An examination of Homo naledi early juveniles recovered from the Rising Star cave system, South Africa.

BACKGROUND: Six Homo naledi early juveniles were recovered from U.W. 101 (Dinaledi Chamber), U.W. 102 (Lesedi Chamber), and U.W. 110 in the Rising Star cave system. AIM: This paper develops the information for the H. naledi early juvenile life stage, as defined by a combination of deciduous and permanent dentition, and the eruption of the first permanent molar. SUBJECTS AND METHODS: The growing number of young individuals recovered from the Rising Star cave system allows us to gain a better understanding of their variation, or lack thereof, and provides a basis to estimate broad ranges for age at death of the individuals. The individuals are identified and described through craniodental remains and spatial associations. RESULTS AND CONCLUSION: Our results show that the teeth are remarkably consistent across the localities in their metric and non-metric traits, and our analyses refine previous estimations on dental eruptions with the first permanent molar erupting first in the sequence among permanent teeth.

Descriptive catalog of Homo naledi dental remains from the 2013 to 2015 excavations of the Dinaledi Chamber, site U.W. 101, within the Rising Star cave system, South Africa.

More than 150 hominin teeth, dated to ∼330-241 thousand years ago, were recovered during the 2013-2015 excavations of the Dinaledi Chamber of the Rising Star cave system, South Africa. These fossils comprise the first large single-site sample of hominin teeth from the Middle Pleistocene of Africa. Though scattered remains attributable to Homo sapiens, or their possible lineal ancestors, are known from older and younger sites across the continent, the distinctive morphological feature set of the Dinaledi teeth supports the recognition of a novel hominin species, Homo naledi. This material provides evidence of African Homo lineage diversity that lasts until at least the Middle Pleistocene. Here, a catalog, anatomical descriptions, and details of preservation and taphonomic alteration are provided for the Dinaledi teeth. Where possible, provisional associations among teeth are also proposed. To facilitate future research, we also provide access to a catalog of surface files of the Rising Star jaws and teeth.

Immature remains and the first partial skeleton of a juvenile Homo naledi, a late Middle Pleistocene hominin from South Africa.

Immature remains are critical for understanding maturational processes in hominin species as well as for interpreting changes in ontogenetic development in hominin evolution. The study of these subjects is hindered by the fact that associated juvenile remains are extremely rare in the hominin fossil record. Here we describe an assemblage of immature remains of Homo naledi recovered from the 2013-2014 excavation season. From this assemblage, we attribute 16 postcranial elements and a partial mandible with some dentition to a single juvenile Homo naledi individual. The find includes postcranial elements never before discovered as immature elements in the sub-equatorial early hominin fossil record, and contributes new data to the field of hominin ontogeny.

Homo naledi cranial remains from the Lesedi chamber of the rising star cave system, South Africa.

Excavations in the Lesedi Chamber (U.W. 102) of the Rising Star cave system from 2013 to 2015 resulted in the recovery of 131 fossils representing at least three individuals attributed to Homo naledi. Hominin fossils were recovered from three collection areas within the Lesedi Chamber. A partial skull with near complete dentition (LES1) and an associated partial skeleton were recovered from Area 102a, while craniodental remains from two other individuals were recovered from Areas 102b and 102c. Here we present detailed anatomical descriptions and metrical comparisons of the Lesedi Chamber H. naledi craniodental remains that preserve diagnostic morphology. The LES1 skull is a presumed male that is slightly larger in size, and shows greater development of ectocranial structures compared to other H. naledi specimens from the Dinaledi Chamber of the Rising Star cave system. Otherwise the Lesedi fossils are notably similar to the Dinaledi fossils in shape and morphology. The Lesedi fossils also preserve the delicate nasal and lacrimal bones that are otherwise unrecorded in the Dinaledi sample. Limited morphological differences between the Dinaledi and Lesedi Chamber hominin samples provides support for the hypothesis that these two assemblages share a close phyletic relationship.

Root grooves on two adjacent anterior teeth of Australopithecus africanus.

Tooth root grooves and other ante-mortem dental tissue loss, not associated with caries found on or near the cementoenamel junction (CEJ), are commonly termed non-carious cervical lesions. Three main processes are implicated in forming these lesions: abrasion, dental erosion, and abfraction. As yet, these lesions have not been described in non-Homo hominins. In this study, South African fossil hominin collections were examined for evidence of any type of non-carious cervical lesion. Only one individual shows ante-mortem root grooves consistent with non-carious cervical lesions. Two teeth, a mandibular right permanent lateral incisor (STW 270) and canine (STW 213), belonging to the same Australopithecus africanus individual, show clear ante-mortem grooves on the labial root surface. These lesions start below the CEJ, extend over a third of the way toward the apex, and taper to a point towards the lingual side. The characteristics of these grooves suggest the predominant aetiology was erosive wear. In addition, they are extremely similar to clinical examples of dental erosion. These are the oldest hominin examples of non-carious cervical lesions and the first described in a genus other than Homo. Further, the lesions suggest that this individual regularly processed and consumed acidic food items.

Description and analysis of three Homo naledi incudes from the Dinaledi Chamber, Rising Star cave (South Africa).

This study describes three incudes recovered from the Dinaledi Chamber in the Rising Star cave system in South Africa. All three bones were recovered during sieving of excavated sediments and likely represent three Homo naledi individuals. Morphologically and metrically, the Dinaledi ossicles resemble those of chimpanzees and Paranthropus robustus more than they do later members of the genus Homo, and fall outside of the modern human range of variation in several dimensions. Despite this, when overall size is considered, the functional lengths in H. naledi and P. robustus are very similar to those predicted for a human with a similar-sized incus. In this sense, both taxa seem to show a relatively elongated functional length, distinguishing them from chimpanzees. The functional length in H. naledi is slightly longer in absolute terms than in P. robustus, suggesting H. naledi may already show a slight increase in functional length compared with early hominins. While H. naledi lacks the more open angle between the long and short processes found in modern humans, considered a derived feature within the genus Homo, the value in H. naledi is similar to that predicted for a hominoid with a similar-sized incus. Principal components analysis of size-standardized variables shows H. naledi falling outside of the recent human range of variation, but within the confidence ellipse for gorillas. Phylogenetic polarity is complicated by the absence of incus data from early members of the genus Homo, but the generally primitive nature of the H. naledi incudes is consistent with other primitive features of the species, such as the very small cranial capacity. These ossicles add significantly to the understanding of incus variation in hominins and provide important new data on the morphology and taxonomic affinities of H. naledi.

Body size, brain size, and sexual dimorphism in Homo naledi from the Dinaledi Chamber.

Homo erectus and later humans have enlarged body sizes, reduced sexual dimorphism, elongated lower limbs, and increased encephalization compared to Australopithecus, together suggesting a distinct ecological pattern. The mosaic expression of such features in early Homo, including Homo habilis, Homo rudolfensis, and some early H. erectus, suggests that these traits do not constitute an integrated package. We examined the evidence for body mass, stature, limb proportions, body size and dental size dimorphism, and absolute and relative brain size in Homo naledi as represented in the Dinaledi Chamber sample. H. naledi stature and body mass are low compared to reported values for H. erectus, with the exception of some of the smaller bodied Dmanisi H. erectus specimens, and overlap with larger Australopithecus and early Homo estimates. H. naledi endocranial volumes (465-560 cc) and estimates of encephalization quotient are also similar to Australopithecus and low compared to all Homo specimens, with the exception of Homo floresiensis (LB1) and the smallest Dmanisi H. erectus specimen (D4500). Unlike Australopithecus, but similar to derived members of genus Homo, the Dinaledi assemblage of H. naledi exhibits both low levels of body mass and dental size variation, with an estimated body mass index of sexual dimorphism less than 20%, and appears to have an elongated lower limb. Thus, the H. naledi bauplan combines features not typically seen in Homo species (e.g., small brains and bodies) with those characteristic of H. erectus and more recent Homo species (e.g., reduced mass dimorphism, elongated lower limb).

The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa.

New ages for flowstone, sediments and fossil bones from the Dinaledi Chamber are presented. We combined optically stimulated luminescence dating of sediments with U-Th and palaeomagnetic analyses of flowstones to establish that all sediments containing Homo naledi fossils can be allocated to a single stratigraphic entity (sub-unit 3b), interpreted to be deposited between 236 ka and 414 ka. This result has been confirmed independently by dating three H. naledi teeth with combined U-series and electron spin resonance (US-ESR) dating. Two dating scenarios for the fossils were tested by varying the assumed levels of 222Rn loss in the encasing sediments: a maximum age scenario provides an average age for the two least altered fossil teeth of 253 +82/-70 ka, whilst a minimum age scenario yields an average age of 200 +70/-61 ka. We consider the maximum age scenario to more closely reflect conditions in the cave, and therefore, the true age of the fossils. By combining the US-ESR maximum age estimate obtained from the teeth, with the U-Th age for the oldest flowstone overlying Homo naledi fossils, we have constrained the depositional age of Homo naledi to a period between 236 ka and 335 ka. These age results demonstrate that a morphologically primitive hominin, Homo naledi, survived into the later parts of the Pleistocene in Africa, and indicate a much younger age for the Homo naledi fossils than have previously been hypothesized based on their morphology.

New fossil remains of Homo naledi from the Lesedi Chamber, South Africa.

The Rising Star cave system has produced abundant fossil hominin remains within the Dinaledi Chamber, representing a minimum of 15 individuals attributed to Homo naledi. Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species.

Homo naledi and Pleistocene hominin evolution in subequatorial Africa.

New discoveries and dating of fossil remains from the Rising Star cave system, Cradle of Humankind, South Africa, have strong implications for our understanding of Pleistocene human evolution in Africa. Direct dating of Homo naledi fossils from the Dinaledi Chamber (Berger et al., 2015) shows that they were deposited between about 236 ka and 335 ka (Dirks et al., 2017), placing H. naledi in the later Middle Pleistocene. Hawks and colleagues (Hawks et al., 2017) report the discovery of a second chamber within the Rising Star system (Dirks et al., 2015) that contains H. naledi remains. Previously, only large-brained modern humans or their close relatives had been demonstrated to exist at this late time in Africa, but the fossil evidence for any hominins in subequatorial Africa was very sparse. It is now evident that a diversity of hominin lineages existed in this region, with some divergent lineages contributing DNA to living humans and at least H. naledi representing a survivor from the earliest stages of diversification within Homo. The existence of a diverse array of hominins in subequatorial comports with our present knowledge of diversity across other savanna-adapted species, as well as with palaeoclimate and paleoenvironmental data. H. naledi casts the fossil and archaeological records into a new light, as we cannot exclude that this lineage was responsible for the production of Acheulean or Middle Stone Age tool industries.

Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa.

We describe the physical context of the Dinaledi Chamber within the Rising Star cave, South Africa, which contains the fossils of Homo naledi. Approximately 1550 specimens of hominin remains have been recovered from at least 15 individuals, representing a small portion of the total fossil content. Macro-vertebrate fossils are exclusively H. naledi, and occur within clay-rich sediments derived from in situ weathering, and exogenous clay and silt, which entered the chamber through fractures that prevented passage of coarser-grained material. The chamber was always in the dark zone, and not accessible to non-hominins. Bone taphonomy indicates that hominin individuals reached the chamber complete, with disarticulation occurring during/after deposition. Hominins accumulated over time as older laminated mudstone units and sediment along the cave floor were eroded. Preliminary evidence is consistent with deliberate body disposal in a single location, by a hominin species other than Homo sapiens, at an as-yet unknown date.

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa.

Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.

Estimating fossil hominin body mass from cranial variables: an assessment using CT data from modern humans of known body mass.

Body mass estimates are integral to a wide range of inferences in paleoanthropology. Most techniques employ postcranial elements, but predictive equations based on cranial variables have also been developed. Three studies currently provide regression equations for estimating mass from cranial variables, but none of the equations has been tested on samples of known mass. Nor have the equations been compared to each other in terms of performance. Consequently, this study assessed the performance of existing cranial equations using computed tomography scans from a large, documented sample of modern humans of known body mass. Virtual models of the skull were reconstructed and measured using computer software, and the resulting variables were entered into three sets of published regression equations. Estimated and known body masses were then compared. For most equations, prediction errors were high and few individuals were estimated within ±20% of their known mass. Only one equation satisfied the accuracy criteria. In addition, variables that had been previously argued to be good predictors of mass in hominins, including humans, did not estimate mass reliably. These results have important implications for paleoanthropology. In particular, they emphasize the need to develop new equations for estimating fossil hominin body mass from cranial variables.

Post-mortem whole body computed tomography of opioid (heroin and methadone) fatalities: frequent findings and comparison to autopsy.

OBJECTIVE: To investigate frequent findings in cases of fatal opioid intoxication in whole-body post-mortem computed tomography (PMCT). METHODS: PMCT of 55 cases in which heroin and/or methadone had been found responsible for death were retrospectively evaluated (study group), and were compared with PMCT images of an age- and sex-matched control group. Imaging results were compared with conventional autopsy. RESULTS: The most common findings in the study group were: pulmonary oedema (95 %), aspiration (66 %), distended urinary bladder (42 %), cerebral oedema (49 %), pulmonary emphysema (38 %) and fatty liver disease (36 %). These PMCT findings occurred significantly more often in the study group than in the control group (p < 0.05). The combination of lung oedema, brain oedema and distended urinary bladder was seen in 26 % of the cases in the study group but never in the control group (0 %). This triad, as indicator of opioid-related deaths, had a specificity of 100 %, as confirmed by autopsy and toxicological analysis. CONCLUSIONS: Frequent findings in cases of fatal opioid intoxication were demonstrated. The triad of brain oedema, lung oedema and a distended urinary bladder on PMCT was highly specific for drug-associated cases of death. KEY POINTS: Frequent findings in cases of fatal opioid intoxication were investigated. Lung oedema, brain oedema and full urinary bladder represent a highly specific constellation. This combination of findings in post-mortem CT should raise suspicion of intoxication.

Cardiothoracic ratio in postmortem computed tomography: reliability and threshold for the diagnosis of cardiomegaly.

The aim of this study was to evaluate the reliability of the cardiothoracic ratio (CTR) in postmortem computed tomography (PMCT) and to assess a CTR threshold for the diagnosis of cardiomegaly based on the weight of the heart at autopsy. PMCT data of 170 deceased human adults were retrospectively evaluated by two blinded radiologists. The CTR was measured on axial computed tomography images and the actual cardiac weight was weighed at autopsy. Inter-rater reliability, sensitivity, and specificity were calculated. Receiver operating characteristic curves were calculated to assess enlarged heart weight by CTR. The autopsy definition of cardiomegaly was based on normal values of the Zeek method (within a range of both, one or two SD) and the Smith method (within the given range). Intra-class correlation coefficients demonstrated excellent agreements (0.983) regarding CTR measurements. In 105/170 (62 %) cases the CTR in PMCT was >0.5, indicating enlarged heart weight, according to clinical references. The mean heart weight measured in autopsy was 405 ± 105 g. As a result, 114/170 (67 %) cases were interpreted as having enlarged heart weights according to the normal values of Zeek within one SD, while 97/170 (57 %) were within two SD. 100/170 (59 %) were assessed as enlarged according to Smith's normal values. The sensitivity/specificity of the 0.5 cut-off of the CTR for the diagnosis of enlarged heart weight was 78/71 % (Zeek one SD), 74/55 % (Zeek two SD), and 76/59 % (Smith), respectively. The discriminative power between normal heart weight and cardiomegaly was 79, 73, and 74 % for the Zeek (1SD/2SD) and Smith methods respectively. Changing the CTR threshold to 0.57 resulted in a minimum specificity of 95 % for all three definitions of cardiomegaly. With a CTR threshold of 0.57, cardiomegaly can be identified with a very high specificity. This may be useful if PMCT is used by forensic pathologists as a screening tool for medico-legal autopsies.

Access routes and reported decision criteria for lumbar epidural drug injections: a systematic literature review.

PURPOSE: To review lumbar epidural drug injection routes in relation to current practice and the reported criteria used for selecting a given approach. MATERIAL AND METHODS: This was a HIPPA-compliant study. Employing a systematic search strategy, the MEDLINE and EMBASE databank as well as the Cochrane Library were searched for studies on epidural drug injections. The following data were noted: access route, level of injection, use of image guidance, and types and doses of injected drugs. Justifications for the use of a particular route were also noted. Data were presented using descriptive statistics. RESULTS: A total of 1,211 scientific studies were identified, of which 91 were finally included (7.5%). The interlaminar access route was used in 44 of 91 studies (48.4%), the transforaminal in 37 of 91 studies (40.7%), and the caudal pathway in 26 of 91 studies (28.6%). The caudal pathway was favored in the older studies whereas the transforaminal route was favored in recent studies. Decision criteria related to correct needle placement, concentration of injected drug at lesion site, technical complexity, costs, and potential complications. Injection was usually performed on the level of the lesion using local anesthetics (71 of 91 studies, 78.0%), steroids (all studies) and image guidance (71 of 91 studies, 78%). CONCLUSIONS: The most commonly used access routes for epidural drug injection are the interlaminar and transforaminal pathways at the level of the pathology. Transforaminal routes are being performed with increasing frequency in recent years.

FORDISC and the determination of ancestry from cranial measurements.

Determining the ancestry of unidentified human remains is a major task for bioarchaeologists and forensic anthropologists. Here, we report an assessment of the computer program that has become the main tool for accomplishing this task. Called Fordisc, the program determines ancestry through discriminant function analysis of cranial measurements. We evaluated the utility of Fordisc with 200 specimens of known ancestry. We ran the analyses with and without the test specimen's source population included in the program's reference sample, and with and without specifying the sex of the test specimen. We also controlled for the possibility that the number of variables employed affects the program's ability to attribute ancestry. The results of the analyses suggest that Fordisc's utility in research and medico-legal contexts is limited. Fordisc will only return a correct ancestry attribution when an unidentified specimen is more or less complete, and belongs to one of the populations represented in the program's reference samples. Even then Fordisc can be expected to classify no more than 1 per cent of specimens with confidence.