75 Sq. 31, 70–71 m 5 165 Sq. 30, 50–51 m 6 172 7–8 70 Sq. 29, 31–32 m 9 200 1991 10 260 11 480 12 680 26 13 190 14–18 130 1992 19 340 20 430 21–22 620 25 12/23 700 24–29 150 1993 30–31 150
27 24 28
18 17 16
15 14 13
23 12 11 10
22 21 20 19 Overhang N
01
1 2 9 1 m
3 4 8
5 6 7
Shelter wall Figure 3. Site plan showing the major excavation units. paintings could be older than the pictures of horses and sieve for the deposits. Periodically, fine screening was riders. The most convincing specimens include worn done and selected samples were subjected to tub and triangular-shaped pieces found within a metre of the mechanical flotation. heavily painted area in square 5 (33–34 cm below the Initial work by A. Campbell and N. Walker in 1988, surface) and square 6 (90–100 cm). who excavated a 1-m square near the wall to a depth of 80 cm, recovered a small sample of lithics, sherds, fauna and nutshell fragments. In 1989, Campbell and Excavations Robbins excavated nine 1-m squares near the shelter wall, including squares 1–6 in front of the White Thirty-one 1-metre squares have been excavated to Elephant painting and the adjacent heavily painted varying depths at WPS (Figure 3). Excavations were area (Robbins, 1989a, 1991). The excavation of these carried out in 10 cm levels; using a 4/5-mm mesh squares was hampered by large boulders, especially in Tsodilo Hills White Paintings Rock Shelter 1089
located 74·5 m from the base of the shelter wall. The bases of squares 30–31 were also augured to 350 cm for the purpose of deeper exploration. All of the outlying test pits produced archaeological material. Additional auguring was carried out in 1993 in order to explore the site beyond the areas sampled by the test pits. The feasibility of using an auger was tested in an area known to be rich in deposits and this proved to be an efficient and excellent method for rapid recovery. A series of 12 auger holes covered the area to the west of the excavations between square 31 and the edge of the ancient Tsodilo lake beds documented by Brook (Brook, 1992; Robbins et al., 1994). In most cases, the base of the auger holes was established when hard calcrete deposits were encountered. The first five auger holes demonstrated that cultural material (primarily LSA debitage and sherds) extended to a distance of 174·5 m from the shelter wall. The depths of these auger holes ranged from 165–290 cm. The next seven auger holes, placed between 183·5 and 354·5 metres from the shelter wall, were all sterile and encountered hard calcrete at shallow depths ranging from 15 to 90 cm.
Stratigraphy, Sediments, and Palaeoenvironmental Inferences The stratigraphy of the main WPS excavation is shown in Figure 5. Eleven stratigraphic units are identified. In an attempt to understand more about the sediment Figure 4. The central block of excavations from above. sequence and its relation to artefact discoveries, we examined samples of sediment recovered in 1991 from the case of squares 1–4, while they were absent in the south wall of square 12 to a depth of 547·5 cm and square 9 suggesting that deeper deposits might be in 1992 from 540–705 cm in the south wall of square found further from the wall. For this reason, in 1991 a 23. At both locations entire columns of sediment were central block of nine 1-m squares (10–18) was exca- removed in increments of 7·5 cm with a sample size in vated further from the wall in front of the shelter at the the range 400–500 g (Ivester, 1995). Larger samples of edge of the drip line (Figure 4). This work uncovered up to 1300 g were collected from coarser deposits. 550 cm of deposits in the deepest unit, square 12, but Mean grain size, sorting, skewness and kurtosis were the base of the deposits was not reached. In 1992, determined by the graphical method of Folk & Ward squares 19–23 were excavated as part of the central (1957). Sediment gravel content varied up to 30% by block for the purpose of exploring the deposits below weight, the mean of the non-gravel portion of the 550 cm and enlarging the sample from the lower levels sediments varied from 1·95–2·28 (medium to fine of the site. The excavations reached a depth of 7 m in sand), the sorting varied from 0·69 (moderately well squares 12 and 23 (Figure 4). Following the completion sorted) to 0·22 (poorly sorted), skewness varied from of the excavation, sediment sampling was conducted by 0·06 (near symmetrical) to 0·22 (fine-skewed), and G. A. Brook, and then the site was back-filled. It is kurtosis varied from 1·17 (leptokurtic) to 2·43 (very emphasised that the deeper central block of squares leptokurtic). Carbonate ranged from 2–11% of the provided the bulk of information about the site and untreated sand, silt and clay weight. The results of our much of the sequence described below, especially sediment analyses will be presented in detail elsewhere. the preceramic levels, is largely based on artefacts Here we will focus on the stratigraphy and palaeo- recovered from this area. environmental significance of the sediment units In addition to the main excavation (squares 1–23), identified. outlying test squares 24 to 31 were excavated (1992– An interpretation of the sequence is as follows. Units 1993) to a depth of 150 cm in order to examine the 1–10 are largely of aeolian origin, each being deposited spatial extent of the site in the more accessible upper during a period of dry climate and dune activity in the levels in areas more distant from the overhang. The region. Deposition was probably relatively rapid in most distant unit from the overhang was square 31 geological terms, covering one or two to several 1090 L. H. Robbins et al.
16N 13N 10N 19N 19E 20E 21E 22E 22S 23S 23W 12W 0 1 1.4 2a 5.7 2b 4.5 4.1 39.4 5.0 33.4 8.0 100 20.6 3a 4.5 5 3b 41.8 4.1 3b 36.7 36.7 4 6 38.8 39.4 200 37.4 31.1 > 48 48.0 7a 35.8 > 48 300 7b
8a 33.9 8b 9a Depth (cm) 400
9b 55.4
500 66.4 10a 10b
11 600 94.3
700 East South North West Cobbles or pebbles Ages in squares shown Ages in squares 11 and 11/12 Ages in square 12 Figure 5. Wraparound stratigraphic cross section of the central block of excavated squares, with ages obtained in squares 13 and 19–23. Square numbers and wall orientation are indicated. thousand years. At the top of each aeolian unit there is because of varying degrees of staining by organic a coarser layer, sometimes marked by a stone line or matter. Unit 5 and all of the underlying units are continuous schist horizon, or in other cases by a distinctly lighter in colour (10YR6/3, pale brown). darker, buried soil A horizon. In Figure 5 prominent Significantly, the upper surface of Unit 5 is irregular layers of this kind are denoted with an ‘‘a’’. These ranging from about 75-cm deep in square 19 to about coarser sediments accumulated, or soil development 200 cm in square 20. This irregularity indicates the progressed, when there was virtually no input of former presence at the site of a sand ridge, roughly aeolian sand to the shelter. At these times the shelter paralleling the drip line of the rock shelter (Figure 3). floor was relatively stable and weathered material This ridge appears to be at a higher level and broader falling from the ceiling of the shelter, and tumbling towards the northern wall of the shelter suggesting over the edge of the roof near the drip line, accumu- sand transport during its formation from the south or lated on the aeolian sands. It is likely that these coarser southeast. Even today the floor of WPS slopes upwards layers record periods of increased moisture at the site from south to north indicating that the same wind when aeolian activity was reduced as a result of an direction has affected the character of today’s floor. increased vegetation cover on the nearby dunes. At the From the crest of the Unit 5 ridge the surface sloped same time a greater abundance of water may have downwards towards the back wall of the shelter and increased the rate of rock breakdown increasing the outwards (westwards) away from the shelter. The ridge supply of coarser debris to the shelter. Unit 11 in the is also visible, although it is more subdued, in Unit 6. sequence, a carbonate-indurated rock breccia, appears In the darker sediments above Unit 5 there are three to record a period of significantly increased moisture soils, including the present soil (Unit 1), and two and rock breakdown at the shelter subsequent to the buried soils (Units 2 and 3) with preserved A and B onset of significant aeolian activity at the site. horizons (Units 2a and 2b, and 3a and 3b). The buried The uppermost four units of the sequence shown in A horizons are distinctly darker than the overlying Figure 5 (Units 1–4) are darker (10YR4/1 to 10YR5/3, and underlying sediments. For example, Unit 2a is dark grey to brown) than the underlying sediments very dark grey (10YR3/1) compared to dark grey Tsodilo Hills White Paintings Rock Shelter 1091
(10YR4.1) for Unit 1 and dark greyish-brown for ably clear archaeological sequence is present, but there Unit 2b. are some uncertainties regarding the relationship of Large cobbles and pebbles are most common at the the sequence to the available dates. When these stratigraphic boundaries located below the drip line, uncertainties are evident alternative possibilities will and so they are more apparent in squares 13, 22 and 23 be discussed, especially for the Lower Fish deposits (Figure 5). Below Unit 3 most of the sediment units are described below. marked by an upper thin horizon of angular pebbles At any site with soft sand a major concern must and cobbles, visible as a line of stones. Generally, this be bioturbation. Humans trampling the surface will upper layer (designated by ‘‘a’’ in Figure 5) has a undoubtedly disturb at least the upper several centi- higher calcium carbonate content than the underlying metres of the deposit. Another possibility is that bur- looser sand. The capping stone horizons are more rowing animals and insects have disturbed areas of the marked in the case of Units 9 and 10 and in the field we site, though burrows and pockets of porous deposits referred to these as ‘‘schist fall horizons’’. were seldom evident. Evidence that bioturbation has A prominent feature of the stratigraphy below 5m is been relatively modest at WPS includes a clear stra- a steeply-sloping, carbonate-cemented talus cone made tigraphy, with two buried soils in the upper 200 cm of up of cobble- and pebble-sized clasts, largely of schist the deposit, both with preserved A and B horizons. In from the nearby rock walls. This was observed clearly addition, several refits of bone artefacts, pottery and in squares 12, 21, 22 and 23. Significantly, it extends ostrich egg shell fragments indicate vertical movements beyond the drip line into the shelter and it is clearly the in the range of 0–30 cm and a horizontal scatter (we product of weathering by seepage coming from joints cannot be sure bioturbation caused horizontal separ- in the schist of the back wall and roof, and flowing ation as this may have occurred when the items across the floor of the rock shelter. Units 8 and 7 are were originally discarded) usually of less than a metre. draped over this feature and the basal sands of these With the assumption that bioturbation by plants, two units are soft while the upper, coarser unit is animals and insects must have affected WPS to some indurated by carbonate cement. degree, we anticipated some vertical mixing of arte- The presence of the cemented breccia of Unit 11 and facts, charcoal, ostrich egg shell and bone within the the extremely marked schist spall horizons of Units 10a profile. However, if disturbances have been modest, as and 9a are an indication that the climate was signifi- the relatively undisturbed stratigraphy described above cantly wetter, and possibly also colder at times in this and refits suggest, then despite some mixing we should interval of time. Water would be needed to produce the still be able to discern the cultural and chronological breakdown material and cold temperatures, perhaps record. including some frost, could have speeded up the pro- To further our understanding of the nature of cess. As we shall see later, MSA artefacts have been cultural deposition at Tsodilo, so that we could better found in these sediments suggesting that MSA use of interpret the sediment and archaeological record, we the site was at a time of generally increased moisture excavated two test pits in a trash midden located 3 m availability. outside of the nearby Zhu village that was inhabited during the time of our work in 1992. Our ethno- archaeological excavations showed that 30 cm of Site Chronology deposits had accumulated in a period of 3 years. Amidst the numerous mongongo nut shells and other As with other deep sites in sandy areas, developing a debris, we found a 1991 Pula (a Botswana coin) in the reliable chronology for WPS was a challenge. Conven- 10–15 cm level. This example provides a clear idea of tional and AMS radiocarbon ages were obtained on the nature of deposition, or potentially, the movement bulk and small individual samples of charcoal, ostrich of a larger object in a year or less. egg shell, and bone. In addition, both OSL and TL Radiocarbon and TL/OSL ages obtained for the ages were obtained for quartz sand exposed by the White Paintings site are listed in Table 1 and the excavations. Radiocarbon ages were calibrated using locations of selected, dated samples are shown in relationships in Bard et al. (1990) and Kitagawa & van Figure 5. Of these 40 ages only 33 apply to the central der Plicht (1998). Where possible, strata within the block of excavated squares and only 23 of these are range of radiocarbon dating were dated by radio- considered to be reliable. Radiocarbon dates on char- carbon and OSL/TL to compare results. OSL ages coal below 180 cm in square 23 are clearly too young were obtained from the University of Washington and probably represent the ages of tree roots burned by laboratory (Feathers, 1997), and TL ages from the deeply penetrating brush fires. The radiocarbon ages University of Botswana (W. Downey, this paper). The on bone collagen from squares 11/12 are also sus- initial radiocarbon chronology for the site appeared to pect, being significantly younger than surrounding be reasonably straightforward when comparatively few materials. This may point to downward bioturbation dates had been obtained (Robbins et al., 1994), but as of the large bone fragments. Only one of the lumi- more samples were processed, the results became nescence sequences, the University of Botswana TL increasingly problematic. As will be shown, a reason- sequence presented for the first time here, resulted in an 1092 L. H. Robbins et al.
Table 1. Radiocarbon, TL and OSL ages for the WPS sediment sequence
Depth Dating Radiocarbon Square (cm) Material method Lab ID age year/ Age ka*
1–4† 62 Charcoal C14 Beta 33052 500 60 0·50·06 5 77 Charcoal C14 Beta 33681 2640130 3·00·1 5/6 155–165 Charcoal C14 Beta 37489 1780 70 2·00·1 690–100 Charcoal C14 Beta 33053 3700130 4·30·1 8 70 Charcoal C14 Beta 33055 110 80 Burned root?‡ 940–50 Charcoal C14 Beta 33056 1080100 1·20·1 11 110–120 Charcoal C14 Beta 47865 4330160 5·00·2 11 390–400 Ostrich egg shell C14-AMS UCR 3364 28,890300 33·90·3 11/12 180–190 Ostrich egg shell C14 SMU 2656 33,020270 38·80·3 11/12 180–190 Ostrich egg shell C14-AMS AA 31280 31,880510 37·40·6 11/12 320–330 Bone C14 Beta 47866 20,340520 23·90·6‡ 11/12 440–450 Bone C14-AMS Beta 47867 20,110160 23·60·2‡ 12 120–130 Ostrich egg shell C14-AMS UCR 3365 35,510560 41·80·7 12 150–160 Ostrich eggs hell C14 UGA 6731 31,220320 36·70·4 13 100 Quartz sand TL U. Botswana 5·70·6 13 230 Quartz sand TL U. Botswana 48·04·8 13 500 Quartz sand TL U. Botswana 66·46·5 13 605 Quartz sand TL U. Botswana 94·39·4 14 40–50 Charcoal C14- Beta 47864 2260 80 2·40·1 17 20–30 Ostrich egg shell C14-AMS 200 50 0·20·05 19 120 Quartz sand OSL U. Washington 20·61·9 20/21 250 Quartz sand OSL U. Washington 35·82·6 21 110–120 Ostrich egg shell C14-AMS UCR 3366 3900 50 4·50·1 21 110–120 Ostrich egg shell C14-AMS UCR 3367 28,360240 33·40·3 21 190–200 Ostrich egg shell C14-AMS AA 31729 26,460300 31·10·3 21 250–260 Ostrich egg shell C14 UGA 6730 >42,000 >48 22 60–70 Ostrich egg shell C14-AMS UCR 3370 3570 60 4·10·1 22 110–120 Ostrich egg shell C14-AMS UCR 3368 3860 50 4·50·1 22 110–120 Charcoal C14-AMS AA 35233 3555 45 4·10·05 23 40–50 Bone C14-AMS OXA 6038 1225 60 1·40·1 23 50–60 Ostrich egg shell C14-AMS UCR 3369 33,490440 39·40·5 23 110–120 Ostrich egg shell C14 UGA 6728 6840 40 8·00·05 23 150–160 Ostrich egg shell C14 UGA 6731 31,220320 36·70·4 23 170–180 Ostrich egg shell C14-AMS UCR 3289 33,470250 39·40·3 23 180 Charcoal C14-AMS Beta 55732 3479 90 4·00·1‡ 23 210–220 Ostrich egg shell C14 UGA 6729 >40,000 >48 23 230 Charcoal C14-AMS Beta 55733 Modern Burned root?‡ 23 285 Charcoal C14-AMS Beta 55734 Modern Burned root?‡ 23 450 Quartz sand OSL U. Washington 55·44·7 23 610 Quartz sand OSL U. Washington 38·34·0‡ 23 700 Quartz sand OSL U. Washington 58·45·3‡ 27 139 Charcoal C14 Beta 55731 60 80 Burned root?‡
*Radiocarbon ages calibrated according to Bard et al. (1990). The equation C14 age=54+U-series age was used to calibrate ages up to 35,000 year . For ages of 35,000 to 43,000, calibration involved adding 6 ka to the age. †Sample taken at the intersection of four squares. ‡Signifies an age that we consider suspect and so did not use in developing a chronology for the site. internally consistent long-term chronology for the site. Feathers (1997) for sand from 120, 250, and 440 cm in In addition, the youngest TL age of 5·7 ka for Unit 2b developing a chronology for the site. is consistent with radiocarbon ages on charcoal and We begin our discussion with the uppermost ostrich egg shell for this same unit suggesting that deposits and work down. Two radiocarbon ages of the TL approach is giving viable ages for the site c.0·20·1kaat20–30 cm in square 17, and (Figure 5). As noted by Feathers (1997), the youngest 1·40·1kaat40–50 cm in square 23, suggest depo- three ages of the University of Washington OSL sition of Unit 1 during the last 1·0kaorso(Figure 5). sequence appear to be reliable, but the last two As will be discussed, this age estimate is also supported ages appear significantly too young. By contrast, the by archaeological finds such as maize and trade beads University of Botswana TL ages for the deeper MSA as well as ceramics and iron artefacts. We also have deposits at 500 and 605 cm do seem to provide reason- some confidence in the age range of Unit 2. For this able age estimates given comparative evidence for unit we have a radiometric age of 5·00·2 ka for a MSA dates at other sites (Brooks et al., 1990). We bulk charcoal sample from 110–120 cm in square 11, have therefore only used the OSL ages provided by an AMS radiocarbon age of 4·10·05 ka on an Tsodilo Hills White Paintings Rock Shelter 1093 individual charcoal fragment from 110–120 cm in arguments just presented on the ages of Units 2–7. square 22, a TL age of 5·7 ka on quartz sand from However, one possible, and perhaps likely, explanation 100 cm in square 13, and three AMS radiocarbon ages for the presence of both older and younger material in for ostrich egg shell at 100–120 cm, 60–70 cm and Units 4 and 3 is that the older material was eroded 110–120 cm in square 21 (4·50·1 ka), 22 (4·1 from Unit 5 and deposited in these younger, lower- 0·1 ka) and 22 (4·50·1 ka), respectively. As will be elevation units. Certainly, the crest of the Unit 5 ridge shown, most of the barbed points were found between around the drip line of the shelter was higher than the 80/90 and 130 cm amidst a large quantity of fish bones surrounding surface. If LSA peoples discarded egg (the Upper Fish deposits). In addition to this, we shell onto this ridge, it is quite possible that some of obtained an age of 8 ka on ostrich egg shell from these fragments were transported by water, wind, or by 110–120 cm in square 23. This sample occurs very close biogenic processes, into the accumulating sediments to the upper surface of Unit 3 and may help define its of Units 4 and 3. However, until further work is age. However, a problem with this date is that it was conducted, the exact ages of these upper stratigraphic obtained on a bulk sample of ostrich egg shell frag- units will remain uncertain. ments and if these fragments contained pieces of Below about 250 cm, the chronology for Units 7–11 c. 30 ka and pieces of c. 5 ka, an 8 ka age could have is tentative as it is based on only three TL ages and two emerged and be intermediate between the two age OSL ages. As argued above, the upper surface of Unit ranges of the ostrich egg shell fragments. Nevertheless, 7 at 230 cm appears to date to around 48 ka. In square except for one age (4·1 ka in square 22), the samples 23 at 450 cm, Feathers (1997) dated sand from Unit 9b dated were all recovered near the upper surface of Unit to 55·44·7 ka. However, because no field gamma 3. Together these ages suggest that this surface was spectrometer measurements were made at the sample exposed at least in the period 5·7–4·1 ka, and possibly site, and because the sample was taken from between in the period 8–4·1 ka, and that Unit 2 was deposited two prominent schist layers, the annual radiation dose from about 4·1–1·4 ka. The apparent concentration of estimate from the analysis of a sample of the surround- artefacts across the upper surface of Unit 3 implies a ing sediment is likely to be approximate only. If the stable surface not subjected to rapid accumulation of schist layers in any way attenuated the radiation from sediment. the surrounding sediments, the estimated age is likely Two ostrich egg shell ages of >48 ka in squares 21 to be too young. In square 13 we obtained TL ages of and 23 at 250–260 and 210–220 cm, respectively, and a 66·46·5 ka and 94·39·4 ka for sand at 500 and TL age of 484·8 ka at 230 cm in square 13, suggest 605 cm depth, respectively. However, because our deep that the top of Unit 7 was exposed around 48 ka. We stratigraphy does not extend into square 13, we cannot also have several ages for the upper part of Unit 5 and be absolutely certain which units these ages apply to. the basal sediments of Unit 4, which probably date a This is because below 230 cm, samples for TL dating stable surface after deposition of Unit 5 and before from square 13 were collected by sand auger and this deposition of Unit 4. In squares 11/12 at 180–190 cm procedure did not allow variations in stratigraphy to we have ostrich egg shell ages of 37·4 and 38·8 ka, in be differentiated. In auguring, we did not encounter square 21 at 190–200 cm we have another ostrich egg thick schist horizons similar to those in squares 20–23, shell age of 31·1 ka, and in square 23 at 150–160 and but as square 13 is some distance from the drip line of 160–170 cm two ostrich egg shell ages of 36·7 and the shelter we did not expect these horizons to be 39·4 ka, respectively. In addition, in Unit 6, square 20 as prominent. Based on extrapolation of the deep we have an OSL age on sand at 250 cm of 35·8ka stratigraphy exposed in squares 20–23, and given that (Feathers, 1997). These ages, and the age of Unit 7a, the OSL age of 55·4 may be too young, Unit 9a suggest that Units 6 and 5 were deposited in the probably dates to around 65 ka and Unit 8a to around interval 48–31 ka. However, the distribution of ages 58 ka. In all likelihood the TL age at 605 cm was taken suggests a slightly narrower time period, namely from the soft sands of Unit 10, thus dating this unit to 39–37 ka for accumulation of these two units. The age around 95 ka and Unit 11 to older than this. of 31·1 ka for ostrich egg shell recovered from 190– 200 cm in square 21 raises the possibility that the upper surface of Unit 4 dates to about this period. Finally, an The Archaeological Sequence OSL age of 20·6 ka for sand at 120 cm in square 19 (Feathers, 1997) implies this age for the basal part of In the presentation of the WPS archaeological Unit 3b in the sequence. If the above arguments are sequence we follow the excavations from the sub- correct, and there are many uncertainties, Unit 3a surface deposits to the base of the site. This approach would then date in the period 20·6–8/5·7 ka or be late will enable us to describe the changes that were glacial or early Holocene in age. observed by the excavators during the actual field Ages of 41·8 ka for ostrich egg shell from 120– work. Whereas 10 cm levels were used during the field 130 cm in square 12 in Unit 3a, 36·7 ka for ostrich egg work, the overall sequence presented below was clear shell from 150–160 cm in square 12, and 33·4 ka from during the excavations and is well-supported by the 110–120 cm in square 21, pose problems given the artefact analysis (Murphy, 1999). 1094 L. H. Robbins et al.
Table 2. Lithic debitage and angular waste totals by depth in squares 10–29 (from Murphy, 1999)
Depth QAW QD BCD CHD JAD TWBF BLC SD MCCD OFGD Totals
0–10 54 185 10 7 6 1 0 4 8 9 284 10–20 25 209 1 1 10 1 0 6 5 11 269 20–30 50 392 4 4 25 0 0 11 19 26 531 30–40 59 551 7 8 18 2 1 8 16 40 710 40–50 69 662 11 6 24 0 1 16 30 39 858 50–60 82 577 32 17 20 3 0 17 31 33 812 60–70 139 594 34 15 30 1 1 26 20 44 904 70–80 161 764 39 31 30 6 3 27 45 43 1149 80–90 132 567 36 16 24 2 0 28 51 30 886 90–100 141 491 31 16 28 4 1 29 43 44 828 100–110 273 568 52 29 29 7 3 89 68 105 1223 110–120 196 573 50 33 46 8 4 111 109 130 1260 120–130 241 529 59 37 45 5 2 113 114 141 1286 130–140 40 316 14 5 17 1 1 35 40 36 505 140–150 54 280 14 4 12 7 0 28 18 15 432 150–160 26 110 14 5 14 1 1 21 21 26 239 160–170 42 126 10 5 7 0 0 28 12 24 254 170–180 65 212 25 14 12 4 0 63 40 21 456 180–190 62 182 16 6 9 1 4 103 19 24 426 190–200 44 159 12 6 6 4 0 46 12 12 301 200–210 52 142 7 2 4 0 0 26 12 11 256 210–220 55 257 10 2 6 1 0 30 26 15 402 220–230 58 264 5 3 3 1 0 16 16 23 389 230–240 94 596 4 13 7 5 0 28 30 8 785 240–250 161 758 18 19 9 5 0 27 42 19 1058 250–260 157 762 15 17 12 4 6 32 54 42 1101 260–270 76 299 7 9 8 4 2 12 38 10 465 270–280 55 216 3 4 8 1 1 7 38 12 345 280–290 22 152 2 6 3 1 0 3 17 11 217 290–300 80 130 4 2 0 0 1 4 13 4 238 300–310 33 57 0 1 0 1 0 3 5 1 101 310–320 9 41 3 0 0 0 0 4 1 4 62 320–330 53 64 1 1 1 0 0 1 0 2 123 330–340 87 100 5 1 0 0 0 9 3 4 209 340–350 103 119 3 0 0 0 0 5 1 3 234 350–360 47 120 3 1 2 1 0 6 7 5 192 360–370 35 56 1 4 1 0 0 7 7 6 117 370–380 37 77 5 5 4 0 1 12 7 11 159 380–390 10 92 5 0 1 3 0 10 31 9 161 390–400 28 142 7 5 6 1 2 26 26 10 253 400–410 30 189 5 2 4 2 0 42 28 10 312 410–420 54 173 10 8 17 1 1 58 36 22 380 420–430 31 131 8 5 11 2 0 72 35 11 306 430–440 8 128 12 2 7 6 0 22 50 7 242 440–450 47 241 13 14 27 10 0 63 55 29 499 450–460 66 139 15 6 9 6 1 52 37 34 365 460–470 46 137 13 6 10 7 0 73 51 41 384 470–480 43 160 7 19 15 7 0 83 57 44 435 480–490 36 112 13 20 23 8 0 84 78 27 401 490–500 12 95 8 13 9 4 0 55 42 36 274 500–510 15 70 6 12 6 1 2 53 32 26 223 510–520 6 46 4 8 7 2 0 37 25 28 163 520–530 22 71 7 22 17 8 0 80 29 30 286 530–540 18 76 11 18 12 8 0 71 35 35 284 540–550 12 58 17 26 16 7 3 80 34 46 299 550–560 6 43 16 13 8 3 0 47 35 20 191 560–570 16 87 18 9 18 3 0 64 30 41 286 570–580 13 50 6 0 9 3 0 41 15 24 161 580–590 44 85 7 2 5 0 0 26 10 15 194 590–600 24 49 9 1 4 1 0 30 5 7 130 600–610 11 46 3 1 4 0 0 10 0 10 85 610–620 21 55 3 3 3 0 0 16 7 23 131 620–630 6 22 1 0 2 3 0 7 6 7 54 630–640 0 27 0 1 1 1 0 4 0 0 34 640–650 6 22 0 0 0 0 0 1 4 4 37 650–660 14 43 4 5 4 0 0 3 4 9 86 Tsodilo Hills White Paintings Rock Shelter 1095
Table 2. Continued
Depth QAW QD BCD CHD JAD TWBF BLC SD MCCD OFGD Totals
660–670 7 33 2 2 3 0 0 12 4 7 70 670–680 5 35 3 0 6 3 0 8 12 1 73 680–690 0 12 0 0 8 0 0 10 4 12 46 690–700 0 9 1 5 2 0 0 3 16 0 36 Totals: 3826 14,895 801 583 754 182 42 2284 1870 1669 26,906
QAW=quartz angular waste; QD=quartz debitage; BCD=brown chert debitage; CHD=chalcedony debitage; JAD=jasper debitage; TWBF=transparent with black flecks debitage; BLC=black chert debitage; SD=silcrete debitage; MCCD=multi-colour chert debitage; OFGD=other fine grained debitage.
Summaries of the artefact finds and the main such as monitor lizards, porcupine and springhare. distinctive characteristics of each part of the sequence Fish were sometimes obtained from people along the will be presented below, followed by specialist reports Ncamaseri River. He related that the emphasis was on on the fauna and other materials. Table 2 and Figure 6 eating smaller animals in comparison to large game. present an overview of the lithic data by depth. It He recounted that they did not keep cattle, or work in can be seen that the highest frequencies of stone stone (though they were keeping cattle when we con- artefacts correspond to the two fish-rich zones (3 and ducted fieldwork). We asked whether refuse was 5) described below. thrown in a specific area at the shelter such as a dump Each division in the sequence should be viewed as and were told that it was simply discarded on the spot representing distinctive occupation zones in a broad and was left lying, unless it was moved about by dogs. sense. As in the case of other southern African rock Subsurface (0–10 cm) evidence of ash areas under shelters, the distinctive sets of deposits are seldom the overhang at WPS that appear to represent overlap- preserved as discrete ‘‘moments in time’’. It is stressed ping hearths are in keeping with the oral tradition of that the relationships between the occupation zones families sleeping ‘‘fire after fire’’. Numerous mongongo and the 11 stratigraphic units is general and in a nut shells and bones of small bovids, duiker, spring- number of instances these ‘‘cultural’’ zones clearly hare, tortoise, and fish are also consistent with the overlap the stratigraphic units. In addition, it also tradition. should be mentioned that there is no standardised nomenclature for lithic industries in the Kalahari, Historic/Late Prehistoric evidence. A nylon button similar to those established in South Africa, or in the found in square 14 (10–20 cm) indicates very recent use Matopo Hills of Zimbabwe (Robbins & Murphy, of the site, yet the deposits also contain microlithic 1998a). Until more sites are excavated and com- artefacts (the lithics are assumed to be older than the parative studies are done, it seemed best to avoid period indicated by oral tradition since people were not applying terms established elsewhere beyond making using stone tools at the time, if the tradition is correct). general statements. Some sherds and European glass trade beads were recovered. The beads were coloured white, cream, tan, rose, red and blue/black. These bead colours were Late Prehistoric/Historic: 0–20/30 cm, Unit 1 popular in the middle of the last century. According to Oral tradition of site use. Oral traditions concerning the Andersson (1857; 375) who visited Lake Ngami, in the use of rock shelters are quite rare in Africa. At WPS, region about 200 km to the southeast of Tsodilo in oral traditions obtained in August 1989 indicate that 1853: ‘‘small beads of the following colours, pink, the shelter was used as a temporary rainy season camp dull-white, light-green, brick-coloured, light-blue, about 60/70 years ago by local Zhu, San. A Zhu elder, dark-blue and yellow, are chiefly in demand’’. Most of estimated to have been about 71 years old at the time the WPS beads (11) were found under the overhang when he was interviewed, recalled using the shelter as a in the 1989 excavation and 9 of them were found youth. At that time, a group of people camped under between the surface and 20 cm. There were also some the overhang and slept ‘‘family after family and fire iron beads, a copper bead (square 22, 20–30) as well as after fire’’ (Robbins, 1991). Interestingly, he reported small ostrich eggshell beads and bead preforms. Egg- that they also maintained another nearby settlement shell beads were also found that were broken during with houses on the hill that was used during the same manufacture. period. It was located about a 10 min walk from the The 0–10 cm level produced several maize kernels shelter. They occasionally killed large game such as and the 10–20 cm level yielded the mid-shaft fragment eland, giraffe, and gemsbok some distance away from of a maize ear with 12 rows (Robbins, 1991). The ear is the shelter and brought back pieces of the meat from identical to maize that was periodically being grown the kill site. They also foraged and ate small animals at Tsodilo at the time of our fieldwork by both 1096 L. H. Robbins et al.
Tool count 0 10 20 3040 5010 2030 40 50 10 20 30 40 50 10 20 30 40 50 0 Sq. 23 Sq. 12 Sq. 11 Sq. 10
100
200
260 cm 300
400
500 480 cm
600
0 Sq. 22 Sq. 21 Sq. 20 Sq. 19 Depth (cm) 100
200
300
340 cm 400
430 cm 500
600 620 cm 620 cm
700 Figure 6. The number of stone tools by depth in squares 10–12 and 19–23. Dashed lines show the depth of excavation in the square.
Hambukushu (Bantu speakers) and Zhu. A cowpea Later Stone Age contemporary with Early Iron Age: was found in the 20–30 cm level. These deposits also 30–70/80 cm, Units 2a and upper 2b yielded evidence of what is almost certainly desiccated cow dung (0–10, 10–20, 20–30 cm). Whether the cattle These levels produced no historic artefacts, maize or that deposited the dung belonged to the Zhu (contrary cow dung. Early Iron Age ceramics were recovered to the oral tradition) or to neighbouring Hambukushu, along with considerable debitage and typical Wilton- whose immediate ancestors also lived at Tsodilo during like LSA microlithic tools, grindstones, hammer the same period, cannot be ascertained. stones, bone artefacts (most appear to have been link Quite clearly, the maize, which post-dates the voyage shaft/arrow points and were concentrated in squares of Columbus to America and the European trade 1–4, in front of the shelter), ostrich egg shell beads, beads matching Andersson’s description, indicate a fauna and mongongo nut shell fragments. Whereas recent age for the deposits, whereas the ‘‘LSA lithics’’ most of the pottery consists of undecorated body may be several hundred years earlier. sherds, comb stamping and incised sherds are Tsodilo Hills White Paintings Rock Shelter 1097
Table 3. The Number of Identifiable Specimens (NISP) and the Minimum Number of Individuals by which mammalian species, monitor lizard and snake are represented in the main culture-stratigraphic units of WPS. Daggers indicate extinct species
Late Prehistoric/ Late LSA/ Mainly Upper Mainly Lower Historic EIA fish fish Linnaean name Vernacular name NISP MNI NISP MNI NISP MNI NISP MNI
Crocidura cf. hirta Probable lesser red musk shrew 0 0 1 1 1 1 1 1 Lepus sp. Hare 3 1 2 1 4 2 2 1 Pedetes capensis Springhare 81 3 97 8 332 19 112 5 Cryptomys damarensis Damaraland molerat 2 1 2 1 15 3 0 0 Saccostomus campestris Pouched mouse 0 0 1 1 1 1 0 0 Gerbillurus paeba Hairy-footed gerbil 1 1 0 0 1 1 0 0 Tatera cf. leucogaster Probable bushveld gerbil 1 1 2 2 11 8 0 0 Otomys cf. angoniensis Probable Angoni vlei rat 3 1 1 1 5 1 0 0 Hystrix africaeaustralis Porcupine 1 1 4 1 10 1 1 1 Cercopithecus aethiops Vervet monkey 0 0 0 0 1 1 0 0 Otocyon megalotis Bat-eared fox 4 1 4 1 11 1 9 2 Mellivora capensis Honey badger 0 0 0 0 2 1 0 0 Genetta sp. Genet 1 1 0 0 0 0 0 0 Viverridae gen. et sp. indet. Indeterminate mongoose 22 3 3 1 7 2 1 1 Hyaenidae gen. et sp. indet. Hyena 0 0 2 1 2 1 0 0 Felis libyca Wildcat 0 0 0 0 0 0 2 1 Felis cf. caracal Probable caracal 0 0 3 1 0 0 0 0 Panthera pardus Leopard 1 1 2 1 0 0 0 0 Carnivora gen et sp. indet. Indeterminate mongoose-size carnivore 1 1 4 1 10 1 3 1 Carnivora gen et sp. indet. Indeterminate wildcat-size carnivore 1 1 2 2 0 0 2 1 Orycteropus afer Aardvark 0 0 2 1 0 0 0 0 Equus burchelli Plains zebra 2 1 7 1 10 1 0 0 Equus capensis† Cape zebra 0 0 0 0 0 0 2 1 Equus spp. Zebras—general 2 1 8 1 10 1 2 1 Ceratotherium simum White rhinoceros 0 0 0 0 0 0 1 1 Rhinocerotidae gen. et sp. indet. Rhinoceros(es)—general 0 0 0 0 8 1 1 1 Phacochoerus aethiopicus Warthog 0 0 1 1 8 1 0 0 Potamochoerus porcus Bushpig 0 0 0 0 6 1 0 0 Suidae-general Pigs—general 0 0 1 1 16 1 2 1 Giraffa camelopardalis Giraffe21000000 Taurotragus oryx Eland 0 0 0 0 1 1 0 0 Tragelaphus strepsiceros Greater kudu 0 0 0 0 1 1 0 0 Tragelaphus scriptus Bushbuck 0 0 1 1 0 0 1 1 Hippotragus cf. equinus Probable roan antelope 0 0 2 1 1 1 0 0 Kobus cf. leche Probable lechwe 0 0 0 0 3 1 0 0 Redunca cf. arundinum Probable southern reedbuck 2 1 2 1 17 2 7 2 Alcelaphus buselaphus/ Hartebeest and/ror tsessebe 2 1 2 1 15 3 6 1 Damaliscus lunatus Megalotragus priscus†‘‘Giant hartebeest’’ 00 000011 Connochaetes taurinus Blue wildebeest 1 1 0 0 0 0 0 0 Aepyceros melampus Impala 0 0 0 0 1 1 0 0 Sylvicapra grimmia Gray duiker 5 1 4 1 8 2 0 0 Oreotragus oreotragus Klipspringer 0 0 0 0 0 0 1 1 Raphicerus campestris Steenbok 3 1 3 1 3 1 0 0 Ovis aries Sheep 0 0 1 1 0 0 0 0 Bovini gen. et sp. indet. Buffalo 0 0 0 0 4 1 0 0 Bovidae spp.—small Small bovids 90 3 177 7 102 3 28 2 Bovidae spp.—small-medium Small-medium bovids 22 1 49 2 170 4 55 3 Bovidae spp.—large-medium Large-medium bovids 20 1 52 2 173 4 80 2 Bovidae spp.—large Large bovids 5 1 19 2 25 2 8 1 Varanus cf. niloticus Monitor lizard 3 1 3 1 6 1 2 1 Python sebae? African python? 5 1 13 1 7 1 0 0
common. Similar ceramics are dated to between mixed results (Table 1). The ceramic data are not 550–1090 at the nearby Early Iron Age villages of sufficient to sort out stratigraphically distinct periods Divuyu ( 550–730) and Nqoma ( 850–1090) of Divuyu- and Nqoma-related occupations in the (Campbell et al., 1994). This ceramic relationship shelter. Analysis of the lithic materials also did not would seem to provide a reasonable overall age esti- reveal any meaningful changes in artefacts/raw mate ( 550–1090) for the WPS deposits, whereas the material usage within the levels of these deposits radiocarbon dates for the levels concerned afforded (Tables 3–4)(Murphy, 1999). 1098 L. H. Robbins et al.
Table 4. The number of tortoise fragments by depth at WPS were also recovered in the outlying test units and several of the auger holes (e.g. the auger hole at Depth 168·5 m from the wall produced a sherd at a depth of (cm) N 60 cm). For this reason, we suggest that the occu- pation, or at least the periodic use of the site was 0–10 57 widespread during the time of the local Early Iron Age 10–20 30 42 (c. 550–1090). These levels at WPS also occasionally 20–30 contain iron beads. For example, in the 1989 work 10 30–40 44 out of 14 iron beads were found in the 30–40 cm level. 40–50 42 The presence of typical Early Iron Age items in what is 50–60 62 60–70 39 otherwise an LSA context may be explained by contact 70–80 92 and exchange with local village peoples of Divuyu and 80–90 30 Nqoma. 90–100 39 100–110 56 Evidence of livestock. Significantly, almost all of the 110–120 61 120–130 67 identifiable fauna (Table 3) from the levels with 130–140 11 ceramics is wild, despite the fact that nearby Early Iron 140–150 10 Age village peoples kept domesticated livestock. On 150–160 8 the other hand, many of the same wild species occur at 160–170 9 170–180 5 both WPS and the Tsodilo villages (see Turner, 1987). 180–190 8 The single exception to the wild fauna at WPS was a 190–200 6 domesticated sheep jaw recovered from square 23 at 200–210 2 40–50 cm. This mandible has been dated by AMS to 210–220 14 122560 (OXA 6038, Sealy & Yates, 1996). This 220–230 9 230–240 10 direct date falls into the time range of Divuyu where 240–250 52 sheep/goats, as well as wild fauna were important. 250–260 5 While there is only one specimen of a domesticate, it is 260–270 13 quite possible that some of the other unidentifiable 270–280 5 280–330 0 bone fragments were also from domesticated animals. 330–340 1 340–350 2 Lithics. Lithics are highlighted by numerous crescents 350–390 0 (segments), backed bladelets, backed points, side and 390–400 1 end scrapers, burins, and awls. A few drills were also 400–560 0 560–570 1 recovered from these levels which may have been 570–700 0 associated with ostrich eggshell bead production. Total 832 Beyond these retouched tools, a number of bladelets were associated with these levels. There were also quartz/quartzite bipolar cores, flat bladelet cores, and core reduced pieces. Cores made out of other raw Ceramics. A total of 376 potsherds were recovered materials included a number of bladelet cores, both from the 31 squares at WPS. (Murphy et al., no date). multi and single platform cores, and core reduced Seventy-two sherds were decorated. The density of pieces. sherds varied from 3 to 31 per square with the highest densities generally located in the area protected by the The Upper Fish deposits: 80/90–130 cm, Units 2b (lower overhang. At Divuyu there were 952 decorated sherds, part), 3a, and 3b (upper part) whereas 566 decorated sherds were found at Nqoma While historic artefacts and ceramics were used to (Hendrickson, 1986). Most of the WPS sherds (93%) distinguish the first two divisions in the WPS sequence were found in levels above 60 cm. Those few sherds described above, the deposits between 80/90–130 cm in that underlie these deposits could be intrusive due to the central block of excavations are clearly marked by bioturbation. The highest frequency of sherds (N=71) (1) a relative abundance of fish bones, and (2) the was in the 30–40 cm level, while the highest number of presence of broken barbed bone spear or harpoon decorated sherds (N=19) was in the 40–50 cm level. points. The fish were mainly Clarius sp., a catfish which Two pieces of the same decorated rim found in square can grow to over 1 m in length, and cichlids, also 9, at 40–50 and 60–70 cm provide an indication of the known as tilapia. The increase in fish bones noted degree of vertical movement of the material in these above occurred in most squares in the central block of deposits. However, other sherd refits were separated by excavations at the same approximate depth. There only 10 cm of deposits. were, for example, 2215 fish bones (33% of the bones, Sherds are widely distributed in the site occurring in N=9060) in the 110–120 cm level in squares 10–23, in the 1989 and 1991–1992 excavation areas and they comparison to 43 fish bones (4% of the bones, Tsodilo Hills White Paintings Rock Shelter 1099
N=1177) found in the 30–40 cm level (in the deposits The size characteristics of the fish, studied by K. contemporary with the Early Iron Age). Stewart (Robbins et al., 1994), suggest exploitation The depth of greatest fish bone concentration varies during spawning runs. At present, in the Okavango with square, and peaks may be sharp (e.g. squares 13 River large spawning runs in shallow water flood and 14), or broad and bimodal (e.g. square 16), plains, especially of catfish, are associated with the depending on the geometry of the Unit 3 upper surface. annual flood resulting from rainfall to the north in In general, fish bone frequencies were comparatively Angola (Wilson & Dincer, 1976; Merron & Bruton, high in squares 10–19. Radiocarbon ages for Unit 3a, 1989). These floods occur during the dry season in and the basal sediments on Unit 2b, support an age of Botswana. The flood typically reaches Mohembo in the 5·7/8 to 4·1 ka, or a middle Holocene age, for this northern panhandle of the Okavango in March and the buried soil A horizon (Table 1). If correct, this middle flood maximum reaches the Maun area in the south of Holocene age agrees well with regional palaeoclimatic the delta in August. If the Tsodilo fishing opportunities data which shows that this period was comparatively peaked during the same general period, dry season wet (Brook et al., 1996). In addition, recent work at occupation was likely. However, tortoise shell frag- Toteng, revealing that Lake Ngami was also enlarged ments found in the deposits suggest wet season occu- between 4·6–3·7 ka, agrees very well with the Tsodilo pation as well since that is when tortoises are most data (Robbins et al., 1998b). The bones of lechwe, active. Overall, the Upper Fish deposit appears to have reedbuck, as well as the numerous fish bones at been widespread at the site. For example, catfish WPS, indicate nearby wetlands and water at this time. (Clarius sp.) bones were found between 90–110 cm in However, the OSL age of 20·61·9 ka for Unit 3b square 30, one of the outlying test pits that is situated (Feathers, 1997) suggests that the Unit 3b aeolian far from the overhang. However, the auger holes did sands were deposited some time after 21 ka, and that not pick up clear traces of the Upper Fish deposits in the surface lay exposed until deposition of the Unit 2b the area between square 31 and the Tsodilo lake beds. aeolian sands some time after about 4·1 ka. This fixes Perhaps we are seeing evidence that the site was used as the age of the Upper Fish deposits to the period a large-scale aggregation camp where people focused 21–4 ka, and so these deposits could be of Late-Glacial on fish exploitation as well as hunting and foraging. or of Early-to-Mid-Holocene Age. However, it is Alternatively, a smaller group that revisited WPS stressed that no radiocarbon dates were obtained from and camped at different locations at the site over an the Upper Fish deposits that are either Early Holocene extended period could also account for the widespread or Terminal Pleistocene in age and all of the radio- debris. carbon dated samples were taken from fish-bone-rich There are both uniserially and biserially barbed deposits. Moreover, the microlithic industry, described points and one point may well have had three rows of below, is more in keeping with a Mid Holocene Age in barbs (Robbins et al., 1994)(Figure 7). Refitting of two relation to regional comparisons and the barbed bone pieces of a biserially barbed point with an old break points are clearly associated finds (Deacon, 1984). provides an idea of the amount of vertical movement The abundance of fish bones found in association of artefacts in these deposits and initial horizontal with the barbed points implies that intensive fish scatter or horizontal movement after deposition. The procurement provided a major part of the Mid pieces were from square 13, 80–90 cm and square Holocene subsistence pattern at WPS in addition to 11, 100–110 cm (Figure 7). Another interesting bone hunting and foraging. A mongongo nut shell frag- artefact from square 20, 110–120 cm is a small ment directly dated to 4·1 ka demonstrates long-term decorated fragment that could have been either a point familiarity with a Kalahari staple wild food resource or an ornament. The decoration consists of two that is well-documented in the ethnographic record engraved fish spine-like designs similar to a design (Lee, 1979)(Table 1, AA35233). The abundance of fish that also occurs on one of the notable Tsodilo rock is almost certainly due to their availability in the paintings on Female Hill (Campbell & Robbins, 1993). nearby area. It is stressed that the area at Tsodilo is dry The Upper Fish deposits also contained numerous today and the nearest fish are in the Okavango River LSA microlithic artefacts. The retouched tools found about 45 km east of Tsodilo, though the seasonal in the Upper Fish levels are generally characterised by flooding of the Ncamaseri/Xeidum River, which is backed bladelets, backed points, crescents, side and connected to the Okavango, could have brought fish to end scrapers, burins, and awls. Notched tools appear within 17 km of the site. This is almost certainly too for the first time and again, several drills were recov- great a distance to account for the numbers of fish ered. These kinds of artefacts are typical finds in bones and associated fish spears/harpoons given the Holocene assemblages at many sites of southern Africa comparative ethnographic and archaeological data (Deacon, 1984). Non-retouched bladelets and flakes regarding optimal foraging strategies as well as the dominate the assemblage. Cores are predominantly nature of intensive fish procurement (Kelley, 1995). quartz/quartzite with numerous bipolar examples. While the fish may have come from a nearby lake, Non-quartz cores are also common, notably bladelet there are currently no Mid Holocene Ages for the and multiplatform cores. Radial cores initially appear Tsodilo lake deposits. and core-reduced pieces are numerous. The grinding/ 1100 L. H. Robbins et al.
in
cm
Figure 7. Barbed bone point fragments. Upper row (depths from left to right): square 13, 80–90 and square 11, 100–110 (refit), 100–110, 120–130, 110–120, 100–110, and 120–130. Lower row (depths from left to right): 30–40, 120–130, 290–300, 100–110, 230–240 and 120–130. pounding equipment in the deposits is also noteworthy. The levels between approximately 130/140–210 cm Eighteen hammerstones and 12 grindstones were produced a scatter of LSA lithics and fauna. Although recovered from the central block of squares. Square 13 the sample of deposits excavated was reduced in the at 100 cm yielded a double concave grindstone that has central block to 8 squares, there was a substantial a red tint that may be due to grinding ochre. Square 14 decrease in the density of lithics (debitage, tools and (100–110 cm) appears to have been the location of a cores) and bone fragments in the squares that were grinding area where several large concave grindstones excavated (see Murphy, 1999, for comparative data and other grindstones were recovered. Finally, the including average volume per square by levels). More- deposits also contained a number of ostrich egg shell over, the percentage of fish bones drops substantially. beads including unfinished specimens and fragments For example, in the 120–130 cm level 30% of the bones (Robbins, 1999). (1918 fish bones, N=6365) were from fish, while the 140–150 cm level contained 17% fish bones (180 fish bones, N=1046). Only one barbed bone point frag- Low density LSA: 130/140–210 cm, Units 3b, 4, and 5 ment, a hallmark of the overlying Upper Fish deposits, The dense ‘‘bone harpoon’’ fishing-based levels that was found in these levels (square 12, 160–170 cm). This were so striking in the immediately overlying deposits lone point may well be intrusive in the deposits, given (3 above) were no longer evident as the excavations the clustering of points in the overlying Upper Fish proceeded below about 130 cm. In addition, there was deposits. Artefacts also decreased in frequency at the a marked increase in fragments of unworked ostrich base of the most distant test pits (30–31) between eggshell beginning at approximately 150 cm (Robbins, 130–150 cm (and they were rare in the auger holes 1999). Although the lithic assemblage is not abundant, placed at the base of these squares). The appropriate it does not reveal a clear technological change in the deposits (between 130/140–200 cm) were not repre- kinds of artefacts that would support a long period of sented at all in most of the outlying auger holes. site abandonment at one or more times during the Overall, the changing density and distribution of the period 48–21 ka. On the other hand, the archaeology material may reflect less intensive, as well as changing of this time period is inadequately known in much of use of the site during the period, perhaps by fewer southern Africa, especially in the interior. people who tended to use the area closer to the Tsodilo Hills White Paintings Rock Shelter 1101 overhang. The decline in fish bones and increase in 210 cm and equating with Unit 6 and the upper surface ostrich egg shell suggests a subsistence strategy that of Unit 7, that is 7a (Table 2). The size of the fish was more oriented towards collecting than fishing. support exploitation of spawning runs and the abun- As noted above, unworked ostrich egg shell dance of bones along with occasional finds of fresh fragments were numerous. The highest frequencies of water mollusc (bivalve) shell fragments imply procure- egg shell appear at a depth of approximately 170– ment from a nearby source of water. The shell frag- 180 cm and extend continuously into the underlying ments were clustered between 210–270 cm and were Lower Fish levels to a depth of 250 cm. The dense found in six different squares in the central block. distribution of egg shell fragments extends over much Peaks in fish bone frequency vary from square to of the central block of excavations. The ostrich eggs square because Units 6 and 7a are not horizontal but may have been exploited mainly for food since almost slope gently away from the shelter so that the horizons all of them are not worked. A finished bead was found rich in fish are deeper in squares 16–18 than in 19–22. at 170–180 cm and another at 190–200 cm, while 3 Where Unit 7a is horizontal through a square, such as bead preforms were found at 170–180, 180–190 and in squares 20 and 21, there is a single peak in fish bone 190–200 cm. A broken bead preform recovered from frequency at this depth (Figure 8). Where the upper square 21, 190–200 cm was dated by AMS to 31·1ka surface of Unit 7a varies in depth within a square, (Table 1, AA31729) (Robbins, 1999). In addition, two which is the case in squares 19 and 22, there is a pieces of a broken ostrich egg shell disk found in broader bimodal peak in fish bone frequency squares 11 and 12 (180–190 cm) were refit along an old (Figure 8). Differences in fish bone distribution could break. The disk was directly dated by AMS to 37·4ka also be, in part, a product of prehistoric refuse disposal (Table 1, AA31280). The disk may have either been an patterns where the outer edge of a disposal area can ornament broken in manufacture, or the by-product of have fewer bones than the centre, especially if people cutting an opening into an eggshell for use as a water were situated under the overhang and tossed refuse container. If it was from a water container, it is the away from them. Differential bone preservation, inside oldest evidence of an important feature of traditional and outside of the drip line could also be another Kalahari technology. There was also a single fragment factor. In the Lower Fish deposits, no worked eggshell, of an egg shell with a worn concave edge that also or ostrich eggshell beads were recovered. Both micro- could be from the entrance of a water container liths and bone artefacts were present. These levels are from square 21, 190–200 cm. The high frequencies of clearly Late Pleistocene, based on the presence of the unworked egg shell compared to beads/bead preforms extinct Cape zebra, Equus capensis. As argued above, contrasts significantly with the first three divisions in Unit 7a was probably deposited around 48 ka. If the the sequence (Historic/Late Prehistoric, LSA contem- 48 ka estimate is correct, the microlithic technology porary with EIA and Upper Fish levels) where there evident in the deposits would be one of the earliest were fewer unworked egg shell fragments and more known in the LSA in Africa. Elsewhere in southern evidence of beads and bead working (see Robbins, Africa, the oldest LSA microlithic assemblages date to 1999). between 39,000–19,000 (Wadley, 1993). For this The stone artefacts from the deposits are highlighted reason, a younger age seems more likely. If this is the by burins and awls. Of interest, side and end scrapers case, than the 36 ka OSL age, obtained directly from are found in roughly equal proportions as opposed to the richest fish bone deposits at 250 cm is more reason- the levels above 130 cm, where side scrapers are much able, given the comparative archaeological evidence. more numerous. Backed blades and crescents (seg- This issue will be discussed further in the conclusion. ments) continue to be evident but in reduced numbers. In one of the richest levels (240–250 cm), 30% of the However, no backed points were found. Other re- bones were from fish (1008 fish bones). In many touched artefacts include notches and several drills. respects, the Lower Fish deposits are similar to the Unretouched bladelets were common finds, though less Upper Fish deposits, though there were only a few numerous than in overlying levels. Cores continue to poorly preserved barbed bone points in the Lower be dominated by quartz/quartzite bipolar varieties and Fish, as well as some faunal changes such the pre- flat bladelet cores. Other raw materials were also used viously mentioned Equus capensis. There is also a to make bladelet cores as well as multi-platform, single decline in the diversity of species of mammals platform and radial cores. The most noticeable change (Table 3). However, there is a relative increase in the in the lithic technology in these deposits is that the first large/medium bovid class among the bones not identi- blade cores are evident. fiable to species. The subsistence evidence is most interesting in regard to combining intensive fishing, procurement of larger game animals and collecting The Lower Fish deposits: 210–280 cm, Unit 6, upper (ostrich eggs and tortoises). In the levels that immedi- surface of Unit 7 ately overlie these deposits (the Low Density LSA), Excavations uncovered another series of LSA levels just discussed, it appears that the collecting of ostrich with abundant fish bones, lithic materials and eggs intensified in the face of declining fish resources. unworked ostrich egg shell beginning at approximately Another contrast with the Upper Fish levels (3, above) 1102 L. H. Robbins et al.
Number of fish bones
0 100 200 300 100 200 300 100 200 300 100 200 300 0 Sq. 22 Sq. 21 Sq. 20 Sq. 19 50
100
150
200 Depth (cm) 250
300
350 340 cm
400 Figure 8. The number of fish bones by depth in squares 19–22. Dashed lines show the depth of excavation in each square. is that the lack of evidence from the auger holes suggest Three fragments of the artefact, with old breaks, were that the Lower Fish deposits are less widespread at the refit in the lab from square 22, 250–260 cm, 260– site, with concentrations in the areas nearer to the 270 cm and square 21, 280–290 cm. Another small shelter itself in the central block of excavations. For piece of a point base with traces of two circular example, the outlying test squares 30–31 only yielded incisions (from square 22, 250–260 cm) could be an traces of artefacts in the appropriate depths in the additional part of this artefact, but a missing portion auguring at the base of the units and there were no prevents definite refitting of this fragment. This small bones. In addition, three of the outlying auger holes piece could also have been a barbed point fragment. (129·5, 159·5 and 169·5 m from the shelter wall) The refitting of the artefact provides some understand- reached depths varying between 210 and 290 cm and ing of the range of movement of artefacts in these all of the holes were sterile in relation to providing deposits (c. 30/40 cm). On the other hand, it should be evidence of the Lower Fish deposits. Thus, it may be noted that the discovery of two large fish vertebrae in that the Lower Fish occupation was intensive, but was an articulated position in square 21, 240–250 cm sug- more concentrated near the shelter. gests that in some areas of these deposits there was very little movement. The refitted point tapers gradually Bone artefacts and is marked by a series of at least 36 incisions. It is Ten bone artefacts were recovered from the Lower uncertain whether the incisions were functional, such Fish deposits (Robbins & Murphy, 1998b). While the as for hafting, decorative, or whether they could have artefacts are fragmentary, the available evidence some other symbolic or conceptual meaning. shows that there was a sophisticated and diverse bone technology in use. There were uniserial barbed bone Lithics spears, or harpoon points as well as two kinds of Lithic materials are comparatively abundant in the barbless points not found in the Upper Fish levels Lower Fish deposits. Individual 10 cm levels yielded (Figure 9). The barbed points from the Lower Fish an average of 56 pieces of debitage per m2. The include a weathered basal fragment (square 21, 250– assemblage can be described as microlithic and about 260) with traces of one barb, a base with incisions 24% of the raw materials documented in the debitage (square 11, 230–240) and another possible specimen are from non-local jasper, chert, chalcedony, and from square 12, 290–300. One of the barbless points silcrete. The rest was locally available quartz and (square 19, 250–260 cm) is wider, and was probably quartzite. Notable retouched artefacts include backed longer, than the typical bone link shaft/arrow points bladelets, crescents (segments), backed points, notches, that were common finds in deposits contemporary with becs, burins, and awls (Figure 10). The initial discovery the local Early Iron Age. Another unique bone point is of burins in these late Pleistocene deposits seemed one of the most interesting artefacts in the deposits. unusual. For this reason, a group of the tools was Tsodilo Hills White Paintings Rock Shelter 1103
cm
in
Figure 9. Bone artefacts from the Lower Fish deposits. Top: Point from square 19, 250–260. Middle: Barbed point base from square 21, 250–260. Lower: Point refit from three pieces, square 22, 250–260 and 260–270, and square 21, 280–290. inspected by the late M. S. Maxwell who is known for Fish deposits to the use of large blades struck from his work with burin-rich assemblages in the Canadian prepared cores (Figure 10). In addition, tool numbers Arctic. Maxwell (pers. comm.) confirmed that the in the various squares decrease during this interval. artefacts in question were functional burins. Side and The large blade industry coincides with evidence for a end scrapers were also recovered in approximately lengthy period of dry conditions seen in the sedi- equal numbers. The deepest drill in the WPS sequence ments deposited between 300–400 cm (Figure 5). As was also recovered from the 230–240 cm level. mentioned earlier, Units 8 and 7 are largely aeolian in Unretouched bladelets are still very numerous, how- origin and Unit 8a is a very indistinct stone line, ever an increasing number of blades in the assemblage suggesting that the wet period it represents was either seems to indicate a trend toward larger ‘‘flake-blades’’ not very wet or not very long. The interval represented which become increasingly important in the deeper by Units 8 and 7 was therefore lengthy and dry, based levels of the site. Cores are once again dominated by on our TL and OSL ages possibly extending from quartz/quartzite bipolar and flat bladelet cores, with about 65 ka to 48 ka with a wetter interval, although numerous examples of multi-platform cores. Non- not significantly wetter, in the middle of this interval quartz cores are dominated by multi-platform and perhaps around 54 ka (represented by Unit 8a). The bladelet varieties with fairly high numbers of core only comparable blade industry that has been dated in reduced pieces. the Kalahari is the intermediate industry 2C at Gi pan Below approximately 260/270 cm, that is below Unit which dates to about 34 ka (Brooks et al., 1990). 7a, the Upper Fish deposits diminish and the fre- While the overall frequency of large blades is not quencies of artefacts, bones and eggshell also decline. great, the increase in size was very noticeable. Some are The next major change in the deposits appears at over 60 mm in length. This shift is more of scale than approximately 300 cm near the upper surface of of overall morphology of the tools being produced. sediment Unit 8. For example, the large backed blade shown in Figure 10 is quite like a greatly enlarged crescent. Unretouched bladelets continue to be evident along Large blade, Early LSA/Transitional MSA: 300–410/ with the large blades, as do bipolar, flat bladelet and 420 cm: Units 7b and 8 multi-platform cores. In the lower part of the deposits Beginning at 300 cm there is a noticeable shift from the blades outnumber bladelets. Other tools include re- microlithic technology seen in the overlying Lower touched blades, burins, large scrapers, notches, and 1104 L. H. Robbins et al.
cm
Figure 10. Stone artefacts from the Lower Fish, Large Blade, and MSA deposits. Row 1 (Lower Fish): the left hand four are segments, the remainder are distally backed points. Row 2 (Large Blade) from left to right: two backed segments, two retouched blades, and an unretouched blade. Row 3 (Large Blade): end scrapers. Row 4 (MSA) from left to right: three bifacial points and two unifacial points. Row 5 (MSA): unifacial points. awls. The large blades continue into the underlying There were only a few fragments of ostrich egg shell, MSA. For this reason, as well as others, such as the use none of which was worked and there was only one of prepared tortoise cores and blade cores, we think possible bone artefact, a barbless bone point frag- that this material is transitional to the MSA. ment recovered from 350 cm. The sample of deposits Fauna are not as common as in the overlying levels, included seven 1-m squares where an average of 20 which may reflect poorer conditions of preservation as pieces of debitage was recovered per square (10 cm well as overall changes in the density of material at the level). This is nearly a three-fold decrease in lithic site. However, out of 2047 bone fragments found material compared to the Lower Fish. More than between 3 and 4 m depth, 120 (6%) were fish. Almost likely, this reflects a more periodic, or short term use of all of the non-fish bone fragments were unidentifiable. the site, possibly because of the much drier conditions Tsodilo Hills White Paintings Rock Shelter 1105 suggested by the sediments. Auger holes placed at the slightly more frequent. There are also some denticu- base of outlying test pits (30–31) were sterile below lates, notches, burins, awls, and becs. Of interest, the 310 cm and all of the outlying auger holes closer to the large blades noted for the overlying transitional lake deposits encountered calcrete at shallower depths. deposits, continue to be found mainly in the upper part Thus, the large blade occupation may be restricted to of the MSA deposits, above 620 cm, showing some the rock shelter and closely adjacent areas. continuity with the early LSA in the Tsodilo area. However, blades were also found at the very base of the deposits at 7 m. It also should be noted that MSA levels: 410/420–700 cm, Units 9–11 bladelets were found extending to a depth of 660 cm, During the excavations it was observed that the base of but in significantly reduced numbers in comparison to the lowest schist fall at the WPS marks the appearance the LSA deposits, and in proportion to large blades. of the Middle Stone Age which is clearly recognised by Cores were numerous in the MSA levels. The large the production of unifacial and bifacial points from number of cores indicates that tool manufacture was prepared (tortoise) cores (Figure 10). The U.B. TL date an important activity during this period. Most of the of 66·46·5 ka from 500 cm is consistent with the quartz/quartzite group are bipolar or multi-platform, dating evidence from Gi, the nearest dated MSA site in but blade cores are also common. In addition, several the Kalahari (see below) (Brooks et al., 1990). How- disc cores and prepared (tortoise) cores were made out ever, it should be noted that the final MSA dates to as of these local raw materials. However, non-local raw recently as 28 ka at Rose Cottage Cave in South Africa materials dominate in the production of MSA cores, and there are other comparatively recent ages from including multi-platform, prepared (tortoise), disc and sites with MSA levels in western Zimbabwe (Clark, blade cores. 1999). The occurrence of the MSA below the base of Why is there such a dramatic increase in stone the schist fall is perhaps the clearest example at WPS of artefacts during the MSA at the shelter? While the a major archaeological change that is associated with a answer to this question is uncertain, there may have major event in the sedimentary record. However, it been an increase in human occupation of the Tsodilo should be noted that the MSA, as a whole, persists area. As we have argued above, the Unit 11, 10a and 9a through several wet and dry episodes. Seventy-seven sediments suggest comparatively moist conditions at MSA points were recovered from the six squares that the shelter, with Unit 10b being of aeolian origin. Our sampled these deposits. These artefacts are readily estimated age range for Units 11–9, which contain recognisable and are widely distributed at other MSA MSA artefacts, is 65–>95 ka which is consistent with sites throughout southern Africa (Singer & Wymer, the dating range obtained for the MSA at Gi, to the 1982; Volman, 1984; Kuman, 1989). The MSA levels southwest of Tsodilo. Using protein diagenesis of are marked by a dramatic increase in stone artefacts, ostrich eggshell, Brooks et al. (1990) estimated their per excavated square, including debitage and formal Unit 4, the MSA unit at Gi, to be 65–85 ka, an age tools (Table 2). Fauna was poorly preserved, and none range that fits well with a TL age on sands from near was recovered below 580 cm. Only 234 bone fragments the top of the unit of 7711 ka. were recovered in the MSA levels, of which 15 (6%) Within the MSA deposits some changes were were from fish. Nonetheless, the use of fish during the evident, in addition to those already mentioned. Below MSA is the oldest known for the interior of southern 620 cm the number of MSA points drops off, with only Africa. Most likely, the comparative absence of fauna five recovered from among these eight levels. Other is due to poor conditions of preservation. No ostrich retouched tools are also rare as are cores. No prepared egg shell, or bone points were recovered in the MSA (tortoise) cores were found below 620 cm. We are not deposits. sure if the levels below 620 cm represent a distinctive, Interestingly, the analysis of raw materials reveals a earlier period within the MSA, or if the differences significant change in raw material selection. Through- result from sampling error due to the small number of out the MSA deposits, an average of 55% of the raw excavation units (two squares) at this depth. material is imported chert and silcrete. While the specific sources of these materials are not known, silcrete is common to the southeast of Tsodilo on the Fauna Boteti river and at MSA localities such as Kudiakam Approximately 68,296 bone fragments were recovered pan, also to the southeast (Robbins, 1989b). This from WPS, most of which were unidentifiable. About finding regarding the use of raw materials contrasts 77% appeared to be from mammals while 21% were substantially with the more recent LSA levels where the fish bones. Most of the rest were from tortoises. In locally available quartz and quartzite was heavily util- addition, there were some bird bones, as well as ised (Table 2). This preference for exotic raw materials occasional finds of fresh water mollusc shell fragments. is one of the major features that separates the very The birds are currently under study, but include early levels of the site from the more recent ones. Other the white breasted cormorant, at least two species significant tools recovered in the MSA deposits include of ducks/geese, helmeted guineafowl and francolin large side and end scrapers, with side scrapers being (Avery, pers. comm.). 1106 L. H. Robbins et al.
Mammals molerat, pouched mouse, gerbils, and vlei rat), although recent Kalahari hunter–gatherers also The 1989–1993 excavations produced 1780 highly consumed micromammals (Silberbauer, 1981). fragmentary mammal bones that were identifiable to The fauna is instructive mainly for its palaeo- skeletal part and taxon. (There were also 25 very large environmental implications. In supplement to Table 3, snake vertebrae that the excavators sorted with the Figure 11 shows that springhare dominates through- mammal bones that have been tentatively identified as out. Springhare are large burrowing rodents (average African python.) The number of identifiable bones in adult weight around 3 kg) that occur widely through- each 10 cm horizontal excavation unit tends to be very out the dry interior of southern Africa (Skinner & small and the bones have therefore been grouped by Smithers, 1990). Recent Kalahari hunter–gatherers culture-stratigraphic unit. Only two identifiable bones commonly obtained individuals with specialised probes were recovered below the Lower Fish unit, and they that immobilised the animals in their burrows (Lee, are ignored here, on the assumption that they could be 1979; Silberbauer, 1981). Prehistoric foragers also intrusive. The Low Density LSA provided very few exploited them routinely, and springhare bones are identifiable specimens and these have been lumped prominent not only at WPS but also in the terminal with those from the Lower Fish unit into which the Pleistocene LSA layers of Drotsky’s Cave in the Low Density LSA grades downwards. Gcwihaba Hills, (Robbins et al., 1996b) and in the late Table 3 presents the Number of Identifiable Holocene LSA layers at Thamaga 1 Rock Shelter near Specimens (NISP) and the Minimum Number of Gaborone (Robbins, 1987), roughly 125 km and Individuals (MNI) represented for each taxon in each 800 km to the south, respectively, and still further of the four principal culture-stratigraphic units. Klein south in the Holocene LSA layers of Powerhouse & Cruz-Uribe (1984) outline the assumptions used to Cave, Limerock Shelters 1 and 2 and other rock calculate the MNI’s. The ‘‘general’’ zebra, pig, and shelters in the Northern and Eastern Cape Provinces of rhinoceros categories and the bovid size categories South Africa (Klein, 1979). Springhare strongly prefer include bones that were identifiable to species and arid, short grass habitats, and individuals could not bones that were not. Other analysts, for example Brain thrive in a moist, bushy setting. The abundance (1981), use essentially the same bovid size categories of springhare throughout the WPS sequence thus but frequently label them 1, 2, 3, and 4 from smallest to constrains the extent of past environmental change. largest. In the WPS fauna, small bovid species repre- At the same time, together with abundant fish bones sented by identifiable elements are klipspringer and and sedimentologic/geomorphic observations, the pres- steenbok; small-medium bovids are bushbuck, ence or abundance of reedbuck, lechwe, bushbuck, southern reedbuck, impala, gray duiker and sheep; bushpig, and Angoni vlei rat in the Upper Fish unit, the large-medium bovids are kudu, roan antelope, lechwe, Lower Fish unit, or both indicates that a perennial or hartebeest or tsessebe, and blue wildebeest; and large near perennial water body formerly stood nearby where bovids are eland, ‘‘giant’’ hartebeest and buffalo. none did historically. As a group, these animals suggest Table 3 shows that the fauna comprises mainly an expansion northwards of the faunal community extant species, but the Lower Fish unit provided bones associated historically with the Okavango Delta of the extinct ‘‘Cape zebra’’ and ‘‘giant hartebeest’’. (Smithers, 1971). However, it is interesting to note that Both disappeared in southern Africa around 10 ka hippopotamus, crocodiles, water turtles and aquatic (Klein, 1984) and their occurrence in the Lower Fish frogs were not found at WPS. Their absence could unit is thus consistent with the Late Glacial age implied reflect habitat differences, hunting/fishing preferences, by the radiocarbon and luminescence dating. sample size or a combination of these factors. The During sorting, a tally was made of identifiable bottom line is that the Tsodilo Hills were surely less arid bones with different kinds of macroscopically con- when the Upper and Lower Fish units accumulated. spicuous damage. Burned bones dominated (121), Figure 11 shows that the most conspicuous variation followed by specimens with porcupine-gnawing (14), in gross taxonomic abundance occurs within the bovid acid-etching (2), carnivore-chewing (2), weathering (2), size categories. Small-medium and especially large- and stone tool cut marks (1). Carnivore-chewed and medium bovid bones are significantly more numerous especially cut pieces would probably increase in in the Lower and Upper Fish units than they are in the number if the bones were examined microscopically, overlying Late LSA/EIA and Late Prehistoric/Historic but the macroscopic pattern is adequate to suggest that units. The reason is probably greater moisture, which people were the main bone accumulators. Together not only opened niches for water-dependent species with the relatively low frequency of carnivore indi- like reedbuck and lechwe, but which also improved viduals (Table 3), the low frequency of acid-etched pasture conditions for less water-reliant species like bones precludes an important role for hyenas. Simi- impala, kudu, roan antelope, and hartebeest/tsessebe. larly, the rarity of porcupine-gnawed bones rules out The relatively moist conditions indicated by the fauna an important porcupine contribution. A non-human and sediments almost surely promoted larger, denser accumulator, perhaps a barn owl (Tyto alba), is prob- hunter–gatherer populations that those observed in the able only for the micromammal bones (from shrew, Kalahari historically. Tsodilo Hills White Paintings Rock Shelter 1107
White Paintings Site
Small-medium Carnivores Pigs bovids Large bovids
Approx. years BP Springhare Zebras Small bovids Large-medium NISPs × 1000 bovids 0 Late prehistoric/ (250) 0.5 early historic 1 Late LSA/ (423) 1.5 early IA ?4 Mainly (860) ?8 Upper Fish Zone ?43/?32 Mainly Lower Fish Zone (304) ?50/?36 0 100% of NISP
Figure 11. The proportional representation of the main mammalian taxa in the principal culture-stratigraphic units at WPS. As discussed in the text, the dating of the WPS units is problematic. The age of the Lower Fish zone is particularly uncertain.
Tortoises lying LSA/EIA and Late Prehistoric/Historic levels. In the 1989 excavations of squares 1–9 remains of both However, a leopard tortoise fragment was found in the hingeback (Kinixys belliana) and leopard tortoise (Geo- 1989 work from the Late Prehistoric/Historic 10–20 cm chelone pardalis) were recovered (Stewart et al., 1991). level (Stewart et al., 1991). While both species of This paper reports on the additional remains found in tortoise are found in the region at present, some the 1991–1993 excavations of squares 10–31. Most of varieties of hingeback tortoises are generally found the specimens are unidentifiable carapace fragments. near more permanent water sources. Table 4 reveals that tortoise fragments were found in A few additional snake vertebral elements were every 10 cm level from the surface to a depth of recovered in the 1991–1993 work. These include 270 cm. Tortoise fragments were most numerous in the African python from the 20–30 cm level (1) and in the LSA/EIA, and in the Upper and Lower Fish deposits, 70–80 cm level (1). A colubrid or elapid snake was and a single specimen was recovered from the MSA. It identified from the 110–120 cm level. was possible to identify the species of tortoise on 10 specimens on the basis of peripheral carapace bones as well as a single specimen from a costal bone. Leopard The WPS, Tsodilo Hills and Regional tortoise (Geochelone pardalis) was found in the follow- Palaeoenvironmental Records ing levels (the NISP is indicated): 0–10 cm (1), 20–30 (1), 30–40 (1), 40–50 (2), 60–70 (1) and 70–80 (2); while As we have seen above, the sequence at WPS consists hingeback tortoise (Kinixys belliana) was found in of a series of aeolian sediment units, each followed by levels 100–110 (1), 130–140 (1) and 220–230 (1). Al- a period of wetter conditions with soil development or though relatively few bones could be identified to the accumulation of coarser material at the sand sur- species, it is interesting to note that hingeback tortoise face. Over the last 50 ka, this record appears to agree is associated with the Lower and Upper Fish deposits, well with other palaeoenvironmental data from the while leopard tortoise is found in the over- Tsodilo Hills and with regional data for the summer 1108 L. H. Robbins et al.
Lakes at Dry conditions Tsodilo Hills Wet conditions 0 0 (a)(b) (c)
10 10
20 20
30 30 Age (thousands of years ago) Age (thousands of years ago)
40 40
Dunes Submerged Speleothems Speleothems Tufas
50 50 0 2 4 6 8 108 6 4 2 0 Number of ages Number of ages Figure 12. Histograms of ages for drier (a) and wetter (c) climates during the last 50 ka in the summer rainfall zone of southern Africa, and lacustrine periods at the Tsodilo Hills (b). Data for (a) and (c) are from Beaumont & Vogel (1993); Blu¨mel et al. (1998); Brook et al. (1996, 1997, 1999); Buch et al. (1992); Burney et al. (1994); Butzer et al. (1978); Cooke & Verhagen (1977); Heine (1992); Holmgren et al. (1994); Marker (1972); O’Connor & Thomas (1999); Railsback et al. (1994); Rust (1984); Shaw & Cooke (1986); Stokes et al. (1997, 1998); Talma et al. (1974); Thomas & Shaw (1991); Thomas et al. (1997) and Vogel (1989).
rainfall zone of southern Africa for the same time extent from 27–23 ka and 17–10 ka ago with crossing period. Figure 12 is a summary of age data for wet and dunes and lunette dunes of local/subregional extent dry conditions in the summer rainfall zone of southern forming around 6 ka and 2–1 ka, respectively. Based Africa during the last 50 ka and evidence of former on six TL ages for dune sands in the SW Kalahari in lakes southwest of Tsodilo Hills. Data for Figure 12(a) Namibia, Blu¨mel et al. (1998) argue for an early & (c) are from a variety of sites in South Africa, Holocene dry phase from 10–8 ka ago and an earlier Botswana, Namibia, Zimbabwe and Zambia. The aeolian interval from c.20–17 ka. Stokes et al. (1997) figure is an updated version of Figure 3 in Brook et al. report significant aeolian activity in southern Africa (1999). Thomas et al. (1997) suggest that in the SW 46–41, 26–20 and 16–9 ka ago based on OSL dating of Kalahari of Botswana and South Africa (rainfall=150– dunes in the SW Kalahari and in SW Zimbabwe in the 200 mm/year) linear dune construction was of regional NE Kalahari. Stokes et al. (1998) add that in this area Tsodilo Hills White Paintings Rock Shelter 1109
(rainfall up to 800 mm/year) the arid phases were 7a. Brook et al. (1997) recognise a wet period in the short-lived (5–20 ka) in comparison to the intervening summer rainfall zone of southern Africa at 50–43 ka humid periods (20–40 ka) and appear to have been that is also visible in the histogram of cave speleothem restricted to pre-Holocene times. O’Connor & Thomas and tufa ages shown in Figure 12(c). Six ages for dune (1999) record periods of dune building in a degraded sands suggest a period of aeolian activity at 44–37 ka linear dune field in western Zambia at 32–27, 16–13, (Figure 12(a)). Units 6 and 5 in the WPS sequence were 10–8, and 5–4 ka ago in an area that today receives probably deposited during this aeolian interval. Only a around 1400 mm of rainfall annually. colour difference marks the break between these two Lacustrine carbonates southwest of the Male and units suggesting that the intervening ‘‘wet’’ period was Female Hills at Tsodilo, which contain freshwater not that significant climatically. Slight increases in fish mollusc shells and diatoms, indicate permanent lakes bone frequencies and tools at around 200 cm depth in this shallow basin, that varied in size seasonally, at (Figures 6 & 8) appear to record the wet interval 36–32, 26·5–22·5 and 19–11 ka (Figure 12(b)). Based represented by the upper surface of Unit 5, which in on the widespread evidence for the 19–11 ka lake, it age correlates well with the 36–32 ka lake at Tsodilo, appears to have been the most extensive and possibly and with the wetter conditions at 34–29 ka indicated by longest lasting of the three (Brook et al., 1992; Robbins the cave speleothem/tufa record in the summer rainfall et al., 1994; Brook, unpublished data). Lake develop- zone of southern Africa (Figure 12(c)). The evidence of ment is also recorded at Gi, southwest of Tsodilo, at aeolian activity at Tsodilo from 354to284ka 28·1–26·2 ka and c. 37 ka, these dates agreeing well agrees well with the submerged speleothem and dune with the two earlier lake phases at Tsodilo (Brooks activity evidence in Figure 12(a), suggesting aeolian et al., 1990). In addition, OSL ages on a diatom bed at activity from 31–26 ka. This activity may have Moremaoto along the Boteti River record two concur- deposited Unit 4 at WPS. The lake phase at Tsodilo rent palaeolake phases between 32 and 27 ka (Shaw from 26·5–22·5 ka, and the peak in speleothem and et al., 1997), dates which agree well with our evidence tufa ages in the summer rainfall region from 27 ka to of palaeolakes at Tsodilo 36–32, and 26·5–22·5 ka. 21 ka, may correspond to the hiatus in aeolian sedi- OSL ages for sands in the linear dunes immediately mentation at WPS represented by the upper surface of south of the Tsodilo Hills suggest aeolian activity Unit 4, and to slightly increased fish bone and tool 35–28 ka and at c.98·19·2 ka (Thomas et al., in numbers (Figure 8). Based on the OSL age for the base prep.). of Unit 3b this unit was deposited beginning around In total, 12 species of freshwater mollusc have been 20 ka suggesting correlation with apparent aeolian discovered in the lacustrine carbonates southwest activity (12 ages) in the summer rainfall region from of the Male and Female Hills, all occurring in the 24–17 ka (Figure 12(a)). Unit 3a and the upper surface Okavango River system today (C. Appleton, pers. of Unit 3b, where the Upper Fish deposits dated to comm.). However, no large unionacean bivalves were 20–6 ka, would then appear to correlate well with the found and their absence could be interpreted as indi- 19–14 ka lake at Tsodilo and with a sharp peak in cating a paucity or absence of fish in the Tsodilo lakes speleothem and tufa ages in the summer rainfall region since these bivalves have a larval stage which is an at 19–14 ka. However, the majority of the radiocarbon obligatory parasite of fish. However, large bivalve dates (seven dates from six squares, Table 1) for the shells (probably Mutela) have been discovered in WPS Upper Fish deposits are Mid Holocene, and as dis- sediments down to depths of 280–290 cm. If these were cussed previously, there are no radiocarbon dates from obtained from the lakes at Tsodilo, this suggests the WPS that apply to the 19–14 ka lake. Thus, as men- presence of fish in these waters. In anthropology there tioned previously, it is most likely that the Upper Fish is considerable interest in determining the factors that archaeological assemblage, including the majority of may have had an impact on the health of ancient the barbed bone points, was produced during the Mid peoples and for this reason it should be noted that Holocene. three species of molluscs found in the ancient lake are The aeolian and submerged speleothem record of hosts for parasites. At Tsodilo, the lacustrine carbon- Figure 12(a) suggests dry periods from 16–12 and ates contained shells of Biomphalaria pfeifferi, the 11–8 ka that we find no evidence of in the WPS intermediate host of the parasite causing intestinal sequence. The absence of aeolian material dating to schistosomiasis, and Bulinus globosis and Bulinus afri- 16–12 ka may reflect the continued presence of a canus, the intermediate hosts of the parasite causing lake, perhaps somewhat smaller and more seasonal, urinal schistosomiasis. The presence of these molluscs immediately west of the WPS site after 14 ka. Such a in the lake waters suggests that people using this area lake would have prevented aeolian sand from entering may have been affected by both intestinal and urinal the shelter. However, the absence of Early Holocene schistosomiasis. Interestingly, none of these species Age sand is puzzling. However, Robbins et al. (1994) that act as parasite hosts have been identified from the report a radiocarbon age for lacustrine carbonate of molluscs found at WPS. 90·1 ka (UGA-6520, 763181 years ), which sug- The Lower Fish deposits and bone points from gests a period of increased moisture around this time. 210–280 cm appear to be associated with Units 6 and A possible early Holocene aeolian unit (Unit C) in 1110 L. H. Robbins et al.
Rhino Cave in the Female Hill, that contains thin clay Discussion and Conclusions layers deposited in standing water ponded in the cave after heavy rains, is further evidence that the Early In conclusion, archaeological data from WPS has Holocene had a changeable climate. During wetter revealed important evidence of occupations spanning intervals a shallow, seasonal lake may have developed the Historic/Late Prehistoric, LSA/EIA, early LSA, near WPS preventing aeolian transport into it. How- early LSA/transitional MSA, and MSA periods. As the ever, so far we have discovered no evidence of a large, discussion of the archaeological sequence and the permanent, Holocene Age lake at Tsodilo. By contrast palaeoenvironmental record has shown, there is a the aeolian phases in Figure 12(a) at 6–3 and 2–1ka strong relationship between evidence of comparatively appear to be represented in the WPS sequence as wet conditions at the site and more substantial occu- aeolian Units 2 and 1, with a slightly wetter interval at pation. Throughout the sequence, the upper surfaces of 2–1 ka in the speleothem and tufa record being aeolian sand units, defined by stone lines, thick schist recorded by the buried soil A horizon of Unit 2a. This horizons, or by soil A-horizon development, are where wetter interval is also apparent in the slightly higher peaks, and in some cases very marked peaks, in stone numbers of fish bones and tools in Unit 2a at around tools, fish bones and mammal bones occur. The 50 cm depth (Figures 6 and 8). Tsodilo Hills were a ‘‘magnet’’ during these periods, Prior to 50 ka the regional record of palaeoenviron- and at times (the two fish-rich units) could be consid- mental conditions is tentative. However Stokes et al. ered as part of the greater Okavango system. This is a (1998) report ages of 7311, 10114, 10915 and significant finding that furthers our understanding of 10218 ka for dune building in the northeastern the complex nature of the changing Kalahari environ- Kalahari of western Zimbabwe. Other OSL ages ments and human adaptations to those conditions. beyond 50 ka, presented by Stokes et al. (1998), are The site also has shed some new light on some key difficult to interpret due to stratigraphic age reversals. issues in southern African archaeology in particular, In addition, Bateman & Thomas (pers. comm.) and anthropology in general. First, there has been have obtained sand sheet OSL ages for the southern considerable anthropological interest and debate Kalahari of South Africa of 60·22·5 and regarding the nature of Kalahari foragers and the 58·62·3 ka. The U-series ages of submerged speleo- degree of interaction between foragers and agro- thems in Namibia suggest drier climatic intervals at pastoralists. The site is one of a few rock shelters in 61·43·6, 107·66·6, 112·05·3 and 129·96·9 ka, southern Africa where site use can be associated with while similar age dating on cave speleothems in oral traditions, in this case as a temporary rainy season presently dry areas, where there is little speleothem camp, last used by Zhu about 60–70 years ago. Because development today, indicates wetter climatic periods in the site can be related to recent use by Zhu and is also the southern African rainfall region at 111–103, 93–83 adjacent to where other peoples have lived, it is ideally and 77–69 ka (Brook et al., 1997, 1999). The dune ages situated for the recovery of data bearing on the issue of of 60·22·5 and 58·62·3 ka, and the submerged interaction. The Late Prehistoric/Historic record has speleothem age of 61·43·6 ka appear to point to a indicated that maize and domestic cattle were known in dry period of climate from about 61–59 ka. This period the area prior to what has been termed the ‘‘ethno- corresponds reasonably well with our chronology for graphic present’’, but that stone tool use, along with the deposition of Units 8 and 7 from 65–50 ka. Unit 8a considerable foraging for wild foods probably con- is defined by an indistinct stone line, and by very small tinued into a relatively recent period. Interestingly, peaks in stone tool numbers (Figure 6), which suggest research at the site in levels contemporary with the EIA that it represents only a slightly wetter interval within (containing pottery and iron beads) has shown that the this period. The wet periods of Brook et al. (1997) at fauna is almost exclusively wild despite the fact that 77–69 and 93–83 ka correlate reasonably well with our nearby village peoples kept substantial herds of live- estimated ages for Units 9a and 10a, both of which stock. This finding demonstrates the viability and show a peak in MSA artefacts (Figure 8). Unit 11, also importance of wild foods to people during the period characterised by a peak in MSA tools (Figure 6) could when agropastoralism was known and widespread well have been deposited during the 111–103 ka wet trade networks, as well as intensive specular hematite interval of Brook et al. (1997). The OSL age of 73 ka mining, existed in the immediate area. from Stokes et al. (1998) could well define the age of At WPS, the discovery of a long record of fish aeolian Unit 9b, and the Stokes et al. (1998) dune sand exploitation was initially quite surprising given the ages of 109, 102 and 101 ka, the OSL age of location of the site in the Kalahari several days walking 98·19·2 ka for dune sand 4m below the surface of the distance across the sand veldt from the nearest perma- linear dune south of Tsodilo (Thomas, pers. comm.). nently flowing water. The long record of fish exploi- The submerged speleothem ages of 107 and 112 ka, tation, to 4 m in square 10 and 4·5 m in square 11, goes could help to refine the age range of aeolian Unit 10b back to about 65 ka if our chronology for this site is (112–94 ka?), which we have tentatively dated to correct. The dating of the Lower Fish deposits and the 94·39·4 ka based on a TL age for sand at 605 cm in deepest barbed bone point fragments remains problem- square 13. atic. Quite clearly, the presence of Equus capensis Tsodilo Hills White Paintings Rock Shelter 1111 indicates a Late Pleistocene Age and the underlying The Late Pleistocene bone artefacts and burins ostrich eggshell dates from the Low Density LSA show found in the Lower Fish (early LSA) deposits are that the deposits probably formed before 30 ka. The especially significant in light of recent findings of bone interpretation of the dates, along with site stratigraphy artefacts in the MSA at Katanda in Congo, and at and the regional palaeoclimatic sequence, has sug- Blombos Cave in South Africa (Brooks et al., 1995; gested an age of approximately 48 ka. It is logical to Henshilwood & Sealy, 1997). When taken together, believe that the source of the numerous fish, especially these sites, along with the early LSA discovery of in the 240–250 cm level, was nearby. A nearby source ostrich egg shell beads at Ekapune ya Muto in Kenya, would have been the Tsodilo lake, yet there are no ages adds a new perspective, as well as raises new questions for the lake in the 48 ka range. However, there is a lake about the early development of complex ‘‘Upper stage that dates to between 36–32 ka. In the Lower Fish Palaeolithic’’ technology in Africa (Ambrose, 1998). deposits, fish bones were most numerous at c. 250 cm, Did such developments begin in Africa? Clearly, the which has been OSL dated to approximately 36 ka; an new data from WPS, along with other sites seriously age that agrees well with the lake Tsodilo dates. The challenges the Eurocentric bias that has long existed 36 ka OSL sample was collected from the same squares regarding the advent of classic ‘‘Upper Palaeolithic’’ and depth that produced the highest frequencies of fish technology. bones for the Lower Fish units. In addition, compara- Particularly significant is the fact that at WPS, in tive archeological findings are important to consider the deeper deposits, there appears to be some conti- given the fact that the stone artefact assemblage from nuity between the early LSA and the MSA lithics as the Lower Fish is clearly microlithic with segments and evidenced by the presence of large blades above the other backed tools. As noted previously, elsewhere in levels where typical MSA points were encountered, and southern Africa the earliest LSA microlithic assem- that these large blades continue to be found within blages date to between approximately 39,000–19,000 the MSA levels among typical ‘‘mode 3’’ technology (Deacon, 1984; Wadley, 1993). As far as we are aware, with MSA points and prepared cores. It was also dur- the only LSA microlithic assemblage in Africa that is ing the MSA occupation that there was a substantial possibly older than 40 ka is at Matupi Cave in the Ituri shift towards the use of non-local raw materials. Ob- area of Congo, and this assemblage lacks formal viously, more research is necessary to broaden the backed tools (Van Noten, 1977). Earlier backed pieces perspective on these trends noted at WPS and to do occur in South Africa in Howiesons Poort assem- answer the question posed above. blages, but these assemblages occur stratified between MSA levels (Volman, 1984; Wurz, 1999). At WPS, this is not the case with respect to the Lower Fish Deposits Acknowledgements which clearly overlie a blade assemblage that lacks Research was funded by the National Geographic MSA points. Society and the National Science Foundation. We are A major contribution of the work at WPS is the grateful to the authorities of the National Museum, finding that the distribution of bone ‘‘harpoons’’ and Monuments and Art Gallery of Botswana for facilitat- the exploitation of freshwater aquatic resources can no ing this research. We thank all of our field assistants, longer be considered as restricted to the sites of East especially A. Matseka, Naill, Heather and Judy Africa, the Nile Valley and the Sahara. Overall, our Campbell, J. Clark, J. Harris, D. Cherry, M. findings have shown that food economies were diverse Samuchau, T. Ferone, Gxau, Tsorro, L. Murphy, and fluctuated considerably through time in this part Richard, Sarah, and Marion Hartland-Rowe, and of the Kalahari. This is an important finding, given the D. Robbins. We gratefully acknowledge the help of tendency of anthropologists to rely on contemporary numerous lab assistants, especially B. Smith, S. Cloud, and recent Kalahari hunter–gatherer subsistence J. Nickelson, K. Nichols and M. McNally. In addition, patterns in the development of models. Nonetheless, we are grateful to A. S. Brooks and J. Kokis for there were certain long-term staple food resources that submitting the ostrich eggshell samples for AMS were exploited at Tsodilo such as mongongo nuts dating at U.C. Riverside as part of their project to (AMS dated to c.4·1 ka), springhare, tortoises, catfish, date eggshell by protein diagenesis and to J. Sealy and and a variety of small to medium sized bovids. R. Yates for submitting the sheep jaw for AMS dating Through much of the sequence (extending from as part of their project to better understand the spread periods 1–4) ostrich eggs were exploited, presumably of livestock in southern Africa. Finally, we appreciate for food as well as for making beads. A bead broken in the assistance of J. A. Holman with the reptile bones manufacture from the 190–200 cm level was AMS and C. 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