Anthropological evaluation of left-right differences in the femur of southern African populations

Bilateral asymmetries were tested on a series of anthropological measurements recorded from 566 femora of 161 males and 122 females of southern African populations. Uni- and multivariate statistics revealed that there is a high degree of side differences apparent in the morphological features of the femur, and close to 75% of all femora could be correctly assigned to their respective sides. While most dimensions were greater on the left side, anteroposterior diameter of the proximal shaft, bicondylar width and collo-diaphyseal angle yielded significantly higher mean values on the right side. Anteroposterior diameter of the proximal shaft loaded highest in both canonical discriminant analyses. This result indicates that, overall, the left leg is stronger and is more suited to withstand axial forces and mediolateral bending. Thus, the findings seem to further support the hypothesis that most people, regardless of handedness, use their left leg for weight-bearing, whereas the right leg is more likely to be used for other tasks.     

Is sexual dimorphism in the femur a "population specific phenomenon"?

The patterns of sexual dimorphism as well as the differences in amount between the populations were studied on a sample of 162 male and 159 female left femora, which were classified as Zulu, Sotho, Xosa and South Africans of European extraction. Multivariate analyses revealed that even adjacent African tribes exhibit a different pattern of sexual dimorphism, but there were similarities between Zulu and European femora. Furthermore, relative size differences, i.e. shape, discriminated more clearly between the sexes than did absolute size. Bicondylar width yielded a statistically significant higher degree of sexual dimorphism in Europeans when compared to African populations. This finding was interpreted in terms of the biomechanical demands on the femur under different living conditions. On the other hand, sexual dimorphism of femoral length did not differ among the populations. This was unexpected since femoral length correlates highly with stature, which was reported to show a lesser degree of sexual dimorphism in Africans than in Europeans. Detailed analyses of the results of the present study led to suggest that different living conditions may affect bones in complex ways of which linear growth is only one aspect.     

Disuse-induced deterioration of bone strength is not stopped after free remobilization in young adult rats

The effect of unilateral hindlimb immobilization and subsequent free remobilization on mechanical properties of femur was examined in young adult rats. Right hindlimb of 17 weeks old male rats was immobilized for 2 weeks. Rats were sacrificed either directly after immobilization (E0) or after 4 weeks of free remobilization (E4). Mechanical properties in three-point bending as well as dry mass (m_dry), geometry, apparent density (d_app), and mineralization of dry bone tissue were measured post mortem in right and left femora of experimental rats (E0, E4) and in right femora of age-matched controls (C0, C4). Differences between right femora of experimental and control animals and between right and left femora of experimental animals were analyzed. After immobilization only d_app in E0 was significantly lower than in C0. Side-to-side differences in E0 were present only in m_dry and d_app. Surprisingly, 4 weeks after remobilization the differences between experimental and control femora were more pronounced. Mineralization, d_app, maximum bending moment (M_max), yield bending moment (M_y) and stiffness of the right femur were lower in E4 than in age-matched C4. Side-to-side differences in remobilized rats (E4) were still significant for m_dry and d_app. Additionally, the medullary area was larger, and M_max, M_y, stiffness and work to failure were lower in the right femur than in the left. It is concluded, that the processes of bone deterioration initiated during immobilization do not cease immediately after resumption of normal mechanical loading.     

The femur of extinct bunodont otters in Africa (Carnivora,Mustelidae, Lutrinae)

This study compares fossil femora attributed to extinct African bunodont lutrines with extant mustelids and ursids to reconstruct locomotor behavior. Due to the immense size differences among taxa, shape data were used to compare morphology. Based on morphological differences, the fossil femora are suggested to belong to different taxa with different locomotor abilities and habitat preferences. The Langebaanweg femur is the oldest and has a typical mustelid morphology suggesting that it was a locomotor generalist like most mustelids. The West Turkana form is more like extant nonbunodont otters, but much larger, and may have belonged to a semiaquatic taxon. The enormous Omo femur shares some features with truly aquatic taxa (e.g., Enhydra) and is the most likely to have been fully aquatic. The same may hold true for the Hadar species as it is most similar to that from the Omo. If these femora truly belong to bunodont lutrines, then they are more diverse in postcranial morphology than in dental morphology.     

A fossil hominoid proximal femur from Kikorongo Crater, southwestern Uganda

The external morphology of a fragmentary right proximal femur from southwestern Uganda is described here. Discovered in the Kikorongo Crater of Queen Elizabeth National Park in 1961, this specimen was informally assigned to Homo sapiens (although never described) and tentatively dated to the late Pleistocene. However, because aspects of the external morphology of the femur align the fossil with the African great apes, we suggest that the Kikorongo femur may be the first postcranial fossil of the genus Pan. Like the African apes, the Kikorongo specimen lacks both an obturator externus groove and an intertrochanteric line. It has a short femoral neck with a circular cross section, and a narrow and deep superior notch. Using resampling statistics and discriminant function analysis, the Kikorongo femur clustered with the genus Pan, as opposed to Gorilla or Homo. However, if the specimen is from Pan, it would be large for this taxon. Furthermore, features that clearly distinguish the external morphology of Plio-Pleistocene hominin proximal femora from African ape femora, such as the shape of the femoral neck in cross section and femoral neck length, have converged in Holocene humans and African apes. Unfortunately, the internal morphology of the femoral neck of the Kikorongo fossil was not discernable. Although we hypothesize that the Kikorongo femur is from the genus Pan, there is such variability in the proximal femora of modern humans that, although it would be an unusual human, it remains possible that this fossil represents H. sapiens.     

Another look at shape variation in the distal femur of Australopithecus afarensis: implications for taxonomic and functional diversity at Hadar

Previous studies have recognized two patterns of distal femoral morphology among the specimens from Hadar (Ethiopia) assigned to Australopithecus afarensis. Size and shape differences between the well-preserved large (AL 333-4) and small (AL 129-1a) distal femora have been used to invoke both taxonomic and functional differences within the A. afarensis hypodigm. Nevertheless, prior studies have not analyzed these specimens in a multivariate context, nor have they compared the pattern of shape differences between the fossils to patterns of sexual dimorphism among extant taxa (i.e., the manner in which males and females differ). This study reexamines morphometric differences between the above specimens in light of observed levels of variation and patterns of sexual dimorphism among extant hominoids. Eight extant reference populations were sampled to provide a standard by which to consider size and shape differences between the fossils. Samples include three populations of modern humans, two subspecies of Pan troglodytes, three subspecies of Gorilla gorilla, Pan paniscus, and Pongo pygmaeus. Using size ratios and scale-free "shape" data (both derived from 2-D coordinate landmarks), size and shape differences between the fossils were evaluated against variation within each reference population using an exact randomization procedure. Growth Difference Matrix Analysis (GDMA) was used to test whether the pattern of morphological differences between the fossils differs significantly from patterns of sexual dimorphism observed among the ten extant groups. Overall morphometric affinities of the fossils to extant taxa were explored using canonical variates analysis (CVA).Results of the randomization tests indicate that the size difference between the Hadar femora can be easily accommodated within most hominoid taxa at the subspecific level (though not within single-sex samples). In addition, the magnitude of shape differences between the fossils can be commonly sampled even within most single-sex samples of a single hominoid subspecies. The pattern of morphological differences between the fossils does not differ statistically from any average pattern of femoral shape dimorphism observed among living hominoids. Moreover, contrary to prior claims, and despite a size disparity between the fossils greater than is typically observed within some chimpanzee and human populations, the two Hadar fossils appear to be much more similar to one another in overall shape than either specimen is to any extant hominoid group.     

Genetic diversity,evolutionary history and implications for conservation of the lion (Panthera leo) in West and Central Africa

Aim In recent decades there has been a marked decline in the numbers of African lions (Panthera leo), especially in West Africa where the species is regionally endangered. Based on the climatological history of western Africa, we hypothesize that West and Central African lions have a unique evolutionary history, which is reflected by their genetic makeup. Location Sub‐Saharan Africa and India, with special focus on West and Central Africa. Method In this study 126 samples, throughout the lion’s complete geographic range, were subjected to phylogenetic analyses. DNA sequences of a mitochondrial region, containing cytochrome b, tRNAPro, tRNAThr and the left part of the control region, were analysed. Results Bayesian, maximum likelihood and maximum parsimony analyses consistently showed a distinction between lions from West and Central Africa and lions from southern and East Africa. West and Central African lions are more closely related to Asiatic lions than to the southern and East African lions. This can be explained by a Pleistocene extinction and subsequent recolonization of West Africa from refugia in the Middle East. This is further supported by the fact that the West and Central African clade shows relatively little genetic diversity and is therefore thought to be an evolutionarily young clade. Main conclusions The taxonomic division between an African and an Asian subspecies does not fully reflect the overall genetic diversity within lions. In order to conserve genetic diversity within the species, genetically distinct lineages should be prioritized. Understanding the geographic pattern of genetic diversity is key to developing conservation strategies, both for in situ management and for breeding of captive stocks.     

Mammalian body size changes and Plio-Pleistocene environmental shifts: implications for understanding hominin evolution in eastern and southern Africa

This study examines geographic and temporal variation in three mammalian taxa co-occurring in eastern and southern Africa. The selected taxa-the spotted hyena (Crocuta crocuta), the plains zebra (Equus burchellii), and the impala (Aepyceros melampus)--are geographically widespread in modern times and are abundant in eastern and southern African Plio-Pleistocene fossil sites. Craniodental measurements of modern conspecifics from known geographic locations are compared using multivariate statistical methods to discern patterns of modern geographic variation within taxa. Modern and fossil samples are statistically compared to assess the nature and extent of inferred shifts in body size, both between modern samples and through time in each region. These results indicate that modern spotted hyenas and plains zebras exhibit mainly size variation between regions, with southern African samples possessing statistically larger craniodental metrics than eastern African samples. Comparison of fossil and modern samples reveals that the fossil assemblages do not show the same pattern of geographic variation. Significant temporal changes are more numerous between fossil and modern eastern African samples, and these changes are not mirrored by similar changes in the southern African samples. The changes experienced by taxa in eastern Africa appear to have been more extreme and wide-ranging than those in southern Africa, a presumed refugium. This result accords well with genetic studies of several large mammal species and paleoenvironmental studies suggesting that eastern African localized environments were more affected by tectonism and volcanism than were those in southern Africa. This study suggests that different evolutionary scenarios may have existed within Africa during the Plio-Pleistocene, but that both regions played unique and complementary roles in the evolution of African hominins and the broader faunal community.     

Anthropometric studies of the long bones of the "shell mound" Indians

The “shell mound” Indians exhibit both sexual and bilateral variations in comparative long bone lengths. Mean long bone lengths are shortest in the Indian group when compared to those reported for both Caucasians and Negroes. The radiohumeral and humero-femoral indices of the “shell mound” Indians are higher than those reported for either Caucasians or Negroes. There is a relatively high degree of anterior-posterior curvature of the femur in the Indian group when compared to the femora of Caucasian and Negroes. There is apparently no correlation between maximum femoral length and trochanter length in comparing right and left sides in either sex. The collo-diaphyseal angles are greater on the average on the left side in both sexes. The femora of male “shell mound” Indians exhibits greater average collo-diaphyseal angles than do the femora of male Caucasians.     

Phylogenetic analysis of coadaptation in behavior, diet, and body size in the African antelope

Several authors have suggested that African antelope (familyBovidae) exemplify coadaptation of ecological, behavioral,and morphological traits. We tested four hypotheses relatedto the ecology and behavior of 75 species of African antelopeusing both conventional statistical techniques and techniques that account for the nonindependence of species by consideringtheir phylogenetic relationships. Specifically, we tested thehypotheses that (1) dietary selectivity is correlated negativelywith body mass, (2) dietary selectivity is correlated negativelywith group size, (3) gregarious species either flee or counterattackwhen approached by predators, but solitary and pair-livingspecies seek cover to hide, and (4) body mass and group sizeare correlated positively. Each of these hypotheses was examinedfor the global data set (family Bovidae) and, when possible,within the two antelope subfamilies (Antilopinae and Bovinae)and within 7 of the 10 antelope tribes. The results of ourconventional and phylogenetically corrected analyses supportedthe hypotheses that group and body size vary predictably with feeding style and that antipredator behavior varies with groupsize. The hypothesis that body mass and group size are correlatedpositively was supported by conventional statistics, but thesetwo traits were only weakly related using a phylogeneticallycorrected analysis. Moreover, qualitative and quantitativecomparisons within each of the eight major African antelope tribes generally gave little support for the four hypothesestested. Thus, although our analyses at the subfamily levelprovided results that were consistent with prior hypotheses,our analyses at the level of tribes were equivocal. We discussseveral possible explanations for these differences.     

Geometric morphometric analyses provide evidence for the adaptive character of the Tanganyikan cichlid fish radiations

The cichlids of East Africa are renowned as one of the most spectacular examples of adaptive radiation. They provide a unique opportunity to investigate the relationships between ecology, morphological diversity, and phylogeny in producing such remarkable diversity. Nevertheless, the parameters of the adaptive radiations of these fish have not been satisfactorily quantified yet. Lake Tanganyika possesses all of the major lineages of East African cichlid fish, so by using geometric morphometrics and comparative analyses of ecology and morphology, in an explicitly phylogenetic context, we quantify the role of ecology in driving adaptive speciation. We used geometric morphometric methods to describe the body shape of over 1000 specimens of East African cichlid fish, with a focus on the Lake Tanganyika species assemblage, which is composed of more than 200 endemic species. The main differences in shape concern the length of the whole body and the relative sizes of the head and caudal peduncle. We investigated the influence of phylogeny on similarity of shape using both distance-based and variance partitioning methods, finding that phylogenetic inertia exerts little influence on overall body shape. Therefore, we quantified the relative effect of major ecological traits on shape using phylogenetic generalized least squares and disparity analyses. These analyses conclude that body shape is most strongly predicted by feeding preferences (i.e., trophic niches) and the water depths at which species occur. Furthermore, the morphological disparity within tribes indicates that even though the morphological diversification associated with explosive speciation has happened in only a few tribes of the Tanganyikan assemblage, the potential to evolve diverse morphologies exists in all tribes. Quantitative data support the existence of extensive parallelism in several independent adaptive radiations in Lake Tanganyika. Notably, Tanganyikan mouthbrooders belonging to the C-lineage and the substrate spawning Lamprologini have evolved a multitude of different shapes from elongated and Lamprologus-like hypothetical ancestors. Together, these data demonstrate strong support for the adaptive character of East African cichlid radiations.     

The Odocoileus virginianus Femur: Mechanical Behavior and Morphology

Biomechanical research relies heavily on laboratory evaluation and testing with osseous animal structures. While many femora models are currently in use, including those of the European red deer (Cervus elaphus), the Odocoileus virginianus femur remains undocumented, despite its regional abundance in North America. The objective of this study was to compare biomechanical and morphological properties of the Odocoileus virginianus femur with those of the human and commonly used animal models. Sixteen pairs of fresh-frozen cervine femora (10 male, 6 female, aged 2.1 ± 0.9 years) were used for this study. Axial and torsional stiffnesses (whole bone) were calculated following compression and torsion to failure tests (at rates of 0.1 mm/sec and 0.2°/sec). Lengths, angles, femoral head diameter and position, periosteal and endosteal diaphyseal dimensions, and condylar dimensions were measured. The results show that the cervine femur is closer in length, axial and torsional stiffness, torsional strength, and overall morphology to the human femur than many other commonly used animal femora models; additional morphological measurements are comparable to many other species’ femora. The distal bicondylar width of 59.3mm suggests that cervine femora may be excellent models for use in total knee replacement simulations. Furthermore, the cervine femoral head is more ovoid than other commonly-used models for hip research, making it a more suitable model for studies of hip implants. Thus, with further, more application-specific investigations, the cervine femur could be a suitable model for biomechanical research, including the study of ballistic injuries and orthopaedic device development.     

The femur in early human evolution.

Uni- and multivariate analyses of 5 fossil and 215 extant hominoid femora show that two morphological patterns of hominid femora existed about two million years ago. Femora classified as Homo sp. indet. (KNMER 1472 and 1481) are more like Homo sapiens although not identical.Those classified as Australopithecus robustus (SK 82 and 97) and A. boisei (KNM-ER 1503) are similar to one another but uniquely different from any living hominoid. The strong mophological constrasts imply biomechanical and possible locomotor differences, although these are as yet unknown.     

A morphometric and taxonomic assessment of a hominine femur from the lower member,Koobi Fora,Lake Turkana

Previous research by this author and others has indicated that species-level differentiation within the hominines can be detected in the femur. The femoral shaft of Homo erectus, relative to H. sapiens, demonstrates small anteroposterior diameters, a distally placed point of minimum shaft breadth, and increased cortical thickness resulting in medullary stenosis. This pattern has been identified in specimens from Choukoutien (I and IV), Olduvai (OH 28), and Lake Turkana (KNM ER 737). Findings reported here include anatomical comparisons and univariate and multivariate analyses based on external and internal shaft morphology. These results indicate that the femoral pattern characteristic of H. erectus can be identified in KNM ER 1481a recovered at Lake Turkana below the KBS tuff. Recent dating of that tuff indicates a date of ca. 1.8 mya, thereby yielding a date for KNM ER 1481a of ? 2.0 mya. Known H. erectus femora extend over a broad span and yet show very low, variability; this pronounced stasis would strongly suggest that, at least in this portion of the postcranium, H. erectus was in a period of profound morphological stasis.     

Testing assumptions of the Gilbert and Gill method for assessing ancestry using the femur subtrochanteric shape

In 1990, Gilbert and Gill proposed a simple metric technique using femoral subtrochanteric anteroposterior and mediolateral diaphyseal diameters for discriminating between Native American and American Black and White femora in medicolegal and bioarchaeological contexts. However, there are several inherent assumptions in the method that may affect its validity. The assumptions include minimal sexual dimorphism, temporal and geographical homogeneity within populations, and that differences between populations in femoral subtrochanteric size and shape are primarily due to genetic variation. In this study, these assumptions are tested using femora from seven populations (African, American Black, American White, Australian, Native American, Hispanic, and Polynesian). The results indicate that sexual dimorphism and geographical and temporal heterogeneity in proximal femur diaphyseal shape within Native Americans are not great enough to significantly affect the validity of the Gilbert and Gill method (GGM). Variation between populations is most likely due to combined genetic and environmental factors, but differences in proximal femur shape between Native Americans and American Blacks/Whites are sufficient to allow accurate discrimination between these groups. Caution, however, must be taken during investigations where populations other than Native Americans or American Blacks/Whites are present, and therefore, the GGM may have limited forensic anthropological application in many parts of the world.     

The distribution of breaking strength in the human femur shaft

703 standardized test specimens of dry cortical bone from different shaft regions of human femora were subjected to compression till failure parallel to the long axis of the shaft. The rate of load increase was 50 kg/cm²/sec. The significance of four sources of variation was tested, i.e. cross-sectional area (site), quadrant (position), side of the body, and individual, in three analyses of variance. All main effects and the interactions site x position, site x individual, position x individual, body side x individual are significant. A constant pattern of strength distribution in the proximal three cross-sectional areas is shown: this pattern is changed in the two distal cross-sectional areas, but it is the same on the left and right sides of the body apart from variations by the main effects. The pattern of strength distribution in the two distal cross-sectional areas probably changes with age. The distributions of mean compressive strength of femur shafts from two age groups are presented diagrammatically in Fig. 1, and the respective means are given in Fig. 2.     

Taxonomic affinities of the Eppelsheim femur

The taxonomic affinities of the Eppelsheim femur, known as Paidopithex, have been unclear for more than a century. Over the years, due to similarities with Pliopithecus, some authors have considered it a large pliopithecid, while others refer to it as Dryopithecus. The issue could not be resolved, because no definitive Dryopithecus femora were available. With the discovery of the Dryopithecus laietanus skeleton from Can Llobateres (CLl 18800), it has become possible to test the attribution of the Eppelsheim femur to Dryopithecus on the basis of direct morphological and metrical comparisons. By means of allometric techniques, we show that the Eppelsheim and D. laietanus femora fit different hindlimb morphologies with regard to relative length and relative head/neck size, with Paidopithex significantly differing from Dryopithecus, but more closely resembling Pliopithecus. Paidopithex also differs from Dryopithecus in other important aspects, such as its lower neck/shaft angle, lack of elevation of the femoral head above the greater trochanter, more posteriorly oriented lesser trochanter, and proximal shaft diameter thicker anteroposteriorly than mediolaterally. In these features, Paidopithex most closely resembles Pliopithecus in spite of differences in body mass (ca. 22 kg vs. ca. 10 kg, respectively). These features suggest that Paidopithex used a primitive locomotor pattern associated with arboreal quadrupedalism, instead of the more derived pattern displayed by Dryopithecus. Currently available evidence confirms that the attribution of Paidopithex to Dryopithecus can be rejected. Paidopithex could be a large and otherwise unknown pliopithecid, but the possibility cannot be ruled out that it represents a third kind of catarrhine.     

Some genetic traits in Solomon Island populations. II. Hand clasping, arm folding, and handedness

Among 1,438 persons in four Solomon Island populations, handclasp showed no age, sex, or tribal differences. The percentage of R-claspers (right thumb on top), 66.4, exceeded those previously reported for Caucasian and Mongoloid peoples and resembled those for Oceanic and African samples. Handclasp was associated with handedness but not with armfold; it showed no assortative mating and no simple form of inheritance. Armfold showed an age association (more R-folders among the youngest children), but none with sex or tribe, no assortative mating, and no pattern of inheritance. Its frequency, 41.4%, resembled those of populations around the world. Left handedness, 2.8% over all four tribes, paralleled contact with Western culture.     

人类股骨断面面积与形状的不对称性——基于三维激光扫描的形态测量分析

人类股骨横断面面积、形状及其左右侧差异记载的人类演化、人群差异及生存活动的重要信息一直为古人类学研究所关注。多年来, 对股骨断面的研究通常采用破坏性地切割或者制作模型的方法。本文利用三维激光表面扫描技术, 无损、快捷、方便地获取了20对现代中国人左右侧股骨外轮廓的三维数据, 采用CAD软件及几何形态测量方法对两侧股骨断面轮廓的大小及形状进行了对比和分析。初步研究结果发现: 两侧股骨的横断面相对面积差异极其显著, 绝对面积差异不显著, 不对称方式表现为波动不对称性, 而不是偏向不对称性; 个体之间两侧股骨横断面外轮廓形状的波动不对称性极其显著, 偏向不对称性虽有差异但不显著; 平均形状和面积分析结果似乎表明股骨稍有偏左侧优势。虽然本文所采用的标本量有限, 所得出的结论需要更多标本的进一步验证, 但是, 本文的研究结果提示利用三维激光扫描技术获取股骨横断面外轮廓数据, 并采用形态测量方法分析确实能够揭示出一些以往研究方法不能发现的重要信息, 这种研究骨骼不对称性的新方法值得进一步的应用。