Sandrine Prat

3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya

Human evolutionary scholars have long supposed that the earliest stone tools were made by the genus Homo and that this technological development was directly linked to climate change and the spread of savannah grasslands. New fieldwork in West Turkana, Kenya, has identified evidence of much earlier hominin technological behaviour. We report the discovery of Lomekwi 3, a 3.3-million-year-old archaeological site where in situ stone artefacts occur in spatiotemporal association with Pliocene hominin fossils in a wooded palaeoenvironment. The Lomekwi 3 knappers, with a developing understanding of stone’s fracture properties, combined core reduction with battering activities. Given the implications of the Lomekwi 3 assemblage for models aiming to converge environmental change, hominin evolution and technological origins, we propose for it the name ‘Lomekwian’, which predates the Oldowan by 700,000 years and marks a new beginning to the known archaeological record.

The Oldest Anatomically Modern Humans from Far Southeast Europe: Direct Dating, Culture and Behavior

Background Anatomically Modern Humans (AMHs) are known to have spread across Europe during the period coinciding with the Middle to Upper Paleolithic transition. Whereas their dispersal into Western Europe is relatively well established, evidence of an early settlement of Eastern Europe by modern humans are comparatively scarce. Methodology/Principal Finding Based on a multidisciplinary approach for the study of human and faunal remains, we describe here the oldest AMH remains from the extreme southeast Europe, in conjunction with their associated cultural and paleoecological background. We applied taxonomy, paleoecology, and taphonomy combined with geomorphology, stratigraphy, archeology and radiocarbon dating. More than 160 human bone remains have been discovered. They originate from a well documented Upper Paleolithic archeological layer (Gravettian cultural tradition) from the site of Buran-Kaya III located in Crimea (Ukraine). The combination of non-metric dental traits and the morphology of the occipital bones allow us to attribute the human remains to Anatomically Modern Humans. A set of human and faunal remains from this layer has been radiocarbon dated by Accelerator Mass Spectrometry. The direct-dating results of human bone establish a secure presence of AMHs at 31,900+240/−220 BP in this region. They are the oldest direct evidence of the presence of AMHs in a well documented archeological context. Based on taphonomical observations (cut marks and distribution of skeletal elements), they represent the oldest Upper Paleolithic modern humans from Eastern Europe, showing post-mortem treatment of the dead as well. Conclusion/Significance These findings are essential for the debate on the spread of modern humans in Europe during the Upper Paleolithic, as well as their cultural behaviors.

Fossil hominins, quadrupedal primates and the origin of human bipedalism: a 3D geometric morphometric analysis of the Primate hamate

This note illustrates the value of studying non-human primates, especially quadrupedal primates, in order to investigate the origins of human bipedalism. Two distinct hypotheses postulate that hominins and African great apes share a common ancestor predominantly engaged in specialized forms of locomotion, i.e., arboreal orthogrady (climbing or arboreal bipedalism) on the one hand and semiterrestrial locomotion (which includes climbing and quadrupedalism) on the other. Both hypotheses are supported by analysis of the wrist morphology of Pliocene hominins, and both have recently been challenged by a third hypothesis based on the study of Ardipithecus ramidus wrist morphology, which has shown general affinities between the latter hominin and quadrupedal primates. However, all three interpretations rely on rather limited knowledge of the variability of wrist bones in quadrupedal primates. Here, we propose to address the question of the origins of human bipedalism by means of a three-dimensional analysis of a carpal bone, the hamate, whose morphology appears to vary according to the locomotor behaviour of primates. We compared the original specimens of Pliocene hominins (Australopithecus) with a large sample of non-human primates, including various quadrupedal anthropoids. Our results confirm that, on the one hand, the shape of the hamate in primates varies significantly according to their locomotor behaviour and, on the other hand, that the hypothesis of the semiterrestrial origin of human bipedalism can be rejected. The affinities between Pliocene hominins and most of extant quadrupedal primates indicate that the hands of early hominins partly retained a morphology inherited from a generalist quadrupedal ancestor, which concurs with the hypothesis recently proposed from the hand bones of Ar. ramidus.RésuméCette note vise à illustrer l’intérêt d’étudier les primates non-humains, notamment quadrupèdes, pour mieux caractériser l’origine de la bipédie humaine. Deux hypothèses stipulent que les homininés partageraient avec les grands singes africains un ancêtre commun impliqué majoritairement dans une forme de locomotion spécialisée, à savoir : l’hypothèse d’une orthogradie arboricole (grimper ou bipédie arboricole) et l’hypothèse d’une semi-terrestrialité (qui inclue quadrupédie et grimper). Ces deux propositions sont notamment supportées par l’analyse morphologique du poignet des homininés pliocènes. Ces propositions ont été récemment remises en cause par une troisième interprétation fondée sur l’étude morphologique des os du poignet d’Ardipithecus ramidus, et qui a mis en évidence des affinités globales entre ce dernier homininé et des singes quadrupèdes. Cependant, ces trois propositions reposent sur une connaissance limitée de la variabilité de ces os chez les primates quadrupèdes. Nous proposons donc d’aborder la question de l’origine de la bipédie humaine par l’analyse tri-dimensionnelle d’un os carpien, l’hamatum, dont la morphologie varierait selon les modes locomoteurs des primates, en considérant des fossiles originaux d’homininés (Australopithecus) ainsi qu’un large échantillon d’anthropoïdes actuels, incluant une grande variété de primates quadrupèdes. Nos résultats confirment d’une part, que la forme de l’hamatum des primates varie selon les comportements locomoteurs, et d’autre part, que l’hypothèse d’une origine semiterrestre de la bipédie humaine peut être rejetée. Les affinités entre les homininés pliocènes et la plupart des primates quadrupèdes actuels soutiennent que les mains des homininés anciens ont en partie retenu une morphologie héritée d’un primate quadrupède généraliste. Ce résultat est en accord avec l’hypothèse récemment proposée à partir des os de la main d’Ar. ramidus.

Least Destructive Rapid Scanning of Human Teeth to Test Their Suitability for U-Series Analysis

Excavations in the Grotte de la Chevre have taken place since the 19th century and yielded more than 100 human specimens together with numerous artifacts from the Middle Paleolithic, Upper Paleolithic, and more recent times. Unfortunately, due to considerably different excavation standards in earlier excavations, none of the specimens can be securely provenienced. Some of the remains may represent oldest humans fossils found in historic Brittany. This can only be confirmed through direct dating. On faunal materials, U-series dating is usually carried out a series of analyses along a cross-section profile, which necessitates the cutting of the specimen. Here, we present a rapid scanning method, which allows the assessment of whether a sample is actually suited for U-series dating with minimal sample damage. Laser ablation ICP-MS was used for the analysis of U-series isotopes close to the surface of the roots of two teeth from the Grotte de la Chevre. The laser analysis created pits with a diameter of about 200µm and a depth of about 100µm. This allowed the assessment of the 230 Th concentrations close to the surface of the dentine where the oldest apparent U-series ages are expected. In the first sample, all isotopic con centrations were too low for the calculation of meaningful U-series results, while the second sample yielded very low 230 Th/ 238 U activity ratios, indicating a recent age of perhaps a few thousand years. Consequently, both teeth did not require any further destruction. Rapid scanning can be applied to a large number of samples to identify those which will most likely yield reasonable age estimations, leading to informed decisions about geochronological sampling strategies, including radiocarbon. We envisage that laser ablation spot analyses also could be used to obtain U-series depth profiles, which are required for open system dating, as well as depth profiles for other isotopes (e.g., Sr, Pb) to gain insights into prehistoric human migrations.

Longitudinal studies of craniofacial growth in Primates: a short review of radiographic studies

Growth studies on human and nonhuman primates contribute to a range of research topics such as somatic growth and the establishment of charts for growth and skeletal maturity, and therefore provide a valuable evolutionary perspective. Longitudinal studies, especially long-term ones, provide the most accurate data to assess the factors that influence growth and development, and to construct growth velocity curves. In this note, we present the main long-term longitudinal radiographic studies of craniofacial growth in human and nonhuman primates. Such studies are extremely rare as they are costly and difficult to implement, especially when ethical and health constraints arise due to the use of X-ray radiographs.RésuméLes études portant sur la croissance des primates humains et non humains sont utilisées dans différents domaines de recherche tels que la croissance somatique, l’établissement de chartes de croissance et de maturation squelettique ou dans une perspective évolutive. Les études longitudinales, et en particulier celles entreprises sur une longue durée, apparaissent comme les plus pertinentes pour reconstruire les courbes de vitesse de croissance et évaluer les facteurs qui influencent la croissance et le développement. Dans cette note, les principales études radiographiques longitudinales portant sur la croissance crânio-faciale des primates humains et non humains sont présentées. Ces études sont très rares car coûteuses et difficiles à mettre en place en particulier pour des raisons éthiques et sanitaires lorsque des radiographies sont effectuées.