The Experts below are selected from a list of 1185 Experts worldwide ranked by ideXlab platform

Jeanjacques Hublin - One of the best experts on this subject based on the ideXlab platform.

  • Recent origin of low trabecular bone density in modern humans
    Proceedings of the National Academy of Sciences of the United States of America, 2014
    Co-Authors: Habiba Chirchir, Jeanjacques Hublin, Tracy L. Kivell, Christopher B. Ruff, Kristian J. Carlson, Bernhard Zipfel
    Abstract:

    Humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). Some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or how and when the present trabecular patterns emerged over the course of human evolution. Here, we test the hypotheses that (i) recent modern humans have low trabecular density throughout the upper and lower limbs compared with other primate taxa and (ii) the reduction in trabecular density first occurred in early Homo erectus, consistent with the shift toward a modern human locomotor anatomy, or more recently in concert with diaphyseal gracilization in Holocene humans. We used peripheral quantitative CT and microtomography to measure trabecular bone of limb epiphyses (long bone articular ends) in modern humans and chimpanzees and in fossil hominins attributed to Australopithecus africanus, Paranthropus robustus/early Homo from Swartkrans, Homo Neanderthalensis, and early Homo sapiens. Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations.

  • taxonomic differences in deciduous upper second molar crown outlines of Homo sapiens Homo Neanderthalensis and Homo erectus
    Journal of Human Evolution, 2014
    Co-Authors: Shara E Bailey, Stefano Benazzi, Caroline Souday, Claudia M Astorino, Kathleen S Paul, Jeanjacques Hublin
    Abstract:

    A significant number of Middle to Late Pleistocene sites contain primarily (and sometimes only) deciduous teeth (e.g., Grotta del Cavallo, Mezmaiskaya, Blombos). Not surprisingly, there has been a recent renewed interest in deciduous dental variation, especially in the context of distinguishing Homo Neanderthalensis and Homo sapiens. Most studies of the deciduous dentition of fossil hominins have focused on standard metrical variation but morphological (non-metric and morphometric) variation also promises to shed light on long standing taxonomic questions. This study examines the taxonomic significance of the crown outline of the deciduous upper second molar through principal components analysis and linear discriminant analysis. We examine whether or not the crown shape of the upper deciduous second molar separates H. Neanderthalensis from H. sapiens and explore whether it can be used to correctly assign individuals to taxa. It builds on previous studies by focusing on crown rather than cervical outline and by including a large sample of geographically diverse recent human populations. Our samples include 17 H. Neanderthalensis, five early H. sapiens, and 12 Upper Paleolithic H. sapiens. In addition, we include two Homo erectus specimens in order to evaluate the polarity of crown shape differences observed between H. Neanderthalensis and H. sapiens. Our results show that crown outline shape discriminates H. sapiens and H. Neanderthalensis quite well, but does not do well at distinguishing H. erectus from H. sapiens. We conclude that the crown outline shape observed in H. sapiens is a primitive retention and that the skewed shape observed in H. Neanderthalensis is a derived condition. Finally, we explore the phylogenetic implications of the results for the H. erectus molars.

  • a comprehensive morphometric analysis of the frontal and zygomatic bone of the zuttiyeh fossil from israel
    Journal of Human Evolution, 2012
    Co-Authors: Sarah E Freidline, Philip Gunz, Ivor Jankovic, Katarina Harvati, Jeanjacques Hublin
    Abstract:

    The Zuttiyeh hominin craniofacial fossil was discovered in Israel in 1925. Radiometric dates and the archaeological context (Acheulo-Yabrudian) bracket the associated cave layers to between 200 and 500 ka (thousands of years ago), making it one of the earliest cranial fossils discovered in the Near East thus far. Its geographic position, at the corridor between Africa and Eurasia, in combination with its probable Middle Pleistocene date make it a crucial specimen for interpreting later human evolution. Since its discovery, qualitative descriptive and traditional morphometric methods have variously suggested affinities to Homo erectus (Zhoukoudian), Homo Neanderthalensis (Tabun), and early Homo sapiens (Skhul and Qafzeh). To better determine the taxonomic affinities of the Zuttiyeh fossil, this study uses 3D semilandmark geometric morphometric techniques and multivariate statistical analyses to quantify the frontal and zygomatic region and compare it with other Middle to Late Pleistocene African and Eurasian hominins. Our results show that the frontal and zygomatic morphology of Zuttiyeh is most similar to Shanidar 5, a Near East Neanderthal, Arago 21, a European Middle Pleistocene hominin, and Skhul 5, an early H. sapiens. The shape differences between archaic hominins (i.e., Homo heidelbergensis and H. Neanderthalensis) in this anatomical region are very subtle. We conclude that Zuttiyeh exhibits a generalized frontal and zygomatic morphology, possibly indicative of the population that gave rise to modern humans and Neanderthals. However, given that it most likely postdates the split between these two lineages, Zuttiyeh might also be an early representative of the Neanderthal lineage. Neanderthals largely retained this generalized overall morphology, whereas recent modern humans depart from this presumably ancestral morphology.

  • what lies beneath an evaluation of lower molar trigonid crest patterns based on both dentine and enamel expression
    American Journal of Physical Anthropology, 2011
    Co-Authors: Shara E Bailey, Matthew M Skinner, Jeanjacques Hublin
    Abstract:

    Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany D-04103KEY WORDS H. Neanderthalensis; H. sapiens; Neandertals; modern humans; Pan;Australopithecus; middle trigonid crest; microCT; discrete dental traitsABSTRACT The nearly ubiquitous presence of a con-tinuous crest connecting the protoconid and metaconidof the lower molars (often referred to as the middletrigonid crest), is one of several dental traits that distin-guish Homo Neanderthalensis from Homo sapiens.Thisstudy examined variation in trigonid crest patterns on theenamel and dentine surfaces to (1) evaluate the concord-ance between the morphology of trigonid crests at theinner dentine and the outer enamel surfaces; (2) examinetheir developmental origin(s); and (3) examine trait polar-ity through comparison with Australopithecus africanusand Pan. The sample included 73 H. Neanderthalensis,67 contemporary H. sapiens,5A. africanus,and24Panlower molars. Results indicate general agreement inthe morphology observed on the dentine and enamel surfa-ces. All but one H. Neanderthalensis molar shows sometrigonid crest development, whereas trigonid crests occurin low frequency in contemporary humans. Pan and A.africanus both also show high frequencies of a continuoustrigonid crest. However, the origin of the trigonid crest dif-fers among groups. H. Neanderthalensis uniquely pos-sesses a ‘middle’ trigonid crest that originates from themesial accessory ridge of one or both cusps. Based on ourresults we suggest that presence of a continuous middletrigonid crest at the dentine surface is primitive andthe lack of any trigonid crest is derived. Genetic driftmay explain the high frequency of trigonid crests inH. Neanderthalensis. However, stillappears to be derived relative to Pan and A. africanusin its high frequency of the mesial-mesial trigonidcrest configuration. Am J Phys Anthropol 000:000–000,2011.

  • mandibular molar root morphology in neanderthals and late pleistocene and recent Homo sapiens
    Journal of Human Evolution, 2010
    Co-Authors: Kornelius Kupczik, Jeanjacques Hublin
    Abstract:

    Abstract Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo . Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo Neanderthalensis , and Late Pleistocene (Aterian) and recent Homo sapiens . We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible ( n  = 127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens . In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M 1 and M 2 is small. In contrast, Aterian H. sapiens root surface areas peak at M 2 . Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens .

Axel Timmermann - One of the best experts on this subject based on the ideXlab platform.

  • quantifying the potential causes of neanderthal extinction abrupt climate change versus competition and interbreeding
    Quaternary Science Reviews, 2020
    Co-Authors: Axel Timmermann
    Abstract:

    Abstract Anatomically Modern Humans are the sole survivor of a group of hominins that inhabited our planet during the last ice age and that included, among others, Homo Neanderthalensis, Homo denisova, and Homo erectus. Whether previous hominin extinctions were triggered by external factors, such as abrupt climate change, volcanic eruptions or whether competition and interbreeding played major roles in their demise still remains unresolved. Here I present a spatially resolved numerical hominin dispersal model (HDM) with empirically constrained key parameters that simulates the migration and interaction of Anatomically Modern Humans and Neanderthals in the rapidly varying climatic environment of the last ice age. The model simulations document that rapid temperature and vegetation changes associated with Dansgaard-Oeschger events were not major drivers of global Neanderthal extinction between 50 and 35 thousand years ago, but played important roles regionally, in particular over northern Europe. According to a series of parameter sensitivity experiments conducted with the HDM, a realistic extinction of the Neanderthal population can only be simulated when Homo sapiens is chosen to be considerably more effective in exploiting scarce glacial food resources as compared to Neanderthals.

  • Quantifying the potential causes of Neanderthal extinction: Abrupt climate change versus competition and interbreeding
    'Elsevier BV', 2020
    Co-Authors: Axel Timmermann
    Abstract:

    © 2020 The Author(s). Anatomically Modern Humans are the sole survivor of a group of hominins that inhabited our planet during the last ice age and that included, among others, Homo Neanderthalensis, Homo denisova, and Homo erectus. Whether previous hominin extinctions were triggered by external factors, such as abrupt climate change, volcanic eruptions or whether competition and interbreeding played major roles in their demise still remains unresolved. Here I present a spatially resolved numerical hominin dispersal model (HDM) with empirically constrained key parameters that simulates the migration and interaction of Anatomically Modern Humans and Neanderthals in the rapidly varying climatic environment of the last ice age. The model simulations document that rapid temperature and vegetation changes associated with Dansgaard-Oeschger events were not major drivers of global Neanderthal extinction between 50 and 35 thousand years ago, but played important roles regionally, in particular over northern Europe. According to a series of parameter sensitivity experiments conducted with the HDM, a realistic extinction of the Neanderthal population can only be simulated when Homo sapiens is chosen to be considerably more effective in exploiting scarce glacial food resources as compared to Neanderthals11sci

David Kaniewski - One of the best experts on this subject based on the ideXlab platform.

  • palaeovegetation from a Homo Neanderthalensis occupation in western liguria archaeopalynology of madonna dell arma san remo italy
    Journal of Archaeological Science, 2005
    Co-Authors: David Kaniewski, Josette Renaultmiskovsky, H De Lumley
    Abstract:

    Abstract This study presents a short local vegetation history of Western Liguria (San Remo), northwest Italy, based on a palynological analyses of an 8.30-m-long archaeological section in the dune covering Madonna dell'Arma cave. Madonna dell'Arma is one of the Mousterian caves currently located on the Ligurian coastal zone. The site contains Levallois-type Mousterian tools, four pieces of skull attributed to Homo Neanderthalensis and fauna remains belonging to Rhinoceros mercki , Elephas sp. and Hippopotamus amphibius . This study is of interest as the site is situated in an area where data on palaeovegetation are scarce. In fact, the archaeopollen analyses of Madonna dell'Arma cave's surroundings provide a rare local picture of vegetation during the beginning of OIS 4, posterior to 73,100 yr BP. The palynological taxa are grouped into three vegetation units by PCA (principal components analysis). These data suggest a huge Mediterranean pre-steppic forest ( Pinus , Quercus ilex and several herbs) colonizing the area during this substage. The adjacent valleys were colonized by a caducifoliate–alluvial forest and Mediterranean scrub vegetation. These vegetation characteristics suggest a semi-arid coastal climate with an increase of precipitation according to altitude. The PCA analyses of the palynological sections inside and outside the cave suggest a nearly continuous vegetation succession from OIS 5a to OIS 4.

  • reconstitution des paysages et des climats contemporains des Homo Neanderthalensis d apres l analyse pollinique de deux sites mousteriens ligures la grotte de madonna dell arma san remo et la grotte de santa lucia superiore toirano
    2002
    Co-Authors: David Kaniewski
    Abstract:

    Les analyses palynologiques des sites archeologiques de Madonna dell'Arma (Bussana, San Remo, Ligurie, Italie) et de Santa Lucia superiore (Toirano, Ligurie, Italie) permettent de reconstituer le cadre paleoenvironnemental et paleoclimatique de la Ligurie durant le Paleolithique moyen. La grotte de Madonna dell'Arma, situee sur le littoral ligure entre le torrent de l'Argentina et l'embouchure de l'Armea, renferme de nombreuses informations sur la vegetation contemporaine de l'occupation du site par les Homo Neanderthalensis et les Homo sapiens sapiens. Les sequences polliniques ont permis de differencier trois phases distinctes de depots dans la totalite du site, dont une partie karstique, un remplissage externe et une fraction gallo-romaine. Le remplissage de la partie karstique, dont la base repose sur une plage tyrrhenienne, s'est globalement effectue sous un climat chaud a tempere, en condition semi-aride, favorisant l'implantation durable d'une vegetation mediterraneenne. Cet episode interglaciaire, probablement integre dans le stade isotopique 5a, est marque par de courtes phases de degradation thermique et d'excedent pluviometrique ayant engendre l'expansion de zones marecageuses a proximite du site. Cette recrudescence de l'humidite a genere le developpement d'une foret alluviale en retrait du littoral et l'extension des elements mesophiles sur les bas-reliefs ligures. Surmontant cette phase interglaciaire, des depots, derivant vraisemblablement du stade isotopique 4, ont enregistre une variation du couvert vegetal consecutive a la degradation climatique suivant cet episode. La partie externe du site, attribuee au stade isotopique 3, est caracterisee apres une instabilite climatique favorisant tour a tour l'essor des taxons mediteraneens et des arbres mesophiles. Cette fluctuation du couvert vegetal tend a se reduire de l'assise vers le sommet de la sequence et s'effectue en faveur des elements mediterraneens. Dans la courte sequence gallo-romaine, l'instabilite climatique, percue au niveau de l'assise des depots entre des phases semi-arides et des epanchements d'humidite comparables aux niveaux mousteriens, tend a se reduire au profit de l'installation d'un climat mediterraneen stable. L'evolution du paysage environnant la commune de Toirano, dans l'arriere-pays ligure, montre deux phases heterogenes d'essor du couvert arbore en contexte global steppique. Le remplissage pollinique de la grotte de Santa Lucia superiore s'est globalement opere sous un climat plus frais que l'actuel, permettant l'emergence et l'expansion de Betula dans le domaine mediterraneen. Cependant, l'agencement sporadique d'especes arbustives temperees, voire thermophiles, suggere un repli du froid souscrivant a la reapparition de la foret caducifoliee. Le maintien de celle-ci lors de degradations climatiques semble du a la presence de zones abritees servant de refuges a un cortege floristique ecologiquement exigeant. Les oscillations des facteurs climatiques, deduites de la vegetation fossile, discriminent des paysages arides, marques par un deficit thermique precedant et succedant a des phases humides ou l'essor disparate des temperatures module la structure des corteges floristiques. Les milieux ouverts, dominants dans la sequence, se distinguent par une vegetation a Poaceae, a Asteraceae dont Artemisia et a Amaranthaceae-Chenopodiaceae ou se discernent de vastes frequences de Cichoroideae, marqueurs d'alteration en contexte archeologique. L'ensemble de la sequence semble traverser les stades isotopiques 4 et 3. La nature essentiellement sablo-argileuse des remplissages sedimentaires des grottes de Madonna dell'Arma et de Santa Lucia superiore a entraine une evolution physico-chimique des milieux de depots nefaste a la conservation de l'integralite de la pluie pollinique mousterienne et gallo-romaine. Les processus de conservation differentielle ou d'apport preferentiel en contexte karstique generent d'une part, une multiplication des niveaux steriles et d'autre part, une baisse de la concentration sporopollinique. Aces phenomenes se surimposent des discontinuites stratigraphiques perturbant toute approche chronologique ainsi que des lacunes intra-sequentielles perceptibles dans l'absence d'une dynamique de vegetation. Outre ces processus, la grotte de Madonna dell'Arma a enregistre l'intrusion de pollens exotiques actuels ou sub-actuels tels qu'acacia ayant contamine les zones Mad. 8 (Mousterien) et Mad. 12 (Gallo-romain). Par opposition, la grotte de Santa Lucia superiore est principalement marquee par le processus de conservation differentielle, percu dans l'ample representation des Asteraceae Cichoroideae. Dans cette configuration karstique, les conclusions paleoenvironnementales et paleoclimatiques resultant des analyses polliniques de Madonna dell'Arma et de Santa Lucia superiore doivent etre confrontees avec des resultats d'autres disciplines et integrees dans un contexte local afin d'obtenir une plus grande exactitude.

H De Lumley - One of the best experts on this subject based on the ideXlab platform.

  • palaeovegetation from a Homo Neanderthalensis occupation in western liguria archaeopalynology of madonna dell arma san remo italy
    Journal of Archaeological Science, 2005
    Co-Authors: David Kaniewski, Josette Renaultmiskovsky, H De Lumley
    Abstract:

    Abstract This study presents a short local vegetation history of Western Liguria (San Remo), northwest Italy, based on a palynological analyses of an 8.30-m-long archaeological section in the dune covering Madonna dell'Arma cave. Madonna dell'Arma is one of the Mousterian caves currently located on the Ligurian coastal zone. The site contains Levallois-type Mousterian tools, four pieces of skull attributed to Homo Neanderthalensis and fauna remains belonging to Rhinoceros mercki , Elephas sp. and Hippopotamus amphibius . This study is of interest as the site is situated in an area where data on palaeovegetation are scarce. In fact, the archaeopollen analyses of Madonna dell'Arma cave's surroundings provide a rare local picture of vegetation during the beginning of OIS 4, posterior to 73,100 yr BP. The palynological taxa are grouped into three vegetation units by PCA (principal components analysis). These data suggest a huge Mediterranean pre-steppic forest ( Pinus , Quercus ilex and several herbs) colonizing the area during this substage. The adjacent valleys were colonized by a caducifoliate–alluvial forest and Mediterranean scrub vegetation. These vegetation characteristics suggest a semi-arid coastal climate with an increase of precipitation according to altitude. The PCA analyses of the palynological sections inside and outside the cave suggest a nearly continuous vegetation succession from OIS 5a to OIS 4.

Jose Maria Bermudez De Castro - One of the best experts on this subject based on the ideXlab platform.

  • hominin teeth from the early late pleistocene site of xujiayao northern china
    American Journal of Physical Anthropology, 2015
    Co-Authors: Song Xing, Jose Maria Bermudez De Castro, Maria Martinontorres, Wu Liu
    Abstract:

    It is generally accepted that from the late Middle to the early Late Pleistocene (∼340-90 ka BP), Neanderthals were occupying Europe and Western Asia, whereas anatomically modern humans were present in the African continent. In contrast, the paucity of hominin fossil evidence from East Asia from this period impedes a complete evolutionary picture of the genus Homo, as well as assessment of the possible contribution of or interaction with Asian hominins in the evolution of Homo sapiens and Homo Neanderthalensis. Here we present a comparative study of a hominin dental sample recovered from the Xujiayao site, in Northern China, attributed to the early Late Pleistocene (MIS 5 to 4). Our dental study reveals a mosaic of primitive and derived dental features for the Xujiayao hominins that can be summarized as follows: i) they are different from archaic and recent modern humans, ii) they present some features that are common but not exclusive to the Neanderthal lineage, and iii) they retain some primitive conformations classically found in East Asian Early and Middle Pleistocene hominins despite their young geological age. Thus, our study evinces the existence in China of a population of unclear taxonomic status with regard to other contemporary populations such as H. sapiens and H. Neanderthalensis. The morphological and metric studies of the Xujiayao teeth expand the variability known for early Late Pleistocene hominin fossils and suggest the possibility that a primitive hominin lineage may have survived late into the Late Pleistocene in China.

  • hominin variability climatic instability and population demography in middle pleistocene europe
    Quaternary Science Reviews, 2011
    Co-Authors: Robin Dennell, Maria Martinontorres, Jose Maria Bermudez De Castro
    Abstract:

    Abstract We propose a population model for Middle Pleistocene Europe that is based on demographic “sources” and “sinks”. The former were a small number of “core” or populations in glacial refugia in southern Europe from which hominins expanded northwards in interstadial and interglacial periods; occupation outside glacial refugia would have been restricted to warm or temperate periods, and populations at the northern limit of the Middle Pleistocene range would have been “sink” populations in that they depended upon recruitment from source populations further south. Southwest Asia would also have been a likely source of immigrant, source populations. We argue as an alternative to an “ebb and flow” model in which groups retreated to refugia when conditions worsened that local extinction outside refugia would have been frequent. In extreme situations, Europe may have been a population “sink” (i.e. unpopulated) that was replenished from source populations in Southwest Asia. We suggest that this pattern of repeated colonisation and extinction may help explain the morphological variability of European Middle Pleistocene hominins, particularly Homo heidelbergensis and its apparent non-lineal evolution towards Homo Neanderthalensis .

  • Surprisingly rapid growth in Neanderthals
    Nature, 2004
    Co-Authors: Fernando Ramirez Rozzi, Jose Maria Bermudez De Castro
    Abstract:

    Life-history traits correlate closely with dental growth1, so differences in dental growth within Homo can enable us to determine how somatic development has evolved and to identify developmental shifts that warrant species-level distinctions2,3,4. Dental growth can be determined from the speed of enamel formation (or extension rate)5,6. We analysed the enamel extension rate in Homo antecessor (8 teeth analysed), Homo heidelbergensis (106), Homo Neanderthalensis (‘Neanderthals’; 146) and Upper Palaeolithic-Mesolithic Homo sapiens (100). Here we report that Upper Palaeolithic-Mesolithic H. sapiens shared an identical dental development pattern with modern humans, but that H. antecessor and H. heidelbergensis had shorter periods of dental growth. Surprisingly, Neanderthals were characterized by having the shortest period of dental growth. Because dental growth is an excellent indicator of somatic development1, our results suggest that Neanderthals developed faster even than their immediate ancestor, H. heidelbergensis. Dental growth became longer and brain size increased from the Plio-Pleistocene in hominid evolution. Neanderthals, despite having a large brain, were characterized by a short period of development. This autapomorphy in growth is an evolutionary reversal, and points strongly to a specific distinction between H. sapiens and H. Neanderthalensis.