Christine Berge

Obstetrical interpretation of the Australopithecine pelvic cavity

The pelvic cavities two australopithecines (Al 288, Sts 14) are studied biometrically in relation to a sample of extant human and non-human primates. Human obstetrical characteristics correspond to (1) a generic adaptation of the pelvic outlet which is opened ventrally to the ischial tuberosities, and (2) a sexual adaptation of the female inlet which is particularly enlarged between the hip joints and the pubic rami. The australopithecine pelvis presents most of these characteristics, but offers some significant dissimilarities notably an extreme biacetabular enlargement and a very specific morphology of the pubic region. A series of deductions leads us to suggest a Homo-like obstetrical mechanism for Australopithecus, characterized by the rotation and the flexion of the neonate, with fetal skull size similar to the one of the neonate chimpanzee, in the pelvic cavity. The constraints on the fetal skull are consequently as important as in human delivery. This means that the phenomenon of encephalization which took place during the evolution of the hominids could not be the result of an increase of the neonate cerebral capacity but was rather a consequence of neotenic change in growth-rhythm of the newborn.

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.

A new reconstruction of Sts 14 pelvis (Australopithecus africanus) from computed tomography and three-dimensional modeling techniques.

The purpose of this study is to propose a new reconstruction of the australopithecine Sts 14 pelvis from original fossils. Digital models created from CT images allow us to perform mirroring operations, select valid regions after digital interposition, and reassemble parts. The key-element of the reconstruction is the sacroiliac joint, restored from right and left articular surfaces, which places of the pubic symphysis close to the sagittal plane. The complete pelvis is obtained by 3D model mirroring of hip-bone and sacrum. The present reconstruction of the Sts 14 pelvis is consistent with Schmids (1983) [Folia Primatol. 40, 283-306, 1983] and Häusler and Schmids A.L. 288-1 [J. Hum. Evol. 29, 363-383, 1995] pelvic reconstructions by illustrating a relatively platypelloid shape of the pelvic cavity and laterally inclined iliac blades. The pelvic morphology suggests that australopithecines had a less posteriorly tilted sacrum in erect posture than modern humans. As compared with Lovejoys [Am. J. Phys. Anthropol. Suppl. 50, 460, 1979] A.L. 288-1 pelvic reconstruction, the less transversely flattened shape of the Sts 14 pelvic cavity led to obstetrical mechanics characterized as in humans by ante-ischiatic birth and a curved trajectory. We deduce a human-like movement of rotation and flexion of the fetal skull in the Sts 14 pelvic cavity.

Geometric morphometrics of the shoulder girdle in extant turtles (Chelonii).

The aim of this study was to identify shape patterns of the shoulder girdle in relation to different functional and environmental behaviours in turtles. The Procrustes method was used to compare the shoulder girdles (scapula and coracoid) of 88 adult extant turtles. The results indicate that four shape patterns can be distinguished. The shoulder girdles of (1) terrestrial (Testudinidae), (2) highly aquatic freshwater (Trionychidae, Carettochelyidae) and (3) marine turtles (Cheloniidae, Dermochelyidae) correspond to three specialized morphological patterns, whereas the shoulder girdle of (4) semi‐aquatic freshwater turtles (Bataguridae, Chelidae, Chelydridae, Emydidae, Kinosternidae, Pelomedusidae, Platysternidae, Podocnemididae) is more generalized. In terrestrial turtles, the long scapular prong and the short coracoid are associated with a domed shell and a mode of locomotion in which walking is predominant. By contrast, highly aquatic freshwater turtles share traits with marine turtles. In both, the short scapular prong and the long coracoid are associated with a flat shell, and swimming locomotion. The enlarged attachment sites of the biceps, coracobrachialis magnus, and supracoracoideus also give these strong swimmers a mechanical advantage during adduction and retraction of the arm. Increasing size leads to allometrical shape changes that emphasize mechanical efficiency both in terrestrial and in aquatic turtles.

Multivariate analysis of the pelvis for hominids and other extant primates: Implications for the locomotion and systematics of the different species of australopithecines

Casts of innominate bones from five australopithecines and one Homo erectus were studied by factorial analysis (11 measurements) in relation to a sample of 367 innominate bones belonging to 19 genera of extant catarrhines. The australopithecine pattern differs from that of Homo (H. erectus, H. sapiens). It corresponds to another type of bipedal adaptation. The gracile species (A. africanus, A. afarensis), which are less advanced in the australopithecine specialization than the robust one (A. robustus), are quite close to the human lineage. Regarding the pelvic morphology, the species A. africanus and A. afarensis belong to the same morphofunctional pattern, the differences between them being merely allometric.

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.

Use and Manufacture of Tools to Extract Food by Captive Gorilla gorilla gorilla: Experimental Approach

The use and manufacture of tools to extract ants and termites is a welldocumented behaviour in wild chimpanzees [Goodall, 1964; Boesch and Boesch, 1990; Yamakoshi and Yamakoshi, 2004]. In contrast, it has never been observed in other great apes in their natural habitat. In captivity, the use of tools to extract ants and fruits has rarely been described in other primates, except in some New World monkeys, the capuchins [Visalberghi, 1990; Westergaard et al., 1997]. Captive gorillas have been seen using sticks to obtain food that was out of reach and pieces of wood as weapons and projectiles [Natale et al., 1986, 1988; Nakamichi, 1998]. This use, as a prolongation of the arm, is totally different in terms of sensorimotor intelligence from manufacturing tools [Piaget, 1952; Parker and Gibson, 1977]. The aim of this study is to test the ability of captive gorillas to use and manufacture tools for static food extraction.

Étude des hétérochronies par superposition procruste : application aux crânes de primates Hominoidea

Abstract 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.

The Evolution and Growth of the Hominid Pelvis

Previous studies have shown that the pelvis of an adult Australopithecus resembles that of a human neonate both in morphometric features and qualitative anatomical characters (Berge, 1993). In this study, the thin-plate spline was used to compare the shape of the ilium of Australopithecus (adult) and Homo (adult and neonate). The spline highlights three aspects of the ilium (anterior, medial and posterior), that feature significantly in the comparisons. The adult australopithecine and the human neonate are similar in all three of these aspects in the broad upper portion of the ilium. However, differences in shape are more apparent when the australopithecine is compared with the human adult. This result is consistent with the hypothesis that hominid evolution has been strongly influenced by heterochrony.

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.