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1. Palaeoenvironmental setting of Mojokerto Homo erectus , the palynological expressions of Pleistocene marine deltas, open grasslands and volcanic mountains in East Java

   https://doi.org/10.1111/jbi.13770  

   Morley, Robert J. ; Morley, Harsanti P. ; Zaim, Yahdi ; Huffman, O. Frank ( January 2020 , Journal of Biogeography)

   To determine the vegetation and landscape experienced byHomo erectuspopulations which first inhabited Java.

   Perning, near Mojokerto, East Java, the 1936 discovery locality of a fossil child's skull widely attributed toH. erectus, and laterally equivalent sediments at Jetis.

   Terrestrial, mangrove and aquatic plants.

   A comprehensive suite of samples was collected at close spacing through a coastal sedimentary succession analysed concurrently for its depositional origins. The section traversed particularly informative marine, delta front and delta plain deposits, including the bonebed in which theH. erectuswas discovered.

   Rich palynomorph recovery indicative of mangroves was obtained in the mud‐dominated marine Mollusk Member II at the base of the analysed section. The overlying deltaic strata are characterized by grass pollen and phytoliths, while still retaining mangrove and wetland signals in key samples near the level of theH. erectusbed.

   The vertical stratigraphic series of facies in the Perning and adjacent Jetis sections indicates a landscape with four potentialHomohabitats: muddy deltas with widespreadNypaswamps; a poorly vegetated sandy delta; extensive open savanna grasslands in the lowlands up river of the delta; and volcanoes in the upper reaches of the catchment with perhumid montane podocarp and broad‐leaf forests and probable open fire‐climaxCasuarina junghuhnianaforest. Palynological data support an Early Pleistocene geological age for MojokertoH. erectusat about 1.43 Myr.

    

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2. Neuromechanical linkage between the head and forearm during running

   https://doi.org/10.1002/ajpa.24234  

   Yegian, Andrew K. ; Tucker, Yanish ; Bramble, Dennis M. ; Lieberman, Daniel E. ( January 2021 , American Journal of Physical Anthropology)

   The main objective was to test the hypothesis of a neuromechanical link in humans between the head and forearm during running mediated by the biceps brachii and superior trapezius muscles. We hypothesized that this linkage helps stabilize the head and combats rapid forward pitching during running which may interfere with gaze stability.

   Thirteen human participants walked and ran on a treadmill while motion capture recorded body segment kinematics and electromyographic sensors recorded muscle activation. To test perturbations to the linkage system we compared participants running normally as well as with added mass to the face and the hand.

   The results confirm the presence of a neuromechanical linkage between the head and forearm mediated by the biceps and superior trapezius during running but not during walking. In running, the biceps and superior trapezius activations were temporally linked during the stride cycle, and adding mass to either the head or hand increased activation in both muscles, consistent with our hypothesis. During walking the forces acting on the body segments and muscle activation levels were much smaller than during running, indicating no need for a linkage to keep the head and gaze stable.

   The results suggest that the evolution of long distance running in earlyHomomay have favored selection for reduced rotational inertia of both the head and forearm through synergistic muscle activation, contributing to the transition from australopith head and forelimb morphology to the more human‐like form ofHomo erectus. Selective pressures from the evolution of bipedal walking were likely much smaller, but may explain in part the intermediate form of the australopith scapula between that of extant apes and humans.

    

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3. Relative tooth size, Bayesian inference, and Homo naledi

   https://doi.org/10.1002/ajpa.24353  

   Irish, Joel D. ; Grabowski, Mark ( June 2021 , American Journal of Physical Anthropology)

   Size‐corrected tooth crown measurements were used to estimate phenetic affinities amongHomo naledi(~335–236 ka) and 11 other Plio‐Pleistocene and recent species. To assess further their efficacy, and identify dental evolutionary trends, the data were then quantitatively coded for phylogenetic analyses. Results from both methods contribute additional characterization ofH. naledirelative to other hominins.

   After division by their geometric mean, scaled mesiodistal and buccolingual dimensions were used in tooth size apportionment analysis to compareH. nalediwithAustralopithecus africanus,A. afarensis,Paranthropus robustus,P. boisei,H. habilis,H. ergaster,H. erectus,H. heidelbergensis,H. neanderthalensis,H. sapiens, andPan troglodytes. These data produce equivalently scaled samples unaffected by interspecific size differences. The data were then gap‐weighted for Bayesian inference.

   Congruence in interspecific relationships is evident between methods, and with many inferred from earlier systematic studies. However, the present results placeH. naledias a sister taxon toH. habilis,based on a symplesiomorphic pattern of relative tooth size. In the preferred Bayesian phylogram,H. nalediis nested within a clade comprising allHomospecies, but it shares some characteristics with australopiths and, particularly, earlyHomo.

   Phylogenetic analyses of relative tooth size yield information about evolutionary dental trends not previously reported inH. nalediand the other hominins. Moreover, with an appropriate model these data recovered plausible evolutionary relationships. Together, the findings support recent study suggestingH. naledioriginated long before the geological date of the Dinaledi Chamber, from which the specimens under study were recovered.

    

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4. The endocast from Dana Aoule North ( DAN5 / P1 ): A 1.5 million year‐old human braincase from Gona, Afar, Ethiopia

   https://doi.org/10.1002/ajpa.24717  

   Bruner, Emiliano ; Holloway, Ralph ; Baab, Karen L. ; Rogers, Michael J. ; Semaw, Sileshi ( February 2023 , American Journal of Biological Anthropology)

   The nearly complete cranium DAN5/P1 was found at Gona (Afar, Ethiopia), dated to 1.5–1.6 Ma, and assigned to the speciesHomo erectus. Its size is, nonetheless, particularly small for the known range of variation of this taxon, and the cranial capacity has been estimated as 598 cc. In this study, we analyzed a reconstruction of its endocranial cast, to investigate its paleoneurological features. The main anatomical traits of the endocast were described, and its morphology was compared with other fossil and modern human samples. The endocast shows most of the traits associated with less encephalized human taxa, like narrow frontal lobes and a simple meningeal vascular network with posterior parietal branches. The parietal region is relatively tall and rounded, although not especially large. Based on our set of measures, the general endocranial proportions are within the range of fossils included in the speciesHomo habilisor in the genusAustralopithecus. Similarities with the genusHomoinclude a more posterior position of the frontal lobe relative to the cranial bones, and the general endocranial length and width when size is taken into account. This new specimen extends the known brain size variability ofHomo ergaster/erectus, while suggesting that differences in gross brain proportions among early human species, or even between early humans and australopiths, were absent or subtle.

    

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5. A distinguishing feature of Pongo upper molars and its implications for the taxonomic identification of isolated hominid teeth from the Pleistocene of Asia

   https://doi.org/10.1002/ajpa.23928  

   Ortiz, Alejandra ; Bailey, Shara E. ; Delgado, Miguel ; Zanolli, Clément ; Demeter, Fabrice ; Bacon, Anne‐Marie ; Nguyen, Thi M. H. ; Nguyen, Anh T. ; Zhang, Yingqi ; Harrison, Terry ; et al ( October 2019 , American Journal of Physical Anthropology)

   The taxonomic status of isolated hominoid teeth from the Asian Pleistocene has long been controversial due to difficulties distinguishing between pongine and hominin molars given their high degree of morphometrical variation and overlap. Here, we combine nonmetric and geometric morphometric data to document a dental pattern that appears to be taxonomically diagnostic amongPongo. We focus on the protoconule, a cuspule of well‐documented evolutionary history, as well as on shape differences of the mesial fovea of the upper molars.

   We examined 469 upper molars of eight hominid genera (Australopithecus,Paranthropus,Homo,Meganthropus,Sivapithecus,Pan,Gorilla, andPongo), including representatives ofHomo erectusand extinct and recentPongo. Analyses were conducted at the enamel‐dentine junction to overcome the limitations introduced by dental wear.

   We found that a moderate or large protoconule is present in ~80% of Pleistocene and extantPongo. Conversely, a moderate to pronounced protoconule in hominins,Meganthropus, and African great apes occurs in low frequencies (~0–20%). Canonical variate analyses for the mesial fovea show that Pleistocene and extantPongocluster together and are clearly differentiated from all other groups, except forSivapithecus.

   This study suggests that the protoconule and the shape of the mesial fovea in upper molars are useful features for the taxonomic identification of isolated hominid teeth. By identifying these new features, our results can contribute to the better understanding of hominoid evolutionary history and biogeography during the Asian Pleistocene. However, we emphasize that the reported features should be used in combination with other diagnostic variables for the most accurate taxonomic assessments.

    

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