Late Middle Pleistocene hominin teeth from Panxian Dadong, South China

Shape variation in modern human upper premolars

Morphological variation in modern human dentition is still an open field of study. The understanding of dental shape and metrics is relevant for the advancement of human biology and evolution and is thus of interest in the fields of dental anthropology, as well as human anatomy and medicine. Of concern is also the variation of the inner aspects of the crown which can be investigated using the tools and methods of virtual anthropology. In this study, we explored inter- and intra-population morphometric variation of modern humans' upper third and fourth premolars (P3s and P4s, respectively) considering both the inner and outer aspects of the crown, and discrete traits. We worked by means of geometric morphometrics on 3D image data from a geographically balanced sample of human populations from five continents, to analyse the shape of the dentinal crown, and the crown outline in 78 P3s and 76 P4s from 85 individuals. For the study of dental traits, we referred to the Arizona State University Dental Anthropology System integrated with more recent classification systems. The 3D shape variation of upper premolar crowns varied between short and mesio-distally broad, and tall and mesio-distally narrow. The observed shape variation was independent from the geographical origin of the populations, and resulted in extensive overlap. We noted a high pairwise correlation (r1 = 0.83) between upper P3s and P4s. We did not find any significant geographic differences in the analysed non-metric traits. Our outcomes thus suggest that geographical provenance does not play a determinant role in the shaping of the dental crown, whose genesis is under strict genetic control.

Concurrent Asian monsoon strengthening and early modern human dispersal to East Asia during the last interglacial

The relationship between initial Homo sapiens dispersal from Africa to East Asia and the orbitally paced evolution of the Asian summer monsoon (ASM)-currently the largest monsoon system-remains underexplored due to lack of coordinated synthesis of both Asian paleoanthropological and paleoclimatic data. Here, we investigate orbital-scale ASM dynamics during the last 280 thousand years (kyr) and their likely influences on early H. sapiens dispersal to East Asia, through a unique integration of i) new centennial-resolution ASM records from the Chinese Loess Plateau, ii) model-based East Asian hydroclimatic reconstructions, iii) paleoanthropological data compilations, and iv) global H. sapiens habitat suitability simulations. Our combined proxy- and model-based reconstructions suggest that ASM precipitation responded to a combination of Northern Hemisphere ice volume, greenhouse gas, and regional summer insolation forcing, with cooccurring primary orbital cycles of ~100-kyr, 41-kyr, and ~20-kyr. Between ~125 and 70 kyr ago, summer monsoon rains and temperatures increased in vast areas across Asia. This episode coincides with the earliest H. sapiens fossil occurrence at multiple localities in East Asia. Following the transcontinental increase in simulated habitat suitability, we suggest that ASM strengthening together with Southeast African climate deterioration may have promoted the initial H. sapiens dispersal from their African homeland to remote East Asia during the last interglacial.

Morphological and morphometric analyses of a late Middle Pleistocene hominin mandible from Hualongdong, China

Excavations in Hualongdong (HLD), East China, have yielded abundant hominin fossils dated to 300 ka. There is a nearly complete mandible that fits well with a partial cranium, and together they compose the skull labeled as HLD 6. Thus far, detailed morphological description and comparisons of the mandible have not been conducted. Here we present a comprehensive morphological, metric, and geometric morphometric assessment of this mandible and compare it with both adult and immature specimens of Pleistocene hominins and recent modern humans. Results indicate that the HLD 6 mandible exhibits a mosaic morphological pattern characterized by a robust corpus and relatively gracile symphysis and ramus. The moderately developed mental trigone and a clear anterior mandibular incurvation of the HLD 6 mandible are reminiscent of Late Pleistocene hominin and recent modern human morphology. However, the weak expression of all these features indicates that this mandible does not possess a true chin. Moreover, a suite of archaic features that resemble those of Middle Pleistocene hominins includes pronounced alveolar planum, superior transverse torus, thick corpus, a pronounced endocondyloid crest, and a well-developed medial pterygoid tubercle. The geometric morphometric analysis further confirms the mosaic pattern of the HLD 6 mandible. The combination of both archaic and modern human features identified in the HLD 6 mandible is unexpected, given its late Middle Pleistocene age and differs from approximately contemporaneous Homo members such as Xujiayao, Penghu, and Xiahe. This mosaic pattern has never been recorded in late Middle Pleistocene hominin fossil assemblages in East Asia. The HLD 6 mandible provides further support for the high morphological diversity during late Middle Pleistocene hominin evolution. With these findings, it is possible that modern human morphologies are present as early as 300 ka and earlier than the emergence of modern humans in East Asia.

Hominin evolution and diversity: a comparison of earlier-Middle and later-Middle Pleistocene hominin fossil variation in China

Historical views of Asia as an evolutionary 'backwater' are associated with the idea that Homo erectus experienced long periods of stasis and ultimately went extinct. However, recent discoveries of well-dated Middle Pleistocene hominin fossils in China have considerably challenged these ideas and provide sufficient data to propose a testable model that explains the patterning of variation in Middle Pleistocene China, and why it changed over time. A series of hominin fossil studies comparing earlier-Middle and later-Middle Pleistocene groups confirm that the expressions of certain traits shift around 300 ka. Fossils from the later Middle Pleistocene are more variable with a mix of archaic traits as well as ones that are common in Western Eurasian early Homo sapiens and Neanderthals. The period around 300 ka appears to have been a critical turning point for later-Middle Pleistocene morphological changes in China. It coincides with a phase of climatic instability in the Northern Hemisphere between Marine Isotope Stages 12 and 10 that would have led to changes in gene flow patterning, and regional population survival/extinction. This localized and testable model can be used for future explorations of hominin evolution in later Pleistocene eastern Eurasia. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.

Late Quaternary Proboscidean Sites in Africa and Eurasia with Possible or Probable Evidence for Hominin Involvement

This paper presents a list of >100 publicly known late Quaternary proboscidean sites that have certain or possible traces of hominin utilization in Africa, Europe, and Asia, along with a sample of references, chronometric or estimated ages, and brief descriptions of the associated materials and bone modifications. Summary discussions of important sites are also presented. Lower Palaeolithic/Early Stone Age hominins created far fewer proboscidean site assemblages than hominins in later Palaeolithic phases, in spite of the time span being many times longer. Middle Palaeolithic/Middle Stone Age hominins created assemblages at eight times the earlier hominin rate. Upper Palaeolithic/Later Stone Age hominins created site assemblages at >90 times the rate of Lower Palaeolithic hominins. Palaeoloxodon spp. occur in nearly one third of the sites with an identified or probable proboscidean taxon and Mammuthus species are in nearly one half of the sites with identified or probable taxon. Other identified proboscidean genera, such as Elephas, Loxodonta, and Stegodon, occur in few sites. The sites show variability in the intensity of carcass utilization, the quantity of lithics bedded with bones, the extent of bone surface modifications, such as cut marks, the diversity of associated fauna, and mortality profiles.

Comparative dental study between Homo antecessor and Chinese Homo erectus: Nonmetric features and geometric morphometrics

The Chinese Middle Pleistocene fossils from Hexian, Xichuan, Yiyuan, and Zhoukoudian have been generally classified as Homo erectus s.s. These hominins share some primitive features with other Homo specimens, but they also display unique cranial and dental traits. Thus, the Chinese Middle Pleistocene hominins share with other European and Asian hominin populations the so-called 'Eurasian dental pattern'. The late Early Pleistocene hominins from Gran Dolina-TD6.2 (Spain), representing the species Homo antecessor, also exhibit the Eurasian dental pattern, which may suggest common roots. To assess phylogenetic affinities of these two taxa, we evaluated and compared nonmetric and metric dental features and interpreted morphological differences within a comparative hominin framework. We determined that the robust roots of the molars, the shelf-like protostylid, the dendrite-like pattern of the enamel-dentine junction surface of the upper fourth premolars and molars, the strongly folded dentine of the labial surface of the upper incisors, and the rare occurrence of a mid-trigonid crest in the lower molars, are all characteristic of Chinese H. erectus. With regard to H. antecessor, we observed the consistent expression of a continuous mid-trigonid crest, the absence of a cingulum in the upper canines, a complex root pattern of the lower premolars, and a rhomboidal occlusal contour and occlusal polygon and protrusion in the external outline of a large a bulging hypocone in the first and second upper molars. Using two-dimensional geometric morphometrics, we further demonstrated that H. antecessor falls outside the range of variation of Chinese H. erectus for occlusal crown outline shape, the orientation of occlusal grooves, and relative locations of anterior and posterior foveae in the P⁴s, P₃s, M¹s, M²s, and M₂s. Given their geographic and temporal separation, the differences between these two species suggest their divergence occurred at some point in the Early Pleistocene, and thereafter they followed different evolutionary paths.

Human Evolution in Asia: Taking Stock and Looking Forward

We review the state of paleoanthropology research in Asia. We survey the fossil record, articulate the current understanding, and delineate the points of contention. Although Asia received less attention than Europe and Africa did in the second half of the twentieth century, an increase in reliably dated fossil materials and the advances in genetics have fueled new research. The long and complex evolutionary history of humans in Asia throughout the Pleistocene can be explained by a balance of mechanisms, between gene flow among different populations and continuity of regional ancestry. This pattern is reflected in fossil morphology and paleogenomics. Critical understanding of the sociocultural forces that shaped the history of hominin fossil research in Asia is important in charting the way forward.

Morphological description and evolutionary significance of 300 ka hominin facial bones from Hualongdong, China

Late Middle Pleistocene hominins in Africa displaying key modern morphologies by 315 ka are claimed as the earliest Homo sapiens. Evolutionary relationships among East Asian hominins appear complex due to a growing fossil record of late Middle Pleistocene hominins from the region, reflecting mosaic morphologies that contribute to a lack of consensus on when and how the transition to modern humans transpired. Newly discovered 300 ka hominin fossils from Hualongdong, China, provide further evidence to clarify these relationships in the region. In this study, facial morphology of the juvenile partial cranium (HLD 6) is described and qualitatively and quantitatively compared with that of other key Early, Middle, and Late Pleistocene hominins from East Asia, Africa, West Asia, and Europe and with a sample of modern humans. Qualitatively, facial morphology of HLD 6 resembles that of Early and Middle Pleistocene hominins from Zhoukoudian, Nanjing, Dali, and Jinniushan in China, as well as others from Java, Africa, and Europe in some of these features (e.g., supraorbital and malar regions), and Late Pleistocene hominins and modern humans from East Asia, Africa, and Europe in other features (e.g., weak prognathism, flat face and features in nasal and hard plate regions). Comparisons of HLD 6 measurements to group means and multivariate analyses support close affinities of HLD 6 to Late Pleistocene hominins and modern humans. Expression of a mosaic morphological pattern in the HLD 6 facial skeleton further complicates evolutionary interpretations of regional morphological diversity in East Asia. The prevalence of modern features in HLD 6 suggests that the hominin population to which HLD 6 belonged may represent the earliest pre-modern humans in East Asia. Thus, the transition from archaic to modern morphology in East Asian hominins may have occurred at least by 300 ka, which is 80,000 to 100,000 years earlier than previously recognized.

Early Pleistocene hominin teeth from Meipu, southern China

The rarity and poor preservation of hominin fossils from the East Asian Early Pleistocene hamper our understanding of their taxonomy and possible phylogenetic relationship with other members of the genus Homo. In the 1970s, four isolated hominin teeth were recovered from the Meipu site, southern China, which biostratigraphic analysis placed in the late Early Pleistocene. Early reports assigned the teeth to late Homo erectus. Since then, the teeth have not been re-evaluated, nor has reliable dating been performed at the Meipu site. Here, biostratigraphic and paleomagnetic dating allow for a more precise chronological constraint of the Meipu hominins in the late Early Pleistocene, between 780 ka and 990 ka, making them one of the few known hominins for this time in mainland Asia. The comparison of the morphology of the Meipu teeth with other members of the genus Homo reveals that the Meipu teeth preserve traits such as moderate shoveling of the I¹, the square crown contour of M¹, and a buccolingually wider lingual cusp in P⁴ that make them closer to early Homo specimens from Africa and Homo ergaster from Dmanisi (Georgia). In addition, the Meipu teeth exhibit features that are more typical for late mainland East Asian H. erectus, such as the moderately convex I¹ labial surface and a pronouncedly convex I₂ labial surface. In these features, the Meipu hominins are morphologically intermediate between African/Dmanisi early Homo and East Asian Middle Pleistocene hominins. This study contributes to a better understanding of the morphologies and the taxonomic status of East Asian Early Pleistocene hominins, a time period for which the hominin evidence with secure stratigraphic context is scarce.

Hominin diversity in East Asia during the Middle Pleistocene: A premolar endostructural perspective

Following the recent studies of East Asian mid-Middle to early Late Pleistocene hominin material, a large spectrum of morphological diversity has been recognized and the coexistence of archaic ('Homo erectus-like') and derived ('modern-like') dental morphological patterns has been highlighted. In fact, for most of these Chinese fossils, generally categorized as 'archaic Homo sapiens' or 'post-H. erectus Homo', the taxonomic attribution is a matter of contention. With the help of μCT techniques and a deformation-based 3D geometric morphometric approach, we focused on the morphological variation in the enamel-dentine junction (EDJ) of 18 upper and lower premolars from Chinese Middle Pleistocene hominins. We then compared our results with a number of fossil and modern human groups, including Early Pleistocene H. erectus from Sangiran; late Early Pleistocene hominins from Tighenif, Algeria; classic Neanderthals; and modern humans. Our results highlight an evolutionary/chronological trend of crown base reduction, elevation of EDJ topography, and EDJ surface simplification in the hominin groups studied here. Moreover, this study brings insights to the taxonomy/phylogeny of 6 late Middle Pleistocene specimens whose evolutionary placement has been debated for decades. Among these specimens, Changyang premolars show features that can be aligned with the Asian H. erectus hypodigm, whereas Panxian Dadong and Tongzi premolars are more similar to Late Pleistocene Homo. Compared with early to mid-Middle Pleistocene hominins in East Asia, late Middle Pleistocene hominins evince an enlarged morphological variation. A persistence of archaic morphotypes and possible admixture among populations during the late Middle Pleistocene are discussed.

26Al/10Be Burial Dating of the Middle Pleistocene Yiyuan Hominin Fossil Site, Shandong Province, Northern China

The Yiyuan hominin fossil site is one of the few localities in China where a partial skullcap and several loose teeth of Homo erectus have been discovered. Yiyuan was previously assigned broadly to the Middle Pleistocene by biostratigraphical correlation and ESR/U-series dating. Here, we report the first application of a radio-isotopic dating method to the site. ²⁶Al/¹⁰Be burial dating results derived from two sand samples from the fossiliferous deposits show that the hominin fossils can be confidently dated to 0.64 ± 0.08 Ma (million years ago). The reliability of this age is supported by the zero age of modern fluvial sediment near the cave. Our result is consistent with the age estimation based on biostratigraphic correlation and supports the argument that the Yiyuan and Zhoukoudian Locality 1 H. erectus fossils are contemporaneous. The results presented here, along with other recent chronological studies on Chinese Middle Pleistocene hominin sites, indicate that the time span from 600–400 ka (thousand years ago) is a critical period for human evolution in East Asia. Importantly, this time bracket includes several major climatic changes that would have influenced hominins, both morphologically and behaviorally.

Archaic human remains from Hualongdong, China, and Middle Pleistocene human continuity and variation

Middle to Late Pleistocene human evolution in East Asia has remained controversial regarding the extent of morphological continuity through archaic humans and to modern humans. Newly found ∼300,000-y-old human remains from Hualongdong (HLD), China, including a largely complete skull (HLD 6), share East Asian Middle Pleistocene (MPl) human traits of a low vault with a frontal keel (but no parietal sagittal keel or angular torus), a low and wide nasal aperture, a pronounced supraorbital torus (especially medially), a nonlevel nasal floor, and small or absent third molars. It lacks a malar incisure but has a large superior medial pterygoid tubercle. HLD 6 also exhibits a relatively flat superior face, a more vertical mandibular symphysis, a pronounced mental trigone, and simple occlusal morphology, foreshadowing modern human morphology. The HLD human fossils thus variably resemble other later MPl East Asian remains, but add to the overall variation in the sample. Their configurations, with those of other Middle and early Late Pleistocene East Asian remains, support archaic human regional continuity and provide a background to the subsequent archaic-to-modern human transition in the region.

Dentine morphology of Atapuerca-Sima de los Huesos lower molars: Evolutionary implications through three-dimensional geometric morphometric analysis

OBJECTIVES

This study aims to explore the affinities of the Sima de los Huesos (SH) population in relation to Homo neanderthalensis, Arago, and early and contemporary Homo sapiens. By characterizing SH intra-population variation, we test current models to explain the Neanderthal origins.

MATERIALS AND METHODS

Three-dimensional reconstructions of dentine surfaces of lower first and second molars were produced by micro-computed tomography. Landmarks and sliding semilandmarks were subjected to generalized Procrustes analysis and principal components analysis.

RESULTS

SH is often similar in shape to Neanderthals, and both groups are generally discernible from Homo sapiens. For example, the crown height of SH and Neanderthals is lower than for modern humans. Differences in the presence of a mid-trigonid crest are also observed, with contemporary Homo sapiens usually lacking this feature. Although SH and Neanderthals show strong affinities, they can be discriminated based on certain traits. SH individuals are characterized by a lower intra-population variability, and show a derived dental reduction in lower second molars compared to Neanderthals. SH also differs in morphological features from specimens that are often classified as Homo heidelbergensis, such as a lower crown height and less pronounced mid-trigonid crest in the Arago fossils.

DISCUSSION

Our results are compatible with the idea that multiple evolutionary lineages or populations coexisted in Europe during the Middle Pleistocene, with the SH paradigm phylogenetically closer to Homo neanderthalensis. Further research could support the possibility of SH as a separate taxon. Alternatively, SH could be a subspecies of Neanderthals, with the variability of this clade being remarkably higher than previously thought.

The fossil teeth of the Peking Man

This study provides new original data, including the endostructure of most Zhoukoudian H. erectus teeth preserved to date, since the publication of Black in 1927 and Weidenreich in 1937. The new evidence ratifies the similarities of Zhoukoudian with other East Asian mid-Middle Pleistocene hominins such as Hexian and Yiyuan, and allows defining a dental pattern potentially characteristic of this population commonly referred to as classic H. erectus. Given the possible chronological overlaps of classic H. erectus with other archaic Homo, the characterization of this group becomes a key issue when deciphering the taxonomy and evolutionary scenario of the Middle Pleistocene hominins in East Asia. Internally, the most remarkable feature of Zhoukoudian teeth is the highly crenulated enamel-dentine junction (EDJ) and its imprint on the roof of the pulp cavity. So far, this "dendrite-like" EDJ has been found only in East Asia Middle Pleistocene hominins although a large group of samples were assessed, and it could be useful to dentally define classic H. erectus in China. The crenulated EDJ surface, together with the stout roots and the taurodontism could be a mechanism to withstand high biomechanical demand despite a general dentognathic reduction, particularly of the crowns, in these populations.

A mandible from the Middle Pleistocene Hexian site and its significance in relation to the variability of Asian Homo erectus

OBJECTIVES

This study presents the first detailed morphological description and comparison of a Middle Pleistocene hominin mandibular fragment (PA 831) and associated teeth from the Hexian site in Eastern China. We aim to investigate where the Hexian mandible fits within the genus Homo variability in the light of an increased and better characterized Asian fossils record.

METHODS

Comparative samples include Pleistocene Homo mandibles and teeth from Africa, Asia, and Europe, as well as earlier African hominins (Australopithecus and early Homo) and Holocene recent humans. Both conventional morphological description and metric analysis were used. In addition, virtual reconstructions of the enamel dentine junction (EDJ) surface, pulp cavity, and roots with micro-CT were used to the mandible and teeth.

RESULTS

The Hexian mandible is characterized by a plesiomorphic structural pattern for the Homo clade, with strong corpus robustness and a subparallel and low-positioned mylohyoid line that differentiates the swollen subalveolar planum from the shallow subalveolar fossa. Features that are derived compared to early Homo include a moderately curved dental arcade, a well-developed lateral prominence placed at the M₂ -M₃ level, and multiple mental foramina. The Hexian mandible's complex enamel surface and strong, stout root structure are primitive traits for the Homo clade. Finally, the highly crenulated "dendrite-like" EDJ found in the molars may represent a dental feature specific to the continental Asian Homo erectus, but more data is needed to confirm this.

CONCLUSIONS

Mandibular and dental features indicate that the Hexian mandible and teeth differ from northern Chinese H. erectus and European Middle Pleistocene hominins, but show some affinities with the Early Pleistocene specimens from Africa (Homo ergaster) and Java (H. erectus), as well as the Middle-Late Pleistocene mandible from Penghu, Taiwan. Compared to contemporaneous continental Asian hominin populations, the Hexian fossils may represent the survival of a primitive hominin, with more primitive morphologies than other contemporaneous or some chronologically older Asian hominin specimens.

The first archaic Homo from Taiwan

Recent studies of an increasing number of hominin fossils highlight regional and chronological diversities of archaic Homo in the Pleistocene of eastern Asia. However, such a realization is still based on limited geographical occurrences mainly from Indonesia, China and Russian Altai. Here we describe a newly discovered archaic Homo mandible from Taiwan (Penghu 1), which further increases the diversity of Pleistocene Asian hominins. Penghu 1 revealed an unexpectedly late survival (younger than 450 but most likely 190–10 thousand years ago) of robust, apparently primitive dentognathic morphology in the periphery of the continent, which is unknown among the penecontemporaneous fossil records from other regions of Asia except for the mid-Middle Pleistocene Homo from Hexian, Eastern China. Such patterns of geographic trait distribution cannot be simply explained by clinal geographic variation of Homo erectus between northern China and Java, and suggests survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans in the region.

Growing evidence reveals great diversity of archaic Asian hominins. Here, Chang and colleagues describe a newly discovered archaic Homo mandible from Taiwan, which suggests the survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans to eastern Asia.

Middle Pleistocene hominin teeth from Longtan Cave, Hexian, China

Excavations at the Longtan Cave, Hexian, Anhui Province of Eastern China, have yielded several hominin fossils including crania, mandibular fragments, and teeth currently dated to 412 ± 25 ka. While previous studies have focused on the cranial remains, there are no detailed analyses of the dental evidence. In this study, we provide metric and morphological descriptions and comparisons of ten teeth recovered from Hexian, including microcomputed tomography analyses. Our results indicate that the Hexian teeth are metrically and morphologically primitive and overlap with H. ergaster and East Asian Early and mid-Middle Pleistocene hominins in their large dimensions and occlusal complexities. However, the Hexian teeth differ from H. ergaster in features such as conspicuous vertical grooves on the labial/buccal surfaces of the central incisor and the upper premolar, the crown outline shapes of upper and lower molars and the numbers, shapes, and divergences of the roots. Despite their close geological ages, the Hexian teeth are also more primitive than Zhoukoudian specimens, and resemble Sangiran Early Pleistocene teeth. In addition, no typical Neanderthal features have been identified in the Hexian sample. Our study highlights the metrical and morphological primitive status of the Hexian sample in comparison to contemporaneous or even earlier populations of Asia. Based on this finding, we suggest that the primitive-derived gradients of the Asian hominins cannot be satisfactorily fitted along a chronological sequence, suggesting complex evolutionary scenarios with the coexistence and/or survival of different lineages in Eurasia. Hexian could represent the persistence in time of a H. erectus group that would have retained primitive features that were lost in other Asian populations such as Zhoukoudian or Panxian Dadong. Our study expands the metrical and morphological variations known for the East Asian hominins before the mid-Middle Pleistocene and warns about the possibility that the Asian hominin variability may have been taxonomically oversimplified.

Temporal labyrinths of eastern Eurasian Pleistocene humans

One of the morphological features that has been identified as uniquely derived for the western Eurasian Neandertals concerns the relative sizes and positions of their semicircular canals. In particular, they exhibit a relatively small anterior canal, a relatively larger lateral one, and a more inferior position of the posterior one relative to the lateral one. These discussions have not included full paleontological data on eastern Eurasian Pleistocene human temporal labyrinths, which have the potential to provide a broader context for assessing Pleistocene Homo trait polarities. We present the temporal labyrinths of four eastern Eurasian Pleistocene Homo, one each of Early (Lantian 1), Middle (Hexian 1), and Late (Xujiayao 15) Pleistocene archaic humans and one early modern human (Liujiang 1). The labyrinths of the two earlier specimens and the most recent one conform to the proportions seen among western early and recent modern humans, reinforcing the modern human pattern as generally ancestral for the genus Homo. The labyrinth of Xujiayao 15 is in the middle of the Neandertal variation and separate from the other samples. This eastern Eurasian labyrinthine dichotomy occurs in the context of none of the distinctive Neandertal external temporal or other cranial features. As such, it raises questions regarding possible cranial and postcranial morphological correlates of Homo labyrinthine variation, the use of individual "Neandertal" features for documenting population affinities, and the nature of late archaic human variation across Eurasia.

The late Early Pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure

Fieldwork performed during the last 15 years in various Early Pleistocene East African sites has significantly enlarged the fossil record of Homo erectus sensu lato (s.l.). Additional evidence comes from the Danakil Depression of Eritrea, where over 200 late Early to early Middle Pleistocene sites have been identified within a ∼1000 m-thick sedimentary succession outcropping in the Dandiero Rift Basin, near Buia. Along with an adult cranium (UA 31), which displays a blend of H. erectus-like and derived morpho-architectural features and three pelvic remains, two isolated permanent incisors (UA 222 and UA 369) have also been recovered from the 1 Ma (millions of years ago) Homo-bearing outcrop of Uadi Aalad. Since 2010, our surveys have expanded to the nearby (4.7 km) site of Mulhuli-Amo (MA). This is a fossiliferous area that has been preliminarily surveyed because of its exceptional concentration of Acheulean stone tools. So far, the site has yielded 10 human remains, including the unworn crown of a lower permanent molar (MA 93). Using diverse analytical tools (including high resolution μCT and μMRI), we analysed the external and internal macromorphology and microstructure of the three specimens, and whenever possible compared the results with similar evidence from early Homo, H. erectus s.l., H. antecessor, H. heidelbergensis (from North Africa), Neanderthals and modern humans. We also assessed the UA 369 lower incisor from Uadi Aalad for root completion timing and showed that it compares well with data for root apex closure in modern human populations.