Hominin Species Research Articles

Continuity and variability in prehistoric fishing practices by Homo sapiens in Island Southeast Asia: new ichthyofaunal data from Asitau Kuru, Timor-Leste

ABSTRACTHuman adaptations to marine resources were critical in the successful colonization of Island Southeast Asia (ISEA) and the Pacific since the Late Pleistocene. Fishing the dense biomass of ichthyofauna present in this maritime region required the cognitive capability to conceptualize fish ecology and develop methods and technologies to exploit these challenging underwater environments. This likely gave our species an edge over other hominin species in depauperate island landscapes. This paper reviews the limited number of archaeological sites in ISEA where fish bone assemblages and fishing gears have been recovered, incorporating new archaeological data from the site of Asitau Kuru (Jerimalai), Timor-Leste. Our findings indicate continuity in fishing behavior over several millennia with a near-shore exploitation of local marine habitats including trolling, line fishing and spearing. These data indicate the ecological plasticity of our species and the enduring fishing traditions passed on to generations through learned behavior.

Cochlear morphology of Indonesian Homo erectus from Sangiran

Homo erectus s.l. is key for deciphering the origin and subsequent evolution of genus Homo. However, the characterization of this species is hindered by the existence of multiple variants in both mainland and insular Asia, as a result of divergent chronogeographical evolutionary trends, genetic isolation, and interbreeding with other human species. Previous research has shown that cochlear morphology embeds taxonomic and phylogenetic information that may help infer the phylogenetic relationships among hominin species. Here we describe the cochlear morphology of two Indonesian H. erectus individuals (Sangiran 2 and 4), and compare it with a sample of australopiths, Middle to Late Pleistocene humans, and extant humans by means of linear measurements and both principal components and canonical variates analyses performed on shape ratios. Our results indicate that H. erectus displays a mosaic morphology that combines plesiomorphic (australopithlike) features (such as a chimplike round cochlear cross section and low cochlear thickness), with derived characters of later humans (a voluminous and long cochlea, possibly related to hearing abilities)—consistent with the more basal position of H. erectus. Our results also denote substantial variation between the two studied individuals, particularly in the length and radius of the first turn, as well as cross-sectional shape. Given the small size of the available sample, it is not possible to discern whether such differences merely reflect intraspecific variation among roughly coeval H. erectus individuals or whether they might result from greater age differences between them than currently considered. However, our results demonstrate that most characters found in later humans were already present in Indonesian H. erectus, with the exception of Neanderthals, which display an autapomorphic condition relative to other Homo species.

Tropical forests in the deep human past.

Since Darwin, studies of human evolution have tended to give primacy to open ‘savannah’ environments as the ecological cradle of our lineage, with dense tropical forests cast as hostile, unfavourable frontiers. These perceptions continue to shape both the geographical context of fieldwork as well as dominant narratives concerning hominin evolution. This paradigm persists despite new, ground-breaking research highlighting the role of tropical forests in the human story. For example, novel research in Africa's rainforests has uncovered archaeological sites dating back into the Pleistocene; genetic studies have revealed very deep human roots in Central and West Africa and in the tropics of Asia and the Pacific; an unprecedented number of coexistent hominin species have now been documented, including Homo erectus, the ‘Hobbit’ (Homo floresiensis), Homo luzonensis, Denisovans, and Homo sapiens. Some of the earliest members of our own species to reach South Asia, Southeast Asia, Oceania and the tropical Americas have shown an unexpected rapidity in their adaptation to even some of the more ‘extreme’ tropical settings. This includes the early human manipulation of species and even habitats. This volume builds on these currently disparate threads and, for the first time, draws together a group of interdisciplinary, agenda-setting papers that firmly places a broader spectrum of tropical environments at the heart of the deep human past.This article is part of the theme issue ‘Tropical forests in the deep human past’.

Climate-inferred distribution estimates of mid-to-late Pliocene hominins

During the mid-to-late Pliocene (ca. 4–3 Ma), several hominin species were present in central Sahel, eastern and southern Africa. The potential for the discovery of hominin remains from this interval is limited by the availability of exposed Pliocene deposits and the ability to investigate them. As a result, most discoveries have been made in the Afar region of Ethiopia and in the Lake Turkana basin, thus unveiling only a portion of Pliocene hominins' probable geographical presence. In this study we provide a continental view of geographic areas potentially accessible to these hominins. To do so, we estimate the climatic envelope suitable for mid-to-late Pliocene hominin presence, using the earth system model IPSL-CM5A and the Maxent habitat suitability algorithm. Our analysis reveals high habitat suitability for these hominin species in semi-arid regions where annual thermal amplitude and mean annual precipitation are moderate, mostly corresponding to tropical xerophytic shrublands. Our habitat model estimates geographically continuous, suitable climatic conditions for hominins between central Sahel and northeastern Africa, but not between eastern and southern Africa. This discontinuity suggests that southern African and eastern African hominins were separated by an environmental barrier that could only be crossed during particularly favourable periods or by undertaking long-range dispersal over climatically hostile habitats. Under climate conditions of northern hemisphere summer at perihelion this climatic barrier is not present. In contrast, the Turkana basin, the Laetoli region, and a large part of southern Africa remain suitable for all precession angles, suggesting that these areas may have functioned as refugia. The constant presence of these stable areas combined with the periodic establishment of corridors for dispersion can potentially explain hominin diversity in eastern Africa. • Paleoclimatic reconstructions and HSM depict high suitability in semi-arid regions • Eastern and southern suitable areas are disconnected under mean Pliocene climate • Under specific precession configurations this climatic barrier disappears • Turkana basin and the Laetoli region could have work as climatic refugia • High Pliocene Hominin diversity could be linked with periodic presence of corridors.

Mosaic habitats at Woranso-Mille (Ethiopia) during the Pliocene and implications for Australopithecus paleoecology and taxonomic diversity

Many important Pliocene hominin specimens have been recovered from Woranso-Mille, a paleontological research area in the Afar region of Ethiopia, including the complete cranium of Australopithecus anamensis, a partial skeleton of Australopithecus afarensis, mandibular and maxillary elements representing a new species, Australopithecus deyiremeda, and a partial foot of an as-yet-unnamed species. Woranso-Mille is the only site, so far, to have reported the co-existence of more than one early hominin species between 3.8 and 3.3 Ma and the temporal overlap between A. anamensis and A. afarensis. Thus, the site has important implications for our understanding of the paleoecology and taxonomic diversity of early hominins and their ecological niche. This paper explores the paleohabitats of Woranso-Mille through its faunal community ecological structure and taxonomic composition using correspondence analysis and Forbes modified similarity index. The results suggest that Pliocene Woranso-Mille was a mosaic of different habitat types, with riparian woodland and floodplain grassland along rivers draining into a lake, along with less mesic habitats such as woodland, grassland, and shrubland. The apparent high level of vegetation heterogeneity may have promoted dietary specializations and niche differentiation among the different Australopithecus species at Woranso-Mille and allowed for their co-existence at the site.

ТЕХНОЛОГИЧЕСКИЙ РЕПЕРТУАР НЕАНДЕРТАЛЬЦЕВ ТЕШИК-ТАША: НОВЫЕ ДАННЫЕ

The article presents the results of the technological analysis of the Teshik-Tash grotto lithic collection from the Kunstkamera funds (Saint Petersburg). Because the Teshik-Tash industry has an indisputable anthropological link to the Neanderthal population, which is unique for the western part of Central Asia, it is important to fully characterize the technological repertoire of this hominin species by studying the Teshik-Tash collection. Using the methods of mathematical statistics, the metric parameters of the artefacts were analyzed and the technical and typological homogeneity of the Teshik-Tash site complex (layers 1–5) was established, which indicates the representativeness of the sample at our disposal. The applied scar-pattern analysis revealed the dominance of the radial core reduction method aimed at obtaining non-standardized asymmetric blanks. At the same time, the toolkit contains the points with signs of Levallois knapping to obtain blanks: symmetry, regularity of convergent or longitudinally convergent dorsal surfaces, the presence of convex symmetric dihedral butts, overhang reduction. Thus, the problem of the Levallois component in the Teshik-Tash grotto industry remains open. The extent to which the Neanderthal population of Teshik-Tash used the Levallois technology will probably become clear after analysis of the Teshik- Tash grotto collections, stored in the funds of the Anuchin Research Institute and the Museum of Anthropology of MSU and the State Museum of history of Uzbekistan in Tashkent.

Lithic bipolar methods as an adaptive strategy through space and time

The use of bipolar (on anvil) methods for resource exploitation has been identified in the archaeological record from the late Pliocene through to the Holocene. During all phases of human evolution, bipolar knapping and wedging were applied by different hominin species in a wide range of ecological settings. Studies on lithic bipolar methods have mainly focused on understanding the functional aspects of this technology. This paper explores the variability of the application of these methods during the Paleolithic on a macro scale. Through the meta-analysis of published data from 167 sites, it is posited that the use of bipolar methods may have had a significant impact on hominin expansion, adaptation, and survival strategies. Furthermore, the recurrent use of bipolar methods is not only an indicator of its success as an adaptive strategy, but also of how hominins were able to evaluate different types of efficiency through time.

Resolving the "muddle in the middle": The case for Homo bodoensis sp. nov.

Recent developments in the field of palaeoanthropology necessitate the suppression of two hominin taxa and the introduction of a new species of hominins to help resolve the current nebulous state of Middle Pleistocene (Chibanian) hominin taxonomy. In particular, the poorly defined and variably understood hominin taxa Homo heidelbergensis (both sensu stricto and sensu lato) and Homo rhodesiensis need to be abandoned as they fail to reflect the full range of hominin variability in the Middle Pleistocene. Instead, we propose: (1) introduction of a new taxon, Homo bodoensis sp. nov., as an early Middle Pleistocene ancestor of the Homo sapiens lineage, with a pan‐African distribution that extends into the eastern Mediterranean (Southeast Europe and the Levant); (2) that many of the fossils from Western Europe (e.g. Sima de los Huesos) currently assigned to H. heidelbergensis s.s. be reassigned to Homo neanderthalensis to reflect the early appearance of Neanderthal derived traits in the Middle Pleistocene in the region; and (3) that the Middle Pleistocene Asian fossils, particularly from China, likely represent a different lineage altogether.

A multi-proxy approach to exploring Homo sapiens\u2019 arrival, environments and adaptations in Southeast Asia

The capability of Pleistocene hominins to successfully adapt to different types of tropical forested environments has long been debated. In order to investigate environmental changes in Southeast Asia during a critical period for the turnover of hominin species, we analysed palaeoenvironmental proxies from five late Middle to Late Pleistocene faunas. Human teeth discoveries have been reported at Duoi U’Oi, Vietnam (70–60 ka) and Nam Lot, Laos (86–72 ka). However, the use of palaeoproteomics allowed us to discard the latter, and, to date, no human remains older than ~ 70 ka are documented in the area. Our findings indicate that tropical rainforests were highly sensitive to climatic changes over that period, with significant fluctuations of the canopy forests. Locally, large-bodied faunas were resilient to these fluctuations until the cooling period of the Marine Isotope Stage 4 (MIS 4; 74–59 ka) that transformed the overall biotope. Then, under strong selective pressures, populations with new phenotypic characteristics emerged while some other species disappeared. We argue that this climate-driven shift offered new foraging opportunities for hominins in a novel rainforest environment and was most likely a key factor in the settlement and dispersal of our species during MIS 4 in SE Asia.

A chimpanzee enamel-diet δ13C enrichment factor and a refined enamel sampling strategy: Implications for dietary reconstructions

Reconstructing diets from stable carbon isotopic signals in enamel bioapatite requires the application of a δ13C enamel-diet enrichment factor, or the isotopic offset between diet and enamel, which has not been empirically determined for any primate. In this study, an enamel-diet enrichment factor (ε∗enamel-diet) of 11.8 ± 0.3‰ is calculated for chimpanzees (Pan troglodytes) at Ngogo in Kibale National Park, Uganda, based on a comprehensive isotopic assessment of previously analyzed dietary plant data and new isotopic analyses of enamel apatite. Different enamel sampling methods are evaluated to determine the potential influence of weaning on isotopic enamel values and dietary interpretations. The new chimpanzee enrichment factor and a sampling strategy that excludes teeth that formed before weaning completion are applied to all known chimpanzee δ13Cenamel data, either previously published or newly derived in this study, resulting in a dietary range of almost 6‰ across all chimpanzees sampled. This new chimpanzee enamel-diet enrichment factor is then used to reassess dietary reconstructions of 12 fossil hominin species whose isotopic enamel signatures have been determined. Results reveal hominin diets that are isotopically more positive than previously reconstructed, highlighting the widespread contribution of 13C-enriched C4/crassulacean acid metabolism (CAM) resources in fossil hominin diets and emphasizing the broad use of these resources during human evolution. These findings stress the importance of ascertaining and employing an appropriate enrichment factor for dietary reconstructions of specific taxa as well as standardizing the sampling protocol for tooth enamel in isotopic paleodietary reconstructions.

Paleospecies as cognitive construct: The meme of “Homo floresiensis”

Creation and subsequent abandonment of a number of earlier species considered human ancestors: Eoanthropus dawsoni, Hesperopithecus haroldcooki, Homo gardarensis and Ramapithecus punjabicus is presented using cases from the history of science. This review indicates that the fossil evidence for these species has been questionable from the beginning but that mental images – memes – they invoked were attractive to students of human evolution and as such persisted even if not confirmed by further finds, with new research still being disputed. Against this background the status of the recent construction of the hominin species “Homo floresiensis” is discussed showing that despite dubious interpretations of the objective data and a relatively long time of non-confirmation due to paucity of newly discovered skeletal remains, the “species” still exists in minds of scholars and in the scientific literature extending into textbooks.

An etiology of human modernity

Following the refutation of the replacement hypothesis, which had proposed that a ‘superior’ hominin species arose in Africa and replaced all other humans existing at the time, the auto-domestication hypothesis remains the only viable explanation for the relatively abrupt change from robust to gracile humans in the Late Pleistocene. It invokes the incidental institution of the domestication syndrome in humans, most probably by newly introduced cultural practices. It also postulates that the induction of exograms compensated for the atrophy of the brain caused by domestication. This new explanation of the origins of modernity in humans elucidates practically all its many aspects, in stark contrast to the superseded replacement hypothesis, which explained virtually nothing. The first results of the domestication syndrome’s genetic exploration have become available in recent years, and they endorse the human self-domestication hypothesis.

Molar biomechanical function in South African hominins Australopithecus africanus and Paranthropus robustus.

Diet is a driving force in human evolution. Two species of Plio-Pleistocene hominins, Paranthropus robustus and Australopithecus africanus, have derived craniomandibular and dental morphologies which are often interpreted as P. robustus having a more biomechanically challenging diet. While dietary reconstructions based on dental microwear generally support this, they show extensive dietary overlap between species, and craniomandibular and dental biomechanical analyses can yield contradictory results. Using methods from anthropology and engineering (i.e. anthroengineering), we quantified the molar biomechanical performance of these hominins to investigate possible dietary differences between them. Thirty-one lower second molars were 3D printed and used to fracture gelatine blocks, and Bayesian generalized linear models were used to investigate the relationship between species and tooth wear, size and shape, and biomechanical performance. Our results demonstrate that P. robustus required more force and energy to fracture blocks but had a higher force transmission rate. Considering previous dietary reconstructions, we propose three evolutionary scenarios concerning the dietary ecologies of these hominins. These evolutionary scenarios cannot be reached by investigating morphological differences in isolation, but require combining several lines of evidence. This highlights the need for a holistic approach to reconstructing hominin dietary ecology.

Northern Hemisphere Glaciation, African climate and human evolution

The hypothesis of a connection between the onset (or intensification) of Northern Hemisphere Glaciation, the stepwise increase in African aridity (and climate variability), and an important mammalian (including hominin) species turnover is a textbook example of the initiation of a scientific idea and its propagation in science. It is, however, also an example of the persistent popularity of a hypothesis despite mounting evidence against it. A critical review of key publications on the topic and statistical re-analysis of key records of global ice volume and African climate leads to three conclusions: (1) The Northern Hemisphere Glaciation was a gradual process occurring between ∼3.5 and 2.5 Ma, not a single event at ∼2.8 Ma or at any other time. (2) A consistent stepwise (+/−0.2 Ma) transition toward greater aridity in Africa at ∼2.8 Ma does not exist; instead, there are regionally different, gradual transitions partly in connection with the intensification of the Northern Hemisphere Glaciation, but above all with the establishment of the tropical Walker Circulation after ∼2 Ma. (3) Mammalian (including hominin) species turnovers at this time also appear to have been gradual, rather than stepwise.

One hominin taxon or two at Malapa Cave? Implications for the origins of Homo

A report on the skeletons of two individuals from the Malapa cave site in South Africa attributes them both to a new hominin species, Australopithecus sediba. However, our analysis of the specimens’ mandibles indicates that Australopithecus sediba is not a ‘Homo-like australopith’, a transitional species between Australopithecus africanus and Homo. According to our results, the specimens represent two separate genera: Australopithecus and Homo. These genera are known to have jointly occupied sites, as seen in several early South African caves, so one cannot rule out the possibility that Malapa also contains remains of the two taxa. Our results lead us to additionally conclude that all the Australopithecus species on which the relevant mandibular anatomy is preserved (not only the ‘robust’ australopiths but also the ‘gracile’ – more generalised – ones) are too specialised to constitute an evolutionary ancestor of Homo sapiens. Furthermore, given that the Malapa site contains representatives of two hominin branches, one of which appears to be Homo, we must seek evidence of our origins much earlier than the date assigned to Malapa, approximately 2 million years before present. Support for this claim can be found in Ethiopian fossils attributed to the genus Homo and dated at 2.4 and 2.8 million years before present.Significance:
 
 The proposed hominin species Australopithecus sediba, from the Malapa Cave in South Africa, seems to actually consist of two species, each of which represents a different hominin genus: Homo and Australopithecus. If, indeed, this is the case, Homo must have originated prior to the Malapa remains, contrary to the scenario suggested in the original report on Au. sediba.

Dental caries in South African fossil hominins

Once considered rare in fossil hominins, caries has recently been reported in several hominin species, requiring a new assessment of this condition during human evolution. Caries prevalence and location on the teeth of South African fossil hominins were observed and compared with published data from other hominin samples. Teeth were viewed macroscopically, with lesion position and severity noted and described. For all South African fossil hominin specimens studied to date, a total of 10 carious teeth (14 lesions), including 4 described for the first time here, have been observed. These carious teeth were found in a minimum of seven individuals, including five Paranthropus robustus, one early Homo, and one Homo naledi. All 14 lesions affected posterior teeth. The results suggest cariogenic biofilms and foods may have been present in the oral environment of a wide variety of hominins. Caries prevalence in studied fossil hominins is similar to those in pre-agricultural human groups, in which 1–5% of teeth are typically affected.Significance:
 
 This study adds to the growing evidence that dental caries was present throughout the course of human evolution. Caries prevalence in the fossil species studied is similar to those in non-agricultural human groups, with 1–5% of teeth displaying cavities.
 Differences in prevalence and position of dental caries can provide insight into dietary aspects of past populations. South African fossil hominins display lesions on their posterior teeth, suggesting sugary foods were consumed.

New horizons in reconstructing past human behavior: Introducing the "Tübingen University Validated Entheses-based Reconstruction of Activity" method.

An accurate reconstruction of habitual activities in past populations and extinct hominin species is a paramount goal of paleoanthropological research, as it can elucidate the evolution of human behavior and the relationship between culture and biology. Variation in muscle attachment (entheseal) morphology has been considered an indicator of habitual activity, and many attempts have been made to use it for this purpose. However, its interpretation remains equivocal due to methodological shortcomings and a paucity of supportive experimental data. Through a series of studies, we have introduced a novel and precise methodology that focuses on reconstructing muscle synergies based on three-dimensional and multivariate analyses among entheses. This approach was validated using uniquely documented anthropological samples, experimental animal studies, histological observations, and geometric morphometrics. Here, we detail, synthesize, and critically discuss the findings of these studies, which overall point to the great potential of entheses in elucidating aspects of past human behavior.

A Phylogenetic Networks perspective on reticulate human evolution

SUMMARYWe present a methodological phylogenetic reconstruction approach combining Maximum Parsimony and Phylogenetic Networks methods for the study of human evolution applied to phenotypic craniodental characters of 22 hominin species. The approach consists in selecting and validating a tree-like most parsimonious scenario out of several parsimony runs based on various numerical constraints. An intermediate step from tree to network methods is implemented by running an analysis with a reduced apomorphous character dataset that generates multiple parsimonious trees. These most parsimonious trees are then used as input for a Phylogenetic Networks analysis that results in consensus and reticulate networks. We show here that the phylogenetic tree-like definition of the genus Homo is a relative concept linked to craniodental characters that come in support of hypothetical Last Common Ancestors of the most parsimonious scenario and infer that the Homo reticulate network concords with recent findings in paleogenomic research regarding its mode of evolution.

Evolutionary perspective of the genus Homo: new approaches

No consensus exists in human evolution research regarding the definition of genus Homo and its mode of evolution. Based on a database that comprises more than 350 characters scored on 22 hominin species from Late Miocene to Holocene, we address methodologically these two questions with a quantitative taxonomic approach that combines Maximum Parsimony (MP) phylogenetic reconstruction with a Phylogenetic Networks method. Based on tree-based MP, we identify three Homo most parsimonious definitio...

Biomechanics of the human thumb and the evolution of dexterity

SummarySystematic tool production and use is one of humanity’s defining characteristics, possibly originating as early as >3 million years ago.1, 2, 3 Although heightened manual dexterity is considered to be intrinsically intertwined with tool use and manufacture, and critical for human evolution, its role in the emergence of early culture remains unclear. Most previous research on this question exclusively relied on direct morphological comparisons between early hominin and modern human skeletal elements, assuming that the degree of a species’ dexterity depends on its similarity with the modern human form. Here, we develop a new approach to investigate the efficiency of thumb opposition, a fundamental component of manual dexterity, in several species of fossil hominins. Our work for the first time takes into account soft tissue as well as bone anatomy, integrating virtual modeling of musculus opponens pollicis and its interaction with three-dimensional bone shape form. Results indicate that a fundamental aspect of efficient thumb opposition appeared approximately 2 million years ago, possibly associated with our own genus Homo, and did not characterize Australopithecus, the earliest proposed stone tool maker. This was true also of the late Australopithecus species, Australopithecus sediba, previously found to exhibit human-like thumb proportions. In contrast, later Homo species, including the small-brained Homo naledi, show high levels of thumb opposition dexterity, highlighting the increasing importance of cultural processes and manual dexterity in later human evolution.