Was “Lucy” more human than her “child”? Observations on early hominid postcranial skeletons

Fully adult partial skeletons attributed to Australopithecus afarensis (AL 288-1, “Lucy”) and to Homo habilis (OH 62, “Lucy's child”), respectively, both include remains from upper and lower limbs. Relationships between various limb bone dimensions of these skeletons are compared to those of modern African apes and humans. Surprisingly, it emerges that OH 62 displays closer similarities to African apes than does AL 288-1. Yet A. afarensis, whose skeleton is dated more than 1 million years earlier, is commonly supposed to be the ancestor of Homo habilis. If OH 62, classified as Homo habilis by its discoverers, does indeed represent a stage intermediate between A. afarensis and later Homo, a revised interpretation of the course of human evolution would be necessary.     

足籽骨的放射片研究

本文对山东枣庄市916人足放射片进行了足籽骨的观察与测量。发现每足有1-7个籽骨,其中二个者占77.8％,三个者占16.9％;籽骨位于跖骨头下方者占94.5％,位于趾间关节下方者占5.5％;各跖骨头籽骨出现率:Ⅰ占99.9％、Ⅱ占 2.2％、Ⅲ占0.3％、Ⅳ占0.5％、Ⅴ占6.4％;(足母)趾趾间关节籽骨占12.6％;二分及三分籽骨出现率占3.9％,明显低于欧美人。此外,本文认为籽骨是在先天籽骨原基基础上,加以后天运动的影响而形成。     

Axial loading induces rotation of the proximal carpal row bones around unique screw-displacement axes

The changes in carpal bone alignment secondary to the aplication of an axial compressive load through the major wrist motor tendons while the wrist is kept in neutral position (isometric loading) have been investigated on 13 fresh cadaver specimens using a biplanar radiographic method of kinematic analysis. The scaphoid, lunate and triquetrum rotate an average of 5.1, 4.2 and 3.8°, respectively, around different ‘screw displacement axes’, all implying flexion, radial deviation and supination. Based on these findings, a new interpretation of the mechanism by which the wrist remains stable under physiologic loads is provided.     

Posterior dental size reduction in hominids: The Atapuerca evidence

In order to reassess previous hypotheses concerning dental size reduction of the posterior teeth during Pleistocene human evolution, current fossil dental evidence is examined. This evidence includes the large sample of hominid teeth found in recent excavations (1984–1993) in the Sima de los Huesos Middle Pleistocene cave site of the Sierra de Atapuerca (Burgos, Spain). The lower fourth premolars and molars of the Atapuerca hominids, probably older than 300 Kyr, have dimensions similar to those of modern humans. Further, these hominids share the derived state of other features of the posterior teeth with modern humans, such as a similar relative molar size and frequent absence of the hypoconulid, thus suggesting a possible case of parallelism. We believe that dietary changes allowed size reduction of the posterior teeth during the Middle Pleistocene, and the present evidence suggests that the selective pressures that operated on the size variability of these teeth were less restrictive than what is assumed by previous models of dental reduction. Thus, the causal relationship between tooth size decrease and changes in food-preparation techniques during the Pleistocene should be reconsidered. Moreover, the present evidence indicates that the differential reduction of the molars cannot be explained in terms of restriction of available growth space. The molar crown area measurements of a modern human sample were also investigated. The results of this study, as well as previous similar analyses, suggest that a decrease of the rate of cell proliferation, which affected the later-forming crown regions to a greater extent, may be the biological process responsible for the general and differential dental size reduction that occurred during human evolution. © 1995 Wiley-Liss, Inc.     

Electron microscopic study of the mandibular glands of Kalotermes flavicollis Fabr. (Isoptera; Calotermitidae)

Summary The mandibular glands of Kalotermes were examined in different castes. They showed sexual dimorphism in the soldiers and primary reproductives. Moreover, in female soldiers and queens, mandibular gland cells contained numerous crystalline structures of mitochondrial origin. The role of these glands (secretion of saliva or pheromone) is discussed.

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Résumé Les glandes mandibulaires de Calotermes sont étudiées dans les différentes castes. Elles présentent un dimorphisme sexuel chez les soldats et les sexués. Après la mue imaginale, les cellules glandulaires ont toujours une activité sécrétrice. De plus, chez les soldats femelles et les reines, elles contiennent de nombreuses formations cristallines d'origine mitochondriale. Le rôle de ces glandes (sécrétion de salive ou de phéromone) est discuté.

     

The relationship between split-line orientation and in vivo bone strain in galago (G. crassicaudatus) and macaque (Macaca mulatta and M. fascicularis) Mandibles

There is still disagreement concerning the functional significance of split-line patterns in bone. This study was undertaken to reexamine the mechanical forces hypothesis for split-line formation by comparing split-line patterns with in vivo mandibular bone strain patterns. The relationship between split-line orientation and in vivo stress and strain patterns on macaque and galago mandibles was examined during jaw opening and the power stroke of mastication and incision. An attempt was made to relate split-line orientation to the direction of tensile stress and strain along the primate mandible. In addition, we also investigated the alternative possibility that split-line orientation is related to the direction of low stresses (and strains) on the primate mandible. The results of this study showed that there was no consistent relationship between split-line orientation and the principal strains or stresses. Thus, split-lines did not run consistently in the direction of high or low stress and strain. Therefore, we have concluded that split-line orientation provides little useful information for inferring patterns of stress and strain in bone.     

The ultrastructural basis of steroid production in the Y-organ and the mandibular organ of the crabs Hemigrapsus nudus (Dana) and Carcinus maenas L.

Summary The ultrastructure of the steroid producing Y-organ and the mandibular organ of the crustaceans Hemigrapsus nudus and Carcinus maenas has been studied with reference to the well investigated steroid secreting cells (SSC) of mammals. In accordance with the most important characteristic of mammalian SSC, abundant SER could be shown in the Y-organ, where it is unevenly distributed. The amount of SER seems to vary in correlation with the secretion of moulting hormone during the moult cycle. Most Y-organ cells contain a great number of mitochondria of the tubular type, another important characteristic of mammalian SSC. The ultrastructure of the mandibular organ of C. maenas differs considerably from that of the Y-organ. Some SER was found, mitochondria of unusual shape and size were conspicuous. No definite conclusion as to the function of the mandibular organ is yet to be drawn.Dedicated to Prof. Dr. Peter Karlson on the occasion of his 60th birthdaySupported by the Deutsche Forschungsgemeinschaft, grant Ad 24/4We wish to thank Dr. A. Owczarzak, Oregon State University, Corvallis, Oregon, for providing the facilities for our work with H. nudus and Thomas Gallenstein for many helpful discussions of technical problems     

Artificial cranial deformation and the increased complexity of the lambdoid suture

Studies examining an association between artificial cranial deformation and the presence of wormian bones in the lambdoid suture have been inconclusive. Cranial deformation, however, does not seem to have a direct effect of increasing the sutural complexity of the pars lambdica of the lambdoid suture and also increasing the mean number of lambdoidal wormian bones, given their presence.     

快速成型技术在颌骨缺损修复中应用的临床研究

目的：研究以CAD／CAM快速成型模型预成钛支架行颌骨缺损功能和外形重建的临床疗效。方法：选择四川大学华西口腔医院收治的5例颌骨良性肿瘤患者,术前螺旋CT及快速成型技术预成实体模型,并通过反求工程技术将健侧颌骨外形复制,制备钛修复体行患侧缺损修复,观察术后效果。结果：术后3个月、6个月复查患者对自身颌骨功能及外形较满意,均未出现因修复体导致的严重不良反应,张口度都接近恢复至正常,张口运动未出现明显异常,咬合关系良好。结论：运用快速成型技术设计并利用反求工程技术制造的个性化修复体进行颌骨缺损修复的方法能较好地恢复患者颌面部的功能和外形,副反应小,可以达到比较满意的修复效果。