Pattern profile analysis of hominid and chimpanzee hand bones

In a study designed to complement morphological research on hominid hand bones, length and width measurements of the thumb, index, and middle rays were obtained from radiographs of modern human hands. These rays are primary in precision-gripping postures and are therefore the ones most relevant for investigating evolutionary changes in fine manipulation. Pattern profile analysis allows individuals or samples to be plotted against a reference sample in standard deviation units, or Z-scores. It provides an indication of how different measurements are from modern human averages, while taking into consideration the degree of variation present within modern human samples. A pattern profile for chimpanzees is clearly distinct from humans but quite similar to that of a bonobo, demonstrating the promise of pattern analysis. Partial pattern profiles of several of the more complete early hominid bones from Hadar, Swartkrans, and Olduvai (O.H. 7) are presented and compared. Hadar bones are long and wide at midshaft relative to articular widths; both body-size effects and functional differences are likely. Thumb distal phalanges from Swartkrans and Olduvai both have relatively small base widths, but they differ in other proportions. Two first metacarpals from Swartkrans show distinct patterns. The profiles of La Ferrassie I and Shanidar IV show the characteristically large Neanderthal distal phalanges. Profiles of Skhūl IV and P?edmost III are alike in some regions with reference to modern North American white males, though they are less similar overall than are those of the two Neanderthals. © 1995 Wiley-Liss, Inc.     

Early hominid enamel hypoplasia.

Enamel hypoplasia in the South African Plio-Pleistocene fossil hominid sample is examined. The Swartkrans hominids are shown to have a higher incidence of hypoplasia than the Sterkfontein hominids. Within the Swartkrans sample, individuals with hypoplasia of the first upper molar have lower-than-expected ages of death. Possible taphonomic explanations for these observations are discussed.     

Variation in the Habiline Crania – Must it be Taxonomic?

The problem of whether the hominid fossil sample of habiline specimens is comprised of more than one species has received much attention in paleoanthropology. The core of this debate has significant implications about when and how variation must be explained by taxonomy. In this paper, we examine the problem of whether the observed variation in habiline sample must be interpreted to reflect species differences. We test the null hypothesis of no difference by examining the degree of variability in habiline sample in comparison with other single-species early hominid fossil samples from Sterkfontein and Swartkrans (Sterkfontein is earlier than the habiline sample; Swartkrans may be within the habiline time span). We use the standard error test for this analysis, a sampling statistic based on the standard error of the slope of regressions between pairs of specimens that relates all of the homologous measurements each pair shares. We show that the null hypothesis for the habiline sample cannot be rejected. The similarities of specimen pairs within the habiline sample are not more than those observed between the specimens in the two australopithecine samples we analyzed.     

Biomechanical interpretation of the early hominid hip

A new pelvic fragment from Swartkrans provides the opportunity to analyze the hip joint mechanics of the robust form of early hominid. The function of the lateral support system provided by the abductor muscles of the hip appears to be similar to that of the gracile early hominid from Sterkfontein. The system is well adapted for providing the lateral support necessary for efficient bipedalism. The hip extensor mechanism and hip internal rotatory system also appear to be well adapted for efficient bipedalism in a way very similar to the other early hominids. The conclusion reached is that the robust and gracile forms of South African early hominids were basically similar in their locomotor adaptation and were most likely habitual bipeds.     

Habiline variation: A new approach using STET

The problem of whether the hominid fossil sample of habiline specimens is comprised of more than one species has received much attention in paleoanthropology. The core of this debate has critical implications about when and how variation can be explained by taxonomy. In this paper, we examine the problem of whether the observed variation in habiline samples reflects species differences. We test the null hypothesis of no difference by examining the degree of variability in habiline sample in comparison with other single-species early hominid fossil samples from Sterkfontein and Swartkrans (Sterkfontein is earlier than the habiline sample, Swartkrans may be within the habiline time span). We developed a new method for this examination, which we call STandard Error Test of the null hypothesis of no difference (STET). Our sampling statistic is based on the standard error of the slope of regressions between pairs of specimens, relating all of the homologous measurements that each pair shares. We show that the null hypothesis for the habiline sample cannot be rejected. The similarities of specimen pairs within the habiline sample are not more than those observed between the specimens in the australopithecine samples we analyzed.     

Computed tomography and enamel thickness of maxillary molars of Plio-Pleistocene hominids from Sterkfontein, Swartkrans, and Kromdraai (South Africa): An exploratory study.

This paper is one in a series which explores the possibility of using the non-destructive CT technique to identify patterns in tooth enamel distribution and structure of hominid molars from Plio-Pleistocene sites in South Africa, notably Swartkrans, Sterkfontein, and Kromdraai. Whereas previous investigators have emphasised gross differences in absolute and relative or average enamel thickness between hominid taxa, the present study highlights differences in enamel thickness over functionally significant regions of the crown. Differences in the distribution of enamel in A. robustus, A. africanus, and Homo sp. are identified through the use of bivariate and multivariate analyses, and are interpreted in terms of dietary regimes.     

A new pelvic fragment from swartkrans and the relationship between the robust and gracile australopithecines

A recently discovered hominid pelvic fragment from Swartkrans (SK 3155) is described in detail with particular reference to the relationship of the two presently recognized forms of australopithecines in South Africa. Results of this examination and metrical analysis indicate that the acetabulum and iliac blade of the early hominids are similar to Homo sapiens except for a unique pattern of traits: a relatively small sacral articular surface, a relatively small acetabulum, a relatively large iliac fossa, and wide lateral splaying of the iliac blades. The new Swartkrans fossil expresses these traits more strongly than does the gracile australopithecine (Sts 14) and is therefore somewhat less similar to Homo sapiens but it is very unlike any pongid.     

Affinities of the Swartkrans 847 hominid cranium

Further evidence of the presence of a second hominid species at the Swartkrans locality was obtained in 1969 when the SK.847 specimen was discovered by us to represent the same individual as the SK.80 maxilla. The SK.847 specimen had previously been regarded as robust australopithecine, whereas the latter was first attributed to Telanthropus capensis and subsequently to a species of the genus Homo. Recent criticism of our interpretation of these remains has not evaluated and analyzed critically the primary fossil evidence. Instead it relies on a strict adherence to an as yet unsubstantiated hypothesis that posits only a single hominid species at any point in space and time in the Cenozoic history of Hominidae.     

New first metatarsal (SKX 5017) from Swartkrans and the gait of Paranthropus robustus

A new complete hallucal metatarsal (SKX 5017) was recovered from the "lower bank" of Member 1 at Swartkrans (ca. 1.8 m.y. BP). The new metatarsal is attributed to Paranthropus robustus, the predominant hominid found in Member 1 (greater than 95% of hominid individuals). SKX 5017 is similar to Olduvai Hominid 8-H from bed I, Olduvai (ca. 1.76 m.y. BP), and both resemble humans most closely among extant hominoids. The base, shaft, and head of SKX 5017 suggest human-like foot posture and a human-like range of extension (= dorsiflexion) at the hallucal metatarsophalangeal joint, while at the same time the distal articular surface indicates that a human-like toe-off mechanism was absent in Paranthropus. The fossil evidence suggests that Homo habilis and Paranthropus may have attained a similar grade of bipedality at roughly 1.8 m.y. BP.     

New hominid fossils from the Swartkrans formation (1979-1986 excavations): craniodental specimens

Seventy-two individually numbered hominid craniodental fossils from recent excavations at Swartkrans are described. All derive from in situ decalcified breccia and/or unconsolidated sediments. A total of 20 specimens, representing 13 to 16 individuals derive from Member 1 "Lower Bank," two teeth derive from sediments along the Member 1-2 Interface, 38 fossils representing 19 to 24 individuals come from Member 2, and 12 teeth representing 9 to 11 individuals derive from Member 3. All but four of the specimens are attributable at the generic level; one specimen from Member 1 "Lower Bank" and five specimens from Member 2 are attributed to Homo, while the others represent Paranthropus. The proportional representation of Homo in the Swartkrans Formation is markedly higher in Member 2 (c. 33%) than in the Member 1 "Lower Bank" (c. 8%) and Member 1 "Hanging Remnant" (c. 5%) samples.     

Disentangling Early Stone Age palimpsests: determining the functional independence of hominid- and carnivore-derived portions of archaeofaunas

Determining the extent to which hominid- and carnivore-derived components of fossil bone palimpsests formed independently of each other can provide valuable information to paleoanthropologists interested in reconstructing the foraging adaptations of hominids. Because stone tool cutmarks, hammerstone percussion marks, and carnivore tooth marks are usually only imparted on bone during nutrient extraction from a carcass, these bone surface modifications are particularly amenable to the types of analyses that might meet this goal. This study compares the percentage of limb bone specimens that preserve evidence of both hominid- and carnivore-imparted bone damage from actualistic control samples and several Plio-Pleistocene archaeofaunas, including new data from Swartkrans Member 3 (South Africa). We argue that this procedure, which elucidates the degree of hominid-carnivore independence in assemblage formation, will allow researchers to extract for focused analyses high integrity components (hominid and carnivore) from presumably low integrity sites. Comparisons suggest that the hominid- and carnivore-derived components from sites in Olduvai Gorge Bed II (Tanzania), the ST Site Complex at Peninj (Tanzania), and Swartkrans Member 3 formed largely independent of each other, while data from the FLK 22 Zinjanthropus (FLK Zinj) site (Olduvai Gorge Bed I) indicate significant interdependence in assemblage formation. This contrast suggests that some Early Stone Age assemblages (e.g., the Olduvai Gorge Bed II sites, the Peninj ST Site Complex, and Swartkrans Member 3) are probably more useful than others (e.g., FLK Zinj) for assessing the maximal carcass-acquiring abilities of early hominids; in such assemblages as those in the former set, sole hominid-contribution is more confidently discerned and isolated for analysis than in assemblages such as FLK Zinj.     

New australopithecine endocast,SK 1585, from Swartkrans,South Africa

The new SK 1585 endocast, found by Dr. Brain at Swartkrans, 1966, is that of a robust australopithecine, matching the endocast of the Olduvai Hominid 5 in volume, and being almost identical to it in morphology. Aside from Olduvai Hominid 5 it is the only robust australopithecine endocast complete enough to permit easy reconstruction, as only a small portion of the frontal lobe is missing. While the gyral and sulcal patterns are not clear, there are a number of features indicating that the brain is not that of a pongid, but that is has been reorganized to a hominid pattern, particularly the occipital, parietal, and temporal lobes.     

Species attribution of the Swartkrans member 1 first metacarpals: SK84 and SKX 5020

Susman (Am. J. Phys. Anthropol. 75:277-278, 79:451-474; Science 240:781-784; In FE Grine (ed): Evolutionary History of the "Robust" Australopithecines. New York: Aldine de Gruyter, pp. 149-172) has attributed the morphologically similar SK 84 and SKX 5020 hominid first metacarpals to Homo erectus and Australopithecus robustus, respectively, and has inferred that both species exhibited derived pollical morphologies, indicating refined precision grips. Consideration of the structure of his taphonomic arguments indicates that there are no adequate nonmorphological reasons to attribute these specimens securely to one or the other of the craniodentally represented species at Swartkrans. His morphological arguments fail to note any significant differences between the two specimens. Only the contrast in size between the small SK 84 and large SKX 5020 bones might warrant a species distinction; yet comparison of their length ratio to distributions of modern human first metacarpal length ratios indicates that it is not possible to reject conclusively the null hypothesis that they are conspecific. Therefore, early hominid adaptive scenarios based on a derived Homo-like manual functional morphology in A. robustus remain without a secure paleontological basis.     

Functional morphology of the middle ear in Chlorotalpa golden moles (Mammalia, Chrysochloridae): predictions from three models

The ossicular apparatus of golden moles in the genus Chlorotalpa has received comparatively little attention in the literature, although the malleus is known to be intermediate in size between the "unmodified" malleus of Amblysomus and the hypertrophied mallei found in some other golden moles. In the present study, the middle ear structures of three Chlorotalpa species (C. duthieae, C. sclateri, and C. arendsi) are described. Measurements of middle ear structures were applied into three existing models of middle ear function. The predictions from the models suggest that the airborne hearing of Chlorotalpa species is limited to relatively low frequencies, but the impedance transformation by the middle ear apparatus is expected to be reasonably efficient. The sensitivity of the middle ear apparatus to inertial bone conduction is intermediate between that predicted for Amblysomus and that predicted for species with hypertrophied mallei. Hearing in fossorial mammals may be limited by factors other than the middle ear apparatus: the predictions for Chlorotalpa must therefore be treated with caution. However, a consideration of the "intermediate" middle ear morphology of Chlorotalpa species sheds some light on the origin of ossicular hypertrophy in golden moles. The limited enlargement of the malleus seen in Chlorotalpa is expected to have improved seismic sensitivity by bone conduction significantly at low frequencies, while airborne hearing might not have been adversely affected.     

压力波对听觉器官的致伤作用——Ⅰ.致伤部位和损伤特性

本工作用二十余种武器压力波源在不同暴露条件下对近二千只豚鼠进行了系统的致伤实验。结果表明,压力波暴露后致伤部位主要在中耳和内耳;即使压力峰值已高达190dBSPL,听觉中枢还未见有损伤迹象。中耳损伤和内耳损伤的程度都与压力波的强度有关,但两者并不平行,压力峰值大时压力波可以只损伤或主要损伤中耳,压力峰值不很大但重复发数较多或脉宽较大时,则可能只损伤或主要损伤内耳。在一定的条件下,中耳的损伤能缓冲压力波对内耳的冲击,从而减轻内耳的损伤。在中耳损伤或中耳、内耳混合损伤时,豚鼠的听力丧失并没有象在人的噪声性耳聋时(内耳损伤为主)常见的那种突出的高频选择性。     

Evolution of the middle ear apparatus in Talpid moles

The middle ear structures of eight species of mole in the family Talpidae (Mammalia: Eulipotyphla) were studied under light and electron microscopy. Neurotrichus, Parascalops, and Condylura have a simple middle ear cavity with a loose ectotympanic bone, ossicles of a "microtype" morphology, and they retain a small tensor tympani muscle. These characteristics are ancestral for talpid moles. Talpa, Scalopus, Scapanus, and Parascaptor species, on the other hand, have a looser articulation between malleus and ectotympanic bone and a reduced or absent orbicular apophysis. These species lack a tensor tympani muscle, possess complete bullae, and extensions of the middle ear cavity pneumatize the surrounding basicranial bones. The two middle ear cavities communicate in Talpa, Scapanus, and Parascaptor species. Parascaptor has a hypertrophied malleus, a feature shared with Scaptochirus but not found in any other talpid genus. Differences in middle ear morphology within members of the Talpidae are correlated with lifestyle. The species with middle ears closer to the ancestral type spend more time above ground, where they will be exposed to high-frequency sound: their middle ears appear suited for transmission of high frequencies. The species with derived middle ear morphologies are more exclusively subterranean. Some of the derived features of their middle ears potentially improve low-frequency hearing, while others may reduce the transmission of bone-conducted noise. By contrast, the unusual middle ear apparatus of Parascaptor, which exhibits striking similarities to that of golden moles, probably augments seismic sensitivity by inertial bone conduction.     

The use of hyaluronidase and glucosidase to remove mucus from the rat middle ear cavities for SEM studies

Summary To conduct SEM studies on epithelium containing mucus-producing cells it is essential to remove the mucus which normally obscures the epithelial surface. This study presents a method which effectively removes the covering layer of mucus in the rat middle ear. Healthy Sprague-Dawley rats were decapitated and the middle ears dissected free. Incubation and agitation of the middle ear specimens in hyaluronidase (50 IE ml^–1) and/or glucosidase (8%) removed the mucus from the middle ear cavity without altering the surface structures. It was also revealed that substances such as polyvinyl-pyrrolidone (PVP) (used to increase the colloid osmotic pressure of, e.g., the fixative solution) must be omitted when preparing ciliated specimens for SEM.     

The Middle Ear--Morphological Types in Amphibians and Reptiles

The middle ear regions of reptiles and amphibians frequentlyare grouped into morphological types on the basis of structuralresemblances. The arrays of animals resulting from such a groupinghave a fair degree of taxonomic continuity. The types in mostinstances include a "central" pattern, presumed to be primitive,and modifications that are considered to have been derived fromthe "central" type by evolutionary processes. Some understandingof phylogeny, thus, is a necessary precursor to the formationof the groups. This raises problems when, as is often the case,the groups based on ear structures are used as a basis for phylogeneticinterpretations. Among reptiles the theropsid-sauropsid caseis the best known. The principal morphological types are described and discussed.The middle ear, as a sound-transmitting apparatus and in itsassociations with the masticatory apparatus, is highly susceptibleto adaptive modifications. Some morphological types, such asthose in archosaurs and labyrinthodonts, are quite stable. Othersshow marked evolutionary diversity. The middle ear structures,hence, appear quite useful as phylogenetic indicators withinmorphological types but less so when relationships between typesare considered.