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Carbon isotope analyses of tooth enamel have been widely employed by paleoecologists to understand past habitats. Most such studies use large- to medium-bodied mammals and exclude small taxa. However, analysis of fossil small mammals holds promise for resolving questions about past environments because these animals are often present in the fossil record (especially in South African cave sites), are diverse in dietary and habitat preference, yet have limited lifespans and home range sizes. Thus, the carbon isotope compositions of small mammal communities and/or species might reflect the composition of vegetation in local environments at fine scales. In this study, we assessed the degree to which carbon isotope compositions of small mammal tooth enamel record spatial changes in habitat in a southern African savanna environment. Modern small mammal specimens were collected from the pellet accumulations of three barn owl ( Tyto alba africanus ) roosts located within microhabitats varying from open grassland to mixed woodland. We examined rodent carbon isotope compositions within taxa, between taxa, and between tooth types in an effort to characterize variation within this group. We also compared rodent community δ 13 C enamel composition between microhabitat types to evaluate how well small mammal isotope data reflect vegetation composition local to the roosts. Our analyses suggest that the relationship between small mammal community carbon isotopic means and vegetation composition is complex, but that with appropriate taxonomic control and consideration of relative abundance, small mammals have potential as a proxy for reconstructing past habitats. To complement this modern study, we performed isotopic analysis of the enamel of small mammals from three hominin-bearing sites in the Cradle of Humankind World Heritage Site, South Africa. Our results suggest a greater contribution of C4 resources to the diets of small mammals and likely more C4 grass in the past than occurs today.

New fossil discoveries and new analyses increasingly blur the lines between Australopithecus and Homo, changing scientific ideas about the transition between the two genera. The concept of the genus itself remains an unsettled issue, though recent fossil discoveries and theoretical advances, alongside developments in phylogenetic reconstruction and hypothesis testing, are helping us approach a resolution. A review of the latest discoveries and research reveals that (a) despite the recent recovery of key fossil specimens, the antiquity of the genus Homo remains uncertain; (b) although there exist several australopith candidate ancestors for the genus Homo, there is little consensus about which of these, if any, represents the actual ancestor; and (c) potential convergent evolution (homoplasy) in adaptively significant features in late australopiths and basal members of the Homo clade, combined with probable reticulate evolution, makes it currently impossible to identify the direct ancestor of Homo erectus.

Prior to the recovery of Homo naledi from the Dinaledi Chamber of the Rising Star Cave system, the Middle Pleistocene fossil record in Africa was particularly sparse. With the large sample size now available from Dinaledi, the opportunity exists to reassess taxonomically ambiguous teeth unearthed at the nearby site of Sterkfontein. Teeth recovered from Lincoln Cave South and area L/63 at Sterkfontein have been considered ‘most probably Homo ergaster’ and ‘perhaps Archaic Homo sapiens’, respectively. Given the similarities shared between Lincoln Cave, area L/63, and the Dinaledi Chamber with regard to climatic/geologic depositional context and age, two teeth from the former sites, StW 592 and StW 585 respectively, were compared with corresponding tooth types of H. naledi from the Dinaledi Chamber. The results of our study indicate that the Lincoln Cave and area L/63 teeth are morphologically inconsistent with the variation recognised in the H. naledi teeth. Significance: The similar age and climatic/geologic depositional and post-depositional circumstances at Lincoln Cave South, area L/63 at Sterkfontein and the Dinaledi Chamber, Rising Star raise the possibility that these fossils might represent the same species. The teeth StW 592 and StW 585 are not consistent with the variation evident in the known naledi sample. The results of the study do not add to the question of the existence of at least two species of the genus Homo living in close proximity to each other in South Africa at approximately the same time.

Australopiths exhibit a number of derived facial features that are thought to strengthen the face against high and/or repetitive loads associated with a diet that included mechanically challenging foods. Here, we use finite element analysis (FEA) to test hypotheses related to the purported strengthening role of the zygomatic root and “anterior pillar” in australopiths. We modified our previously constructed models of Sts 5 (Australopithecus africanus) and MH1 (A. sediba) to differ in the morphology of the zygomatic root, including changes to both the shape and positioning of the zygomatic root complex, in addition to creating variants of Sts 5 lacking anterior pillars. We found that both an expanded zygomatic root and the presence of “anterior pillars” reinforce the face against feeding loads. We also found that strain orientations are most compatible with the hypothesis that the pillar evolved to resist loads associated with premolar loading, and that this morphology has an ancillary effect of strengthening the face during all loading regimes. These results provide support for the functional hypotheses. However, we found that an anteriorly positioned zygomatic root increases strain magnitudes even in models with an inflated/reinforced root complex. These results suggest that an anteriorly placed zygomatic root complex evolved to enhance the efficiency of bite force production while facial reinforcement features, such as the anterior pillar and the expanded zygomatic root, may have been selected for in part to compensate for the weakening effect of this facial configuration. Anat Rec, 300:171–195, 2017. © 2016 Wiley Periodicals, Inc.

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.

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.

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. DOI: http://dx.doi.org/10.7554/eLife.24232.001, eLife digest Species of ancient humans and the extinct relatives of our ancestors are typically described from a limited number of fossils. However, this was not the case with Homo naledi. More than 1500 fossils representing at least 15 individuals of this species were unearthed from the Rising Star cave system in South Africa between 2013 and 2014. Found deep underground in the Dinaledi Chamber, the H. naledi fossils are the largest collection of a single species of an ancient human-relative discovered in Africa. After the discovery was reported, a number of questions still remained. These questions included: why were so many fossils from a single species found at the one site, and how did they come to rest so far into the cave system? Possible explanations such as H. naledi living in the cave or being washed in by a flood were considered but ruled out. Instead, the evidence was largely consistent with intact bodies being deliberately disposed of in the cave and then decomposing. Now, Hawks et al. – who include many of the researchers who were involved in the discovery of H. naledi – report that yet more H. naledi fossils have been unearthed from a second chamber in the Rising Star cave system, the Lesedi Chamber. The chamber is 30 meters below the surface and there is no direct route between it and the Dinaledi Chamber. Again, the evidence is most consistent with the bodies arriving intact into the chamber, and there were no signs that the remains had been exposed to the surface environment. Also like the Dinaledi Chamber, no remains of other ancient humans or their relatives were found in the Lesedi Chamber. In total, 133 fossils of H. naledi have been found in this second chamber representing at least three individuals: two adults and a juvenile. However, and as Hawks et al. point out, only a small volume of the chamber has been excavated so far, and so there are likely more fossils still to be found. The fossils in the Lesedi Chamber are similar to those found before but include intact examples of bones, like the collarbone, that were previously known only from fragments. Perhaps the most impressive among the new fossils is a relatively complete skull that is part of a partial skeleton. The skull could have housed a brain that was 9% larger than the maximum estimate calculated from the previous H. naledi fossils. Though these new fossils provide us with yet more information about H. naledi, some questions still remain unanswered – the material from the Lesedi Chamber is undated, for example. However, a related study by Dirks et al. does give an estimate for the age of the fossils from the Dinaledi Chamber, while Berger et al. provide an explanation for why this date might be much younger than was previously predicted. DOI: http://dx.doi.org/10.7554/eLife.24232.002

The species Homo naledi was recently named from specimens recovered from the Dinaledi Chamber of the Rising Star cave system in South Africa. This large skeletal sample lacks associated faunal material and currently does not have a known chronological context. In this paper, we present comprehensive descriptions and metric comparisons of the recovered cranial and mandibular material. We describe 41 elements attributed to Dinaledi Hominin (DH1–DH5) individuals and paratype U.W. 101-377, and 32 additional cranial fragments. The H. naledi material was compared to Plio- Pleistocene fossil hominins using qualitative and quantitative analyses including over 100 linear measurements and ratios. We find that the Dinaledi cranial sample represents an anatomically homogeneous population that expands the range of morphological variation attributable to the genus Homo. Despite a relatively small cranial capacity that is within the range of australopiths and a few specimens of early Homo, H. naledi shares cranial characters with species across the genus Homo, including Homo habilis, Homo rudolfensis, Homo erectus, and Middle Pleistocene Homo. These include aspects of cranial form, facial morphology, and mandibular anatomy. However, the skull of H. naledi is readily distinguishable from existing species of Homo in both qualitative and quantitative assessments. Since H. naledi is currently undated, we discuss the evolutionary implications of its cranial morphology in a range of chronological frameworks. Finally, we designate a sixth Dinaledi Hominin (DH6) individual based on a juvenile mandible.

Laser ablation multi-collector ICP-MS (LA-MC-ICP-MS) is increasingly applied to measure the strontium isotope composition ( 87 Sr/ 86 Sr) of fossil or modern tooth samples in order to address questions about mobility. Recently, concerns have been raised that an analytical bias due to instrumental isotopic mass fractionation might be introduced when this method is used to sample across naturally curved tooth enamel surfaces. We address this concern by reanalyzing data that were originally produced using 750 μm linear LA-MC-ICP-MS scans on the external, slightly curved surfaces of fossil hominin teeth ( Australopithecus and Paranthropus ) from South Africa. By re-integrating the first and last 1/3 of the data along the original 750 μm linear scans, we compared 87 Sr/ 86 Sr results produced by sections of each scan with varying degrees of laser focus. The results show no evidence of any analytical scatter between strontium isotope values for the different sections of the curved tooth surfaces and results for the different sections of each linear scan agree well within the precision of the method (external 2σ ± 0.0004). Furthermore, each analytical session was bracketed by analysis of a curved rodent ( Otomys sp.) tooth in-house standard with up to ± 100 μm vertical change along the 750 μm linear scan. Long-term, average LA-MC-ICP-MS 87 Sr/ 86 Sr results for one such Otomys tooth standard (0.72989 ± 0.00029, n = 71) agree well with the solution MC-ICP-MS analysis of the same tooth (0.72976 ± 0.00002). New LA-MC-ICP-MS 87 Sr/ 86 Sr ratios, using both a 213 nm and solid-state 193 nm laser ablation system, for sets of consecutive 750 μm linear scans along the curved, outer tooth enamel surface on another single Otomys tooth in-house standard agree within ± 0.0004 regardless of progressively more extreme vertical change during analysis (± 10 μm to ± 900 μm). These results are similar to LA-MC-ICP-MS Sr isotope analyses, using the same instrumentation and methodology, of an in-house, polished, flat clinopyroxene mineral standard (LA: 0.70482 ± 0.00029, n = 155; solution: 0.70495 ± 0.00003). We conclude that, provided the stable 86 Sr/ 88 Sr ratio is used in conjunction with the exponential law to constantly correct for instrumental isotopic mass fractionation during acquisition, curved tooth enamel surfaces represent no impediment to accurate LA-MC-ICP-MS strontium isotope analyses.

Fossil bovids are widely recognized as valuable ecological indicators, useful for reconstructing paleoenvironments associated with the hominins of Africa. Taxonomic identification of bovid remains in the Plio-Pleistocene fossil deposits of South Africa is based predominantly on dental remains, usually isolated teeth. However, factors such as age and degree of occlusal attrition of teeth often render taxonomic identification difficult. In addition, teeth of closely related bovid taxa can be particularly difficult to diagnose at the species level. Given that closely related bovid species often have differing ecological requirements, imprecise identification of bovids recovered from fossil sites can have significant ramifications when reconstructing environments. This study tests a method for accurately identifying bovid teeth using Elliptical Fourier Function Analysis in order to standardize their identification. The occlusal surfaces of maxillary and mandibular molars of bovid teeth from twenty extant species were digitized and the quantified tooth forms (size and shape) were statistically compared to other closely related bovids. Results indicated that all upper and lower teeth classified correctly using discriminant function analysis ≥85% of the time, suggesting that occlusal surface form can reliably differentiate between closely related, morphologically similar bovids. This method was applied to a sample of fossil bovid teeth previously identified as “medium-sized alcelaphine” from Plovers Lake, Gauteng Province, South Africa. Precise taxonomic identification of these alcelaphines result in the earliest recorded presence of Alcelaphus buselaphus and Connochaetes gnou in Gauteng Province, as well as potentially the earliest documented co-occurrence of these taxa alongside Connochaetes taurinus and Damaliscus dorcas in South Africa. Revising the paleoenvironment reconstructed for Plovers Lake suggests that it was likely not much more densely wooded than the area today. This contradicts the paleoenvironment previously inferred for the site, suggesting that overreliance on rare and/or small-bodied taxa in the initial report on Plovers Lake overemphasized the extent of woodlands that were indicated.

Fossils attributed to Australopithecus sediba are described as having phylogenetic affinities with early Homo to the exclusion of other South African australopiths. With respect to functional anatomy of mastication, one implication of this hypothesis is that A. sediba mandibles should exhibit absolutely and relatively reduced stiffness and strength in comparison to Australopithecus africanus and Paranthropus robustus jaws. Examination of cortical bone distribution in the MH 1 and MH 2 mandibles of A. sediba (evaluated against samples of Pan, early and modern Homo as well as A. africanus and P. robustus) indicate that the A. sediba mandibular corpus was geometrically similar to other South African australopiths. In particular, enhanced torsional rigidity is characteristic of all South African australopiths including A. sediba. These findings are consistent with a hypothesis that masticatory mechanics may have been similar to other australopiths (and distinct from exemplars of early Homo), and as such suggest that A. sediba's mandibles were functionally suited to consume hard and tough objects. Recent mechanical modeling of the A. sediba cranium, however, has been interpreted as indicating that this species was relatively poorly adapted to produce large bite forces and likely experienced relatively modest strains in its facial skeleton. This paradox – that the cranium signals a departure from the australopith morphotype whereas the mandibles conform to a hypodigm of australopith grade – can be resolved, in part, if it is acknowledged that mechanical performance variables offer imperfect insight into what constitutes feeding adaptations.

Australopithecus sediba has been hypothesized to be a close relative of the genus Homo. Here we show that MH1, the type specimen of A. sediba, was not optimized to produce high molar bite force and appears to have been limited in its ability to consume foods that were mechanically challenging to eat. Dental microwear data have previously been interpreted as indicating that A. sediba consumed hard foods, so our findings illustrate that mechanical data are essential if one aims to reconstruct a relatively complete picture of feeding adaptations in extinct hominins. An implication of our study is that the key to understanding the origin of Homo lies in understanding how environmental changes disrupted gracile australopith niches. Resulting selection pressures led to changes in diet and dietary adaption that set the stage for the emergence of our genus., Dietary adaptations of extinct early humans are often inferred from dental microwear data. Here, the authors employ mechanical analyses to show that Australopithecus sediba had limited ability to consume hard foods.

Specimens of Australopithecus sediba from the site of Malapa, South Africa (dating from approximately 2 million years (Myr) ago) present a mix of primitive and derived traits that align the taxon with other Australopithecus species and with early Homo. Although much of the available cranial and postcranial material of Au. sediba has been described, its feeding ecology has not been investigated. Here we present results from the first extraction of plant phytoliths from dental calculus of an early hominin. We also consider stable carbon isotope and dental microwear texture data for Au. sediba in light of new palaeoenvironmental evidence. The two individuals examined consumed an almost exclusive C(3) diet that probably included harder foods, and both dicotyledons (for example, tree leaves, fruits, wood and bark) and monocotyledons (for example, grasses and sedges). Like Ardipithecus ramidus (approximately 4.4 Myr ago) and modern savanna chimpanzees, Au. sediba consumed C(3) foods in preference to widely available C(4) resources. The inferred consumption of C(3) monocotyledons, and wood or bark, increases the known variety of early hominin foods. The overall dietary pattern of these two individuals contrasts with available data for other hominins in the region and elsewhere.

The fossil record of the hominin pelvis reflects important evolutionary changes in locomotion and parturition. The partial pelves of two individuals of Australopithecus sediba were reconstructed from previously reported finds and new material. These remains share some features with australopiths, such as large biacetabular diameter, small sacral and coxal joints, and long pubic rami. The specimens also share derived features with Homo, including more vertically oriented and sigmoid-shaped iliac blades, greater robusticity of the iliac body, sinusoidal anterior iliac borders, shortened ischia, and more superiorly oriented pubic rami. These derived features appear in a species with a small adult brain size, suggesting that the birthing of larger-brained babies was not driving the evolution of the pelvis at this time.

The virtual endocast of MH1 (Australopithecus sediba), obtained from high-quality synchrotron scanning, reveals generally australopith-like convolutional patterns on the frontal lobes but also some foreshadowing of features of the human frontal lobes, such as posterior repositioning of the olfactory bulbs. Principal component analysis of orbitofrontal dimensions on australopith endocasts (MH1, Sts 5, and Sts 60) indicates that among these, MH1 orbitofrontal shape and organization align most closely with human endocasts. These results are consistent with gradual neural reorganization of the orbitofrontal region in the transition from Australopithecus to Homo, but given the small volume of the MH1 endocast, they are not consistent with gradual brain enlargement before the transition.

The Cradle of Humankind cave sites in South Africa preserve fossil evidence of four early hominin taxa: Australopithecus africanus, Australopithecus sediba, Paranthropus robustus and early Homo. In order to integrate this record into a pan-African scenario of human evolutionary history it is critical to have reliable dates and temporal ranges for the southern African hominins. In the past a lack of precise and accurate chronological data has prevented the evaluation of the temporal relationships between the various sites. Here we report new uranium–lead (U–Pb) radiometric ages obtained from sheets of calcium carbonate flowstone inter-bedded between clastic cave sediments at the site of Swartkrans, providing bracketing ages for the fossiliferous deposits. The fossil bearing units of Swartkrans, specifically the Hanging Remnant and Lower Bank of Member 1, are underlain by flowstone layers dated to 2.25 ± 0.05 Ma and 2.25 ± 0.08 Ma and capped by layers of 1.8 ± 0.01 Ma and 1.7 ± 0.07 Ma. The age bracket of the Member 1 deposits is therefore between 2.31 and 1.64 Ma. However, by combining the U–Pb with biostratigraphic data we suggest that this can be narrowed down to between 1.9 and 1.8 Ma. These data can be compared with other recently dated sites and a radiometrically dated U–Pb age sequence formed: Sterkfontein Member 4, Swartkrans Member 1, Malapa, and Cooper's D. From this new U–Pb dataset, a pattern of contemporary flowstone development emerges, with different caves recording the same flowstone-forming event. Specifically overlapping flowstone formation takes place at Swartkrans and Sterkfontein at ~ 2.29 Ma and ~ 1.77 Ma, and at Sterkfontein and Malapa at ∼ 2.02 Ma. This suggests a regional control over the nature and timing of speleothem development in cave deposits and these flowstone layers could assist in future correlation, both internal to specific deposits and regionally between sites.

Accumulating isotopic evidence from fossil hominin tooth enamel has provided unexpected insights into early hominin dietary ecology. Among the South African australopiths, these data demonstrate significant contributions to the diet of carbon originally fixed by C 4 photosynthesis, consisting of C 4 tropical/savannah grasses and certain sedges, and/or animals eating C 4 foods. Moreover, high-resolution analysis of tooth enamel reveals strong intra-tooth variability in many cases, suggesting seasonal-scale dietary shifts. This pattern is quite unlike that seen in any great apes, even ‘savannah’ chimpanzees. The overall proportions of C 4 input persisted for well over a million years, even while environments shifted from relatively closed ( ca 3 Ma) to open conditions after ca 1.8 Ma. Data from East Africa suggest a more extreme scenario, where results for Paranthropus boisei indicate a diet dominated (approx. 80%) by C 4 plants, in spite of indications from their powerful ‘nutcracker’ morphology for diets of hard objects. We argue that such evidence for engagement with C 4 food resources may mark a fundamental transition in the evolution of hominin lineages, and that the pattern had antecedents prior to the emergence of Australopithecus africanus . Since new isotopic evidence from Aramis suggests that it was not present in Ardipithecus ramidus at 4.4 Ma, we suggest that the origins lie in the period between 3 and 4 Myr ago.

This study tests the precision and accuracy of laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) for measuring strontium isotope ratios ( 87 Sr/ 86 Sr) in fossil teeth from Swartkrans and Sterkfontein in South Africa, and explores the extent of diagenesis in these specimens. Compared to solution MC-ICP-MS or thermal ionization mass spectrometry (TIMS) methods, LA-MC-ICP-MS can be faster and less expensive, but has lower precision and accuracy. We found that 87 Sr/ 86 Sr ratios in fossil rodent teeth measured by LA-MC-ICP-MS were offset from solution values by a mean of 0.0005 ± 0.0010 (2 σ ). Because of the very wide spread of biologically available 87 Sr/ 86 Sr ratios (∼0.710 to ∼0.790) in the region, LA-MC-ICP-MS is more than sufficient for assessing the geographic origins of the fossil rodents. The concentration of strontium in modern and fossil enamel from the area is statistically indistinguishable, as is the range of 87 Sr/ 86 Sr ratios in modern rodents and fossil rodents from Swartkrans. Thus, there is little evidence of diagenetic Sr in the fossil enamel. In contrast, the fossil dentine may contain up to ∼50% diagenetic strontium, although many dentine 87 Sr/ 86 Sr ratios are still far removed from the background cave value of 0.729. We propose that LA-MC-ICP-MS will also be of use for investigating the geographic origins of other, non-rodent fossil teeth from the Sterkfontein and Swartkrans collections, and may prove of similar utility at other suitable sites.

In attempting to resolve the phylogenetic relationships of fossil taxa, researchers can use evidence from two sources – morphology and known temporal ranges. For most taxa, the available evidence is stronger for one of these data sources. We examined the limitations of temporal data for reconstructing hominin evolutionary relationships, specifically focusing on the hypothesised ancestor–descendant relationship between Australopithecus sediba and the genus Homo. Some have implied that because the only known specimens of A. sediba are dated to later than the earliest fossils attributed to Homo, the former species is precluded from being ancestral to the latter. However, A. sediba is currently known from one site dated to 1.98 Ma and, thus, its actual temporal range is unknown. Using data from the currently known temporal ranges of fossil hominin species, and incorporating dating error in the analysis, we estimate that the average hominin species’ temporal range is ~0.97 Myr, which is lower than most figures suggested for mammalian species generally. Using this conservative figure in a thought experiment in which the Malapa specimens are hypothesised to represent the last appearance date, the middle of the temporal range, and first appearance date for the species, the first appearance date of A. sediba would be 2.95, 2.47 and 1.98 Ma, respectively. As these scenarios are all equally plausible, and 2.95 Ma predates the earliest specimens that some have attributed to Homo, we cannot refute the hypothesis that the species A. sediba is ancestral to our genus based solely on currently available temporal data. Significance: We correct a common misconception in palaeoanthropology that a species currently known only from later in time than another species cannot be ancestral to it. On temporal grounds alone one cannot dismiss the possibility that A. sediba could be ancestral to the genus Homo.

African wild dogs (Lycaon pictus) occupy an ecological niche characterized by hypercarnivory and cursorial hunting. Previous interpretations drawn from a limited, mostly Eurasian fossil record suggest that the evolutionary shift to cursorial hunting preceded the emergence of hypercarnivory in the Lycaon lineage. Here we describe 1.9—1.0 ma fossils from two South African sites representing a putative ancestor of the wild dog. the holotype is a nearly complete maxilla from Coopers Cave, and another specimen tentatively assigned to the new taxon, from Gladysvale, is the most nearly complete mammalian skeleton ever described from the Sterkfontein Valley, Gauteng, South Africa. the canid represented by these fossils is larger and more robust than are any of the other fossil or extant sub-Saharan canids. Unlike other purported L. pictus ancestors, it has distinct accessory cusps on its premolars and anterior accessory cuspids on its lower premolars—a trait unique to Lycaon among living canids. However, another hallmark autapomorphy of L. pictus, the tetradactyl manus, is not found in the new species; the Gladysvale skeleton includes a large first metacarpal. Thus, the anatomy of this new early member of the Lycaon branch suggests that, contrary to previous hypotheses, dietary specialization appears to have preceded cursorial hunting in the evolution of the Lycaon lineage. We assign these specimens to the taxon Lycaon sekowei n. sp.

Plovers Lake is a dolomitic cave infill located approximately 45 km northwest of Johannesburg in the Bloubank Valley, Gauteng Province, South Africa. Excavations between 2002–2004 revealed a rich and diverse fauna, a moderate-sized stone tool assemblage of Middle Stone Age (MSA) character, and human skeletal remains. Two principal depositional units are recognized: 1) a disturbed ex situ component that was likely displaced from 2) an otherwise relatively undisturbed in situ component from which the human skeletal material was recovered. The in situ depositional unit is bracketed by 2 flowstone layers, with U-series dates of 62.9 (± 1.3) ka for the capping flowstone and 88.7 (±1.6) ka for the underlying flowstone. A single isochron ESR date of 75.6 (± 5.6) ka corroborates the U-series dates. This paper presents an analysis of the mammalian, bird, and reptile faunas recovered from these two units. The two faunal assemblages show close correspondence in taphonomic, taxonomic, and ecological composition, supporting a common origin for both the ex situ and in situ components. Although human skeletal material, cut-marked bone, and stone tools have been recovered, these indications are too rare to consider Plovers Lake a human occupation site. Instead, a high abundance of carnivores, coprolites, and carnivore damaged bones point to brown hyenas as the principal, though not exclusive, bone accumulating agent. In the absence of a significant taphonomic bias relating to accumulating agent, Plovers Lake allows us to document an environment occupied by MSA humans, even if the humans were not resident in the cave itself. We reconstruct the paleoenvironment of Plovers Lake as predominantly grassland, though it was colder, moister, and more wooded than at present. Paleoclimatic conditions appear to have been as different from historic norms as those seen in several fossil localities in the Western Cape, pointing to greater environmental heterogeneity than has previously been documented for the region in the later Pleistocene.

Several authors have proposed that papionin baboons provide appropriate analogs for early hominin niche differentiation. Savanna-dwelling baboons and australopiths both radiated around the same time after Neogene expansion of C4 grasslands, likely experiencing similar environmental changes and faced with solving similar ecological problems. We explore the insights baboons may provide into dietary ecology of savanna-occupying hominins. We compare dietary information from stable isotope data for feces, hair, and tooth dentine collagen of modern chacma baboons (Papio ursinus) with dietary data for Plio-Pleistocene papionins and hominins from South African savannas. Results confirm that, like the australopiths, baboons consume substantial amounts of C4 food sources. However, the magnitude of inter- and intraindividual variation in baboon diets across different seasons and habitats is less than that from specimens of Australopithecus africanus and Paranthropus robustus analyzed to date. Hominins also consumed greater amounts of C4 resources. Thus, though the data demonstrate that the radiation of both primate groups was closely linked with the spread of C4 grasslands, hominins were even more extreme ecological generalists than baboons were. The absence of a fixed-diet in papionins implies that it was unlikely that the more ecologically flexible hominins evolved specializations for any one food type, an interpretation consistent with recent carbon isotope, dental microwear, and ecomorphological studies. We propose that researchers place less emphasis on resolving the foods that were most important for hominin differentiation; instead, future research should focus on questions related to ecological generalism.

Hypotheses to explain diversity among African ungulates focus largely on niche separation along a browser/grazer continuum. However, a number of studies advocate that the browser/grazer distinction insufficiently describes the full extent of dietary variation that occurs within and between taxa. Disparate classification schemes exist because of a lack of uniform and reliable data for many taxa, and failure to incorporate spatio-temporal variations into broader assessments of diet. In this study, we tested predictions for diet and dietary niche separation of African savanna ungulates using stable carbon isotope evidence from faeces for proportions of C3 (browse) to C4 (grass) intake among 19 species from the Kruger National Park, South Africa. Dietary predictions from the literature are confirmed in the case of browsers (black rhinoceros Diceros bicornis, giraffe Giraffa camelopardalis, bushbuck Tragelaphus scriptus, kudu Tragelaphus strepsiceros), mixed-feeders (impala Aepyceros melampus, nyala Tragelaphus angasii), and most grazers (white rhinoceros Ceratotherium simum, Burchell’s zebra Equus burchellii, warthog Phacochoerus africanus, hippopotamus Hippopotamus amphibius, blue wildebeest Connochaetes taurinus, tsessebe Damaliscus lunatus, waterbuck Kobus ellipsiprymnus). In contrast, several species showed results differing from most expectations derived from the available literature, including eland Taurotragus oryx, steenbok Raphicerus campestris, grey duiker Sylvicapra grimmia, buffalo Syncerus caffer, roan antelope Hippotragus equinus and sable antelope Hippotragus niger. Many of these discrepancies can be accounted for by seasonal and/or regional dietary differences. Cluster analysis based on a data matrix that incorporates the extent of spatio-temporal dietary variation among Kruger Park ungulates reveals several distinct categories of feeding preferences that extend beyond a two-edged browser/grazer dichotomy, such as mixed-feeders with a preference for either forage class, and spatial/seasonal shifts between uniform and mixed-feeding styles among variable browsers (e.g. grey duiker) and variable grazers (e.g. buffalo). These results highlight the need for approaches that are sensitive to spatio-temporal variations and the continuity of diet.

Summary 1 We test two nutritional hypotheses for the ecological diversity of ungulates, the browser/grazer (diet type) and diet quality models, among free-ranging herbivores in a South African savanna, the Kruger National Park. Tests are based on assessment of relationships between diet type and diet quality with body mass and hypsodonty, two morphological features that have been associated with both elements. 2 We use stable carbon isotope ratios of faeces to reconstruct diet in terms of proportions of C3 plants (browse) and C4 plants (grass) consumed by different species in different seasons. These data are combined with proxies for diet quality (per cent nitrogen, neutral detergent fibre, acid detergent fibre, and acid detergent lignin) from faeces to track changes in diet quality. 3 Two statistical approaches are used in model selection, i.e. tests of significant correlations based on linear regression analyses, and an information-theory approach (Akaike's Information Criterion) providing insight into strength of evidence for models. 4 Results of both methods show that, contrary to many predictions, body mass and diet type are not related, but these data confirm predictions that diet quality decreases with increasing body size, especially during the dry season. Hypsodonty, as expected, varies with diet type, increasing with increased grass intake. 5 These findings support both a diet type and diet quality model, implying some degree of exclusivity. We propose that congruence between models may be achieved through addition of diet quality proxies not included here, because hypsodonty is more likely a reflection of the abrasive properties of consumed foods, i.e. related to food quality, rather than food type. This implies that adaptation to diets of varying quality, through changes in body size and dental features, has been the primary mechanism for diversification in ungulates. 6 Our interpretation contrasts with several recent studies advocating diet type as the primary factor, exemplifying that further reconciliation between the two models is needed. We discuss the implications of this study for future approaches to achieve a more cohesive understanding of the evolutionary outcomes of herbivore nutrition.

Homo rudolfensis Samples from Olduvai Gorge, East Lake Turkana, and Lake Malawi were included in this study. The East Lake Turkana fossils available prior to 2010 were examined first-hand, while for the Olduvai and Lake Malawi fossils and KNM-ER 60000, 62000, and 62003 we relied on original observations on fossils and casts as well as published reports (Schrenk et al., 1993; Blumenschine et al., 2003; Leakey et al., 2012). We include the following fossils in the hypodigm of H. rudolfensis: KNM-ER 819, KNM-ER 1470, KNM-ER 1482, KNM-ER 1483, KNM-ER 1590, KNM-ER 1801, KNM-ER 1802, KNM-ER 3732, KNM-ER 3891, KNM-ER 60000, KNM-ER 62000, KNM-ER 62003, OH 65, and UR 501. We do recognize that KNM-ER 60000 and KNM-ER 1802 present some conflicting anatomy that some authors have argued precludes them as conspecific specimens (Leakey et al., 2012); by considering both, we aim to be conservative as they encompass more variation within H. rudolfensis., Published as part of Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, , Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei & Bernhard Zipfel, 2015, Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa, pp. 1-35 in eLife e 09560 4 on page 26, DOI: 10.7554/eLife.09560

Australopithecus africanus The samples attributed to Au. africanus from Taung, Sterkfontein and Makapansgat were employed. Original specimens were examined first-hand by the authors., Published as part of Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, , Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei & Bernhard Zipfel, 2015, Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa, pp. 1-35 in eLife e 09560 4 on page 26, DOI: 10.7554/eLife.09560

Paranthropus boisei Samples from the Omo Shungura sequence, East Lake Turkana, Olduvai Gorge and Konso were included in this study. Original specimens from Olduvai Gorge and East Lake Turkana were examined first-hand, while casts and published reports (Tobias, 1967; Suwa et al., 1996, 1997; Do ḿınguez- Rodrigo et al., 2013) were used to study the Omo and Konso materials. Our postcranial considerations of P. boisei are very limited and we did not rely upon the association of KNM-ER 1500 (Grausz et al., 1988) to derive information about the postcranial skeleton of P. boisei. Paranthropus robustus The samples from Kromdraai, Swartkrans, Sterkfontein, Drimolen, Gondolin, and Coopers were included in this study. First-hand observations of original specimens from all localities were used with the exception of Drimolen fossils, which were compared using published reports (Keyser, 2000; Keyser et al., 2000)., Published as part of Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, , Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei & Bernhard Zipfel, 2015, Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa, pp. 1-35 in eLife e 09560 4 on page 26, DOI: 10.7554/eLife.09560

Paranthropus aethiopicus The cranium KNM-WT 17000 was examined first-hand for this study., Published as part of Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, , Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei & Bernhard Zipfel, 2015, Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa, pp. 1-35 in eLife e 09560 4 on page 26, DOI: 10.7554/eLife.09560

Homo erectus Samples from Buia, Chemeron, Daka, Dmanisi, East and West Lake Turkana, Gona, Hexian, Konso, Mojokerto, Olduvai Gorge, Sangiran, Swartkrans, Trinil, and Zhoukoudian were included in this study. South African material is of special interest in this comparison because of the geographic proximity, and because of the difficulty of clearly identifying Homo specimens within the large fossil sample from Swartkrans. In particular, the following specimens from Swartkrans are considered to represent H. erectus: SK 15, SK 18a, SK 27, SK 43, SK 45, SK 68, SK 847, SK 878, SK 2635, SKW 3114, SKX 257/258, SKX 267/ 2671, SKX 268, SKX 269, SKX 334, SKX 339, SKX 610, SKX 1756, SKX 2354, SKX 2355, SKX 2356, and SKX 21204. It has been suggested (Grine et al., 1993, 1996) that SK 847 and Stw 53 might represent the same taxon, and that this taxon is a currently undiagnosed species of Homo in South Africa. However, we agree with Clarke (1977; 2008) that SK 847 can be attributed to H. erectus, and that Stw 53 cannot. Because there is no clear indication that more than one species of Homo is represented in the Swartkrans sample, we consider all this material to belong to H. erectus. We considered ‘ Homo ergaster ’ (and also ‘ Homo aff. erectus ’ from Wood, 1991) to be synonyms of H. erectus for this study; Turkana Basin specimens that are attributed to H. erectus thus include KNM-ER 730, KNM-ER 820, KNM-ER 992, KNM- ER 1808, KNM-ER 3733, KNM-ER 3883, KNM-ER 42700, KNM-WT 15000. Olduvai specimens include OH 9, OH 12 and OH 28. Original fossil materials from Chemeron, Lake Turkana, Swartkrans, Trinil, and Dmanisi were examined first-hand by the authors, while the remainder were based on casts and published reports (Weidenreich, 1943; Wood, 1991; Anton´, 2003; Rightmire et al., 2006; Suwa et al., 2007). A large number of postcranial specimens have been collected from the Turkana Basin and appear consistent with the anatomical range otherwise found in Homo, and inconsistent with known samples of Australopithecus and Paranthropus from elsewhere. These include KNM-ER 1472, KNM-ER 1481, KNM- ER 3228, KNM-ER 737, and others. We may add other fossils from other sites lacking association with craniodental material, such as the partial BOU-VP 12/1 skeleton and even the Gona pelvis. These specimens attributable to Homo but not necessarily to a particular species did inform our understanding of variability within the genus, but for the most part these specimens do not inform our differential diagnosis of H. naledi relative to particular species. For example, the key element of femoral morphology of H. naledi in contrast to other species is the presence of two well-defined mediolaterally running pillars in the femoral neck; the isolated specimens of early Homo do not contradict this apparent autapomorphy. Likewise, no isolated specimens inform us about the humanlike aspects of foot morphology in H. naledi. In these cases, the lack of associations for this evidence actually is less important than the lack of specimens that replicate the distinctive features of the H. naledi morphology., Published as part of Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, , Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei & Bernhard Zipfel, 2015, Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa, pp. 1-35 in eLife e 09560 4 on page 27, DOI: 10.7554/eLife.09560

Australopithecus garhi The cranium BOU-VP-12/130 from Bouri was included, with data taken from a published report (Asfaw et al., 1999)., Published as part of Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, , Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei & Bernhard Zipfel, 2015, Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa, pp. 1-35 in eLife e 09560 4 on page 26, DOI: 10.7554/eLife.09560

Australopithecus sediba The partial skeletons MH1 and MH2 from Malapa, South Africa were included in this study, based on examination of the original specimens by the authors., Published as part of Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, , Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei & Bernhard Zipfel, 2015, Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa, pp. 1-35 in eLife e 09560 4 on page 26, DOI: 10.7554/eLife.09560

Middle Pleistocene Homo Specimens from the latest Lower Pleistocene and MP of Europe and Africa that cannot be attributed to H. erectus were included in our comparisons. These include fossils that have been attributed to H. heidelbergensis, H. rhodesiensis, ‘archaic H. sapiens ’, or ‘evolved H. erectus ’ by a variety of other authors. Specimens attributed to MP Homo include materials from Eliye Springs, Arago, Atapuerca Sima de los Huesos, Bodo, Broken Hill, Cave of Hearths, Ceprano, Dali, Elandsfontein, Jinniushan, Kapthurin, Mauer, Narmada, Ndutu, Petralona, Reilingen-Schwetzingen, Solo, Steinheim, Swanscombe. This grouping includes the following specimens: KNM-ES 11693, Arago 2, Arago 13, Arago 21, Atapuerca 1, Atapuerca 2, Atapuerca 4, Atapuerca 5, Atapuerca 6, Cave of Hearths, SAM-PQ- EH1, Kabwe, Mauer, Ndutu, Sale´, Petralona, Reilingen-Schwetzingen, Steinheim.

© Berger et al. 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.

Acknowledgements We wish to express our gratitude to the National Geographic Society and the National Research Foundation of South Africa for funding the discovery, recovery, and analysis of the H. naledi material. The study reported here was also made possible by grants from the Social Sciences and Humanities Research Council of Canada, the Canada Foundation for Innovation, the British Columbia Knowledge Development Fund, the Canada Research Chairs Program, Simon Fraser University, the DST/NRF Centre of Excellence in Palaeosciences (COE-Pal), as well as by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada, a Young Scientist Development Grant from the Paleontological Scientific Trust (PAST), a Baldwin Fellowship from the L.S.B. Leakey Foundation, and a Seed Grant and a Cornerstone Faculty Fellowship from the Texas AM the Jacobs family for granting access; Wilma Lawrence, Bonita De Klerk, Merrill Van der Walt, and Justin Mukanku for their assistance during all phases of the project; Lucas Delezene for valuable discussion on the dental characters of H. naledi. We would also like to thank Peter Schmid for the preparation of the Dinaledi fossil material; Yoel Rak for explaining in detail some of the characters used in previous studies; William Kimbel for drawing our attention to the possibility that there might be a problem with Dembo et al.’s (2015) codes for the two characters related to the articular eminence; Will Stein for helpful discussion about the Bayesian analyses; Mike Lee for his comments on this manuscript; John Hawks for his support in organizing the Rising Star workshop; and the associate editor and three anonymous reviewers for their valuable comments. We are grateful to S. Potze and the Ditsong Museum, B. Billings and the School of Anatomical Sciences at the University of the Witwatersrand, and B. Zipfel and the Evolutionary Studies Institute at the University of the Witwatersrand for providing access to the specimens in their care; the University of the Witwatersrand, the Evolutionary Studies Institute, and the South African National Centre of Excellence in PalaeoSciences for hosting a number of the authors while studying the material; and the Western Canada Research Grid for providing access to the high-performance computing facilities for the Bayesian analyses. Last but definitely not least, we thank the head of the Rising Star project, Lee Berger, for his leadership and support, and for encouraging us to pursue the study reported here.

The discovery of Homo naledi has expanded the range of phenotypic variation in Homo , leading to new questions surrounding the mosaic nature of morphological evolution. Though currently undated, its unique morphological pattern and possible phylogenetic relationships to other hominin taxa suggest a complex evolutionary scenario. Here, we perform geometric morphometric analyses on H. naledi cranial and mandibular remains to investigate its morphological relationship with species of Homo and Australopithecus . We use Generalized Procrustes analysis to place H. naledi within the pattern of known hominin skull diversity, distributions of Procrustes distances among individuals to compare H. naledi and Homo erectus , and neighbor joining trees to investigate the potential phenetic relationships between groups. Our goal is to address a set of hypotheses relating to the uniqueness of H. naledi , its affinity with H. erectus , and the age of the fossils based on skull morphology. Our results indicate that, cranially, H. naledi aligns with members of the genus Homo , with closest affiliations to H. erectus . The mandibular results are less clear; H. naledi closely associates with a number of taxa, including some australopiths. However, results also show that although H. naledi shares similarities with H. erectus , some distances from this taxon – especially small-brained members of this taxon – are extreme. The neighbor joining trees place H. naledi firmly within Homo . The trees based on cranial morphology again indicate a close relationship between H. naledi and H. erectus , whereas the mandibular tree places H. naledi closer to basal Homo , suggesting a deeper antiquity. Altogether, these results emphasize the unique combination of features ( H. erectus -like cranium, less derived mandible) defining H. naledi . Our results also highlight the variability within Homo , calling for a greater focus on the cause of this variability, and emphasizing the importance of using the total morphological package for species diagnoses.

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. DOI: http://dx.doi.org/10.7554/eLife.09561.001, eLife digest Modern humans, or Homo sapiens, are now the only living species in their genus. But as recently as 20,000 years ago there were other species that belonged to the genus Homo. Together with modern humans, these extinct human species, our immediate ancestors and their close relatives are collectively referred to as ‘hominins’. Now, Dirks et al. describe an unusual collection of hominin fossils that were found within the Dinaledi Chamber in the Rising Star cave system in South Africa. The fossils all belong to a newly discovered hominin species called Homo naledi, which is described in a related study by Berger et al. The unearthed fossils are the largest collection of hominin fossils from a single species ever to be discovered in Africa, and include the remains of at least 15 individuals and multiple examples of most of the bones in the skeleton. Dirks et al. explain that the assemblage from the Dinaledi Chamber is unusual because of the large number of fossils discovered so close together in a single chamber deep within the cave system. It is also unusual that no other large animal remains were found in the chamber, and that the bodies had not been damaged by scavengers or predators. The fossils were excavated from soft clay-rich sediments that had accumulated in the chamber over time; it also appears that the bodies were intact when they arrived in the chamber, and then started to decompose. Dirks et al. discuss a number of explanations as to how the remains came to rest in the Dinaledi Chamber, which range from whether Homo naledi lived in the caves to whether they were brought in by predators. Most of the evidence obtained so far is largely consistent with these bodies being deliberately disposed of in this single location by the same extinct hominin species. However, a number of other explanations cannot be completely ruled out and further investigation is now needed to uncover the series of events that resulted in this unique collection of hominin fossils. DOI: http://dx.doi.org/10.7554/eLife.09561.002

The zygomatic region and lateral orbital wall are important structural components of the primate craniofacial skeleton, providing attachment for muscles, housing and protecting the eye, and resisti...

Hearing in early hominins may have facilitated an increased emphasis on short-range vocal communication in open habitats., Studies of sensory capacities in past life forms have offered new insights into their adaptations and lifeways. Audition is particularly amenable to study in fossils because it is strongly related to physical properties that can be approached through their skeletal structures. We have studied the anatomy of the outer and middle ear in the early hominin taxa Australopithecus africanus and Paranthropus robustus and estimated their auditory capacities. Compared with chimpanzees, the early hominin taxa are derived toward modern humans in their slightly shorter and wider external auditory canal, smaller tympanic membrane, and lower malleus/incus lever ratio, but they remain primitive in the small size of their stapes footplate. Compared with chimpanzees, both early hominin taxa show a heightened sensitivity to frequencies between 1.5 and 3.5 kHz and an occupied band of maximum sensitivity that is shifted toward slightly higher frequencies. The results have implications for sensory ecology and communication, and suggest that the early hominin auditory pattern may have facilitated an increased emphasis on short-range vocal communication in open habitats.