The hominin fossils from the Middle Stone Age (MSA) deposits of Klasies River Main Site have played a significant role in discussions over the emergence of modern human morphology in the Late Pleistocene. While some display manifestly modern characteristics, others evince more archaic traits, leading to differing assessments of the assemblage. Four mandibles with varying degrees of tuber symphyseos development have been the focus of considerable debate. Two likely date to 83-108 ka, one to 89-101 ka, and the oldest to ca. >110-123 ka. Thus, the oldest and youngest may be separated by possibly 23,000 years. Symphyseal expression has been assessed qualitatively in several studies; the sole quantitative evaluation of all four employed a contour guide to record linear measurements in the sagittal plane. Here, we employ diffeomorphic surface mapping (DSM) to contextualize the degree of morphological variation these jaws exhibit in relation to a sample of adult mandibles from Holocene Later Stone Age (LSA) archaeological sites in South Africa spanning ca. 8000 years. DSM was applied to segmented surface volume renderings of high-resolution μ-CT scans of the fossils and CT/μ-CT scans of the LSA jaws. Although differences in chin development among the Klasies fossils exceed those among LSA jaws, their symphyseal variation is comfortably accommodated within the envelope of morphological diversity displayed by the LSA sample. Thus, variation exhibited by these MSA mandibles does not necessarily indicate more than a single population lineage through time.

KNM-ER 64061 is a partial skeleton from the upper Burgi Member of the Koobi Fora Formation (2.02-2.06 Ma) associated taphonomically and geochemically with a nearly complete mandibular dentition (KNM-ER 64060) attributed to Homo habilis. The skeleton comprises the clavicle, scapular fragments, both humeri, both ulnae, both radii, and a fragmentary sacrum and os coxae, making this the most complete H. habilis skeleton recovered thus far. The upper limb elements are similar to those of other early Homo specimens. Notably, the humerus is slender with a weakly-projecting lateral epicondyle, a relatively wide capitulum and a narrow trochlea, and the ulna has a relatively large radial notch. Although KNM-ER 64061 does not preserve a lower limb, limited features of the ischium suggest lower limb mechanics more similar to Homo than to australopiths. Brachial index estimates support previous conclusions that H. habilis had a relatively long forearm compared to Homo erectus. All upper limb elements possess strikingly thick cortices, resembling the condition in australopiths and other early Homo fossils. The stature estimate of 160 cm based on humeral length is intermediate between those for H. habilis (OH 62, KNM-ER 3735) and H. erectus (KNM-ER 1808, KNM-WT 15000). The body mass estimate of 30.7-32.7 kg is slightly lower than other H. habilis specimens and noticeably lower than estimates for H. erectus. KNM-ER 64061 indicates that H. habilis retained more primitive proportions and was smaller in stature and mass than H. erectus.

The resilience of mammalian tooth enamel to fatigue and fracture stems from its anisotropic structure, which is manifest at various hierarchical levels from the nanoscale to the macroscale. At the nanoscale level, the alignment trajectories of thin hydroxyapatite nanocrystals and the organic matrix serve to convey anisotropy and deformability. Various prism packing configurations provide additional structural heterogeneity at the microscale level, while at the mesoscale, the angles at which parazonal and diazonal prisms decussate furnish yet more structural incongruity. At the macroscale level, Hunter-Schreger band (HSB) packing patterns appear to conform to masticatory loading mechanics. This study undertakes a quantitative evaluation of the strength of enamel decussation at the mesoscale in human permanent molars by measuring the degree to which prism pitch angle deviates in adjacent diazones and parazones using scanning electron microscopy. While HSB packing tends to be denser in "functional" cusps, decussational strength tends to be greater in "guiding" cusps, and whereas HSB packing tends to be denser in maxillary molars, decussational strength tends to be greater in mandibular molars. The general lack of concordance between measures of decussation at the mesoscale and macroscale levels may suggest that decussational strength may serve to compensate for lower HSB packing densities in human permanent molars.

Archaeological debris and human skeletal remains from Border Cave (BC) have played prominent roles in interpretations of behavioural and morphological adaptations during the Middle Stone Age (MSA) of southern Africa. However, nagging questions persist about the context and presumed antiquity of some of these human remains, as Later Stone Age (LSA) and Iron Age deposits are also represented in the cave. A pair of human femora and tibiae were recovered in 1941-1942 from the same guano mining dump in the cave from which the well-known human cranium (BC 1) and mandible (BC 2) were extracted. Several measurements of the long bones were recorded by H.B.S. Cooke and colleagues in 1945, but the bones were subsequently lost. They present an interesting set of metrical contrasts. The pilastric and cnemic indices of the BC bones most closely resemble those of South African LSA Khoe-San males, who were mobile hunter-gatherers. However, the BC femur is notably longer than any LSA Khoe-San homologue and most closely resembles the femora of recent Zulu males. It seems likely that the BC bones derived from an Iron Age individual, as comparatively tall statures have been reported for South African Iron Age skeletons, and their pilastric, meric and cnemic indices also overlap substantially with the ranges of the LSA population sample. The missing femora and tibiae add emphasis to questions about the MSA antiquity of the other human bones recovered from the Border Cave mining dump. Significance: Human remains from Border Cave have played prominent roles in interpretations of morphological adaptation during the Middle Stone Age, but there are questions about the context and antiquity of some of them. A pair of femora and tibiae were recovered from the same guano mining dump in the cave that yielded a human cranium and mandible. The long bones have been lost, but metrical data recorded for them suggest they may be from an Iron Age individual. As such, they add to the questions surrounding the context and antiquity of the other human bones from the dump.

Human specimens from Border Cave thought to derive from its Middle Stone Age (MSA) deposits have been widely discussed in relation to Late Pleistocene evolution in southern Africa. Among the most prominent is the adult cranium BC 1. However, there are questions about the context and geochronological age of a number of these remains, including BC 1, which was recovered ex situ from a sediment dump created by miners digging for guano. The cranium has not been directly dated. Previous morphological analyses have clearly demonstrated its complete anatomical modernity, but its possible affinities to recent southern African populations have been a matter of disputation. The frontal sinus volume (FSV) of BC 1 is diminutive in relation to the values recorded for Late Pleistocene sub-Saharan fossils as well as the indigenous populations of southern Africa. While recent sub-Saharan African populations tend to possess comparatively small FSVs, the Later Stone Age (LSA) Khoe-San have notably smaller sinuses compared to the current South African isiNtu-speaking population. Among Late Quaternary fossils and more recent populations from sub-Saharan Africa, the most reasonable comparator for BC 1 appears to be the South African LSA Khoe-San. This may well have ramifications for the context and antiquity of the Border Cave 1 cranium.

The Border Cave human remains have featured in discussions relating to the evolution and the behavior of Late Pleistocene Homo sapiens. Although there are seven specimens that have been held to emanate from its Middle Stone Age (MSA) deposits, the stratigraphic context (and thus the presumed antiquity) of most of them is open to question. Five were recovered ex situ; either from a large sediment dump produced by guano digging in 1940 (BC 1 cranium and BC 2 mandible) or from the collapsed wall of an old excavation (BC 6 humerus, BC 7 ulna, and BC 8 metatarsals). One specimen (BC 3 infant burial) was excavated in 1942 from a grave that had been dug into a MSA layer, and another (BC 5 mandible) was dislodged from a MSA layer in the course of cleaning the excavation face for sediment sampling. Among these seven specimens, only BC 6 and BC 7 exhibit the fragmentary preservation together with chemical signatures consistent with MSA faunal elements from the site. Moreover, these are the only two specimens from Border Cave that share primitive morphology with homologues from other MSA/Middle Paleolithic sites. It is not possible to determine the stratigraphic placement of BC 1, BC 2 and BC 8 with any degree of certainty, although the state of preservation and morphology of BC 1 suggest that its origin is in the Later Stone Age (LSA) rather than the MSA. The BC 3 grave was dug into MSA levels and several workers have argued that the remarkable state of preservation of the infant skeleton and possibly its chemical signature suggests that derivation from the ELSA cannot be ruled out. BC 5 is arguably the only specimen from Border Cave recovered from in situ MSA deposits. Although it was found immediately adjacent to a feature considered to possibly represent a burial, the sediments from which BC 5 was recovered were reasonably deep in the sequence, rendering derivation from the LSA unlikely.

OBJECTIVE:The increased use of medical CT and μCT for internal analyses of primate bones has led to studies combining both data types to maximize sample sizes. However, comparability of data between modalities has yet to be demonstrated. Here, we test whether CT and μCT data from the primate femoral diaphysis can be confidently combined. MATERIALS AND METHODS:Femora from 17 specimens (Pan, Gorilla, Pongo, Hylobates, Ateles, Lagothrix, Mandrillus, Pithecia) were scanned using both CT modalities. Six segmentation methods were evaluated: Manual, 1/3 and 2/3 of maximum value, Full-Width-at-Half-Maximum, Kohler method, and Buie method in Dragonfly 3D World. The R package 'morphomap' was used to extract cortical bone thicknesses and calculate cross-sectional geometric (CSG) properties in cross sections from 80% (proximal) to 20% (distal) of femoral biomechanical length. Percent error was calculated by property and location. Linear regressions evaluated body mass as a predictor of error, and correction factors were developed using regression coefficients and location-specific mean errors. RESULTS:Medical CT consistently underestimated most properties relative to μCT, while cortical thickness and CA were generally overestimated. The greatest percent errors occurred at distal and proximal diaphyseal locations in most comparisons. Regressions showed significant associations between body mass and error at distal sites. Application of regression-based and mean percent corrections reduced error to acceptable ranges. DISCUSSION:Body size and segmentation method significantly impact comparability between medical CT and μCT in cortical thickness and CSG data. Applying location- and property-specific corrections improves measurement reliability in mixed-modality datasets and enhances comparisons across taxa.

When Mary Leakey discovered the OH 5 cranium of Paranthropus boisei alongside Oldowan stone artefacts, it was declared "the oldest yet discovered maker of stone tools"1. Whether Paranthropus made and used tools has been debated ever since2-4, largely because there are no known hand bones that can be definitively attributed to this genus. Here we report fossil hand and foot bones unambiguously associated with craniodental material of P. boisei. KNM-ER 101000 demonstrates that P. boisei shared key manipulative and bipedal adaptations with the genus Homo. Moreover, the hand morphology of KNM-ER 101000 converges on that of gorillas in ways that are consistent with manual food processing and would have facilitated powerful grasping, such as that used in climbing. These fossils suggest that P. boisei was capable of tool making and use in some capacity while also supporting the proposed dichotomy of distinct dietary adaptations between Paranthropus and Homo. In addition to offering insights into the poorly known postcranial functional anatomy of Paranthropus, this discovery illuminates broader patterns of hominin hand evolution and tool use.

OBJECTIVES:This study provides the description and comparative morphometric analysis of a non-hallucial distal pedal phalanx (PP 654270) excavated from near the base of the LBSR Stratigraphic Aggregate in the Pinnacle Point PP5-6N rock-shelter. It derives from a thin combustion feature (probably an in situ hearth) at the contact of two major stratigraphic aggregates, the transition of which has a modeled age range of 91.9-86.0 ka, which places this fossil in MIS 5b. MATERIAL AND METHOD:This phalanx (PP 654270) is assessed as representing a distal phalanx probably from the right side of Ray II or III. This bone adds to the very meager sample of pedal phalanges from the late Pleistocene of southern Africa. We compared the metric variables of this phalanx to several fossil and recent Homo samples. RESULTS:The bone has a comparatively thin cortex and a diffuse trabecular network in the proximal and especially the distal ends. The phalanx is long, narrow, and relatively gracile in comparison to Neandertal homologues. DISCUSSION:The phalanx PP 654270 displays similarities with penecontemporaneous Eurasian Middle Paleolithic and recent modern humans, although it tends to be comparatively long for Ray II and III homologues in these samples.

OBJECTIVES:To document frontal sinus volume (FSV) in a sample of sub-Saharan Africans with a view to evaluating claims that such populations exhibit comparatively small sinuses. This study also addresses questions related to sexual dimorphism, incidence of sinus aplasia, and the possibility that FSV continues to increase through adulthood. MATERIALS AND METHODS:FSV was measured from CT scans of adult crania from the Dart Collection. Sex and age were known for each individual. Linear cranial dimensions were used to compute a geometric mean from which a scaled FSV was computed for each cranium. RESULTS:FSV does not differ significantly between sexes, but females exhibit a higher incidence of aplasia. There is considerable variation in FSV in this sample, with the average ranking among the higher means reported for other population samples. The incidence of FS aplasia falls within the range of values recorded for other population samples. Although our study is cross-sectional rather than longitudinal, there is strong evidence that FSV continues to increase with age throughout adulthood. DISCUSSION:The FSV mean of our sample contradicts the notion that sub-Saharan Africans possess small sinuses. In a global context, geography (climate and altitude) does not appear to be related to FSV. The absence of sexual dimorphism in our sample is unexpected, as significant dimorphism has been reported for most other population samples. Our results support other indications that the frontal sinus continues to expand throughout adulthood, especially in females, and that it is likely due to bone resorption.

How animals respond to seasonal resource availability has profound implications for their dietary flexibility and realized ecological niches. We sought to understand seasonal dietary niche partitioning in extant African suids using intra-tooth stable isotope analysis of enamel. We collected enamel samples from canines of red river hogs/bushpigs (Potamochoerus spp.) and third molars of warthogs (Phacochoerus spp.) in 3 different regions of central and eastern Africa. We analyzed multiple samples from each tooth and used variations in stable carbon and oxygen isotope ratios (δ13C and δ18O) and covariances between them to infer seasonal dietary changes. We found that most Phacochoerus display C4-dominated diets, while most Potamochoerus display C3-dominated diets. Phacochoerus and Potamochoerus that co-occur in the same region display no overlap in intra-tooth δ13C, which suggests dietary niche partitioning. They also show diverging δ13C values as the dry seasons progress and converging δ13C values during the peak of the rainy seasons, which suggests a greater dietary niche separation during the dry seasons when resources are scarce than during the rainy season. We found statistically significant cross-correlations between intra-tooth δ13C and δ18O in most specimens. We also observed a temporal lag between δ13C and δ18O in some specimens. This study demonstrates that intra-tooth stable isotope analysis is a promising approach to investigate seasonal dietary niche variation. However, large inter-individual variations in δ18O at certain localities can be challenging to interpret. Future studies that expand the intra-tooth stable isotope surveys or include controlled feeding experiments will improve its application in ecological studies.

Since the initial discovery of Paranthropus robustus at the site of Kromdraai in 1938, the hypodigm of this species has been expanded by subsequent work at the localities of Swartkrans and Drimolen, with a few fossils also known from Cooper's D, Gondolin and Sterkfontein Member 5. Beginning in 2014, systematic excavations at Kromdraai uncovered a large and previously unknown fossiliferous area, shedding light on Units O and P in the earliest part of the site's stratigraphic sequence. The aim of this paper is to provide detailed descriptions and illustrations of 30 P. robustus craniodental specimens recovered between 2014 and 2017 within the Unit P deposits at Kromdraai. This new sample predates all prior conspecific specimens found at this site (including the holotype of P. robustus from Kromdraai, TM 1517). Its basic dental morphology dimensions and cranial features are compared in a preliminary analysis with other P. robustus samples. The P. robustus sample from Kromdraai Unit P documents previously unknown portions of the P. robustus juvenile cranium. The new dental and cranial remains aid in the exploration of potential morphological distinctions between site-specific P. robustus samples and are compared favorably in size and morphology with the small P. robustus specimens from Drimolen (e.g., DNH 7). These findings do not support the hypothesis that the specimens from Drimolen belong to a different taxonomic group. Instead, they reinforce the presence of a significant degree of sexual dimorphism within P. robustus. The Kromdraai Unit P specimens also contribute to the biodemographic profile of P. robustus. The notable prevalence of infants (i.e., juvenile individuals before the emergence of their first permanent molars) mirrors the natural mortality profiles observed in wild chimpanzees. This suggests a closer resemblance in the processes of accumulation in Kromdraai Unit P and Drimolen than at Swartkrans.

To date, only three Homo habilis specimens have been discovered that have associated craniodental and postcranial elements, providing a limited fossil record of the ontogeny and morphology of early members of the genus Homo. Recently, a nearly complete dentition, likely attributable to H. habilis, was discovered and excavated from early Pleistocene -age fluvial-lacustrine sediments of the upper Burgi Member of the Koobi Fora Formation at site F25787 in Area 13, near Ileret, Kenya. On the surface less than 15 m away, at site F25966, postcranial elements were found, which, if from the same individual as the nearby dentition, would represent the fourth associated craniodental and postcranial assemblage of this species. We developed a geochemical taphonomic history of these ca. 2 Ma hominin fossils using nondestructive X-ray based microanalytical tools (synchrotron and benchtop X-ray fluorescence chemical imaging and micro- and nano -computed tomography volumetric reconstruction), bulk analyses of sediments and paleosols at the excavation sites, and sedimentologic and stratigraphic observations. We integrate the chemical and physical taphonomic histories to test whether teeth (excavated in situ) and postcranial bones (eroded onto the outcrop surface) derive from a single individual. Minor differences in taphonomic history are attributable to the different biomineral properties of the dental and osseous components and to differences in physical damage during early post-mortem scavenging, dispersal, and burial in adjacent depositional settings. Microscale geochemical mapping enabled the temporal ordination of chemical and physical events in the specimens' chemical taphonomic histories. Specifically, authigenic Fe- and K -bearing clays and Y, U, and Sr uptake occurred in post -burial fractures in bones and were also incorporated pervasively throughout dentin in teeth. Barite mineralization occurred along the latest fractures in both materials, and as a coating on tooth roots. The stratigraphic, taphonomic, and geochemical evidence supports the interpretation that the hominin fossils represent a single individual. Successful application of these nondestructive sample characterization methods demonstrates capabilities for thorough interrogation of the taphonomic histories of other potential hominin fossil associations, enabling more robust and accurate palaeontologic constraints using those relationships.

Frontal size variation is comparatively poorly sampled among sub-Saharan African populations. This study assessed frontal sinus size in a sample of Khoe-San skeletal remains from South African Later Stone Age contexts. Volumes were determined from CT scans of 102 adult crania; individual sex could be estimated in 82 cases. Sinus volume is not sexually dimorphic in this sample. The lack of frontal sinus aplasia is concordant with the low incidences recorded for other sub-Saharan African and most other global populations save those that inhabit high latitudes. There is considerable variation in frontal sinus size among global populations, and the Khoe-San possess among the smallest. The Khoe-San have rather diminutive sinuses compared to sub-Saharan Bantu-speaking populations but resemble a northern African (Sudanese) population. Genetic studies indicate the earliest population divergence within Homo sapiens to have been between the Khoe-San and all other living groups, and that this likely occurred in Africa during the span of Marine Isotope Stages 8-6. There is scant information on frontal sinus development among Late Quaternary African fossils that are likely either closely related or attributable to Homo sapiens. Among these, the MIS 3 cranium from Hofmeyr, South Africa, exhibits distinct Khoe-San cranial affinities and despite its large size has a very small frontal sinus. This raises the possibility that the small frontal sinuses of the Holocene South African Khoe-San might be a feature retained from an earlier MIS 3 population.