Pub Date : 2025-03-01Epub Date: 2025-01-13DOI: 10.1016/j.jhevol.2024.103635
Kelsey D. Pugh , Julie A. Strain , Christopher C. Gilbert
Samburupithecus kiptalami is an ape found in Late Miocene deposits (ca. 9.5 Ma) of northern Kenya. Initial assessments of the holotype specimen (KNM-SH 8531), a female-gorilla-sized maxillary fragment preserving the postcanine tooth row, noted similarities to gorillas or to African apes more broadly. More recently, primitive features of the maxilla and dentition have been used to propose a stem hominoid position for Samburupithecus. In particular, Samburupithecus shares some dental features with orepithecids (nyanzapithecines and Oreopithecus). To evaluate these competing hypotheses, and investigate possible affinities to oreopithecids, we reanalyzed the dentition of Samburupithecus quantitatively and assessed qualitative dental and maxillary features shared by oreopithecids and Samburupithecus. Based on the results of our analyses, we suggest that Samburupithecus is a late-occurring African oreopithecid, which we regard as a long-lived family of stem hominoids. The inclusion of Samburupithecus within Oreopithecidae highlights that stem hominoids and oreopithecids, in particular, spanned a large range of body sizes, similar to the range of size variation seen among all extant apes. Finally, the presence of oreopithecids in Africa on either side of a notable gap in the Late Miocene African fossil record of apes (from ∼13 to 10 Ma) demonstrates that the rarity of fossil African apes (i.e., nonhominin hominines) during this period is likely due to sampling biases rather than a recent immigration back into Africa from Eurasia.
{"title":"Reanalysis of Samburupithecus reveals similarities to nyanzapithecines","authors":"Kelsey D. Pugh , Julie A. Strain , Christopher C. Gilbert","doi":"10.1016/j.jhevol.2024.103635","DOIUrl":"10.1016/j.jhevol.2024.103635","url":null,"abstract":"<div><div><em>Samburupithecus kiptalami</em> is an ape found in Late Miocene deposits (ca. 9.5 Ma) of northern Kenya. Initial assessments of the holotype specimen (KNM-SH 8531), a female-gorilla-sized maxillary fragment preserving the postcanine tooth row, noted similarities to gorillas or to African apes more broadly. More recently, primitive features of the maxilla and dentition have been used to propose a stem hominoid position for <em>Samburupithecus</em>. In particular, <em>Samburupithecus</em> shares some dental features with orepithecids (nyanzapithecines and <em>Oreopithecus</em>). To evaluate these competing hypotheses, and investigate possible affinities to oreopithecids, we reanalyzed the dentition of <em>Samburupithecus</em> quantitatively and assessed qualitative dental and maxillary features shared by oreopithecids and <em>Samburupithecus</em>. Based on the results of our analyses, we suggest that <em>Samburupithecus</em> is a late-occurring African oreopithecid, which we regard as a long-lived family of stem hominoids. The inclusion of <em>Samburupithecus</em> within Oreopithecidae highlights that stem hominoids and oreopithecids, in particular, spanned a large range of body sizes, similar to the range of size variation seen among all extant apes. Finally, the presence of oreopithecids in Africa on either side of a notable gap in the Late Miocene African fossil record of apes (from ∼13 to 10 Ma) demonstrates that the rarity of fossil African apes (i.e., nonhominin hominines) during this period is likely due to sampling biases rather than a recent immigration back into Africa from Eurasia.</div></div>","PeriodicalId":54805,"journal":{"name":"Journal of Human Evolution","volume":"200 ","pages":"Article 103635"},"PeriodicalIF":3.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142985462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-02-17DOI: 10.1016/j.jhevol.2024.103637
Shawn Hurst , Ralph Holloway , Heather Garvin , Grace Bocko , Kara Garcia , Zachary Cofran , John Hawks , Lee Berger
Since its discovery, the natural endocast of the Taung cranium has played a central role in the interpretation of human brain evolution. Aspects of the endocast including the identification of the lunate sulcus, possible expansion of the parietal lobe, and rounded profile suggested to R. Dart that the Taung individual was aligned with humans and not with other anthropoid primates, yet these interpretations were immediately controversial and remain so today. We have generated a detailed curvature map of the Taung endocast to evaluate its surface organization with reference to 189 chimpanzee and 20 human brains. These data enable evolutionary consideration of the surface detail of depressions and projections sufficient to mark primary sulci and variations in sulcal organization due to superficial bridges between adjacent gyri. Our results suggest that the lunate sulcus in the Taung endocast displays a gyral bridge between the occipital lobe and the inferior parietal lobule seen in 65% of our adult human brain hemispheres but in only 1.8% of our chimpanzee ones. The frontal lobe organization of the Taung endocast reflects a superior frontal sulcus pattern seen in 92.8% of our adult human brain hemispheres, but in 0% of our adult chimpanzee sample, and an inferior frontal sulcus pattern seen in 100% of our adult human brain hemispheres but in only 2.1% of our chimpanzee ones. The Taung inferior frontal gyrus retains a fronto-orbital sulcus which is seen in 0% of our adult human brain hemispheres and in 100% of our adult chimpanzee ones. These observations help to resolve some apparent inconsistencies of interpretation of the posterior endocast of the Taung specimen while showing that the specimen shared some derived aspects of endocast organization with humans that were not found in chimpanzees.
{"title":"A reanalysis of the Taung endocranial surface: Comparison with large samples of living hominids","authors":"Shawn Hurst , Ralph Holloway , Heather Garvin , Grace Bocko , Kara Garcia , Zachary Cofran , John Hawks , Lee Berger","doi":"10.1016/j.jhevol.2024.103637","DOIUrl":"10.1016/j.jhevol.2024.103637","url":null,"abstract":"<div><div>Since its discovery, the natural endocast of the Taung cranium has played a central role in the interpretation of human brain evolution. Aspects of the endocast including the identification of the lunate sulcus, possible expansion of the parietal lobe, and rounded profile suggested to R. Dart that the Taung individual was aligned with humans and not with other anthropoid primates, yet these interpretations were immediately controversial and remain so today. We have generated a detailed curvature map of the Taung endocast to evaluate its surface organization with reference to 189 chimpanzee and 20 human brains. These data enable evolutionary consideration of the surface detail of depressions and projections sufficient to mark primary sulci and variations in sulcal organization due to superficial bridges between adjacent gyri. Our results suggest that the lunate sulcus in the Taung endocast displays a gyral bridge between the occipital lobe and the inferior parietal lobule seen in 65% of our adult human brain hemispheres but in only 1.8% of our chimpanzee ones. The frontal lobe organization of the Taung endocast reflects a superior frontal sulcus pattern seen in 92.8% of our adult human brain hemispheres, but in 0% of our adult chimpanzee sample, and an inferior frontal sulcus pattern seen in 100% of our adult human brain hemispheres but in only 2.1% of our chimpanzee ones. The Taung inferior frontal gyrus retains a fronto-orbital sulcus which is seen in 0% of our adult human brain hemispheres and in 100% of our adult chimpanzee ones. These observations help to resolve some apparent inconsistencies of interpretation of the posterior endocast of the Taung specimen while showing that the specimen shared some derived aspects of endocast organization with humans that were not found in chimpanzees.</div></div>","PeriodicalId":54805,"journal":{"name":"Journal of Human Evolution","volume":"200 ","pages":"Article 103637"},"PeriodicalIF":3.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The hominin mandible SK 15 was discovered in April 1949 in Swartkrans Member 2, dated to ∼1.4 Ma. Albeit distorted on the right side, the left and right corpus of SK 15 are relatively low and thick, even compared to most Early to Middle Pleistocene Homo specimens. It preserves the left molar row and the right M2 and M3 that show a distalward increase in mesiodistal diameter. SK 15 was originally attributed to Telanthropus capensis but is now generally attributed to Homo erectus/Homo ergaster, even if it was previously suggested to possibly belong to Australopithecus. Similarities between SK 15 and Homo naledi mandible and tooth morphology were also claimed. To clarify the taxonomy of SK 15, we used X-ray microtomography to investigate aspects of bone and tooth structural organization. Geometric morphometric analyses of the dental arcade shape, mandible symphysis outline, and the M2 and M3 enamel-dentine junction shape were conducted. For mandibular symphysis shape, SK 15 exhibits an australopith signal, whereas for both the dental arcade and enamel-dentine junction analyses, the specimen is statistically classified as Paranthropus. Altogether, the results show that SK 15 unambiguously falls outside the variation of H. erectus/H. ergaster and that it is most compatible with the morphology of Paranthropus, albeit showing smaller dimensions and an absence of some dental morphological features (e.g., developed protostylid, distally tapering M3, short molar roots) typically found in specimens of Paranthropus aethiopicus, Paranthropus boisei, and Paranthropus robustus. In particular, SK 15 differs markedly in size and morphology from mandibular remains of P. robustus from Swartkrans Member 2. We thus tentatively attribute SK 15 to Paranthropus capensis, a more gracile species of Paranthropus than the other three currently recognized species of this genus and discuss the implications for the existence of another species of Paranthropus in southern Africa during the Early Pleistocene.
{"title":"Taxonomic revision of the SK 15 mandible based on bone and tooth structural organization","authors":"Clément Zanolli , Jean-Jacques Hublin , Ottmar Kullmer , Friedemann Schrenk , Lazarus Kgasi , Mirriam Tawane , Song Xing","doi":"10.1016/j.jhevol.2024.103634","DOIUrl":"10.1016/j.jhevol.2024.103634","url":null,"abstract":"<div><div>The hominin mandible SK 15 was discovered in April 1949 in Swartkrans Member 2, dated to ∼1.4 Ma. Albeit distorted on the right side, the left and right corpus of SK 15 are relatively low and thick, even compared to most Early to Middle Pleistocene <em>Homo</em> specimens. It preserves the left molar row and the right M<sub>2</sub> and M<sub>3</sub> that show a distalward increase in mesiodistal diameter. SK 15 was originally attributed to <em>Telanthropus capensis</em> but is now generally attributed to <em>Homo erectus/Homo ergaster</em>, even if it was previously suggested to possibly belong to <em>Australopithecus</em>. Similarities between SK 15 and <em>Homo naledi</em> mandible and tooth morphology were also claimed. To clarify the taxonomy of SK 15, we used X-ray microtomography to investigate aspects of bone and tooth structural organization. Geometric morphometric analyses of the dental arcade shape, mandible symphysis outline, and the M<sub>2</sub> and M<sub>3</sub> enamel-dentine junction shape were conducted. For mandibular symphysis shape, SK 15 exhibits an australopith signal, whereas for both the dental arcade and enamel-dentine junction analyses, the specimen is statistically classified as <em>Paranthropus</em>. Altogether, the results show that SK 15 unambiguously falls outside the variation of <em>H</em>. <em>erectus</em>/<em>H. ergaster</em> and that it is most compatible with the morphology of <em>Paranthropus</em>, albeit showing smaller dimensions and an absence of some dental morphological features (e.g., developed protostylid, distally tapering M<sub>3</sub>, short molar roots) typically found in specimens of <em>Paranthropus aethiopicus</em>, <em>Paranthropus boisei</em>, and <em>Paranthropus robustus</em>. In particular, SK 15 differs markedly in size and morphology from mandibular remains of <em>P. robustus</em> from Swartkrans Member 2. We thus tentatively attribute SK 15 to <em>Paranthropus capensis</em>, a more gracile species of <em>Paranthropus</em> than the other three currently recognized species of this genus and discuss the implications for the existence of another species of <em>Paranthropus</em> in southern Africa during the Early Pleistocene.</div></div>","PeriodicalId":54805,"journal":{"name":"Journal of Human Evolution","volume":"200 ","pages":"Article 103634"},"PeriodicalIF":3.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142928664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-01-06DOI: 10.1016/j.jhevol.2024.103633
Austin B. Lawrence , Ashley S. Hammond , Carol V. Ward
Hominin pelvic form differs dramatically from that of other primates by having more laterally facing iliac blades, a wider sacrum, and a larger, transversely broad pelvic inlet. The orientation of the acetabulum may also differ, plausibly related to differences in load transmission during upright posture and habitual bipedal locomotion, which may, in turn, affect overall pelvic geometry. We compared acetabular orientation in humans, a phylogenetically broad sample of extant anthropoid primates, and fossil hominins including Australopithecus afarensis (A.L. 288–1, KSD-VP-1/1), Australopithecus africanus (Sts 14), Australopithecus sediba (MH2), and Homo neanderthalensis (Kebara 2). We measured the three-dimensional orientation of the acetabulum on in silico models of individual hipbones aligned to the median plane by registering models to landmark coordinates on articulated pelves. Humans and fossil hominins both possess significantly more ventrally opening acetabula than other extant anthropoids, which exhibit laterally facing acetabula. The orientation of the hominin acetabulum was essentially humanlike by at least 3.6 Ma, well before the appearance of other unique features in the pelvis of Homo that may be associated with long-distance walking or running, thermoregulation, parturition, and larger body size in this genus. These results suggest that the ventral orientation of the acetabulum is a key component in the suite of pelvic characteristics related to habitual bipedality in hominins and should be considered in future analyses of hominin pelvic morphology.
{"title":"Acetabular orientation, pelvic shape, and the evolution of hominin bipedality","authors":"Austin B. Lawrence , Ashley S. Hammond , Carol V. Ward","doi":"10.1016/j.jhevol.2024.103633","DOIUrl":"10.1016/j.jhevol.2024.103633","url":null,"abstract":"<div><div>Hominin pelvic form differs dramatically from that of other primates by having more laterally facing iliac blades, a wider sacrum, and a larger, transversely broad pelvic inlet. The orientation of the acetabulum may also differ, plausibly related to differences in load transmission during upright posture and habitual bipedal locomotion, which may, in turn, affect overall pelvic geometry. We compared acetabular orientation in humans, a phylogenetically broad sample of extant anthropoid primates, and fossil hominins including <em>Australopithecus afarensis</em> (A.L. 288–1, KSD-VP-1/1)<em>, Australopithecus africanus</em> (Sts 14)<em>, Australopithecus sediba</em> (MH2)<em>,</em> and <em>Homo neanderthalensis</em> (Kebara 2). We measured the three-dimensional orientation of the acetabulum on in silico models of individual hipbones aligned to the median plane by registering models to landmark coordinates on articulated pelves. Humans and fossil hominins both possess significantly more ventrally opening acetabula than other extant anthropoids, which exhibit laterally facing acetabula. The orientation of the hominin acetabulum was essentially humanlike by at least 3.6 Ma, well before the appearance of other unique features in the pelvis of <em>Homo</em> that may be associated with long-distance walking or running, thermoregulation, parturition, and larger body size in this genus. These results suggest that the ventral orientation of the acetabulum is a key component in the suite of pelvic characteristics related to habitual bipedality in hominins and should be considered in future analyses of hominin pelvic morphology.</div></div>","PeriodicalId":54805,"journal":{"name":"Journal of Human Evolution","volume":"200 ","pages":"Article 103633"},"PeriodicalIF":3.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143104453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-01-22DOI: 10.1016/j.jhevol.2024.103636
Pierre Linchamps , Emmanuelle Stoetzel , Laurie Amberny , Christine Steininger , Ronald J. Clarke , Matthew V. Caruana , Kathleen Kuman , Travis Rayne Pickering
The oldest deposit at the hominin-bearing cave of Swartkrans, South Africa, is the Lower Bank of Member 1, dated to ca. 2.2 million years ago. Excavations of this unit have produced a diverse and extensive mammalian fossil record, including Paranthropus robustus and early Homo fossils, along with numerous Oldowan stone tools. The present study focuses on the taxonomic analysis of the micromammalian fossil assemblage obtained from recent excavations of the Lower Bank, conducted between 2005 and 2010, as part of the Swartkrans Paleoanthropological Research Project. The taxonomic composition of this assemblage is dominated by Mystromys, a rodent indicative of grassland environments. Taphonomic analysis indicates an accumulation of prey by Tyto alba (Barn owl) or a related species. Environments inferred from this evidence reflect an open landscape primarily covered by grassland vegetation, but they also feature components of wooded areas, rocky outcrops, and the proximity of a river. The Swartkrans fossil assemblage is compared with Cooper's D (dated to ca. 1.4 Ma) and a modern coprocoenosis of Bubo africanus (spotted eagle-owl) collected within the Swartkrans cave for taxonomic, taphonomic, and paleoecological perspectives. Contrasting fossil and modern micromammalian data provide a better understanding of accumulation processes and facilitate a diachronic reconstruction of changes in climate and landscape evolution. Issues regarding paleoenvironmental reconstruction methodologies based on micromammals are also discussed.
{"title":"New modern and Pleistocene fossil micromammal assemblages from Swartkrans, South Africa: Paleobiodiversity, taphonomic, and environmental context","authors":"Pierre Linchamps , Emmanuelle Stoetzel , Laurie Amberny , Christine Steininger , Ronald J. Clarke , Matthew V. Caruana , Kathleen Kuman , Travis Rayne Pickering","doi":"10.1016/j.jhevol.2024.103636","DOIUrl":"10.1016/j.jhevol.2024.103636","url":null,"abstract":"<div><div>The oldest deposit at the hominin-bearing cave of Swartkrans, South Africa, is the Lower Bank of Member 1, dated to ca. 2.2 million years ago. Excavations of this unit have produced a diverse and extensive mammalian fossil record, including <em>Paranthropus robustus</em> and early <em>Homo</em> fossils, along with numerous Oldowan stone tools. The present study focuses on the taxonomic analysis of the micromammalian fossil assemblage obtained from recent excavations of the Lower Bank, conducted between 2005 and 2010, as part of the Swartkrans Paleoanthropological Research Project. The taxonomic composition of this assemblage is dominated by <em>Mystromys</em>, a rodent indicative of grassland environments. Taphonomic analysis indicates an accumulation of prey by <em>Tyto alba</em> (Barn owl) or a related species. Environments inferred from this evidence reflect an open landscape primarily covered by grassland vegetation, but they also feature components of wooded areas, rocky outcrops, and the proximity of a river. The Swartkrans fossil assemblage is compared with Cooper's D (dated to ca. 1.4 Ma) and a modern coprocoenosis of <em>Bubo africanus</em> (spotted eagle-owl) collected within the Swartkrans cave for taxonomic, taphonomic, and paleoecological perspectives. Contrasting fossil and modern micromammalian data provide a better understanding of accumulation processes and facilitate a diachronic reconstruction of changes in climate and landscape evolution. Issues regarding paleoenvironmental reconstruction methodologies based on micromammals are also discussed.</div></div>","PeriodicalId":54805,"journal":{"name":"Journal of Human Evolution","volume":"200 ","pages":"Article 103636"},"PeriodicalIF":3.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143030341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01Epub Date: 2025-02-17DOI: 10.1016/j.jhevol.2024.103638
B. Gruwier , K. Kovarovic
In this study, we assess the artiodactyl fossil record of the Homo erectus type locality of Trinil (Indonesia) and explore the paleoenvironmental implications for the site and for our understanding of early hominin paleoecology. Combining ecomorphological analyses on postcranial elements of cervids from Trinil (n = 43) with a range of existing paleobiological and paleoecological data on the bovids and cervids, a holistic reconstruction is made of the ecology of the artiodactyl community. The ecomorphological analyses indicate that the cervid Axis lydekkeri was adapted to relatively open environments with wet substrate. In combination with evidence of the other families, these results are compared in a correspondence analysis with the artiodactyl communities of contemporary Asian nature reserves. Trinil was shown to be similar to a number of Mainland Southeast Asian sites and reconstructed as an open woodland habitat with a wet component, possibly in the form of alluvial grasslands. The paleoenvironmental conditions reconstructed for Trinil indicate that Homo erectus was present in relatively open environments but that it still had a significant degree of environmental flexibility and was able to persist in wet and dry environments, with a vegetation structure ranging from grassland to open woodland.
{"title":"Paleoenvironments at the Homo erectus type locality of Trinil (Java, Indonesia): The artiodactyl evidence","authors":"B. Gruwier , K. Kovarovic","doi":"10.1016/j.jhevol.2024.103638","DOIUrl":"10.1016/j.jhevol.2024.103638","url":null,"abstract":"<div><div>In this study, we assess the artiodactyl fossil record of the <em>Homo erectus</em> type locality of Trinil (Indonesia) and explore the paleoenvironmental implications for the site and for our understanding of early hominin paleoecology. Combining ecomorphological analyses on postcranial elements of cervids from Trinil (<em>n</em> = 43) with a range of existing paleobiological and paleoecological data on the bovids and cervids, a holistic reconstruction is made of the ecology of the artiodactyl community. The ecomorphological analyses indicate that the cervid <em>Axis lydekkeri</em> was adapted to relatively open environments with wet substrate. In combination with evidence of the other families, these results are compared in a correspondence analysis with the artiodactyl communities of contemporary Asian nature reserves. Trinil was shown to be similar to a number of Mainland Southeast Asian sites and reconstructed as an open woodland habitat with a wet component, possibly in the form of alluvial grasslands. The paleoenvironmental conditions reconstructed for Trinil indicate that <em>Homo erectus</em> was present in relatively open environments but that it still had a significant degree of environmental flexibility and was able to persist in wet and dry environments, with a vegetation structure ranging from grassland to open woodland.</div></div>","PeriodicalId":54805,"journal":{"name":"Journal of Human Evolution","volume":"200 ","pages":"Article 103638"},"PeriodicalIF":3.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01Epub Date: 2024-12-14DOI: 10.1016/j.jhevol.2024.103624
Christopher M. Smith , Ashley S. Hammond , Alessandro Urciuoli , José Braga , Amélie Beaudet , Marine Cazenave , Jeffrey T. Laitman , Sergio Almécija
The bony labyrinth of the inner ear houses the sensory end-organs responsible for balance (otolithic system in the utricle and saccule, and semicircular canal system) and hearing (cochlea). Study of the bony labyrinth has revealed considerable morphological diversity in the hominin lineage (semicircular canals and cochleae) and aided in reconstructing essential aspects of primate evolution, including positional behavior, audition, and phylogenic affinities. However, evidence of evolutionary change in the hominin otolithic system remains elusive. Such morphological variation in these gravitoinertial sensory end-organs may suggest functional differences as their geometry is linked with positional behavior. We approach the question of evolutionary morphological change in the hominin otolithic system by examining bony vestibule morphology in two South African hominin taxa Paranthropus robustus (n = 9) and Australopithecus africanus (n = 6), compared to extant hominids (Pongo pygmaeus, Gorilla gorilla, Pan troglodytes, and Homo sapiens). We use landmark-based shape analyses of 78 extant hominid inner ears by means of virtual three-dimensional models derived from micro-computed tomography scans. Thirty bony landmarks were chosen to approximate otolithic organ morphology and relative configuration. Results show a distinctive morphology in P. robustus compared to A. africanus and extant hominids. Specifically, P. robustus exhibits anterolateral–posteromedial compression in bony otolithic organ structure, reducing the size of the saccule and vestibular aqueduct. In contrast, A. africanus exhibits a modern-human-like otolithic system. This newfound morphological diversity identifies unique bony features of the P. robustus inner ear which: 1) offers potential evidence for differential positional behavior between P. robustus and A. africanus and 2) presents osteological markers to be used in taxonomic identification of P. robustus remains and in future assessments of Paranthropus classification.
{"title":"Divergent otolithic systems in the inner ear of Paranthropus robustus and Australopithecus africanus","authors":"Christopher M. Smith , Ashley S. Hammond , Alessandro Urciuoli , José Braga , Amélie Beaudet , Marine Cazenave , Jeffrey T. Laitman , Sergio Almécija","doi":"10.1016/j.jhevol.2024.103624","DOIUrl":"10.1016/j.jhevol.2024.103624","url":null,"abstract":"<div><div>The bony labyrinth of the inner ear houses the sensory end-organs responsible for balance (otolithic system in the utricle and saccule, and semicircular canal system) and hearing (cochlea). Study of the bony labyrinth has revealed considerable morphological diversity in the hominin lineage (semicircular canals and cochleae) and aided in reconstructing essential aspects of primate evolution, including positional behavior, audition, and phylogenic affinities. However, evidence of evolutionary change in the hominin otolithic system remains elusive. Such morphological variation in these gravitoinertial sensory end-organs may suggest functional differences as their geometry is linked with positional behavior. We approach the question of evolutionary morphological change in the hominin otolithic system by examining bony vestibule morphology in two South African hominin taxa <em>Paranthropus robustus</em> (n = 9) and <em>Australopithecus africanus</em> (n = 6), compared to extant hominids (<em>Pongo pygmaeus</em>, <em>Gorilla gorilla</em>, <em>Pan troglodytes</em>, and <em>Homo sapiens</em>). We use landmark-based shape analyses of 78 extant hominid inner ears by means of virtual three-dimensional models derived from micro-computed tomography scans. Thirty bony landmarks were chosen to approximate otolithic organ morphology and relative configuration. Results show a distinctive morphology in <em>P. robustus</em> compared to <em>A. africanus</em> and extant hominids. Specifically, <em>P. robustus</em> exhibits anterolateral–posteromedial compression in bony otolithic organ structure, reducing the size of the saccule and vestibular aqueduct. In contrast, <em>A. africanus</em> exhibits a modern-human-like otolithic system. This newfound morphological diversity identifies unique bony features of the <em>P</em>. <em>robustus</em> inner ear which: 1) offers potential evidence for differential positional behavior between <em>P. robustus</em> and <em>A. africanus</em> and 2) presents osteological markers to be used in taxonomic identification of <em>P. robustus</em> remains and in future assessments of <em>Paranthropus</em> classification.</div></div>","PeriodicalId":54805,"journal":{"name":"Journal of Human Evolution","volume":"199 ","pages":"Article 103624"},"PeriodicalIF":3.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142830821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01Epub Date: 2025-01-13DOI: 10.1016/j.jhevol.2024.103632
Tanner Z. Kovach , Artur Petrosyan , Keith N. Wilkinson , Yannick Raczynski-Henk , Kathleen Rodrigues , Ellery Frahm , Emily Beverly , Jayson P. Gill , Jennifer E. Sherriff , Boris Gasparyan , Hayk G. Avetisyan , Artak V. Gnuni , Daniel S. Adler
As a potential corridor connecting Southwest Asia with western and northern Europe, the Armenian Highlands and southern Caucasus hold great potential for increasing our understanding of Upper Paleolithic behavioral and cultural variability. However, given the dearth of Upper Paleolithic sites, we lack the data necessary to answer basic questions regarding the timing and nature of the Upper Paleolithic in this region. Solak-1 is an open-air site located along the upper Hrazdan Valley (1635 m above sea level) in central Armenia. The site preserves a rich Upper Paleolithic lithic assemblage produced almost exclusively on obsidian and is just the fourth Upper Paleolithic sequence in Armenia. The goal of this study is to present geoarchaeological, chronometric, and technological analyses of the Solak-1 site to integrate the site into the regional Upper Paleolithic sequence. Solak-1 is composed of six lithostratigraphic units (LUs 1–6) comprising recently reworked (LUs 1–2), pedogenically modified (LUs 3–5), and primary (LU 6) loess. A single-grain postinfrared infrared stimulated luminescence date of 27.73 ± 3.63 ka was obtained from LU 4. This age is comparable to regional Middle Upper Paleolithic sites in Armenia and Georgia. Technotypological analyses indicate a lithic assemblage dominated by the production of bladelets and bladelet tools from formal and informal cores. Geochemical sourcing of the obsidian highlights a predominance of local raw material use, with rare transport of artifacts over 185 linear km. These results add an important new datapoint to the Upper Paleolithic record of the Armenian Highlands, offering additional insights into technotypological patterning within this period.
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Pub Date : 2025-02-01Epub Date: 2024-12-26DOI: 10.1016/j.jhevol.2024.103630
Adam D. Gordon
The degree of sexual size dimorphism in fossil hominins is important evidence for the evaluation of evolutionary hypotheses, but it is also difficult/impossible to measure directly. Multiple methods have been developed to estimate dimorphism in univariate and multivariate datasets, including when data are missing. This paper introduces 'dimorph', an R package that implements many of these methods and associated resampling-based significance tests and evaluates their performance in terms of Type I error rates and power. Tests evaluated here are those that appear most commonly in the hominin literature: testing whether a fossil sample is significantly more dimorphic than a comparative sample of known dimorphism. Univariate and multivariate methods are applied to metric data from four extant hominoid species: Gorilla gorilla, Homo sapiens, Pan troglodytes, and Hylobates lar. Each species is represented by 47 female and 47 male adult individuals, from which 10 linear postcranial measurements are collected. Data are resampled at a broad range of sample sizes (n = 4 to n = 82), sex ratios (proportion of females range from 0 to 1), and in the case of missing-data methods, proportions of missing data (0–0.9). Type I error rates and power are evaluated by the proportion of tests correctly or incorrectly rejecting null hypotheses regarding dimorphism difference within pairs of samples drawn from these four species, in which one sample stands in for a fossil sample. Results indicate low Type I error rates for all methods, whereas power is variable across methods but often low at sample sizes common to fossil analyses. Recommendations are made for the best significance tests. Additionally, previous work using lack of significant difference as evidence for similarity in dimorphism between fossils and extant species should be re-examined to determine whether those studies have enough power to detect known differences among extant taxa.
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Pub Date : 2025-02-01Epub Date: 2024-12-24DOI: 10.1016/j.jhevol.2024.103625
D.R. Braun , S. Carvalho , R.S. Kaplan , M. Beardmore-Herd , T. Plummer , D. Biro , T. Matsuzawa
The use of broad tool repertoires to increase dietary flexibility through extractive foraging behaviors is shared by humans and their closest living relatives (chimpanzees, Pan troglodytes). However, comparisons between tool use in ancient human ancestors (hominins) and chimpanzees are limited by differences in their toolkits. One feature shared by primate and hominin toolkits is rock selection based on physical properties of the stones and the targets of foraging behaviors. Here, we document the selectivity patterns of stone tools used by wild chimpanzees to crack nuts at Bossou, Guinea, through controlled experiments that introduce rocks unknown to this population. Experiments incorporate specific rock types because previous studies document hominin selection of these lithologies at Kanjera South 2 Ma. We investigate decisions made by chimpanzees when selecting stones that vary in their mechanical properties—features not directly visible to the individual. Results indicate that the selection of anvils and hammers is linked to task-specific mechanical properties. Chimpanzees select harder stones for hammers and softer stones for anvils, indicating an understanding of specific properties for distinct functions. Selectivity of rock types suggests that chimpanzees assess the appropriate materials for functions by discriminating these ‘invisible’ properties. Adults identify mechanical properties through individual learning, and juveniles often reused the tools selected by adults. Selection of specific rock types may be transmitted through the reuse of combinations of rocks. These patterns of stone selection parallel what is documented for Oldowan hominins. The processes identified in this experiment provide insights into the discrete nature of hominin rock selection patterns in Plio-Pleistocene stone artifact production.
人类和他们的近亲（黑猩猩，泛穴居人）共同使用广泛的工具库，通过采掘觅食行为来增加饮食的灵活性。然而，对古代人类祖先（古人类）和黑猩猩使用工具的比较受到工具包差异的限制。灵长类动物和人类工具箱共有的一个特征是，根据石头的物理性质和觅食行为的目标来选择岩石。在这里，我们记录了在几内亚Bossou，野生黑猩猩使用石器来敲开坚果的选择性模式，通过控制实验，引入了未知的岩石。实验纳入了特定的岩石类型，因为以前的研究记录了在Kanjera South 2 Ma这些岩性的人类选择。我们研究了黑猩猩在选择不同机械性能的石头时所做的决定——这些特征对个体来说是不直接可见的。结果表明，砧和锤的选择与特定任务的机械性能有关。黑猩猩选择较硬的石头做锤子，较软的石头做铁砧，这表明它们对不同功能的特定属性有不同的理解。岩石类型的选择性表明黑猩猩通过区分这些“看不见的”属性来评估合适的功能材料。成年人通过个人学习来识别机械特性，青少年经常重复使用成年人选择的工具。特定岩石类型的选择可以通过岩石组合的重复使用来传递。这些选择石头的模式与记载的奥尔多瓦古人类相似。在本实验中确定的过程提供了对上新世-更新世石器制品生产中人类岩石选择模式的离散性质的见解。
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