Search

A large collection of cichlids (N = 133) from Lake Victoria in Africa, with total lengths ranging from 6 to 18 cm was nondestructively imaged using micro-computed tomography. We present a method to efficiently obtain three-dimensional tomographic datasets of the oral and pharyngeal jaws and the whole skull of these fishes to accurately describe their morphology. The tomographic data we acquired (9.8 TB of projection images) yielded 1.5 TB of three-dimensional image stacks used for extracting the relevant features of interest. Herein we present our method and outlooks on analyzing the acquired data; a morphological description of the oral and pharyngeal jaws, a three-dimensional geometric morphometrics analysis of landmarked skull features, and a robust method to automatically extract otoliths from the tomographic data. [ABSTRACT FROM AUTHOR]

It is often assumed that both our species and the last common ancestor (LCA) of Neanderthals and modern humans originated in Africa, with all Eurasian Pleistocene populations expected to ultimately come from Africa. This paper aims to review the Middle Pleistocene fossil record of Africa and Southwest Asia to reinforce the need to at least consider the possibility of a non-African origin for the "sapiens lineage" as a plausible hypothesis. While the fossil record from the late Middle Pleistocene of Africa does suggest that the earliest representatives of Homo sapiens are indeed found in this continent, we found no consistent evidence showing that the LCA necessarily also originated in Africa. At present, based on paleogenetic analyses, the most widely accepted hypothesis suggests that the LCA may have lived during the early Middle Pleistocene. To this information, we must add the constellation of traits observed in H. antecessor , a species that from both morphology and molecular data has been interpreted as being close to the LCA. The morphology of the LCA may be defined by a mosaic of features in the cranium and dentition which, so far, has not been found in the African record. We emphasize that the case for an African origin for the LCA is not a closed one. We suggest caution and the need for further findings and studies, especially in Southwest Asia, which may be a critical region for studying the divergence of H. sapiens and H. neanderthalensis. [ABSTRACT FROM AUTHOR]

Australopiths, a group of hominins from the Plio-Pleistocene of Africa, are characterized by derived traits in their crania hypothesized to strengthen the facial skeleton against feeding loads and increase the efficiency of bite force production. The crania of robust australopiths are further thought to be stronger and more efficient than those of gracile australopiths. Results of prior mechanical analyses have been broadly consistent with this hypothesis, but here we show that the predictions of the hypothesis with respect to mechanical strength are not met: some gracile australopith crania are as strong as that of a robust australopith, and the strength of gracile australopith crania overlaps substantially with that of chimpanzee crania. We hypothesize that the evolution of cranial traits that increased the efficiency of bite force production in australopiths may have simultaneously weakened the face, leading to the compensatory evolution of additional traits that reinforced the facial skeleton. The evolution of facial form in early hominins can therefore be thought of as an interplay between the need to increase the efficiency of bite force production and the need to maintain the structural integrity of the face. [ABSTRACT FROM AUTHOR]

Dormice are widely dispersed across various ecosystems in Eurasia and Africa and among the oldest extant rodent lineages. Despite distinct morphological variation to be present between groups, comprehensive morphometrical studies on the dormouse skull are limited. Here, the form of eight out of the nine extant dormouse genera was analysed using 3D geometric morphometrics and linear biomechanical measurements, providing a better understanding of the overall morphological variation present within Gliridae. Species‐, genus‐ and family‐specific morphological trends in both the size and shape of the cranium and mandible are linked with specific habitats and feeding strategies. Smaller dormice show adaptations to a more arboreal lifestyle such as a relatively enlarged braincase and an inferiorly reoriented foramen magnum. Larger dormice show cranial modifications, including clear flattening of the skull and a more posteriorly positioned foramen magnum, hinting towards a more rupicolous lifestyle. Furthermore, specimens inhabiting arid areas appear to have more inflated auditory bullae, whereas other variable features, such as the length of the incisive foramen, were not associated with either size changes or climatic variables. Lastly, more robust and horizontally orientated zygomatic arches as well as increased robusticity of the molar row appear to be linked with herbivory in dormice, whereas thinner arches and small concave molars are seen in more insectivorous species. This study reveals clear convergent adaptations between dormouse species and results in a better understanding of ecological drivers underpinning the morphological divergence present within Gliridae. [ABSTRACT FROM AUTHOR]

Based on high‐resolution computed tomography, we describe in detail the petrosal and inner ear anatomy of one of the few known African stem paenungulates (Paenungulatomorpha), Ocepeia daouiensis from the Selandian of the Ouled Abdoun phosphate basin (Morocco). The petrosal of Ocepeia displays some remarkable, probably derived features (among eutherians) such as relatively small pars cochlearis, pars canalicularis labyrinth (including small semicircular canals), a large wing‐like pars mastoidea, a large and inflated tegmen tympani, and the dorsoventral orientation of the large canal for the ramus superior. The presence of small semicircular canals in Ocepeia is an interesting shared trait with tenrecoidean afrotherians. Otherwise, and consistent with a general primitive skull morphology, the middle ear and labyrinth of Ocepeia daouiensis is characterised by many plesiomorphic traits close to the eutherian generalised plan. This adds to the rather generalised morphology of the earliest crown paenungulates such as Eritherium, Phosphatherium and Seggeurius to support an ancestral paenungulatomorph morphotype poorly derived from the eutherian pattern. As a result, Ocepeia provides key morphological and fossil data to test phylogenetic relationships of the Afrotheria (including Paenungulatomorpha) at the placental root mostly inferred from molecular studies. [ABSTRACT FROM AUTHOR]

Madagascar is a large island to the south-east of Africa and in many ways continental in size and ecological complexity. Here we aim to define how skull morphology of an endemic and monophyletic clade of rodents (sub-family Nesomyinae), that show considerable morphological variation, have evolved and how their disparity is characterized in context of the geographical and ecological complexity of the island. We performed a two-dimensional geometric morphometric analysis on 370 dorsal and 399 ventral skull images of 19 species (comprising all nine extant endemic genera) and tested the influence of three ecological parameters (climate, locomotor habitat and nychthemeral cycle) in a phylogenetic context on size and shape. The results indicate that skull shape appears to importantly reflect phylogeny, whereas skull size does not carry a significant phylogenetic signal. Skull shape is significantly influenced by climate while, skull size is not impacted by any of the ecological factors tested, which is controversial to expectations in an insular context. In conclusion, Nesomyinae must have evolved under unusual types of local constraints, preventing this radiation from demonstrating strong ecological release. [ABSTRACT FROM AUTHOR]

Molecular phylogenies support the monophyly of Desmodilliscus braueri and Pachyuromys duprasi as a clade basally split from all other gerbillines. While this monophyly supports their placement in a single tribe (Desmodilliscini), no morphological synapomorphies exist among desmodilliscines. This study compares the scale-independent cranial shapes of these two species using geometric morphometrics to determine how they differ and/or converge. Tribal synapomorphies, should they exist, may appear as interspecifically invariable cranial regions. No such invariable cranial regions were detected. The two species significantly differed in cranial size and shape. A small part of shape variation was allometric, with a weak unique allometric effect. No sexual size nor shape dimorphism was found. The sister taxa greatly differed in almost all cranial features, with Pachyuromys (when compared to Desmodilliscus) having a larger-sized cranium, with a larger bulla and suprameatal triangle, a more posteriorly placed palatine foramina, and more anteriorly shifted (and reduced) rostral cranial structures, due to being crowded by the hypertrophied bulla. Cranial variation patterns are consistent with the literature. The extreme morphological divergence among these species is explained by the distant divergence time and ecological differences. Absence of cranial shape synapomorphies does not preclude synapomorphies in other craniodental morphological features (e.g., detailed morphology of the dentition and cranial foramina) or in other morphological structures, such as the postcranial skeleton. [ABSTRACT FROM AUTHOR]

The Lygodactylus genus is one of the most species-rich genera of gekkonid lizards in Africa. It is one of relatively few exclusively diurnal geckos' lineages and its members include some of the smallest gekkonids. Osteological features within Lygodactylus have never been addressed in detail. We here provide a detailed bone-by-bone skull description of Lygodactylus picturatus to expand the knowledgebase on gecko cranial structure. High-Resolution X-ray Computed Tomography (HRCT) has been used, followed by bone-by-bone segmentation and description. As expected, L. picturatus presents some modifications on the basic gekkotan plan due to miniaturisation, such as an increase in the overlap area of the muzzle unit and lost or reduction of jugal bone. In addition, the skull of this species is characterised by the absence of the squamosal, fused nasals, reduced postorbitofrontal bone and extremely rounded parietal bones. Finally, we observed a reduction of the orbital space, in comparison with other miniaturised gekkotans, presumably as a consequence of their diurnal behaviour and niche preference. [ABSTRACT FROM AUTHOR]

The relative contributions of adaptation and genetic drift to morphological diversification of the skulls of echolocating mammals were investigated using two horseshoe bat species, Rhinolophus simulator and R. cf. simulator, as test cases. We used 3D geometric morphometrics to compare the shapes of skulls of the two lineages collected at various localities in southern Africa. Size and shape variation was predominantly attributed to selective forces; the between-population variance (B) was not proportional to the within-population variance (W). Modularity was evident in the crania of R. simulator but absent in the crania of R. cf. simulator and the mandibles of both species. The skulls of the two lineages thus appeared to be under different selection pressures, despite the overlap in their distributions. Difference in the crania of R. cf. simulator was centered largely on the nasal dome region of R. cf. simulator but on the cranium and mandibles of R. simulator. It is likely that the size and shape of the nasal dome, which acts as a frequency-dependent acoustic horn, is more crucial in R. cf. simulator than in R. simulator because of the higher echolocation frequencies used by R. cf. simulator. A larger nasal dome in R. cf. simulator would allow the emission of higher intensity pulses, resulting in comparable detection distances to that of R. simulator. In contrast, selection pressure is probably more pronounced on the mandibles and cranium of R. simulator to compensate for the loss in bite force because of its elongated rostrum. The predominance of selection probably reflects the stringent association between environment and the optimal functioning of phenotypic characters associated with echolocation and feeding in bats. [ABSTRACT FROM AUTHOR]

Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, terrestrial mammals into carnivorous and fully aquatic cetaceans. Protocetids are Eocene whales that represent a unique semiaquatic stage in that dramatic evolutionary transformation. Here, we report on a new medium-sized protocetid, Phiomicetus anubis gen. et sp. nov., consisting of a partial skeleton from the middle Eocene (Lutetian) of the Fayum Depression in Egypt. The new species differs from other protocetids in having large, elongated temporal fossae, anteriorly placed pterygoids, elongated parietals, an unfused mandibular symphysis that terminates at the level of P3, and a relatively enlarged I3. Unique features of the skull and mandible suggest a capacity for more efficient oral mechanical processing than the typical protocetid condition, thereby allowing for a strong raptorial feeding style. Phylogenetic analysis nests Phiomicetus within the paraphyletic Protocetidae, as the most basal protocetid known from Africa. Recovery of Phiomicetus from the same bed that yielded the remingtonocetid Rayanistes afer provides the first clear evidence for the co-occurrence of the basal cetacean families Remingtonocetidae and Protocetidae in Africa. The discovery of Phiomicetus further augments our understanding of the biogeography and feeding ecology of early whales. [ABSTRACT FROM AUTHOR]

Objective: The unaffected relatives of individuals with nonsyndromic orofacial clefts have been shown to exhibit subtle craniofacial differences compared with the general population. Here, we investigate whether these morphological differences extend to the shape of the palate. Design: We conducted a geometric morphometric analysis to compare palate shape in the clinically unaffected parents of children with nonsyndromic cleft lip with or without cleft palate and adult controls of European, Asian, and African ancestry. We conducted pairwise group comparisons using canonical variates analysis, and then confirmed and characterized findings of shape differences using Euclidean distance matrix analysis. Results: Significant differences in palate shape were detected in unaffected mothers (but not fathers) compared to demographically matched controls. The differences in shape were ancestry-specific; mothers of Asian-derived and African-derived ancestry showed wider and shorter palates with higher posterior palatal vaults, while mothers of European-derived ancestry showed narrower palates with higher anterior palatal vaults. Conclusions: Our findings suggest that altered palate shape is a subclinical phenotypic feature, which may be indicative of elevated orofacial cleft risk. The risk phenotype varied by sex and ancestry, suggesting possible etiologic heterogeneity among demographic groups. Understanding the genetic basis of these informative palate shape traits may reveal new genes and pathways relevant to nonsyndromic orofacial clefting. [ABSTRACT FROM AUTHOR]

Background: Skulls serve many functions and as a result, are subject to many different evolutionary pressures. In squamates, many fossorial species occupy a unique region of skull morphospace, showing convergence across families, due to modifications related to head-first burrowing. As different substrates have variable physical properties, particular skull shapes may offer selective advantages in certain substrates. Despite this, studies of variation within burrowers have been limited and are typically focused on a single origin of fossoriality. We focused on seven skink genera (Acontias, Typhlosaurus, Scelotes, Sepsina, Feylinia, Typhlacontias, and Mochlus; 39 sp.) from southern Africa, encompassing at least three independent evolutions of semi-fossoriality/fossoriality. We used microCT scans and geometric morphometrics to test how cranial and mandibular shape were influenced by phylogenetic history, size, and ecology. We also qualitatively described the skulls of four species to look at variation across phylogenetic and functional levels, and assess the degree of convergence. Results: We found a strong effect of phylogenetic history on cranial and mandibular shape, with size and substrate playing secondary roles. There was a clear gradient in morphospace from less specialized to more specialized burrowers and burrowers in sand were significantly different from those in other substrates. We also created an anatomical atlas for four species with each element described in isolation. Every bone showed some variation in shape and relative scaling of features, with the skull roofing bones, septomaxilla, vomer, and palatine showing the most variation. We showed how broad-scale convergence in traits related to fossoriality can be the result of different anatomical changes. Conclusions: Our study used geometric morphometrics and comparative anatomy to examine how skull morphology changes for a highly specialized and demanding lifestyle. Although there was broad convergence in both shape and qualitative traits, phylogenetic history played a large role and much of this convergence was produced by different anatomical changes, implying different developmental pathways or lineage-specific constraints. Even within a single family, adaptation for a specialized ecology does not follow a singular deterministic path. [ABSTRACT FROM AUTHOR]

Commercial captive breeding and trade in body parts of threatened wild carnivores is an issue of significant concern to conservation scientists and policy-makers. Following a 2016 decision by Parties to the Convention on International Trade in Endangered Species of Wild Fauna and Flora, South Africa must establish an annual export quota for lion skeletons from captive sources, such that threats to wild lions are mitigated. As input to the quota-setting process, South Africa’s Scientific Authority initiated interdisciplinary collaborative research on the captive lion industry and its potential links to wild lion conservation. A National Captive Lion Survey was conducted as one of the inputs to this research; the survey was launched in August 2017 and completed in May 2018. The structured semi-quantitative questionnaire elicited 117 usable responses, representing a substantial proportion of the industry. The survey results clearly illustrate the impact of a USA suspension on trophy imports from captive-bred South African lions, which affected 82% of respondents and economically destabilised the industry. Respondents are adapting in various ways, with many euthanizing lions and becoming increasingly reliant on income from skeleton export sales. With rising consumer demand for lion body parts, notably skulls, the export quota presents a further challenge to the industry, regulators and conservationists alike, with 52% of respondents indicating they would adapt by seeking ‘alternative markets’ for lion bones if the export quota allocation restricted their business. Recognizing that trade policy toward large carnivores represents a ‘wicked problem’, we anticipate that these results will inform future deliberations, which must nonetheless also be informed by challenging inclusive engagements with all relevant stakeholders. [ABSTRACT FROM AUTHOR]

By focussing on two objects originating from the former German colony in East Africa, this article showcases an entangled Tanzanian- British-German history. The objects in question are human remains; or, to be more precise, a skull and a tooth. Firstly, the article traces their itineraries. Secondly, it demonstrates how human remains, which were taken as colonial trophies, could become objects of faith and attain their own ›life‹ in Europe. Their interpretation as objects of faith is supposed to challenge the prevailing understanding of the collection of human remains as part of a history of knowledge. Instead, the article offers a different reading which emphasises an African-European dialogue of meanings. [ABSTRACT FROM AUTHOR]

The mammalian skull is an informative and versatile study system critical to research efforts across the broad spectrum of molecular, cellular, organismal and evolutionary sciences. The amount of knowledge concerning mammalian skull continues to grow exponentially, fuelled by the advent of new research methods and new material. Computed microtomography, including X-ray imaging using synchrotron radiation, proved to be an important tool for the descriptive and quantitative analysis of cranial anatomy. A major conceptual change, namely combining genetics and development with evolution into 'evo-devo' studies, also contributed to our knowledge of the mammalian skull enormously. These advances, coupled with novel techniques now allow researchers to integrate the process of cranial development with data from the fossil record, which is also augmented by seminal discoveries from Africa, Asia and both Americas. However, for decades, there has been no comprehensive source covering fundamental aspects of this vibrant field of evolutionary biology. To address this gap, we offer in this theme issue a balanced mix of research papers and reviews from leading experts in the field and a younger generation of scientists from five continents. This article is part of the theme issue 'The mammalian skull: development, structure and function'.

During the mid-19th century Philadelphia physician and pioneering American anthropologist Samuel George Morton amassed a collection of crania from different world populations that is the largest of its time. Morton conducted statistical comparisons between different geographical populations as a way to investigate the nature of human variation, including differences in brain size between groups. His work was influential among Western scientists at the time, also resonating with proponents of slavery who inferred from his findings a 'natural order' of white supremacy. Until relatively recently little attention has been paid to the crania of African origin that found their way into the Morton collection, now housed at the University of Pennsylvania Museum of Anthropology and Archaeology. This paper details Morton's collection, with focus upon what is known about the crania originating from Africa - how they were obtained, where they came from, who they represent, and how Morton and other past and present researchers have used them. [ABSTRACT FROM AUTHOR]

Abstract: While it is generally accepted that modern humans evolved in Africa, the specific physical evidence for that origin remains disputed. The modern-looking Omo 1 skeleton, discovered in the Kibish region of Ethiopia in 1967, was controversially dated at ∼130 ka (thousands of years ago) by U-series dating on associated Mollusca, and it was not until 2005 that Ar–Ar dating on associated feldspar crystals in pumice clasts provided evidence for an even older age of ∼195 ka. However, questions continue to be raised about the age and stratigraphic position of this crucial fossil specimen. Here we present direct U-series determinations on the Omo 1 cranium. In spite of significant methodological complications, which are discussed in detail, the results indicate that the human remains do not belong to a later intrusive burial and are the earliest representative of anatomically modern humans. Given the more archaic morphology shown by the apparently contemporaneous Omo 2 calvaria, we suggest that direct U-series dating is applied to this fossil as well, to confirm its age in relation to Omo 1. [Copyright &y& Elsevier]

Phenotypic variation is channeled by adaptation to local environments and phylogenetic constraints. The morphology of the obligatorily subterranean African mole-rats of the genus Fukomys has been shaped within the context of their underground habitat, posing particular limits on the animals' morphology. Especially the biting apparatus has likely evolved within severe evolutionary constraints, as it is used for feeding on hard geophytes, for digging complex tunnel systems, and for defensive purposes and social interactions in a colony. We studied interspecific differences in bite performance among three taxa, in relation to their skull anatomy and skull shape. Data on biting performance were gathered by in vivo measurements and compared with model simulations. It is shown that the model simulation is a good proxy for in vivo measurement. Scaling of bite force is positively allometric relative to head size. Moreover, differences in biting performance exist between taxa, which may be linked to differences in their ecology. This study will eventually enable us to analyze the evolutionary pattern behind the variation in structure and performance of the biting apparatus in Fukomys mole-rats. [ABSTRACT FROM AUTHOR]

The article presents information on the Fang ancestral sculpture of Equatorial Africa. Since the beginning of the twentieth century, Fang ancestral sculpture of Equatorial Africa figured among the most emblematic and esteemed genres of African art. These anthropomorphic effigies, with an often haphazardly oozing black patina, of upright posture and subtle craftsmanship, were mounted on sewn-bark relic boxes containing the remains, including the skulls, of lineal ancestors. Every family had one or more. Honored and often consulted during rites of propitiation or of divination, these sculptures and the skulls they magically protected constituted the basic wealth of the Fang peoples of the past, a source of welfare, strength, and social power.

Abstract: In East Africa, cape hares (Lepus capensis) and savanna hares (L. victoriae) look much alike where their ranges overlap. Earlier studies suggested discrimination between the two species by several skull traits, but did not present morphometric statisitics. Our present discriminant analysis based on seven metric variables of the occipital bone related to skull length (condylobasal length) resulted in a high (95.1%) overall probability of correct separation of the two species. While all cape hares were classified correctly, correct classification was a bit lower in savanna hares (88.2%). A principal components analysis of the same variables confirmed the shape difference for the two species. Both region and sex-specific variation in the shape of the studied occipital bone complex was found in savanna hares but not in cape hares. The somewhat reduced level of correct identification of savanna hares might be due to a tendency for higher shape variation. Application of our discriminant analysis to other regions in East Africa is discussed. [Copyright &y& Elsevier]

Aim To examine and visualize clines in size and shape of Cercopithecus aethiops Linneus, 1758 (Primate, Cercopithecidae) skulls, and to investigate environmental factors which might best explain the observed variation. Location Sub-Saharan Africa. Methods Eighty-six three-dimensional anatomical landmarks were used to describe 306 skulls of adult C. aethiops sampled over its entire distribution. Geometric morphometric methods for the quantitative analysis of form variation were applied. Size and shape variables were computed and regressed onto geographical coordinates and environmental variables (elevation, temperature, rainfall, moisture and Shannon rainfall diversity index) using both linear and curvilinear models. Components (geographical, environmental, spatially structured environmental and residual) of ecogeographical variation in skull form were partitioned using partial regression. A novel approach for summarizing and visualizing nonlinear patterns of clinal variation using surface rendering of three-dimensional shapes is presented. Results Clinal variation in size and shape was highly significant, and was best described by curvilinear models. There were strong similarities between females and males. The cline in size was especially pronounced, explaining up to about 40% of observed variation, and was mainly longitudinal rather than latitudinal. A major trend of clinal shape variation also occurred from west to east, and corresponded to an expansion of the face relative to the neurocranium in the west. In the east, skulls also tended to be deeper and with narrower zygomatic arches. Geography and the spatially structured environmental component were the major contributors to the explained variance in size in both sexes, but the proportion of variance explained by the latter was smaller in females. In contrast, geography and environment explained similar amounts of variation in shape and their contribution was about twice that of the spatially structured environmental component. About 60–80% of variation in skull form was not explained by any variable in the analysis. The main factors influencing skull size differed in females and males, with rainfall being very influential in males. Both female and male skull shapes were strongly affected by average annual rainfall. Main conclusions A strong spatial and environmental basis to variations in African vervet monkey skull form was evident. However, the observed pattern did not conform to predictions based on Bergmann's rule. Rainfall consistently emerged as an important predictor, which may contribute to intraspecific variation in the size and shape of vervet monkey skulls through its effect on habitat productivity. [ABSTRACT FROM AUTHOR]

Little has been described of the Holocene populations of South-Central Africa, despite the region demonstrating major subsistence shifts relating to dispersals of agriculturalists at least 2,000 years ago. Seven sites with associated human skeletal remains were selected. Hora, Chencherere, Fingura, and Mtuzi represent the Middle Holocene (2,000ߝ5,000 years ago), and Phwadze, Mtemankhokwe, and Nkudzi Bay represent the Late Holocene and the arrival of agriculturalists between 500ߝ2,000 years ago. Focusing on the identity of bra and Chencherere specimens, two questions were addressed: are the various Holocene Malawians similar to each other, or do they suggest morphological change over time? What modern populations are closest to the prehistoric specimens? The archaeological sample was compared to modern sub-Saharan Africans from four regions, plus a historic Khoi-San foraging group. Factor analyses were performed in order to identify complex patterns of variation in metric traits of the skull. According to the results, prehistoric Malawians showed only slight differences between the Late and Middle Holocene, suggesting a population change without any major discontinuity. Later Stone Age skulls did not exclusively show similarities with the Khoi-San, as they frequently fit well within the variation of modern Bantu-speaking groups, especially West-Central Africa. Therefore, we reject the hypothesis that Middle Holocene South-Central Africans have an exclusively Khoi-San ancestry, and support an alternative hypothesis that both Middle and Late Holocene groups share a common biological heritage originating in West-Central Africa in earlier times. [ABSTRACT FROM AUTHOR]

The role of hybridization in the evolution of animal species is poorly understood. Transgressive segregation is a mechanism through which hybridization can generate diversity and ultimately lead to speciation. In this report we investigated the capacity of hybridization to generate novel (transgressive) phenotypes in the taxonomically diverse cichlid fishes. We generated a large F2 hybrid population by crossing two closely related cichlid species from Lake Malawi in Africa with differently shaped heads. Our morphometric analysis focused on two traits with different selective histories. The cichlid lower jaw (mandible) has evolved in response to strong directional selection, and does not segregate beyond the parental phenotype. The cichlid neurocranium (skull) has likely diverged in response to forces other than consistent directional selection (e.g., stabilizing selection), and exhibits marked transgressive segregation in our F2 population. We show that the genetic architecture of the cichlid jaw limits transgression, whereas the genetic basis of skull shape is permissive of transgressive segregation. These data suggest that natural selection, acting through the genome, will limit the degree of diversity that may be achieved via hybridization. Results are discussed in the context of the broader question of how phenotypic diversity may be achieved in rapidly evolving systems. [ABSTRACT FROM AUTHOR]

Ontogenetic studies of African ape skulls lead to an analysis of morphological differences in terms of allometry, heterochrony, and sexual dimorphism. The use of geometric morphometrics allows us 1) to define size and shape variations as independent factors (an essential but seldom respected condition for heterochrony), and 2) to calculate in percentage of shape changes and to graphically represent the parts of shape variation which are related to various biological phenomena: common allometry, intraspecific allometry, and allometric and nonallometric shape discrimination. Three tridimensional Procrustes analyses and the calculation of multivariate allometries, discriminant functions, and statistical tests are used to compare the skulls of 50 Pan troglodytes, and 50 gorilla of different dental stages. The results both complement and modify classical results obtained from similar material but with different methods (Shea [1983] Am. J. Phys. Anthropol. 62:275289; Shea [1983] Folia Primatol. (Basel) 40:32-68; Shea [1985] Size and Scaling in Primate Morphology, New York: Plenum, p. 175-205). As previously described by Shea, the common growth allometric pattern is very important (64% of total shape variation). It corresponds to a larger increase of facial volume than of neurocranial volume, a more obliquely oriented foramen magnum, and a noticeable reshaping of the nuchal region (higher inion). However, the heterochronic interpretation based on common allometry is rather different from Shea. Gorillas differ from chimpanzees not only with a larger magnitude of allometric change (rate peramorphosis), as is classically said, but also grow more in size than in shape (size acceleration). In other words, for a similar stage of growth, gorillas have the size and shape corresponding to older chimpanzees, and for a similar shape, gorillas have a larger size than chimpanzees. In contrast, sexual dimorphism actually corresponds to allometric changes only, as classically demonstrated (time hypermorphosis). Sexual dimorphism is here significant in adult gorillas alone, and solely in terms of allometry (size-related shape and size, given that sagittal and nuchal crests are not taken into account). The study also permits us to differentiate two different shape variations that are classically confused in ontogenetic studies: a very small part of allometric shape change which is specific to each species (1% of the total shape variation), and nonallometric species-specific traits independent of growth (8% of total shape change). When calculated in terms of intraspecific allometries (including common allometry and noncommon allometry), shape changes are more extensive in gorillas (36% of total shape change) than in chimpanzees (29% of total shape change). The allometric differences mainly concern the inion, which becomes higher; the position of the foramen magnum, more dorsally oriented; and the palate, more tilted in adult gorillas than in adult chimpanzees. In contrast, nonallometric species-specific traits in gorillas are the long and fiat vault characterized by a prominent occipital region, the higher and displaced backward glabella, and the protrusive nose. Biomechanical schemes built from shape partition suggest that the increased out-of-plumb position of the head during growth is partially compensated in gorillas by a powerful nuchal musculature due to the peculiar shape of the occipital region. [ABSTRACT FROM AUTHOR]

Seventeen linear measurements (13 from the skull and 4 from the mandible) were taken on 46 skulls of adult H. cristata, 24 of which originated from the Italian peninsula, 11 from North Africa, and 11 from Sicily. Based on the results from a PCA analysis, Italian H. cristata appeared on average to be grouped quite apart from conspecifics from Sicily and Africa, which were in contrast rather mixed. [ABSTRACT FROM AUTHOR]

Two Early Pleistocene fossils from Gona, Ethiopia, were originally assigned to Homo erectus , and their differences in size and robusticity were attributed to either sexual dimorphism or anagenetic evolution. In the current study, we both revisit the taxonomic affinities of these fossils and assess whether morphological differences between them reflect temporal evolution or sexual variation. We generated virtual reconstructions of the mostly complete ∼1.55 Ma DAN5/P1 calvaria and the less complete 1.26 Ma BSN12/P1 fossil, allowing us to directly compare their anterior vault shapes using landmark-based shape analysis. The two fossils are similar in calvaria shape to H. erectus and also to other Early Pleistocene Homo species based on a geometric morphometric analysis of calvaria landmarks and semilandmarks. The DAN5/P1 fossil bears a particularly close affinity to the Georgian H. erectus fossils and to KNM-ER 1813 (H. habilis), probably reflecting allometric influences on vault shape. Combined with species-specific traits of the neurocranium (e.g., midline keeling, angular torus), we confirm that these fossils are likely early African H. erectus. We calculated regression-based estimates of endocranial volume for BSN12/P1 of 882–910 cm3 based on three virtual reconstructions. Although BSN12/P1 is markedly larger than DAN5/P1 (598 cm3), both fossils represent the smallest adult H. erectus known from their respective time periods in Africa. Some of the difference in endocranial volume between the two Gona fossils reflects broader species-level brain expansion from 1.77 to 0.01 Ma, confirmed here using a large sample (n = 38) of H. erectus. However, shape differences between these fossils did not reflect species-level changes to calvaria shape. Moreover, the analysis failed to recover a clear pattern of sexually patterned size or shape differences within H. erectus based on our current assessments of sex for individual fossils. • Neurocranial shape of Gona Pleistocene fossils supports assignment to Homo erectus. • Neurocranial shape in H. erectus does not map onto hypothesized sex differences. • Expanded data set confirms brain expansion in H. erectus between 1.8 and 0.1 Ma. [ABSTRACT FROM AUTHOR]

The origin and patterns of dispersal of anatomically modern humans are the focus of considerable debate. Global genetic analyses have argued for one single origin, placed somewhere in Africa. This scenario implies a rapid expansion, with a series of bottlenecks of small amplitude, which would have led to the observed smooth loss of genetic diversity with increasing distance from Africa. Analyses of cranial data, on the other hand, have given mixed results, and have been argued to support multiple origins of modern humans. Using a large data set of skull measurements and an analytical framework equivalent to that used for genetic data, we show that the loss in genetic diversity has been mirrored by a loss in phenotypic variability. We find evidence for an African origin, placed somewhere in the central/southern part of the continent, which harbours the highest intra-population diversity in phenotypic measurements. We failed to find evidence for a second origin, and we confirm these results on a large genetic data set. Distance from Africa accounts for an average 19–25% of heritable variation in craniometric measurements—a remarkably strong effect for phenotypic measurements known to be under selection. [ABSTRACT FROM AUTHOR]

Discusses the Taung skull discovered by Raymond Dart in Africa and its connection with the diversity in the structure of early hominids. Comparison of the Taung skull and the fossil cranium found by Michel Brunet and his colleagues; Description of the skeletal structure of the early hominids; Chart showing the evolution of ape-like creatures to human.

Modern humans expanded into Eurasia more than 40,000 years ago following their dispersal out of Africa. These Eurasians carried ~2-3% Neanderthal ancestry in their genomes, originating from admixture with Neanderthals that took place sometime between 50,000 and 60,000 years ago, probably in the Middle East. In Europe, the modern human expansion preceded the disappearance of Neanderthals from the fossil record by 3,000-5,000 years. The genetic makeup of the first Europeans who colonized the continent more than 40,000 years ago remains poorly understood since few specimens have been studied. Here, we analyse a genome generated from the skull of a female individual from Zlatý kůň, Czechia. We found that she belonged to a population that appears to have contributed genetically neither to later Europeans nor to Asians. Her genome carries ~3% Neanderthal ancestry, similar to those of other Upper Palaeolithic hunter-gatherers. However, the lengths of the Neanderthal segments are longer than those observed in the currently oldest modern human genome of the ~45,000-year-old Ust'-Ishim individual from Siberia, suggesting that this individual from Zlatý kůň is one of the earliest Eurasian inhabitants following the expansion out of Africa.

The article discusses the author's views about the biological implications about the geo-ecological-morphology of the vervet monkey. It focuses on a study about the subject where it takes on the variations in the morphology of the monkey's skulls in relation to geography and environment. The study, which was conducted in the African tropics, used curvilinear modeling. The author explores the significance of the study, particularly on the morphology in the skull sizes and shapes of the monkeys of both male and female sexes.

The article discusses research regarding the theory of multiregionalism which is the belief that Homo sapiens evolved all over the world. According to author, most scientist believe that modern humans evolved primarily in Africa. An overview of research of fossil skulls from various places including Australia, Indonesia, and Africa which has further debunked the multiregionlism theory.

The article informs that the fossilized skulls of two adults and one child discovered in the Afar region of eastern Ethiopia have been dated at 160,000 years, making them the oldest known fossils of modern humans, or Homo sapiens. The skulls, dug up near a village called Herto, fill a major gap in the human fossil record, an era at the dawn of modern humans when the facial features and brain cases recognize today as human first appeared. Because the Herto fossils represent a transition between more primitive hominids from Africa and modern humans, they provide strong support for the hypothesis that modern humans evolved in Africa and subsequently spread into Eurasia. This hypothesis goes against the theory that modern humans arose in many areas of Europe, Asia, and Africa from other hominids that migrated out of Africa at a much earlier time. Scientists tracking evolution through changes in mitochondrial DNA, which is passed from mother to daughter, have estimated that humans derive their mitochondrial genes from an ancestral mother nicknamed "Eve" who lived in Africa about 150,000 years ago.

For more than a century, scientists have wondered when and where modern humans arose— and what they looked like. Genetic evidence has pointed firmly to Africa in the past 200,000 years, but there have been few fossils from the right time and place to back that up. Dated to 154,000 to 160,000 years ago, skulls are the first strong fossil evidence that modern humans originated in Africa. These skulls belonged to two men and a child. Another half-dozen African fossils thought to be 130,000 to 300,000 years old are poorly dated or fragmentary, and they are not enough to prove the leading model that modern humans arose in Africa. Most recently, population geneticist Sarah Tishkoff of the University of Maryland, College Park, reported at a meeting in April 2003 that the oldest versions of maternally inherited DNA arose 170,000 years ago and are found in the Sandawe people of Tanzania and the !Kung San of the Kalahari desert.

Early American crania show a different morphological pattern from the one shared by late Native Americans. Although the origin of the diachronic morphological diversity seen on the continents is still debated, the distinct morphology of early Americans is well documented and widely dispersed. This morphology has been described extensively for South America, where larger samples are available. Here we test the hypotheses that the morphology of Early Americans results from retention of the morphological pattern of Late Pleistocene modern humans and that the occupation of the New World precedes the morphological differentiation that gave rise to recent Eurasian and American morphology. We compare Early American samples with European Upper Paleolithic skulls, the East Asian Zhoukoudian Upper Cave specimens and a series of 20 modern human reference crania. Canonical Analysis and Minimum Spanning Tree were used to assess the morphological affinities among the series, while Mantel and Dow-Cheverud tests based on Mahalanobis Squared Distances were used to test different evolutionary scenarios. Our results show strong morphological affinities among the early series irrespective of geographical origin, which together with the matrix analyses results favor the scenario of a late morphological differentiation of modern humans. We conclude that the geographic differentiation of modern human morphology is a late phenomenon that occurred after the initial settlement of the Americas., (Copyright © 2010 Wiley-Liss, Inc.)

An important area of biology involves investigating the origins in animals of traits that are thought of as uniquely human. One way that humans appear unique is in the importance they attach to the dead bodies of other humans, particularly those of their close kin, and the rituals that they have developed for burying them. In contrast, most animals appear to show only limited interest in the carcasses or associated remains of dead individuals of their own species. African elephants (Loxodonta africana) are unusual in that they not only give dramatic reactions to the dead bodies of other elephants, but are also reported to systematically investigate elephant bones and tusks that they encounter, and it has sometimes been suggested that they visit the bones of relatives. Here, we use systematic presentations of object arrays to demonstrate that African elephants show higher levels of interest in elephant skulls and ivory than in natural objects or the skulls of other large terrestrial mammals. However, they do not appear to specifically select the skulls of their own relatives for investigation so that visits to dead relatives probably result from a more general attraction to elephant remains.