Body size and body shape in early hominins - implications of the Gona pelvis.
ABSTRACT Discovery of the first complete Early Pleistocene hominin pelvis, Gona BSN49/P27, attributed to Homo erectus, raises a number of issues regarding early hominin body size and shape variation. Here, acetabular breadth, femoral head breadth, and body mass calculated from femoral head breadth are compared in 37 early hominin (6.0-0.26 Ma) specimens, including BSN49/P27. Acetabular and estimated femoral head sizes in the Gona specimen fall close to the means for non-Homo specimens (Orrorin tugenesis, Australopithecus africanus, Paranthropus robustus), and well below the ranges of all previously described Early and Middle Pleistocene Homo specimens. The Gona specimen has an estimated body mass of 33.2kg, close to the mean for the non-Homo sample (34.1kg, range 24-51.5kg, n=19) and far outside the range for any previously known Homo specimen (mean=70.5kg; range 52-82kg, n=17). Inclusion of the Gona specimen within H. erectus increases inferred sexual dimorphism in body mass in this taxon to a level greater than that observed here for any other hominin taxon, and increases variation in body mass within H. erectus females to a level much greater than that observed for any living primate species. This raises questions regarding the taxonomic attribution of the Gona specimen. When considered within the context of overall variation in body breadth among early hominins, the mediolaterally very wide Gona pelvis fits within the distribution of other lower latitude Early and Middle Pleistocene specimens, and below that of higher latitude specimens. Thus, ecogeographic variation in body breadth was present among earlier hominins as it is in living humans. The increased M-L pelvic breadth in all earlier hominins relative to modern humans is related to an increase in ellipticity of the birth canal, possibly as a result of a non-rotational birth mechanism that was common to both australopithecines and archaic Homo.
Article: Neandertal clavicle length.[Show abstract] [Hide abstract]
ABSTRACT: The Late Pleistocene archaic humans from western Eurasia (the Neandertals) have been described for a century as exhibiting absolutely and relatively long clavicles. This aspect of their body proportions has been used to distinguish them from modern humans, invoked to account for other aspects of their anatomy and genetics, used in assessments of their phylogenetic polarities, and used as evidence for Late Pleistocene population relationships. However, it has been unclear whether the usual scaling of Neandertal clavicular lengths to their associated humeral lengths reflects long clavicles, short humeri, or both. Neandertal clavicle lengths, along with those of early modern humans and latitudinally diverse recent humans, were compared with both humeral lengths and estimated body masses (based on femoral head diameters). The Neandertal do have long clavicles relative their humeri, even though they fall within the ranges of variation of early and recent humans. However, when scaled to body masses, their humeral lengths are relatively short, and their clavicular lengths are indistinguishable from those of Late Pleistocene and recent modern humans. The few sufficiently complete Early Pleistocene Homo clavicles seem to have relative lengths also well within recent human variation. Therefore, appropriately scaled clavicular length seems to have varied little through the genus Homo, and it should not be used to account for other aspects of Neandertal biology or their phylogenetic status.Proceedings of the National Academy of Sciences 03/2014; · 9.81 Impact Factor
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ABSTRACT: Human evolution unfolded through a rather distinctive, dynamically constructed ecological niche. The human niche is not only generally terrestrial in habitat, while being flexibly and extensively heterotrophic in food-web connections. It is also defined by semiotically structured and structuring embodied cognitive interfaces, connecting the individual organism with the wider environment. The embodied dimensions of niche-population co-evolution have long involved semiotic system construction, which I hypothesize to be an evolutionarily primitive aspect of learning and higher-level cognitive integration and attention in the great apes and humans alike. A clearly pre-linguistic form of semiotic cognitive structuration is suggested to involve recursively learned and constructed object icons. Higher-level cognitive iconic representation of visually, auditorily, or haptically perceived extrasomatic objects would be learned and evoked through indexical connections to proprioceptive and affective somatic states. Thus, private cognitive signs would be defined, not only by their learned and perceived extrasomatic referents, but also by their associations to iconically represented somatic states. This evolutionary modification of animal associative learning is suggested to be adaptive in ecological niches occupied by long-lived, large-bodied ape species, facilitating memory construction and recall in highly varied foraging and social contexts, while sustaining selective attention during goal-directed behavioral sequences. The embodied niche construction (ENC) hypothesis of human evolution posits that in the early hominin lineage, natural selection further modified the ancestral ape semiotic adaptations, favoring the recursive structuration of concise iconic narratives of embodied interaction with the environment.Frontiers in Psychology 08/2014; 5:834. · 2.80 Impact Factor
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ABSTRACT: Le but de ce travail est d’évaluer le risque de disproportion fœtopelvienne au sein d’espèces d’homininés fossiles. L’observation de 92 cas d’accouchements actuels a permis de recueillir les dimensions du bassin maternel, du crâne fœtal et l’issue du travail (physiologique : n = 43, césarienne pour « disproportion fœtopelvienne » : n = 34 ou extraction instrumentale : n = 15). Les données fossiles proviennent d’une recherche bibliographique incluant 12 reconstructions de bassin et six crânes juvéniles. Les dimensions néonatales fossiles ont été estimées par deux approches : 1) à partir des dimensions des crânes juvéniles et de courbes de croissance humaine et de chimpanzé ; 2) en utilisant les capacités crâniennes néonatales estimées par DeSilva et Lesnik (2008). Malgré un taux d’erreur apparente de 35 %, une analyse discriminante linéaire (ADL) permet de reconnaître une zone d’accouchement eutocique, une zone d’accouchement dystocique et une zone intermédiaire où les variables maternofœtales ne permettent pas de déterminer l’issue du travail. Les combinatoires des couples « virtuels » fossiles entre les reconstructions de bassin et les estimations crâniennes fœtales ont été projetées a posteriori sur l’ADL et traduisent le plus souvent un accouchement eutocique. En effet, la probabilité d’appartenance au groupe d’accouchement eutocique des Australopithèques est en moyenne de 0,99 ± 0,01, de 0,76 ± 0,15 pour les Homo erectus s.l. et de 0,86 ± 0,08 pour les Néandertaliens.Bulletins et Mémoires de la Société d anthropologie de Paris 01/2013; 25.