The endocast morphology of LES1, Homo naledi.

Objectives: Homo naledi is near the extreme of small brain size within Homo but is easily recognized as Homo in other aspects of endocast morphology. This study adds new evidence of the endocast morphology of H. naledi by describing the Lesedi Hominin 1 (LES1) endocranium from the Lesedi Chamber and compares it to the previously known H.

Co-occurrence of Acheulian and Oldowan artifacts with cranial fossils from Gona, Afar, Ethiopia.

Although stone tools generally co-occur with early members of the genus , they are rarely found in direct association with hominins. We report that both Acheulian and Oldowan artifacts and crania were found in close association at 1.26 million years (Ma) ago at Busidima North (BSN12), and ca.

Endocast morphology of from the Dinaledi Chamber, South Africa.

Hominin cranial remains from the Dinaledi Chamber, South Africa, represent multiple individuals of the species This species exhibits a small endocranial volume comparable to , combined with several aspects of external cranial anatomy similar to larger-brained species of such as and Here, we describe the endocast anatomy of this recently discovered species. Despite the small size of the endocasts, they share several aspects of structure in common with other species of , not found in other hominins or great apes, notably in the organization of the inferior frontal and lateral orbital gyri. The presence of such structural innovations in a small-brained hominin may have relevance to behavioral evolution within the genus .

A neurochemical hypothesis for the origin of hominids.

It has always been difficult to account for the evolution of certain human characters such as language, empathy, and altruism via individual reproductive success. However, the striatum, a subcortical region originally thought to be exclusively motor, is now known to contribute to social behaviors and "personality styles" that may link such complexities with natural selection. We here report that the human striatum exhibits a unique neurochemical profile that differs dramatically from those of other primates.

Brain enlargement and dental reduction were not linked in hominin evolution.

The large brain and small postcanine teeth of modern humans are among our most distinctive features, and trends in their evolution are well studied within the hominin clade. Classic accounts hypothesize that larger brains and smaller teeth coevolved because behavioral changes associated with increased brain size allowed a subsequent dental reduction. However, recent studies have found mismatches between trends in brain enlargement and posterior tooth size reduction in some hominin species.

The endocast of the one-million-year-old human cranium from Buia (UA 31), Danakil Eritrea.

Objectives: The Homo erectus-like cranium from Buia (UA 31) was found in the Eritrean Danakil depression and dated to 1 million years. Its outer morphology displays archaic traits, as well as distinctive and derived characters. The present study provides the description and metric comparison of its endocranial anatomy.

Levantine cranium from Manot Cave (Israel) foreshadows the first European modern humans.

A key event in human evolution is the expansion of modern humans of African origin across Eurasia between 60 and 40 thousand years (kyr) before present (bp), replacing all other forms of hominins. Owing to the scarcity of human fossils from this period, these ancestors of all present-day non-African modern populations remain largely enigmatic. Here we describe a partial calvaria, recently discovered at Manot Cave (Western Galilee, Israel) and dated to 54.

New high-resolution computed tomography data of the Taung partial cranium and endocast and their bearing on metopism and hominin brain evolution.

Falk and colleagues [Falk D, Zollikofer CP, Morimoto N, Ponce de León MS (2012) Proc Natl Acad Sci U S A 109(22):8467-8470] hypothesized that selective pressures favored late persistence of a metopic suture and open anterior fontanelle early in hominin evolution, and they put an emphasis on the Taung Child (Australopithecus africanus) as evidence for the antiquity of these adaptive features. They suggested three mutually nonexclusive pressures: an "obstetric dilemma," high early postnatal brain growth rates, and neural reorganization in the frontal cortex. To test this hypothesis, we obtained the first high-resolution computed tomography (CT) data from the Taung hominin.

Variations in size, shape and asymmetries of the third frontal convolution in hominids: paleoneurological implications for hominin evolution and the origin of language.

The study of brain structural asymmetries as anatomical substrates of functional asymmetries in extant humans, great apes, and fossil hominins is of major importance in understanding the structural basis of modern human cognition. We propose methods to quantify the variation in size, shape and bilateral asymmetries of the third frontal convolution (or posterior inferior frontal gyrus) among recent modern humans, bonobos and chimpanzees, and fossil hominins using actual and virtual endocasts. These methodological improvements are necessary to extend previous qualitative studies of these features.

Frontal brain expansion during development using MRI and endocasts: relation to microcephaly and Homo floresiensis.

A major hall of hominid brain evolution is an expansion of the frontal lobes. To determine if a similar trajectory occurs during modern human development, the MRI scans of 118 living infants, children, and adolescents were reviewed and three specific measurements obtained: frontal width (FW), maximal cerebral width (MW), and maximal cerebral length (ML). The infantile brain is uniformly wide but relatively short, with near equal FW and MW.

Language and tool making are similar cognitive processes.

Design features for language and stone toolmaking (not tool use) involve similar if not homologous cognitive processes. Both are arbitrary transformations of internal "intrinsic" symbolization, whereas non-human tool using is mostly an iconic transformation. The major discontinuity between humans and non-humans (chimpanzees) is language.

Variations and asymmetries in regional brain surface in the genus Homo.

Paleoneurology is an important field of research within human evolution studies. Variations in size and shape of an endocast help to differentiate among fossil hominin species whereas endocranial asymmetries are related to behavior and cognitive function. Here we analyse variations of the surface of the frontal, parieto-temporal and occipital lobes among different species of Homo, including 39 fossil hominins, ten fossil anatomically modern Homo sapiens and 100 endocasts of extant modern humans.

Technical note: the midline and endocranial volume of the Taung endocast.

The Taung endocast is one of the best-preserved and most important known in paleoanthropology. Although the endocast is undistorted and preserves distinctive landmarks, Taung has proved a difficult endocast, because it is only about 60% complete. To reconstruct Taung it is necessary to first use the available anatomical landmarks to define the midline of the endocast.

Craniometric ratios of microcephaly and LB1, Homo floresiensis, using MRI and endocasts.

The designation of Homo floresiensis as a new species derived from an ancient population is controversial, because the type specimen, LB1, might represent a pathological microcephalic modern Homo sapiens. Accordingly, two specific craniometric ratios (relative frontal breadth and cerebellar protrusion) were ascertained in 21 microcephalic infants and children by using MRI. Data on 118 age-equivalent control (normocephalic) subjects were collected for comparative purposes.

A new brain endocast of Homo erectus from Hulu Cave, Nanjing, China.

A new brain endocast of Homo erectus from Hulu Cave, Tangshan, Nanjing is described and compared with a broad sample of endocasts of H. erectus, Neanderthals, and recent modern humans. The Nanjing 1 endocast is reconstructed based on two portions of endocranial casts taken from the original fossil fragments.

A bivariate approach to the widening of the frontal lobes in the genus Homo.

Within the genus Homo, the most encephalized taxa (Neandertals and modern humans) show relatively wider frontal lobes than either Homo erectus or australopithecines. The present analysis considers whether these changes are associated with a single size-based or allometric pattern (positive allometry of the width of the anterior endocranial fossa) or with a more specific and non-allometric pattern. The relationship between hemispheric length, maximum endocranial width, and frontal width at Broca's area was investigated in extant and extinct humans.

Validation of plaster endocast morphology through 3D CT image analysis.

A crucial component of research on brain evolution has been the comparison of fossil endocranial surfaces with modern human and primate endocrania. The latter have generally been obtained by creating endocasts out of rubber latex shells filled with plaster. The extent to which the method of production introduces errors in endocast replicas is unknown.

Planum parietale of chimpanzees and orangutans: a comparative resonance of human-like planum temporale asymmetry.

We have previously demonstrated that leftward asymmetry of the planum temporale (PT), a brain language area, was not unique to humans since a similar condition is present in great apes. Here we report on a related area in great apes, the planum parietale (PP). PP in humans has a rightward asymmetry with no correlation to the L>R PT, which indicates functional independence.

Evolution of the brainstem orofacial motor system in primates: a comparative study of trigeminal, facial, and hypoglossal nuclei.

The trigeminal motor (Vmo), facial (VII), and hypoglossal (XII) nuclei of the brainstem comprise the final common output for neural control of most orofacial muscles. Hence, these cranial motor nuclei are involved in the production of adaptive behaviors such as feeding, facial expression, and vocalization. We measured the volume and Grey Level Index (GLI) of Vmo, VII, and XII in 47 species of primates and examined these nuclei for scaling patterns and phylogenetic specializations.

Brain structure variation in great apes, with attention to the mountain gorilla (Gorilla beringei beringei).

This report presents data regarding the brain structure of mountain gorillas (Gorilla beringei beringei) in comparison with other great apes. Magnetic resonance (MR) images of three mountain gorilla brains were obtained with a 3T scanner, and the volume of major neuroanatomical structures (neocortical gray matter, hippocampus, thalamus, striatum, and cerebellum) was measured. These data were included with our existing database that includes 23 chimpanzees, three western lowland gorillas, and six orangutans.

Cognitive imitation in rhesus macaques.

Experiments on imitation typically evaluate a student's ability to copy some feature of an expert's motor behavior. Here, we describe a type of observational learning in which a student copies a cognitive rule rather than a specific motor action. Two rhesus macaques were trained to respond, in a prescribed order, to different sets of photographs that were displayed on a touch-sensitive monitor.