Mortuary sequence

Pillar sites appear to have functioned as mortuary repositories: all have some combination of primary and/or secondary burials in platforms, stone circles, and/or cairns, and none have evidence for habitation or other activity centres. However, preliminary excavations suggest the scope, density, and architecture of the burial deposits vary among the sites.

Lothagam North

Extensive excavations at Lothagam North allowed for reconstruction of the burial sequence for deposits concentrated in the central platform (Grillo and Hildebrand 2013; Hildebrand et al. 2018; Hildebrand and Grillo 2012). The site’s construction began with the removal of ~ 120m2 of Holocene beach sands to create a deep cavity ringed with boulders and reinforced by sandstone slabs. The first burials were placed in pits dug into the soft sandstone bedrock. After the floor space of the cavity was exhausted, subsequent bodies were added above the pits in various positions and orientations. Based on remote sensing of the mortuary cavity and the number of individuals recovered from a 2 ×2m2 unit, the platform contains an estimated minimum of 580 burials (Hildebrand et al. 2018). Positions of the burials documented within this unit illustrate the density of interments within the central platform (Fig. 5).

Fig. 5 Plan (top) and southern profile (bottom) orthophotographs of unit n04e42 with burial extents (coloured and numbered polygons) and stone beads (red marks). Burial extents are drawn around all point provenience data associated with each skeleton. Stone bead locations were recorded in the field via total station. Note the profile view excludes burials 18 and 19 as these burials are located in a pit along the north wall that is not visible in the southern profile Full size image

Platform fill between the burials contained high densities of artifacts, including lithics, ceramic sherds and a ceramic figurine fragment, stone and OES beads, and other adornments. While some artefacts (e.g. many of the stone beads) seem to have been deliberately included as part of a specific burial, others (e.g. highly fragmented pottery sherds that do not refit into whole vessels) appeared to be incorporated into the fill in a more general way (Hildebrand et al. 2018 Supplementary Information). Burial activities stopped before the cavity was completely full, and 30–50 cm of rocky sediment was added, creating a mounded surface capped with rounded, uniformly sized basalt pebbles. Pillars were emplaced within the uppermost cap deposits.

Bodies placed in the central platform did not follow a single funerary convention (Table 1). Two-thirds of the burials were primary; the others were secondary ‘bundle burials’ or features that were too poorly preserved to categorize by burial type. Among primary burials, the bodies were oriented in multiple directions, apparently placed as space permitted: east-west with the head at the east (n = 11), north-south (n = 6), northeast-southwest (n = 5), south-north (n = 4), southeast-northwest (n = 2), southwest-northeast (n = 1), and west-east (n = 1). Skeletons with preserved cranial remains were observed to be facing north (n = 8), west (n = 6), east (n = 4), south (n = 2), northwest (n = 1), northeast (n = 1), and southeast (n = 1). Individuals tended to be flexed on one side, with arms and legs tightly contracted toward the torso and hands in front of the face. Many individuals were highly flexed to a degree that would have been unnatural in life, suggesting bodies may have been bound, wrapped, or shrouded in this position prior to the onset of rigour mortis. Bundle burials were commonly found to be linear arrangements of predominantly long bones representing parts of one or more individuals. We did not observe spatial or funerary patterning with respect to age, sex, or placement of the bundles—men, women, and children who decomposed elsewhere were placed near primary interments. Red ochre staining was occasionally observed on bones within both primary and secondary burials. None of the remains showed evidence of burning or cremation.

Table 1 Mortuary context for burials excavated from GeJi9, GeJi10, and GcJh5 (Ad, adult, Juv, juvenile, M, male, F, female, M?, probable male, F?, probable female,?, sex undetermined) Full size table

Once placed, primary and secondary burials were covered with rocky sediment that often included a heavy piece of basalt (large cobble or small boulder) or sandstone (typically a tabular slab) on/around the head, torso, and/or pelvis. Several of the crania are warped in a manner that suggests that the resulting pressure was imposed while the bodies were fresh. Over time, bodies were compacted by the overburden of additional interments, and their stone markers as the central platform grew into a mound; some skeletons were compressed to < 5 cm in vertical space. The overburden may also have caused repositioning of some bodies. Among the densely clustered burials of Lothagam North, there are no patterns of differentiation by age, sex, or material wealth as reflected by the presence of personal adornment. One possible example of a dedicated area within the mortuary cavity was the close proximity of three infants and one young child (GeJi9 Burials 5, 7, 8, and 10) found at different depths but all within the southern extent of the 2 × 2m2 trench.

One stone circle was excavated at Lothagam North. It held a bundle burial representing at least two adults and one older juvenile. Bone preservation of these elements was significantly better than was seen in the central platform, perhaps because of the shallower depth and lack of rocky overburden. A radiocarbon date on charcoal within this feature falls within the range of dates from the central platform (Hildebrand et al. 2018), suggesting either contemporaneity of use or later recycling of platform fill to a new context.

Other pillar sites

Excavations at Lothagam West and Manemanya were less extensive, but it is clear that these platforms also contain multiple burials. Two partial individuals were recovered from pits within the central platform at Lothagam West, with additional pit features visible in profile. At Manemanya, the lower 1 × 2m2 step of excavations into the platform encountered the feet of an arthritic adult jutting perpendicularly over a burial of a young adult woman. Their positioning suggests the presence of diversely oriented burials, similar to Lothagam North. Platform deposits at both sites were shallower than at Lothagam North, and we encountered sterile substrates beneath the lowest burials. At Kalokol, no human remains were encountered during 2009 excavations into the platform, although our units were placed along the southeast periphery which may have been outside the extent of burial deposits (see Fig. 4).

Cairns at Lothagam West and Kalokol contained burials, but these interments may post-date creation of the central platforms at their respective sites. At Lothagam West, a ~ 5-year-old child was recovered from the centre of a cairn just east of the central platform on the opposite side of the line of pillars. Excavation of the cairn’s margins revealed it to have been dug into platform deposits. At Kalokol, excavations of one cairn in 2012 revealed a central pit containing probable human remains which were not excavated; this feature also intruded into pre-existing platform deposits. In 2017, local collaborators reported looting of a different cairn located just west of the site, approximately 20 m away from the platform outside the curb. Fragmentary human remains were salvaged, but the degree of sun-bleaching and weathering indicated they had been exposed for some time. The poorly preserved bones belong to at least one adult; age and sex could not be determined. The antiquity of the cairns at Kalokol and their association with the platform and pillars remain unclear.

Cultural materials from the burials

Lothagam North

Ornaments, primarily stone and OES beads, were the most common artefacts found in direct association with burials. We recovered 302 stone beads/pendants from deposits at Lothagam North, of which 173 were directly associated with 20 of the 31 excavated burial features (Table 2, Fig. 5). Other burials likely also contained beads, but the proximity of bodies and rocky matrix made it difficult to associate items with specific skeletons. Stone beads span a range of raw materials, colours, and forms (Hildebrand et al. 2018). Mineral and rock groups include (in descending order of frequency) zeolite (analcime), amazonite, talc schist (soapstone), chalcedony, volcanic rock (typically andesite, phonolite, or basalt host rock), fluorite, and limestone. Individual beads made from calcite, gypsum, chlorite (schist), haematite, and an iron precipitate were also noted. Analcime (45%) and amazonite (32%) dominate the assemblage, making for a primarily pink-and-blue colouring. Colours range from orange/red (chalcedonies), deep to light purple (fluorites), dark green (talc), off-white (limestone), and shades of black (volcanics); a brilliant white scolecite (zeolite) bead and a haematite-cemented sandstone pendent add lustre to the collection. Many of these stones and minerals are also represented in the collections from Jarigole, including amazonite (Nelson 1995).

Table 2 Ornamentation and other inclusions for burials excavated from GeJi9, GeJi10, and GcJh5 Full size table

Most were shaped into round beads of varying sizes; other forms included pendants, and incomplete circles that may have been designed as earrings. Jewellery observed in situ includes single ornaments (e.g. an amazonite ‘earring’ with GeJi9 B-29), groupings manufactured from a single type of mineral (e.g. a necklace made of amazonite beads and pendants with GeJi9 B-19), and groupings that included various combinations of raw materials, colours, and forms (e.g. amazonite, basalt, analcime and stromatolite stone beads and organic beads with GeJi9 B-12) (Fig. 6). Mineralogical surveys of the region suggest that many of the raw materials, such as the zeolite and chalcedony, could have been sourced close to Lothagam North. Other materials such as the fluorite and amazonite could have come from the Rift Valley, but from more distant and more distinct (i.e. unitary) sources. Bone beads made from fragile, small faunal diaphyses were also found (GeJi9 B-12, see Fig. 6). OES beads were ubiquitous throughout the central platform deposits. Bead counts from a representative subset of four units (of the excavated ten) yielded 522 whole and 37 partial OES beads, suggesting a total of 1250–1500 OES beads for the Lothagam North excavated units.

Fig. 6 Examples of stone beads accompanying the burials within Lothagam North’s central platform, including a GeJi9 B-12’s assemblage of analcime, stromatolite, amazonite, carnelian, and talc (soapstone) beads, found in conjunction with a bone point; b GeJi9 B-19’s assemblage of primarily amazonite beads and pendants as well as a broken analcime bead and a fragment of rodent tooth/ivory; and c a large amazonite ‘earring’ found with GeJi9 B-29. Image by Carla Klehm Full size image

Other grave goods from Lothagam North include faunal elements; some apparently incorporated into garments. Around the occipital portion of the skull of GeJi9 B-3, 405 gerbil (Gerbiliscus sp.) incisors representing at least 113 animals were configured in a bricklike lattice pattern, suggesting they had been fixed to a headpiece or wrap whose supporting material did not preserve. GeJi9 B-4’s torso was found with 49 hyrax (cf. Heterohyrax sp.) upper incisors from at least 25 animals. Ivory ornaments and bangles were found with several of the burials. GeJi9 B-26A was buried next to 12 perforated hippo (Hippopotamus amphibious) tusks that may have been strung together and worn. This feature overlaid a bundle burial containing three skulls facing into the ground as well as commingled post-cranial bones (GeJi9 B-26B/C/D). East of the platform, an unmodified Nile softshell turtle (Trionyx triunguis) vertebra was found within the stone circle bundle burial (GeJi9 B-6). These examples stand apart from other faunal remains recovered from burial fill, which were highly fragmentary and generally could only be identified to mammal, bird, or fish categories.

Other sites

Only one complete burial was excavated from Manemanya, but the feature included extensive cultural material (Fig. 7). The torso of a probable woman in her late 20s to early 30s (GcJh5 B-1) was covered by 329 stone beads of somewhat diverse shapes and sizes, further accompanied by at least 9559 whole and 978 broken OES beads. Beads were densely concentrated on and immediately around her body, suggesting they were contained with the body within a wrap or shroud. She was buried on her back with her arms at her sides and legs tightly flexed to the right. The body appeared to have been lain on a relatively flat, undisturbed surface. There was charcoal beneath the body. She wore a necklace that included five gourd-shaped stone beads. Hundreds of larger, round stone beads encircled her torso and pelvis in linear arrangements, suggesting they were part of a garment. Twenty-six exceptionally small OES beads clustered bilaterally near her ears, probably worn as elaborate earrings, while staggered dyads of slightly larger OES beads likely decorated a garment or placket extending down her legs. Numerous strands of OES beads were draped over her rib cage, spine, and pelvis but did not extend beneath her torso, nor did they go around her neck. In addition to beads, she wore perforated carnivore teeth as ornaments—pendants on her upper torso made from lion (Panthera leo) and hyena (Hyaena hyaena) teeth, and a bracelet of 42 canid (Canis sp.) teeth around her left wrist (Fig. 7). An ivory bangle encircled her right wrist. An unidentified, badly degraded composite object made of worked bone and ivory was found near her right shoulder. The perforation of the bone component suggests it was worn or hung, and the size of its bone and ivory components are consistent with a very large animal, possibly hippo.

Fig. 7 Examples of stone, shell, and bone adornments found with GcJh5 B-1 at Manemanya. These include (A) ivory fragments, Hyaena hyaena pendant, and Canis sp. tooth bracelet beads; (B) an unidentified bone and ivory object; (C) large and small ostrich eggshell beads; (D) an ivory bracelet, pendant, and other fragments; and (E) numerous large calcite stone beads strung into necklaces, many of which were found still in situ and strung in order (as pictured here). Image by Carla Klehm Full size image

As noted, we encountered a pair of feet from a second individual above GcJh5 B-1’s torso and observed human bone in the walls of the 1 × 2m2 lower trench, indicating other burials are present in deeper reaches of the platform. Further excavation would be needed to determine if the degree of ornamentation seen with the young woman was typical, or if this individual represents an unusual case.

The stone beads at Manemanya are similar to one another in size and shape (as seen in Fig. 7). They were fashioned from raw materials different from those used at Lothagam North. They are almost exclusively calcite, with one bead made from sandstone. With colour variations only slight (off-white to soft pink), the Manemanya beads lack the dramatic hues of the Lothagam North assemblage, but their larger dimensions would still have strong visual impact. Their materials would have been readily available and are easier to work than some of the harder materials (e.g. chalcedonies) found at Lothagam North. The seemingly simpler material technology of the GcJh5 B-1 assemblage, however, is contrasted by the number of accompanying beads. This one burial yielded a stone bead count equivalent to 30 burials at Lothagam North, and more than five times the estimated number of ostrich eggshell beads from Lothagam North’s larger mortuary excavation area.

The other two excavated pillar sites, Kalokol and Lothagam West, yielded fewer burials and, unsurprisingly, almost no burial goods. Only ~ 10 OES beads total were recovered from Lothagam West, most of which were in association with the most complete burial GeJi10 B-3. No beads were recovered from Kalokol.

The human remains

Skeletons excavated from Lothagam North, Lothagam West, and Manemanya represent both males and females, and range in age from neonates to the elderly (Table 3, n = 49). Of the 39 adults and one older adolescent in this sample, 18 are probable males and 12 are probable females. Ten individuals are too poorly preserved or incomplete to estimate sex. Of the individuals whose ages at death could be estimated, eight are young adults (~ 18–30 years), 10 are middle-aged (~ 30–50 years), and five appear to be elderly (50+). Sixteen could only be assessed as adult. Five infants (newborn to 2 years) and five juveniles (2 to 18 years) were also recovered. The scarcity of complete long bones limited estimations of stature, mass, and proportionality. Based on a small sample of adults, males’ stature averaged around 169 cm (n = 9) and females were around 163 cm (n = 3) (methods per Meadows and Jantz 1992; Trotter 1970; Trotter and Gleser 1952). Average body mass estimated from femur head size is approximately 62 kg (n = 3, all probable males) (McHenry 1992; Ruff et al. 1991). Coefficients of variation (CV) for metric variables with a sample size of ≥ 10 are relatively low (mean = 13.28%, n = 20 variables) suggesting that the people buried at these sites may constitute a deme—a subgroup of closely related individuals (Table 4).

Table 3 Estimated age/sex of excavated individuals (n = 49) Full size table

Table 4 Statistical summary of measurements (all in mm) for which ≥10 adults could be assessed Full size table

Indicators of health

We noted no indications of endemic disease or violent causes of death. The most commonly observed pathological features are osteoarthritis, dental hypoplasias, and healed fractures. Osteoarthritis (OA) and degenerative joint disease (DJD), characterized by articular cartilage destruction and associated bony porosity and lipping at joints, are relatively common among the adults. Twenty of the 39 adults have preserved joint surfaces that could be scored for OA, of which 14 skeletons (70%) show some combination of osteophytes, lipping, and/or eburnation. These were typically observed in the spine, shoulders, knees, and feet, although differential preservation of skeletons prevents systematic scoring of all joint surfaces. OA is found more commonly among the middle-aged adults (5 of 8 observed, 63%) and older adults (3 of 4 observed, 75%) compared to the young adults. Distribution is relatively equal between the sexes.

Among the dentitions, two of the 25 individuals possess caries (n = 3 of 331 teeth that could be assessed), and all cases are slight. Tooth wear is moderate: the average mandibular third molar wear score is 2.4 (n = 14), where cusps are moderately blunted with only pinpoint dentine exposure, if any (Smith 1984). Dental calculus is pervasive, particularly in older adults. Calculus is present on most teeth that could be scored (66%, n = 426 teeth assessed). The only case of abscessing was observed in GeJi9 B-25 on the left maxilla around the left second premolar, with a fistula leading into the maxillary sinus. The partial dentition of this elderly man also has large calculus deposits. Periodontal disease and antemortem tooth loss are rare, although poor preservation of jaws and alveolar tissue made these processes difficult to study. By contrast, enamel hypoplasias are seen in 68% of individuals (n = 13/19 dentitions that could be scored). Defects include transverse lines (linear enamel hypoplasia, or LEH), grooves, and pits.

The crania of only five of 49 individuals could be assessed for cribra orbitalia and porotic hyperostosis. An adult woman (GeJi9 B-24A) presents the sole case, with cribriform lesions visible on the orbital roof paired with minor periosteal activity on the right supraorbital area. Another individual, an elderly male over 50 years old (GeJi10 B-3), has indications of low bone mass suggestive of osteoporosis.

Cases of possible infectious disease include GeJi9 B-7, an infant aged 6 to 12 months whose frontal bone shows disorganized new bone endocranially, on the squamous portion. The endocranial bone is highly thickened and vascularized but the outer table appears normal, consistent with a non-specific indicator of haemorrhage or infection (Lewis 2004). GeJi9 B-21A (male, 20–30 years) and GeJi9 B-28 (female, 30–40 years) both show non-taphonomic erosion around the pubic symphysis from either infection or pelvic stress injury. We also documented healed fractures on various fingers, toes, and ribs on three individuals (GeJi9 B-1, B-2, B-25). Healed fractures may also account for mild OA on two rib heads of GcJh5 B-1 and a discrepancy in femur lengths in GeJi9 B-6A.

The young woman from Manemanya buried with thousands of beads (GcJh5 B-1) shows several skeletal anomalies that suggest asymmetries to her face and jaw. Her left zygomatic bears a bony spur along the temporal margin where the temporal fascia attach. This feature, which is not present on the well-preserved right side, may be related to the pattern of greater wear on the right side of the dentition, greater dental calculus on the left side, and asymmetry in the mandibular rami. The right mandibular ramus is more prominently inverted at gonion, with asymmetries extending through the submandibular fossa region (inferior to the mylohyoid line). Other distinguishing features of her skull include four large wormian bones and a notably thin occipital squamous portion which, taken in concert, may suggest a congenital or developmental origin for the asymmetry. Facial asymmetry can arise from congenital, developmental, and acquired factors (Thiesen et al. 2015). One possibility in this case is congenital muscular torticollis (wry-neck). Limited ranges of motion and repose can lead to asymmetries of the face and head (Nilesh and Mukherji 2013). Given that she was also relatively tall (~ 170-180 cm, based on estimated maximum femur length, measured in situ), perhaps her appearance and bearing were in some ways linked to her burial treatment.

Biomechanical indicators of mobility

Biomechanical measures obtained from the 34 eligible midshaft elements are presented in Table 5. Table 6 contains mean values for elements analysed as well as summary data for the southern African comparative groups. For all skeletal elements, I max /I min values fall within the range of variation of the southern African herding and foraging groups (examples in Fig. 8). There are no significant differences in I max /I min for any of the upper limb elements. The I max /I min values for the pillar site tibia and femora recovered are comparatively high relative to the southern African groups; however, tibia CSG property data are very limited. For the femora, there are significant differences between the four groups considered (p = 0.00). However, there are no pairwise significant differences, likely due to the small sample sizes.

Table 5 Cross-sectional geometric (CSG) properties for pillar site individuals Full size table

Table 6 Results of Kruskal-Willis ANOVAs comparing I max /I min CSG properties Full size table