Dental evidence for extended growth in early Homo from Dmanisi.

Human life history is characterized by an extended period of immaturity during which there is a disjunction between cerebral and somatic growth rates. This mode of ontogeny is thought to be essential for the acquisition of advanced cognitive capabilities in a socially complex environment while the brain is still growing. Key information about when and how this pattern evolved can be gleaned from the teeth of fossil hominins because dental development informs about the pace of life history.

Shaft structure of the first metatarsal contains a strong phylogenetic signal in apes and humans.

Objectives: Metatarsal bones constitute a key functional unit of the foot in primates. While the form-function relationships of metatarsals have been extensively studied, particularly in relation to the loss of the grasping ability of the foot in humans in contrast to apes, the effect of phyletic history on the metatarsal morphology and its variability remains largely unknown.

Materials And Methods: Here, we evaluate how the strength of the phylogenetic signal varies from the first to the fifth metatarsal in humans, chimpanzees, gorillas, orangutans, gibbons, and Japanese macaques.

Endocranial ontogeny and evolution in early : The evidence from Herto, Ethiopia.

Fossils and artifacts from Herto, Ethiopia, include the most complete child and adult crania of early . The endocranial cavities of the Herto individuals show that by 160,000 y ago, brain size, inferred from endocranial size, was similar to that seen in modern human populations. However, endocranial shape differed from ours.

Climate effects on archaic human habitats and species successions.

It has long been believed that climate shifts during the last 2 million years had a pivotal role in the evolution of our genus Homo. However, given the limited number of representative palaeo-climate datasets from regions of anthropological interest, it has remained challenging to quantify this linkage. Here, we use an unprecedented transient Pleistocene coupled general circulation model simulation in combination with an extensive compilation of fossil and archaeological records to study the spatiotemporal habitat suitability for five hominin species over the past 2 million years.

The primitive brain of early .

The brains of modern humans differ from those of great apes in size, shape, and cortical organization, notably in frontal lobe areas involved in complex cognitive tasks, such as social cognition, tool use, and language. When these differences arose during human evolution is a question of ongoing debate. Here, we show that the brains of early from Africa and Western Asia (Dmanisi) retained a primitive, great ape-like organization of the frontal lobe.

Early development of the Neanderthal ribcage reveals a different body shape at birth compared to modern humans.

Ontogenetic studies provide clues for understanding important paleobiological aspects of extinct species. When compared to that of modern humans, the adult Neanderthal thorax was shorter, deeper, and wider. This is related to the wide Neanderthal body and is consistent with their hypothetical large requirements for energy and oxygen.

Variation of bony labyrinthine morphology in Mio-Plio-Pleistocene and modern anthropoids.

Objectives: The bony labyrinth of the inner ear has special relevance when tracking phenotypic evolution because it is often well preserved in fossil and modern primates. Here we track the evolution of the bony labyrinth of anthropoid primates during the Mio-Plio-Pleistocene-the time period that gave rise to the extant great apes and humans.

Materials And Methods: We use geometric morphometrics to analyze labyrinthine morphology in a wide range of extant and fossil anthropoids, including New World and Old World monkeys, apes, and humans; fossil taxa are represented by Aegyptopithecus, Microcolobus, Epipliopithecus, Nacholapithecus, Oreopithecus, Ardipithecus, Australopithecus, and Homo.

Evidence for independent brain and neurocranial reorganization during hominin evolution.

Throughout hominin evolution, the brain of our ancestors underwent a 3-fold increase in size and substantial structural reorganization. However, inferring brain reorganization from fossil hominin neurocrania (=braincases) remains a challenge, above all because comparative data relating brain to neurocranial structures in living humans and great apes are still scarce. Here we use MRI and same-subject spatially aligned computed tomography (CT) and MRI data of humans and chimpanzees to quantify the spatial relationships between these structures, both within and across species.

Reconstructing the Neanderthal brain using computational anatomy.

The present study attempted to reconstruct 3D brain shape of Neanderthals and early Homo sapiens based on computational neuroanatomy. We found that early Homo sapiens had relatively larger cerebellar hemispheres but a smaller occipital region in the cerebrum than Neanderthals long before the time that Neanderthals disappeared. Further, using behavioural and structural imaging data of living humans, the abilities such as cognitive flexibility, attention, the language processing, episodic and working memory capacity were positively correlated with size-adjusted cerebellar volume.

Identification of in vivo Sulci on the External Surface of Eight Adult Chimpanzee Brains: Implications for Interpreting Early Hominin Endocasts.

The only direct source of information about hominin brain evolution comes from the fossil record of endocranial casts (endocasts) that reproduce details of the external morphology of the brain imprinted on the walls of the braincase during life. Surface traces of sulci that separate the brain's convolutions (gyri) are reproduced sporadically on early hominin endocasts. Paleoneurologists rely heavily on published descriptions of sulci on brains of great apes, especially chimpanzees (humans' phylogenetically closest living relatives), to guide their identifications of sulci on ape-sized hominin endocasts.

Phylogenetic and environmental effects on limb bone structure in gorillas.

Objectives: The effects of phylogeny and locomotor behavior on long bone structural proportions are assessed through comparisons between adult and ontogenetic samples of extant gorillas.

Materials And Methods: A total of 281 wild-collected individuals were included in the study, divided into four groups that vary taxonomically and ecologically: western lowland gorillas (G. g.

Femoral ontogeny in humans and great apes and its implications for their last common ancestor.

Inferring the morphology of the last common ancestor of humans, chimpanzees and gorillas is a matter of ongoing debate. Recent findings and reassessment of fossil hominins leads to the hypothesis that the last common ancestor was not extant African ape-like. However, an African great-ape-like ancestor with knuckle walking features still remains plausible and the most parsimonious scenario.

Neomorphosis and heterochrony of skull shape in dog domestication.

The overall similarity of the skull shape of some dog breeds with that of juvenile wolves begs the question if and how ontogenetic changes such as paedomorphosis (evolutionary juvenilisation) played a role in domestication. Here we test for changes in patterns of development and growth during dog domestication. We present the first geometric morphometric study using ontogenetic series of dog and wolf crania, and samples of dogs with relatively ancestral morphology and from different time periods.

Individual-based modelling of population growth and diffusion in discrete time.

Individual-based models (IBMs) of human populations capture spatio-temporal dynamics using rules that govern the birth, behavior, and death of individuals. We explore a stochastic IBM of logistic growth-diffusion with constant time steps and independent, simultaneous actions of birth, death, and movement that approaches the Fisher-Kolmogorov model in the continuum limit. This model is well-suited to parallelization on high-performance computers.

Development of Pelvic Sexual Dimorphism in Hylobatids: Testing the Obstetric Constraints Hypothesis.

Pelvic sexual dimorphism in primates is typically seen as the result of female-specific adaptations to obstetric constraints, which arise from the tight fit between the neonate head and the maternal pelvis. However, it remains debated to which extent pelvic dimorphism is a correlate of obstetric constraints, of body size dimorphism, and/or of other factors. Also, little is known on how pelvic dimorphism develops.

Skull 5 from Dmanisi: Descriptive anatomy, comparative studies, and evolutionary significance.

A fifth hominin skull (cranium D4500 and mandible D2600) from Dmanisi is massively constructed, with a large face and a very small brain. Traits documented for the first time in a basal member of the Homo clade include the uniquely low ratio of endocranial volume to basicranial width, reduced vertex height, angular vault profile, smooth nasal sill coupled with a long and sloping maxillary clivus, elongated palate, and tall mandibular corpus. The convex clivus and receding symphysis of skull 5 produce a muzzle-like form similar to that of Australopithecus afarensis.

Development of Modular Organization in the Chimpanzee Pelvis.

The bony pelvis of primates is a composite structure serving a variety of functions, and exhibiting a complex pattern of modularity and integration. Still little is known, however, about how patterns of modularity and integration arise, and how they change throughout ontogeny. Here we study the ontogeny of modularity and integration in developmental and functional units of the pelvis of our closest living relatives, the chimpanzees.

A Stable Finite-Difference Scheme for Population Growth and Diffusion on a Map.

We describe a general Godunov-type splitting for numerical simulations of the Fisher-Kolmogorov-Petrovski-Piskunov growth and diffusion equation on a world map with Neumann boundary conditions. The procedure is semi-implicit, hence quite stable. Our principal application for this solver is modeling human population dispersal over geographical maps with changing paleovegetation and paleoclimate in the late Pleistocene.

Effects of cranial integration on hominid endocranial shape.

Because brains do not fossilize, the internal surface of the braincase (endocast) serves as an important source of information about brain growth, development, and evolution. Recent studies of endocranial morphology and development in great apes, fossil hominins, and modern humans have revealed taxon-specific differences. However, it remains to be investigated to which extent differences in endocranial morphology reflect differences in actual brain morphology and development, and to which extent they reflect different interactions of the brain and its case with the cranial base and face.

Brain development is similar in Neanderthals and modern humans.

While the braincase of adult Neanderthals had a similar volume to that of modern humans from the same period, differences in endocranial shape suggest that brain morphology differed between modern humans and Neanderthals. When and how these differences arose during evolution and development is a topic of ongoing research, with potential implications for species-specific differences in brain and cognitive development, and in life history [1,2]. Earlier research suggested that Neanderthals followed an ancestral mode of brain development, similar to that of our closest living relatives, the chimpanzees [2-4].

Developmental evidence for obstetric adaptation of the human female pelvis.

The bony pelvis of adult humans exhibits marked sexual dimorphism, which is traditionally interpreted in the framework of the "obstetrical dilemma" hypothesis: Giving birth to large-brained/large-bodied babies requires a wide pelvis, whereas efficient bipedal locomotion requires a narrow pelvis. This hypothesis has been challenged recently on biomechanical, metabolic, and biocultural grounds, so that it remains unclear which factors are responsible for sex-specific differences in adult pelvic morphology. Here we address this issue from a developmental perspective.