Terminal Pleistocene Later Stone Age Human Remains from the Mlambalasi Rock Shelter, Iringa Region, Southern Tanzania

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This article is protected by copyright. All rights reserved.

Terminal Pleistocene Later Stone Age Human Remains from the Mlambalasi Rock Shelter, Iringa Region, Southern Tanzania

Short title: Pleistocene LSA Human Remains from the Mlambalasi Rock Shelter, Tanzania Elizabeth A. Sawchuk* Department of Anthropology University of Toronto 19 Russell Street Toronto, Ontario, Canada, M5S 2S2 e-mail: [email protected] Pamela R. Willoughby Department of Anthropology University of Alberta Edmonton, Alberta, Canada, T6G 2H4 e-mail: [email protected] *Corresponding author This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/oa.2323

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Abstract

This paper introduces research at the Mlambalasi rock shelter in the Iringa Region of southern Tanzania. The deposits are composed of a historic and Iron Age occupation, a microlithic Holocene Later Stone Age (LSA), and then a macrolithic Late Pleistocene LSA. Middle Stone Age deposits are also present on the slope in front of the rock shelter. Excavations in A.D. 2002, 2006, and 2010 yielded fragmentary human remains as well as pottery, iron, stone tools, faunal bone, and glass and ostrich eggshell beads. Among the human remains, four individuals are present: two adults and a juvenile were found in the same LSA context, and another adult associated with the Iron Age/historic period. The most complete skeleton is an adult of indeterminate sex that was found in situ in an LSA deposit. Charcoal in proximity to the bone was AMS radiocarbon dated to 12,925 cal BC (OxA-24620), which is consistent with radiocarbon dates on giant land snail shells from above and below the remains. The skeleton exhibits a series of pathological changes such as extensive dental wear and carious lesions, as well as damage most likely caused by termites, post-mortem. The most striking aspect of this individual is its small size; stature and body mass estimations place it in the range of historic Khoesan from southern Africa. Consequently, this research adds to the discourse regarding the existence of small-bodied people in the East African LSA. Findings from this new skeletal sample will contribute to studies of human biology and variation in Africa during the terminal Pleistocene and Holocene. Keywords: Tanzania, Iringa, Mlambalasi, Later Stone Age, Bioarchaeology, Palaeoanthropology, Small body size, Hunter-Gatherer Introduction The Iringa Region of southern Tanzania possesses a dense archaeological record similar to other places in East Africa, but one which has not been as intensively studied. The Mlambalasi rock shelter (HwJf-02) is located about 50 km northwest of the modern city of Iringa (Figures 1 and 2). It is well known among local Tanzanians as the death place of Chief Mkwawa, the 19th century Wahehe leader who killed himself to avoid capture by German colonial forces in 1898. The site also possesses a long archaeological sequence consisting of historic or Iron Age deposits overlying Holocene Later Stone Age (LSA) and terminal Pleistocene LSA levels. The Holocene LSA is dominated by quartz microlithic backed tools struck from bipolar cores. The Late Pleistocene levels have similar backed tools, scrapers and cores that are generally much larger (or macrolithic). Artifacts recovered include lithic tools and debitage, decorated and undecorated pottery, iron and iron slag, giant land snail shells, animal bones, beads, and charcoal. Fragmentary human remains from the LSA and Iron Age are also present. As new human skeletal collections rarely arise in East Africa, these materials have great potential to shed insight into the diversity of Later Pleistocene African populations. The most complete skeleton from site, B-1, is described here in the context of ongoing research on the LSA. Although Homo sapiens fossils appear nearly 200,000 years ago in Africa, little is known about early human populations on this continent until the start of the Holocene or postglacial period around 190,000 years later (Willoughby, 2007). This is in part due to low population density, which may have been caused by environmental stress in the early history of our species. The founding modern human population may have dropped to a few thousand people during the Late Pleistocene (Harpending et al., 1993; Lahr and Foley, 1998; Gagneux et al.,

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1999). Growing evidence suggests this period was characterized by frequent climate shifts from cold, dry conditions to more temperate, humid ones (Cohen et al., 2007; Scholz et al., 2007). Tropical rainforests disappeared during cold periods, and were replaced by savannas or even deserts. In warmer, wetter periods, deserts might have disappeared, creating corridors for the expansion and dispersal of animals and humans. It is possible that people survived cold periods by withdrawing to refugia, potentially located in places like the East African highlands (Gramly and Rightmire, 1973; Ambrose, 1984, Ambrose, 1998a; Klein, 1992). East Africa is one of the few regions in Africa with both Middle and Later Stone Age archaeological deposits, as well as ones transitional between the two industries. Sites with this record include Enkapune ya Muto in central Kenya (Ambrose, 1998b), Lukenya Hill, southeast of Nairobi, Kenya (Gramly, 1976; Kusimba, 1999, 2001), Nasera and Mumba-Höhle rock shelters in northern Tanzania (Mehlman, 1989), and Magubike in southern Tanzania (Willoughby, 2012). Matupi Cave in the eastern Democratic Republic of the Congo (DRC) also possesses a long cultural sequence with the earliest LSA dating back to around 40,000 years before present (BP) (Van Noten, 1977). This suggests that parts of East Africa remained habitable at a time when it appears that much of the African continent was depopulated. Because of the scarcity of archaeological sites with human remains, we know little about the biological affinities of people who lived at this time. Pleistocene LSA human remains from tropical Africa are rare. Human skeletal material dated to the terminal Pleistocene in sub-Saharan Africa has been found at Lukenya Hill, southern Kenya (Gramly and Rightmire, 1973; Gramly, 1976), Ishango, DRC (Brooks et al., 1995), Iwo Eleru, Nigeria (Brothwell and Shaw, 1971; Harvati et al., 2011), as well as Hofmeyr (Grine et al., 2007) and Tuinplaas/Springbok Flats, South Africa (Pike et al., 2004; Houghton and Thackeray, 2011; but also see Pfeiffer et al., 1996). By contrast, early Holocene LSA skeletons from after 12,000 years BP are present in Kenya (at Galana Boi, Lothagam, Kangatotha, and Kabua); Tanzania (Mumba-Höhle, Kinto); Zambia (Mumbwa, Kalemba); the DRC (Ishango); Somalia (Gogoshiis Qabe); and South Africa (multiple sites, see Rightmire 1978; Morris 1992). Much of the Holocene material can be divided into East African skeletons, which are described as tall and linear (Angel et al., 1980; Schepartz, 1987, 1988), and South African ones, which are small-bodied and thought to be ancestral to indigenous South Africans (Stynder et al., 2007a; 2007b). The sparse Late Pleistocene fossil record makes it difficult to study the human populations responsible for the most of the LSA (Rightmire, 1984; Grine et al., 2007; Crevecoeur et al., 2009; Pfeiffer and Harrington, 2011). Many coastal archaeological sites from this time period may have been obscured by rising sea levels in the Holocene. Additionally, our species appears to have experienced a population expansion at the end of the Pleistocene (Cox et al., 2009). Our knowledge of LSA populations is therefore largely based on Holocene material, particularly well-preserved skeletal collections from southern Africa representing the ancestors of the Bushmen or Khoesan. In addition to material culture, LSA South Africans and the Khoesan share a small body size that can be traced back 10,000 years (Pfeiffer and Sealy, 2006). Evidence of diet and development from juvenile and adult remains suggests this pattern may not have been the result of nutritional deficiencies, disease, or stunted childhood growth, but of a selective adaptation that favoured small adult size (Sealy and Pfeiffer, 2000; Pfeiffer and Sealy, 2006; Kurki, 2007; Pfeiffer, 2007; Harrington and Pfeiffer, 2008; Pfeiffer and Harrington, 2010, 2011). Although it has been argued that the unique biological attributes of the Khoesan are a Holocene development (Morris, 2002), the dearth of skeletal remains from the Late Pleistocene make it difficult to trace when this small bodied pattern arose.

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Comparably small remains are present at Middle Stone Age sites such as Klasies River (Rightmire and Deacon, 1991; Pfeiffer and Harrington, 2011). Other specimens from this time period are average sized and even large, however, indicating morphological variability in pre-Holocene populations (Pfeiffer, 2012). The connection between South and East Africa during the LSA has been the focus of a nearly century-long debate. Following the 1913 discovery of a robust calvarium from Boskop, South Africa, certain Stone Age archaeological remains were attributed to an extinct “Boskop race” thought to exist in various parts of sub-Saharan Africa (Dart, 1923; Tobias, 1985). The Boskop were proposed to be a large or “unreduced” proto-Bushman population that preceded and gave rise to the Khoesan. Although the concept was later refuted (Singer, 1958; Rightmire, 1978) and criticized for essentializing early African populations as behaviourally and morphologically similar, the link between the South and East remained a point of interest. Starting in the mid-20th century, discoveries of “Khoisanoid” remains in East Africa fuelled theories that the Khoesan evolved there and then subsequently migrated south, or, alternatively, that the proto-Khoesan range extended up the eastern side of the continent from South Africa to Egypt (Galloway, 1933; Brothwell, 1963; Tobias, 1965, 1972, 1978; Nurse et al., 1985). Existence of an East African Khoesan population has been argued based on osteological, archaeological, linguistic, and genetic evidence. The skeletons purported to have Khoisanoid morphology are said to exhibit paedomorphic, or child-like, crania with smooth, rounded vaults and proportionally small faces (summary of relevant remains in Morris, 2003). In contrast to the small body size of the Khoesan, many of the postcranial remains associated with these skeletons are robust or otherwise large. Archaeologically, LSA stone artifact assemblages found throughout rock shelters in East Africa were originally described as similar to those from the Wilton industry in South Africa (Leakey, 1936), and rock art and petroglyphs were said to be similar to the Bushman artistic style (Willcox, 1984). However, it is difficult to make a connection between these practices without living descendant groups in East Africa. Any resemblance may be due to a shared subsistence strategy, as opposed to a biological or cultural affinity. The most compelling evidence for a link between the East and South African LSA comes from two living groups in Tanzania, the Hadza and Sandawe. These hunter-gatherers speak languages that were originally classified as part of the Khoesan family based solely on their distinctive click noises (Greenberg, 1963). They also share a number of unique genetic markers with the Khoesan that are absent in other humans (Excoffier et al., 1987; Tishkoff et al., 1996, 2009; Semino et al., 2002; Scheinfeldt et al., 2010). These commonalities are found in nuclear, mitochondrial, and Y chromosome DNA, as well as for several indicators in the blood. Although some of this may reflect a deeper history of all humans, the number and strength of the genetic similarities between the Hadza, Sandawe, and Khoesan have been said to be persuasive. Taken in concert, this evidence may suggest that click languages and Khoesan morphology were more widespread in Africa prior to the expansion of “black Africans” associated with the Bantu migration. However, other researchers assert that there is no conclusive link between the LSA East Africans and modern Khoesan, as is the case in southern Africa (Schepartz, 1987, 1988; Morris, 2002, 2003). Reaction to the Boskop race concept, combined with the analysis of new skeletal material, led some researchers to dismiss earlier theories connecting the two regions (Schepartz, 1988; Morris, 2002, 2003). Despite ongoing research, our knowledge of human diversity during this period is limited, emphasizing the importance of new skeletal material. Additional discoveries help broaden our knowledge about LSA human populations and test hypotheses about biological

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relationships. The individuals from Mlambalasi, one of which is from a level dated to the terminal Pleistocene, have the potential to shed light on our species during the expansion period at the end of the last ice ages. In particular, the skeleton from this site cataloged as B-1 may provide an argument for re-addressing the potential diversity of Late Pleistocene human populations. Excavation History and Context of the Remains The Iringa Region in the southern highlands of Tanzania is best known for the famous Acheulean site of Isimila, which was studied in the 1950s (Howell et al., 1962). Despite its altitude and modern-day aridity, this area may have been a refugium during the Pleistocene. Diatom analysis of Western Rift Valley lakes such as Lake Rukwa, Lake Malawi, and Lake Massoko suggests that not all bodies of water dried up during glacial phases (Barker et al., 2002, Barker and Gasse, 2003). Although many lowland lakes did disappear, some in the highlands appear to have persisted. Additionally, sediment cores from the Dama and Deva Deva Swamps in Iringa indicate that parts of the Eastern Arc mountains have been stable grasslands for at least the last 13,000 years, and potentially as long as 48,000 years (Mumbi et al., 2008; Finch et al., 2009; Finch and Marchant, 2011; Willoughby, 2012). This long-term stability could have contributed to the survival of human populations in the region and to the preservation of archaeological sites. The Mlambalasi site consists of a granitic rock shelter complex located midway up a large escarpment. Excavations to date have focused on Room 1, which is approximately 12 m by 8 m with east and southwest entrances separated by a large piece of roof fall (Willoughby, 2010, 2012). This boulder provides a partial fourth wall for the shelter, shielding it from the elements and camouflaging it on the landscape. A second Room is approximately 4 m by 4 m in size and can be accessed via a small crawl space or from a separate entrance upslope. Initial excavations by Paul Msemwa (2002) near the drip-line of the shelter yielded fragmentary human remains from recent Iron Age deposits (later classified as Burial-3, or B-3) (Sawchuk, 2012) (Figure 3). The context of the remains is unclear, but they were found close to the surface and were associated with fire cracked rocks, pottery, lithics, faunal bone, iron slag, iron metal sheeting, shells, and beads. Msemwa believed that the upper 30 cm of the rock shelter deposits were in a disturbed context, and had been subjected to foraging or smelting activities occurring as late as the 20th century. He even noted that potsherds collected from the surface with coarse roulette decorations were similar to those still in use in the area (Msemwa, 2002: 13). In 2006, charcoal from an anthropogenic ash level 25 cm below surface was dated to 460 ± 50 uncalibrated years BP (TO-13416) (1440 cal AD). Test excavations in 2006 confirmed the presence of historic, Iron Age, and LSA occupations (Biittner et al., 2007). Two 1m2 units were placed toward the back of Room 1 and on the slope below the main shelter. The test pit on the slope yielded MSA, LSA, Iron Age, and historic artifacts, but most material was out of context and infested by termites. Inside the rock shelter, the upper 40 cm of deposits were characterized by pottery, iron slag, lithics, and bone. At this depth, we observed a reduction in artifact density and the appearance of a pebble layer containing some LSA artifacts. The pebbles were densest between 40 and 50 cm below the modern ground surface, and were decreasingly present for another 30 cm. The horizon appeared to cap the LSA occupation at the site, marking the transition from the Iron Age. Below the pebble horizon, microlithic quartzite and chert artifacts, ostrich eggshell beads, partly fossilized shell and bone, and an absence of pottery and iron predominated.

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Fragmentary, commingled human remains were discovered under a large piece of roof fall from 70 to 90 cm below the modern ground surface. The primary interment was located in situ and commingled with the lower extent of the pebble layer. There was no sign of a burial pit and the pebbles were undisturbed, suggesting that the skeleton was not intrusive from a younger period. The remains were also overlain and surrounded by numerous cobbles, boulders, and rock slabs from apparent roof collapses. The debris was not interpreted as a burial cairn given its ubiquitous presence throughout the excavation unit and the fact that the rubble was the same material as the surrounding rock shelter. The skeletal remains represent the partial postcrania of one adult (B-1) and the manubrium of a juvenile (B-2). The adult skeleton was lying in a flexed or semi-flexed position facing west, and was found in proximity to flaked stone artifacts, some shell, faunal bone, and an ostrich eggshell bead. Large boulders were encountered in the lower levels, which inhibited further excavation. In 2010, a 2 by 3 m trench was placed over the two former test excavations. Additional remains from the incomplete B-1 and B-3 skeletons were recovered around the locations of the original test units. Further elements of the Iron Age individual (B-3) were discovered out of context, representing part of the upper half of the body to the mid-thorax. If preserved, the remainder of the skeleton may still be interred in the rock shelter. By contrast, fragments of the skull and upper body of B-1 were discovered in situ adjacent to the 2006 test unit and in the same pebble layer (Figure 4). Overlying cobbles and rock slabs were again present, and again appeared to be from roof fall. Comparison of the skeletal elements with the 2006 material strongly suggest that the remains belong to the same adult specimen based on several factors including size, preservation, elements present, and body position. The pebble layer abruptly ended at the mid-thorax, with the boundary of the 2006 excavation unit clearly visible. Also recovered with this skeleton were fused left and right maxillae that may represent a separate adult (B-4). They are consistent in size with the other cranial elements, but the isolated teeth from B-1 do not appear to match the alveoli of the fragment. Although this discrepancy could result from taphonomic damage, the minimum number of individuals at the site may be as high as four (Table 1). Degradation of the bone and tooth remains reflects the dynamic rock shelter environment. All the skeletons are highly fragmented, and the bone breakage is consistent with postmortem stress from sediment compaction and trampling (Villa and Mahieu, 1990). Local Maasai groups currently use the rock shelter to corral livestock, and there are numerous archaeological indications of continued use over time. The remains were also affected by moving water and gravity, as well as various bioturbation agents. Osteophagous insects, most likely termites, produced holes in the crania of B-1 and B-3 and the ribs and vertebrae of B-1 (Britt et al., 2008) (Figure 5). Additionally, the cranial vault of B-1 is delaminated; the internal and external tables have separated at the diplöe, probably caused by weathering and perhaps also heat damage from a nearby hearth. Taphonomic processes may have caused the B-2 and B-4 individuals to become associated with the in situ B-1 skeleton. The rock shelter sediments are silty and poorly consolidated, so the isolated skeletal elements may be intrusive. Given that bone preservation was similar to that of B-1, they may also derive from other LSA individuals buried in close proximity. At present, however, only the B-1 skeleton can be confidently attributed to the Later Stone Age.

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Dating AMS radiocarbon dating of land snail shells (Achatina africana) and charcoal from around the B-1 remains suggests the burial belongs to the terminal Pleistocene (Table 2). In 2006, shell samples from above and below the remains were dated to 12,940 ± 90 (TO-13417) uncalibrated years BP (13,295 cal BC) and 11,710 ± 90 (TO-13418) uncalibrated years BP (11,635 cal BC). The dates were inverted, with the younger from a greater depth, suggesting either that the sediment was disturbed during interment or that the snails entered the sequence independently of humans. Whether or not these shells represent cultural behaviour is important for the interpretation of these dates. Mumba-Höhle rock shelter in northern Tanzania has also been radiocarbon dated using Achatina fragments associated with LSA industries and human remains (Mehlman, 1979). At that site, the shells were specifically interpreted as the food waste of prehistoric hunter-gatherers. Land snail shell middens and the development of so-called escargotières are well established in many regions of North Africa (Lubell et al., 1976), but their existence is debated south of the Sahara (summarized in Mehlman, 1979: 87-89). The snails may reflect expansion of hunter-gatherer diets during the Late Pleistocene (Flannery, 1969). They are also part of the ethnographically documented diet of modern Tanzanian groups such as the Hadza, who seek out snails during the onset of the rainy season in February and March (Mehlman, 1979; Bushozi, 2011). Msemwa (2002: 14) hypothesized the shell fragments at Mlambalasi were anthropogenic, and noted that land snails are still eaten among the Makonde ethnic group of Mtwara, Tanzania. Broken shell fragments were found in both Iron Age and LSA deposits at the site, with a reduction in their density in the intervening pebble layer. Their abundance and distribution, combined with ethnographic evidence for consumption, led us to interpret the shells as connected to food processing. If so, the shell fragments around the burial were likely incorporated from the contemporaneous occupation of the site and the dates derived from them should reflect the approximate antiquity of this LSA occupation. In 2010, charcoal found next to the right shoulder of B-1 was AMS radiocarbon dated to 12,765 ± 55 (OxA-24620) uncalibrated years BP (12,925 cal BC). The charcoal deposit was found beneath the undisturbed LSA pebble layer at the same depth as the skeleton, and did not appear to be intrusive. Bone samples were also submitted for direct dating, but had insufficient collagen for analysis. The fact that the 2010 charcoal sample falls between the dates derived from the shells provides evidence that the B-1 individual is associated with a Pleistocene LSA occupation. Skeletal Analysis The B-1 skeleton was recovered over two field seasons: the lower body in 2006 and the upper body and skull in 2010. The skeleton is fragmentary and is missing several teeth, much of the feet, and the patellae. Several ribs and vertebrae are also absent, as are large portions of the pelvic and pectoral girdles and face. Many of the fragments represent less than 25% of the particular bone, and the skeletal elements preferable for sex and age estimation are not preserved.

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The skeleton is a middle-aged adult, probably 35-50 years old at the time of death. Although fragmentary, the long bones of the skeleton appear to be fully mature, and fragments of the cranial vault show evidence of suture obliteration. The individual’s dentition provides the strongest indication of age. All four third molars are erupted and moderately to severely worn, suggesting a minimum age of 21 years and a likely age of 35 or older. The absence of osteoarthritis and degenerative joint disease implies this individual was not substantially older. However, given the absence of the pubic symphysis and other elements preferable for age estimation, a more precise estimate could not be made (methods as per Buikstra and Ubelaker, 1994). The sex of B-1 is undetermined. Dimorphic features of the pelvis and skull are not diagnostic, while the mandible appears strongly masculine. Osteometric analyses were conflicting; linear discriminant functions applied to the mandible (Saini et al., 2011) were strongly male, while those applied to the metacarpals and first proximal phalanx (Scheuer and Elkington, 1993; Stojanowski, 1999) were female (Table 3). The discordance in estimates is likely due to the use of weaker dimorphic traits, as well as the overall small size of the skeleton. Sex determination techniques tend to assume that males will be larger than females, and are often developed on comparatively robust modern populations. Using morphological evaluation alone, the sex of female skeletons is normally confirmed. Errors are more commonly made when smaller males are classified as female (Meindl et al., 1985). Without population-specific methods and a comparative sample, it is unknown whether the individual was a female or a small male. While the sex of the skeleton may not be confidently determined, the masculine morphology of the mandible is suggestive. This adult skeleton is diminutive, and may be small-bodied. In the absence of complete long bones, stature estimates were based on the diameter of the femoral head (Simmons et al., 1990) and the complete left first and right fifth metacarpals (Meadows and Jantz, 1992). We also estimated the maximum length of the femur (Simmons et al., 1990) and then generated a stature estimate following Trotter and Gleser (1952). Body mass estimates were based only on the maximum diameter of the femoral head (McHenry, 1992; Ruff et al., 1991) (Table 4). The range of stature estimates for a male is 155.3 to 166.3 cm with an average of 160.7 cm. For a female, the range is 150.8 to 163.2 cm with an average of 156.9 cm. The range for mass estimates is 43.67 to 44.58 kg for a male and 44.58 to 50.79 kg for a female, with averages of 44.13 and 47.69 kg respectively. There is little comparative data from other East African LSA skeletons, but they are typically described as tall (Schepartz, 1987, 1988). This skeleton appears to have more in common with LSA populations from southern Africa and their descendants. Stature and mass estimates for the South African LSA population are 157.1 cm and 50.9 kg for males, and 150.9 cm and 42.6 kg for females (Pfeiffer and Sealy 2006; Kurki et al., 2010). These values are close to historic Khoesan averages, which are often used as guidelines for small body size in the archaeological literature: 161 cm and 48 kg for males and 150 cm and 40 kg for females (Truswell and Hansen, 1976). The estimates for the B-1 individual are close to the male averages, while a female would be slightly taller and heavier. Either way, this individual is small and gracile. Twenty-six isolated crowns and various other tooth fragments were recovered in association with the skull. The maxillary teeth are all present except for the right lateral incisor. The right central and lateral incisors, left first molar, and both second molars are absent from the mandibular arcade. It is unclear if the missing teeth were lost ante- or postmortem. The teeth exhibit a moderate to high degree of dental attrition and caries. Whereas a high degree of

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wear is common among prehistoric hunter-gatherers, carious lesions are more unusual (Truswell, 1976; Hillson, 2008). The skeleton has 12 carious lesions on the incisors, canines, premolars, and one first molar (Figures 6 and 7). Most are located in the interproximal spaces between the teeth indicating that this individual suffered from chronic dental caries. The lesions do not appear to be grooves caused by excessive cleaning, which also occur in the interproximal spaces (Unger et al., 2011). Dental caries are more commonly associated with agricultural populations in which cultivated sources of carbohydrates represent a large portion of the diet (Ortner and Putschar, 1985; Hillson, 2005, 2008). The frequency of caries in hunter-gatherers tends to be low: approximately 2-3 lesions per mouth (Ortner and Putschar, 1985: 439). The incidence is even lower prior to the Holocene: “Middle and late Pleistocene cases worldwide can be counted on the fingers of two hands” (Hillson, 2008: 128). Although atypical, a high frequency of caries is present in at least one LSA population from South Africa (Sealy et al., 1992), potentially connected to low fluoride content in the groundwater. In the case of the B-1 skeleton, the disease may indicate the consumption of certain cariogenic foods, such as honey, which is well documented among the Hadza (Marlowe, 2010) and Khoesan (Truswell, 1977). Whether the prevalence of caries in this individual represents broader patterns in this population or an anomalous case is unknown. Other pathological changes on the B-1 dentition included hypoplasias and hypocalcifications, including possible linear enamel hypoplasia (LEH), and a periapical cemental dysplasia (often called a cementoma) on the fourth left mandibular premolar. The etiology of cementomas is poorly understood, but they are usually found in adults and may be related to advanced age (Eversole et al., 1972). Despite poor preservation, there is additional evidence for pathological changes on the B-1 skeleton. The petrous pyramid of the right temporal exhibits a blastic lesion 4.23 mm high and 8.63 mm long, extending postero-superiorly from just above the internal auditory meatus (Figure 8a). It is likely an exostosis or an osteoma, both of which are slow growing neoplastic bony tumours that are typically asymptomatic (Wright et al., 1996; Imhor et al., 2004). It is also possible, although less likely, that this growth could originate from another tumour of the external ear, middle ear, or inner ear. Such cancers are extremely rare, but tend to target the apex of the petrous bone due to its high degree of vascularization (Imhor et al., 2004). On the same side of the skull, the right portion of the sphenoid appears deformed (Figure 8b). When compared to the normal left side, the right pterygoid process is absent, with what appears to be reactive, frothy bone on the anterior surface. Although the specimen is badly damaged and the deformation may be taphonomic, the presence of potential additional bone growth suggests localized remodeling. Interruption of the pterygoid processes can occur as the result of infection, cancer, or facial trauma. The pterygoid plates are vulnerable to infection and certain cancers because they form the posterior border of the pterygopalatine fossa, which connects the nasal and oral cavities, infratemporal and middle cranial fossa, and orbit, and is therefore a natural pathway for the spread of many disease processes (Osborn, 1979: 394). Due to the complex arrangement and delicate bones of the facial skeleton, swelling and tumours anywhere in the vicinity can cause marked destruction of bone and disruption of the pterygoid processes. Pterygoid disruption is also the key diagnostic feature of Le Fort fractures, which separate all or part of the maxilla from the skull base (Hopper et al., 2006). Interpersonal violence, accidents, and falls can cause this type of blunt trauma. However, it is usually accompanied by other complex maxillofacial fractures (Fromm, 1960; Kim and Huoh, 2010), which cannot be identified on this fragmentary skeleton. Other potential pathological changes on this skeleton include a slight asymmetry between the

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mandibular ascending rami, represented by a 2mm difference in ramus height, and a possible non-union fracture indicated by a deformed distal fragment of an intermediate hand phalanx. The other three skeletons excavated from Mlambalasi are incomplete. B-2 is a partial juvenile manubrium that is consistent in size with an older child, based on visual comparison to a modern skeletal reference collection. B-4, the potential second adult found with B-1, is represented by a fused right and left adult maxillae with a grossly carious right lateral incisor and a large lesion representing a periapical abscess or periodontal cyst (Dias et al., 2007). If this fragment does denote a separate individual, the presence of advanced dental disease could indicate a broader pattern of health in this population. The B-3 skeleton consists of the skull, partial thorax, and upper limbs of a possibly female adult. It was discovered several metres away in an Iron Age context and appears to be unrelated to the other skeletons. Only a portion of the rock shelter has been excavated, so additional components of these individuals may be recovered through future research. Discussion New discoveries, such as B-1 from Mlambalasi, may renew discussion on the presence of small-bodied people in East Africa. Based on the few comparable skeletal samples, this individual does not conform to the typical tall, robust, and linear body proportions of previously reported East African LSA populations. Instead, its small body size has more in common with southern African peoples. This does not necessarily imply a biological link between these LSA populations. Hypotheses for why small size develops include the need for thermoregulation, limited food supply, enhanced mobility, and high mortality influencing early reproduction (Perry and Dominy, 2009; Pfeiffer and Harrington, 2011). In southern Africa, small body size may be linked to energetics and accident avoidance. The rate of injury among the South African LSA populations is lower than other mobile hunter-gatherer groups, which Pfeiffer (2007) interprets as possibly related to reduced body mass. Ethnographic studies of modern Khoesan emphasize the centrality of the bow and arrow and persistence hunting, in which small, energetically efficient bodies prove advantageous (Tobias, 1978). Small body size may have emerged multiple times, perhaps amidst the low population densities and climatic instability of the LSA. Given that early modern humans may have endured a population crisis (Harpending et al., 1993; Ambrose, 1998a; Lahr and Foley, 1998; Reich and Goldstein, 1998), and that there is some evidence for increased diversity among earlier populations (Crevecoeur et al., 2009), one characteristic of some terminal Pleistocene and early Holocene groups may have been a small body size. Exploring the incidence of scope of this pattern in East African and other early modern humans may shed light on the importance of body size in human evolution. Conclusions Although fragmentary and incomplete, the Mlambalasi skeletons contribute to our limited knowledge of LSA humans. An adult skeleton from the site exhibits an atypical small body size, as well as advanced dental disease and other pathological changes. This case study does not conform to the previously documented pattern of East African LSA skeletal remains, and suggests further study is needed on diversity in Later Pleistocene African populations. The partial remains of at least one other adult and a juvenile have also been recovered from the site, suggesting other burials may be present. The Mlambalasi rock shelter was repeatedly

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used over the past 15,000 years for both occupation and mortuary purposes, and its deposits offer insights into the behavior of terminal Pleistocene and early Holocene human populations in East Africa. Mlambalasi and other fossiliferous Stone Age sites have an important role to play in understanding this history, as well as the factors that allowed our ancestors to persist. Acknowledgements

Elizabeth Sawchuk would like to acknowledge the Social Sciences and Humanities Research Council of Canada (SSHRC), the Government of Alberta, and the University of Alberta for funding support. She would also like to thank Sandra Garvie-Lok, Nancy Lovell, Pamela Mayne-Correia, and Susan Pfeiffer for their input on this study, Paul Msemwa for permission to study materials from his 2002 excavation, and Jennifer Miller for Figure 3. Pamela Willoughby would like to thank the following for funding the fieldwork in Iringa: The Killam Cornerstone Fund, University of Alberta (2006 and 2008), The Support for the Advancement of Scholarship Fund, Faculty of Arts, University of Alberta (2006), the Wenner-Gren Foundation for Anthropological Research through a Post-PhD research grant (2008), and SSHRC through Standard Research Grants #410-2008-0061 (2008-2011) and #410-2011-0117 (2011-2014). She would also like to thank the Tanzania Commission on Science and Technology (COSTECH) for research clearances, and the Department of Antiquities, Ministry of Natural Resources and Tourism, Government of Tanzania, for excavation permits. Finally, she would like to thank Joyce Nachilema, District Cultural Officer for Iringa Rural, who first showed her the site in 2005.

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Table 1: Skeletal material recovered from the Mlambalasi rock shelter. Skeleton Age Recovered elements Pathological changes B-1 Adult partial cranium, fragmentary

mandible 26 teeth scapulae clavicles sternum atlas axis several cervical and thoracic vertebrae ribs humeri radii ulnae trapezium, lunate, scaphoid several metacarpals proximal, intermediate, and distal manual phalanages os coxae femora tibiae fibula calcaneus talus metatarsals proximal, intermediate pedal phalanges

Carious lesions (12) Hypoplasias and hypocalcalficiations Periapical cemental dysplasia Blastic growth right temporal Potential loss of pterygoid process on sphenoid Possible non-union fracture of an intermediate hand phalanx

B-2 Juvenile manubrium B-3 Adult occipital

mandible – left corpus and ramus clavicle ribs ulna radius trapezium, lunate metacarpals proximal and intermediate pedal phalanges

B-4* Adult maxillae – fused alveolar portions upper right lateral incisor

Periapical abscess Advanced carious lesion on incisor

* this fragment may belong to skeleton B-1

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Table 2: Radiocarbon dates from shell and charcoal around the B-1 remains Depth (cm below surface)

Description Age (years BP) Lab Number

25 Charcoal from Iron Age deposits 460 ± 50 TO-13416 65-70 Achatina shell found above the B-1

skeleton 12,940 ± 90 TO-13417

110-120 Achatina shell found below the B-1 skeleton

11,170 ± 90 TO-13418

69 Charcoal found next to the right shoulder of the B-1 skeleton

12,765 ± 55 OxA-24620

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Table 3: Metric sex estimates for the B-1 skeleton Skeletal element Measurements (mm) Source Interpretation Mandible (left ascending ramus)

Max breadth: 43.42 Min breadth: 34.64 Condylar height: 69.95 Projective height: 65.96 Coronoid height: 60.79

Saini et al., 2011 Male

Left 1st metacarpal Max length: 45/24 ML base: 12.35 AP base: 12.90 ML head: 12.14 AP head: 11.22 Max midshaft diameter: 9.28

Scheuer and Elkington, 1993; Stojankowski, 1999

Female

Left 5th metacarpal ML base: 8.42 AP base: 10.42 ML head: 9.06 AP head: 9.71 Max midshaft diameter: 6.50

Stojankowski, 1999 Female

Right 5th metacarpal Max length: 52.39 ML head: 8.23 AP head: 12.88 Midshaft diamter: 7.45

Stojankowski, 1999 Female

ML: mediolateral AP: anteroposterior

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Table 4: Stature and body mass estimates for the B-1 skeleton. Estimation Skeletal

Element Used Source Equation Result

Stature Femoral head diameter (37.73 mm)

Simmons et al. 1990 Black male: Stature = 1.51(VHD) + 97.82 ± 6.92

155.28 cm (avg)

White male: Stature = 1.11(VHD) + 113.89 ± 6.77 Black female: Stature = 1.59(VHD) + 92.43 ± 5.59

151.29 cm (avg)

White female: Stature = 1.35(VHD) + 99.22 ± 7.16

Simmon et al. 1990 (femur length) Trotter and Gleser 1952 (stature)

Black male: Femur length = 0.54(VHD) + 19.45 ± 2.56 Stature = 2.11(FLm) + 70.35 ± 3.94

155.26 cm (avg)

White male: Femur length = 0.43(VHD) + 23.57 ± 2.32 Stature = 2.38(FLm) + 61.41 ± 3.27 Black female: Femur length = 0.58(VHD) + 17.12 ± 1.99 Stature = 2.28(FLm) + 62.26 ± 3.41

150.82 cm (avg)

White female: Femur length = 0.47(VHD) + 20.22 ± 2.06 Stature = 2.47(FLm) + 56.60 ± 3.72

Left 1st metacarpal length (45.24 mm)

Meadows and Jantz 1992

Black male: Stature = (1.674)(b1) + 88.81 ± 5.57

166.08 cm (avg)

White male: Stature = (1.674)(b1) + 91.89 ± 5.57 Black female: Stature = (1.674)(b1) + 85.33 ± 5.57

163.16 cm (avg)

White female: Stature = (1.674)(b1) + 89.52 ± 5.57

Right 5th metacarpal length (52.39 mm)

Meadows and Jantz 1992

Black male: Stature = (1.433)(b1) + 89.35 ± 5.67

166.33 cm (avg)

White male:

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Stature = (1.433)(b1) + 93.16 ± 5.67 Black female: Stature = (1.433)(b1) + 84.41 ± 5.67

162.25 cm (avg)

White female: Stature = (1.433)(b1) + 89.95 ± 5.67

Body mass Femoral head diameter (37.73 mm)

McHenry 1992; Kurki et al. 2010

Body mass = 2.239(FH) – 39.9

44.58 kg

Ruff et al. 1991; Kurki et al. 2010

Male: Body mass = (2.741 x FH – 54.9) (0.9)

43.67 kg

Female: Body mass = (2.426 x FH – 35.1)(0.9)

50.79 kg

Notes: terminology taken from sources. Results for “white” and “black” formulae averaged as per Sealy and Pfeiffer, 2006 and Kurki et al., 2010. The same femoral head diameter measurement was used in all equations due to the poor condition of the specimen and the similarity between vertical head diameter and max femoral head diameter. VHD = vertical head diameter (femur) FLm = maximum femur length bl = bone length FH = femoral head diameter

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Figure 1. Map of Tanzania, showing the location of the Mlambalasi rock shelter.

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Figure 2. The interior of Room 1 of the Mlambalasi rock shelter.

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Figure 3. Plan map of the Mlambalasi rock shelter with previous excavations indicated (based on illustration by Jennifer Miller).

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Figure 4. B-1 skull (left) and upper thorax (right) in situ.

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Figure 5. Taphonomic changes on the B-1 skeleton. (a) Fragment of the occipital showing holes on the endo- and exocranial surfaces. (b) Rib fragments showing insect tunneling.

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Figure 6. B-1 dentition in anatomical position with caries indicated.

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Figure 7: Carious lesion on the maxillary right central incisor of the B-1 skeleton.

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Figure 8. Pathological changes on the B-1 skeleton, indicated by arrows. (a) Petrous pyramids in anatomical position with blastic lesion on the right fragment. (b) Healthy sphenoid (University of Alberta Osteology collection) (above) compared to B-1 sphenoid (below) with absent right pterygoid process.

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Terminal Pleistocene Later Stone Age Human Remains from the Mlambalasi Rock Shelter, Iringa Region, Southern Tanzania