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C Berge

Publications and source records attributed to C Berge.

10 recordsLinked to original sources
PubMed2002

Heterochronic patterns in primate evolution: evidence from endochondral ossification.

Heterochrony (evolutionary modifications in developmental timing and/or rates) is widely recognized as an important agent of morphological change. The adaptive significance of heterochronic changes might lie either in the advantages of the derived morphologies (organ size and shape) or the derived growth parameters themselves (rate and duration of growth). We have tested these hypotheses by comparing the growth rate, the duration of growth and the relative length of the adult tibia in Primates in a phylogenetic context. We report an evolutionary decrease in growth rates (paedochronocline) and an increase in the duration of growth (perachronocline), lying in the cline from the last common ancestor of Primates, passing through the last common ancestor of Haplorhini, that of Catarrhini, to the last common ancestor of the Hominidae. However, the variation in the relative length of the adult tibia does not show any phylogenetic pattern. The derived growth parameters in themselves (slower rate, longer duration) would be of adaptive significance and they would have been selected because a prolonged learning period prior to maturity conferred advantage. The proximate (developmental) causation of differences in bone growth rate were also investigated and it was found that cell production rate in the growth plates rather than the chondrocyte size, underlies the variation in bone growth rate.

Analysis of Variance↗
PubMed2001

[Heterochronia via procrustean superimposition: application to the skulls of Homonidae primates].

The procrustes superimposition method is well adapted to heterochronic studies in the field of evolutionary biology. 1) The procrustes method gives a precise and mathematical definition of two of the three heterochronic variables: size and shape. 2) It allows us to describe complex anatomical structures and thus to analyse the whole structure and not just to proceed trait by trait. 3) The approach is statistical and the different hypotheses and results may be statistically tested. 4) When applied to heterochronies the method allows us to test if there is a common shape change related to allometry. In the present study of three species of Hominoid primates, the procrustes superimposition reveals that various heterochronic processes are simultaneously present. Size-age-shape dissociations between species, already present in the first ontogenetic stage, are amplified with growth until adult stage. As compared with that of the chimpanzee, the growth of the gorilla skull is accelerated in terms of size-shape covariation and size alone. The growth of the human skull is neotenic as compared with that of the apes.

Adult↗
PubMed2001

Modeling three-dimensional sculptures of australopithecines (Australopithecus afarensis) for the Museum of Natural History of Vienna (Austria): the post-cranial hypothesis.

In March 1999, E. Daynes, a sculptor specializing in fossil hominid reconstruction, asked C. Berge to take over the scientific supervision of the reconstruction of two australopithecine post-crania. The heads had been modeled from two skulls found in Hadar (AL 444-2, AL 417). The sculptures were to be represented in a walking stance. The female proportions (AL 417) are estimated from the skeleton of 'Lucy' (AL 288), and the male proportions (AL 444-2) extrapolated from the female ones. Biomechanical and anatomical data (comparison with great apes and humans) are used to reconstruct both dynamic equilibrium and muscular systems. The reconstruction suggests that the fossils moved the pelvis and shoulders extensively when they walked. The hindlimb muscles (such as adductors, gluteal muscles and calf) are fleshy and not or very little tendinous. As indicated by the Laetoli step prints (belonging to a close and contemporaneous species), the foot is adducted during the walk and the support is internal just before take off. In spite of inevitable approximations, such a reconstruction appears to be particularly helpful to bring out morphological and functional traits of the first hominids which are both close to and different from modern humans.

Animals↗
PubMed1998

Heterochronic processes in human evolution: an ontogenetic analysis of the hominid pelvis.

Changes in pelvic shape in human ontogeny and hominid phylogeny suggest that the heterochronic processes involved differ greatly from the neotenic process traditionally described in the evolution of the skull. The morphology of 150 juvenile and adult pelves of African apes, 60 juvenile and adult pelves of modern humans, two adult pelves and a juvenile hip bone of australopithecines (Sts 14, AL 288, MLD 7) was studied. Multivariate results, ontogenetic allometries, and growth curves confirm that the pelvic growth pattern in humans differs markedly from those of the African apes. The results permit the following conclusions. First, the appearance of a new feature (acetabulo-cristal buttress and cristal tubercle) at the time of human birth allows the addition of traits, such as the attainment of a proportionally narrower pelvis, with more sagittally positioned iliac blades. Pelvic proportions and orientation change progressively in early childhood as bipedalism is practiced. Other changes in pelvic proportions occur later with the adolescent growth spurt. Second, comparison of juvenile and adult australopithecines to modern humans indicates that 1) some pelvic traits of adult Australopithecus resemble those of neonate Homo; 2) the pelvic growth of Australopithecus was probably closer to that of apes, than to that of humans; and 3) prolonged growth in length of hindlimb and pelvis after sexual maturity seems to be a unique feature of Homo. The position of the acetabulo-cristal buttress and of the cristal tubercle on the ilium are similar in adult Australopithecus and neonate Homo suggesting that this feature may have been displaced later during hominid evolution. Progressive displacement of the acetabulo-cristal buttress on the ilium occurs both during hominid evolution (from Australopithecus to Homo sapiens) and human growth (from neonate to adult). This suggests peramorphic evolution of the pelvic morphology of hominids combining three processes of recapitulation (pre-displacement, acceleration and time hypermorphosis). The results lend credence to the hypothesis that no single heterochronic process accounts for all human evolutionary change; rather this reflects a combination of relative changes in growth rhythm and duration, including other perturbations, such as the appearance of new morphological features.

Adolescent↗
PubMed1997

The length of the vertebral column of primates: an allometric study.

The length of the vertebral column of 425 primates (151 prosimians, 76 platyrrhines and 198 catarrhines) was related to body mass from bibliographic sources. Regressions were calculated for the whole sample and separately for the three taxonomic groups quoted above. In parallel, the lengths of the cervical, thoracic and lumbar regions were calculated in a sample of 105 primates (30 prosimians, 19 platyrrhines and 56 catarrhines) and partial correlations established. In all cases except one, the correlation coefficients were significant. Of these, 12 correlations (out of 16) scaled with negative allometry (< 0.33), 4 with positive allometry (> 0.33), and in 6 cases the exponents were not significantly different from the criterion for isometry (0.33). The lumbar region showed the highest variability, mainly in platyrrhines and catarrhines. Results from catarrhines are globally the closest to the expectations of elastic similarity. No obvious direct relationship was found between the length of the vertebral column and the number of vertebrae.

Analysis of Variance↗
PubMed1997

Absence of bleeding complications in patients undergoing cortical surgery while receiving valproate treatment.

Valproate (VPA) is associated with a variety of idiosyncratic hematological effects including thrombocytopenia, inhibition of platelet aggregation, and fibrinogen depletion. This has led some investigators to recommend discontinuation of VPA therapy prior to elective surgical procedures. However, administration of VPA therapy is not altered prior to surgery at the authors' center and no VPA-associated bleeding complications have been observed. Therefore, a retrospective chart review was conducted to verify the clinical observations in patients who had undergone cortical resection while receiving antiepileptic drugs (AEDs). Baseline, surgical, and postoperative laboratory data were available for a total of 313 patients, 111 of whom were receiving VPA and 202 of whom were receiving AEDs without VPA (control patients). Eighty-seven percent of the patients receiving VPA were also being treated with at least one other AED. The control group was approximately equally divided between monotherapy (55%) and polytherapy (45%) treatments. Platelet counts were significantly lower in the control polytherapy (284 +/- 74 x 10(9)/L) and both VPA groups (279 +/- 113 x 10(9)/L) as compared with the control monotherapy group (314 +/- 85 x 10(9)/L). Baseline fibrinogen levels were significantly lower in the VPA than in the control groups (223 +/- 91 g/dl vs. 278 +/- 95 g/dl). Both pre- and postoperatively, the VPA group had lower red blood cells counts, hematocrit, and hemoglobin levels. There was no significant difference between groups in estimated blood loss during surgery or qualitative wound discharge postsurgery. There was only one case of a bleeding complication, which occurred 14 days postoperatively in a patient receiving carbamazepine monotherapy. The results of this study confirm the clinical observations of an absence of bleeding complications in patients receiving VPA therapy at the time of surgery, despite differences in laboratory parameters.

Adult↗
PubMed1986

Effects of size and locomotor adaptations on the hominid pelvis: evaluation of australopithecine bipedality with a new multivariate method.

Three pelves and eight innominate bones belonging to the fossil species, Australopithecus africanus, Australopithecus robustus, Homo erectus, and Homo sapiens, have been studied biometrically and compared with those of recent humans and apes. A new method of logarithmic factorial analysis suppresses both the size effects and the size reference on pelvic proportions. In combination with principal component analysis it allows specializations to be dissociated from allometrical variations. Some morphological differences on the hominid pelvis prove to be mainly allometric. However, the pelvic morphology of australopithecines is clearly differentiated from that of the genus Homo (including H. erectus, OH 28, KNMER 3227). A. africanus (Sts 14, MLD 7, AL 288) is nearer the humans than is A. robustus (SK 50, SK 3155), which appears to be more specialized in the australopithecine lineage. The pelvic morphology of A. africanus, as integrated with the articular pelvic-femoral link, appears to be biometrically equivalent to that of humans.

Animals↗
PubMedDate not supplied

A biomechanical study of the long bones in platyrrhines.

The long bones of 72 individuals of extant platyrrhines, belonging to 17 species (11 genera) were studied by regressions of length, diameters and curvature. Cross-sectional shapes at midshaft and axial and bending strength indicators were also calculated. Results show that forelimb bones scale faster than hindlimb bones, for both length and diameters. Curvature scales faster in the femur than in other bones. Strength indicators showed a high variability in the relative importance of axial and bending loadings. Results are consistent with field observations of locomotor behaviour, mainly as regards quadrupedalism versus suspensory locomotion.

Animals↗