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The taxonomy, phylogeny, and biology of theParanthropusspecies have been the center of debates since the earliest discoveryof the TM 1517 cranium (now attributed toParanthropus robustus)from the Plio-Pleistocene site of Kromdraai (South Africa) in 1938by R. Broom (Broom, 1938). In particular, whetherParanthropusboiseiandP. robustusrepresent two distinct taxa, and whether thetwo species emerged from a common ancestor (i.e., the hypothesisof a monophyletic group) remain largely unresolved (reviewed inConstantino and Wood, 2004,2007;Wood and Schroer, 2017).Besides the taxonomic and phylogenetic aspects, the presence oftwo contemporaneous‘robust’species in the eastern and southernAfrican hominin fossil records raises critical questions regardingpotential occurrences of homoplasies in the hominin clade, withsubstantial implications for our understanding of early hominin paleobiology (Wood and Schroer, 2017). Moreover, the absence ofassociated cranial and postcranial remains attributed toPara-nthropuscomplicate the reconstruction of the behavior of thisenigmatic‘megadont’hominin genus (reviewed in Constantino and Wood, 2007).

Although stone tools generally co-occur with early members of the genus Homo, they are rarely found in direct association with hominins. We report that both Acheulian and Oldowan artifacts and Homo erectus crania were found in close association at 1.26 million years (Ma) ago at Busidima North (BSN12), and ca. 1.6 to 1.5 Ma ago at Dana Aoule North (DAN5) archaeological sites at Gona, Afar, Ethiopia. The BSN12 partial cranium is robust and large, while the DAN5 cranium is smaller and more gracile, suggesting that H. erectus was probably a sexually dimorphic species. The evidence from Gona shows behavioral diversity and flexibility with a lengthy and concurrent use of both stone technologies by H. erectus, confounding a simple "single species/single technology" view of early Homo.

Significance The new species Homo naledi was discovered in 2013 in a remote cave chamber of the Rising Star cave system, South Africa. This species survived until between 226,000 and 335,000 y ago, placing it in continental Africa at the same time as the early ancestors of modern humans were arising. Yet, H. naledi was strikingly primitive in many aspects of its anatomy, including the small size of its brain. Here, we have provided a description of endocast anatomy of this primitive species. Despite its small brain size, H. naledi shared some aspects of human brain organization, suggesting that innovations in brain structure were ancestral within the genus Homo .

Little is known about how occipital lobe asymmetry, width, and height interact to contribute to the operculation of the posterior parietal lobe, despite the utility of knowing this for understanding the relative reduction in the size of the occipital lobe and the increase in the size of the posterior parietal lobe during human brain evolution. Here, we use linear measurements taken on 3D virtual brain surfaces obtained from 83 chimpanzees to study these traits as they apply to operculation of the posterior occipital parietal arcus or bridging gyrus. Asymmetry in this bridging gyrus visibility provides a unique opportunity to study both the human ancestral and human equivalently normal condition in the same individual. Our results show that all three traits (occipital lobe asymmetry, width, and height) are related to this operculation and bridging gyrus visibility but width and not height is the best predictor, against expectations, suggesting that relative reduction of the occipital lobe and exposure of the posterior parietal is a complex phenomenon.

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. We use a multiple-variance Brownian motion approach in association with evolutionary simulations to measure the tempo and mode of the evolution of endocranial and dental size and shape within the hominin clade. We show that hominin postcanine teeth have evolved at a relatively consistent neutral rate, whereas brain size evolved at comparatively more heterogeneous rates that cannot be explained by a neutral model, with rapid pulses in the branches leading to later Homo species. Brain reorganization shows evidence of elevated rates only much later in hominin evolution, suggesting that fast-evolving traits such as the acquisition of a globular shape may be the result of direct or indirect selection for functional or structural traits typical of modern humans.

Labial striations on the anterior teeth have been documented in numerous European pre-Neandertal and Neandertal fossils and serve as evidence for handedness. OH-65, dated at 1.8 mya, shows a concentration of oblique striations on, especially, the left I1 and right I1, I2 and C1, which signal that it was right-handed. From these patterns we contend that OH-65 was habitually using the right hand, over the left, in manipulating objects during some kind of oral processing. In living humans right-handedness is generally correlated with brain lateralization, although the strength of the association is questioned by some. We propose that as more specimens are found, right-handedness, as seen in living Homo, will most probably be typical of these early hominins.

Homo erectus was anatomically variable and behaviorally flexible using both Oldowan and Acheulian artifacts., Although stone tools generally co-occur with early members of the genus Homo, they are rarely found in direct association with hominins. We report that both Acheulian and Oldowan artifacts and Homo erectus crania were found in close association at 1.26 million years (Ma) ago at Busidima North (BSN12), and ca. 1.6 to 1.5 Ma ago at Dana Aoule North (DAN5) archaeological sites at Gona, Afar, Ethiopia. The BSN12 partial cranium is robust and large, while the DAN5 cranium is smaller and more gracile, suggesting that H. erectus was probably a sexually dimorphic species. The evidence from Gona shows behavioral diversity and flexibility with a lengthy and concurrent use of both stone technologies by H. erectus, confounding a simple “single species/single technology” view of early Homo.

Hominin cranial remains from the Dinaledi Chamber, South Africa, represent multiple individuals of the species

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. The human signature of elevated striatal dopamine, serotonin, and neuropeptide Y, coupled with lowered acetylcholine, systematically favors externally driven behavior and greatly amplifies sensitivity to social cues that promote social conformity, empathy, and altruism. We propose that selection induced an initial form of this profile in early hominids, which increased their affiliative behavior, and that this shift either preceded or accompanied the adoption of bipedality and elimination of the sectorial canine. We further hypothesize that these changes were critical for increased individual fitness and promoted the adoption of social monogamy, which progressively increased cooperation as well as a dependence on tradition-based cultural transmission. These eventually facilitated the acquisition of language by elevating the reproductive advantage afforded those most sensitive to social cues.

International audience; 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. We demonstrate both an absolute and relative bilateral increase in the size of the third frontal convolution in width and length between Pan species, as well as in hominins. We also observed a global bilateral increase in the size of the third frontal convolution across all species during hominin evolution, but also non-allometric intra-group variations independent of brain size within the fossil samples. Finally, our results show that the commonly accepted leftward asymmetry of Broca's cap is biased by qualitative observation of individual specimens. The trend during hominin evolution seems to be a reduction in size on the left compared with the right side, and also a clearer definition of the area. The third frontal convolution considered as a whole projects more laterally and antero-posteriorly in the right hemisphere. As a result, the left 'Broca's cap' looks more globular and better defined. Our results also suggest that the pattern of brain asymmetries is similar between Pan paniscus and hominins, leaving the gradient of the degree of asymmetry as the only relevant structural parameter. As the anatomical substrate related to brain asymmetry has been present since the appearance of the hominin lineage, it is not possible to prove a direct relationship between the extent of variations in the size, shape, and asymmetries of the third frontal convolution and the origin of language in hominins.

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. The juvenile brain exhibits a wider MW than FW, while FW of the adolescent brain expands to nearly equal MW, concurrent with an increase in ML. The preferential frontal lobe expansion during modern human development parallels that observed during the evolution of Homo. In 17 microcephalic individuals, only 6 (35%) exhibited preferential frontal lobe hypoplasia, presumably a reflection of multiple etiologies that adversely affect differing brain regions. Compared to 79 modern human adult endocasts and 12 modern microcephalic endocasts, LB1 (Homo floresiensis) clustered more consistently with the microcephalic sample than with the normocephalic sample. Anat Rec, 296:630–637, 2013. © 2013 Wiley Periodicals, Inc.

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. We also test for the possible asymmetries of these features in a large sample of modern humans and observe individual particularities in the fossil specimens. This study contributes important new information about the brain evolution in the genus Homo . Our results show that the general pattern of surface asymmetry for the different regional brain surfaces in fossil species of Homo does not seem to be different from the pattern described in a large sample of anatomically modern H. sapiens , i.e., the right hemisphere has a larger surface than the left, as do the right frontal, the right parieto-temporal and the left occipital lobes compared with the contra-lateral side. It also appears that Asian Homo erectus specimens are discriminated from all other samples of Homo , including African and Georgian specimens that are also sometimes included in that taxon. The Asian fossils show a significantly smaller relative size of the parietal and temporal lobes. Neandertals and anatomically modern H. sapiens , who share the largest endocranial volume of all hominins, show differences when considering the relative contribution of the frontal, parieto-temporal and occipital lobes. These results illustrate an original variation in the pattern of brain organization in hominins independent of variations in total size. The globularization of the brain and the enlargement of the parietal lobes could be considered derived features observed uniquely in anatomically modern H. sapiens .

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. In addition, the same craniometric ratios were determined on the endocasts of 10 microcephalic individuals, 79 normal controls (anatomically modern humans), and 17 Homo erectus specimens. These ratios were then compared with those of two LB1 endocasts. The findings showed that the calculated cerebral/cerebellar ratios of the LB1 endocast [Falk D, et al. (2007) Proc Natl Acad Sci USA 104:2513–2518] fall outside the range of living normocephalic individuals. The ratios derived from two LB1 endocasts also fall largely outside the range of modern normal human and H. erectus endocasts and within the range of microcephalic endocasts. The findings support but do not prove the contention that LB1 represents a pathological microcephalic Homo sapiens rather than a new species, (i.e., H. floresiensis ).

Minor controversies notwithstanding, the evolution of the human brain has been an intermingled composite of allometric and nonallometric increases of brain volume and reorganizational events such as the reduction of primary visual cortex and a relative increase in both posterior association and (most probably) prefrontal cortex, as well as increased cerebral asymmetries, including Broca's and Wernicke's regions, with some of these changes already occurring in australopithecine times. As outlined in Holloway (1967), positive feedback (amplification-deviation) has been a major mechanism in size increases. Exactly how this mélange of organs evolved will require many more paleontological discoveries with relatively intact crania, an unraveling of the genetic bases for both brain structures and their relationship to behaviors, and a far more complete picture of how the brain varies between male and female and among different populations throughout the world. After all, the human brain is still evolving, but for how long is quite uncertain.

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 54.7 ± 5.5 kyr bp (arithmetic mean ± 2 standard deviations) by uranium-thorium dating, that sheds light on this crucial event. The overall shape and discrete morphological features of the Manot 1 calvaria demonstrate that this partial skull is unequivocally modern. It is similar in shape to recent African skulls as well as to European skulls from the Upper Palaeolithic period, but different from most other early anatomically modern humans in the Levant. This suggests that the Manot people could be closely related to the first modern humans who later successfully colonized Europe. Thus, the anatomical features used to support the 'assimilation model' in Europe might not have been inherited from European Neanderthals, but rather from earlier Levantine populations. Moreover, at present, Manot 1 is the only modern human specimen to provide evidence that during the Middle to Upper Palaeolithic interface, both modern humans and Neanderthals contemporaneously inhabited the southern Levant, close in time to the likely interbreeding event with Neanderthals.

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. Allometric regression, using medulla volume as an independent variable, did not reveal a significant difference between strepsirrhines and haplorhines in the scaling of Vmo volume. In addition, correlation analysis using independent contrasts did not find a relationship between Vmo size or GLI and the percent of leaves in the diet. The scaling trajectory of VII volume, in contrast, differed significantly between suborders. Great ape and human VII volumes, furthermore, were significantly larger than predicted by the haplorhine regression. Enlargement of VII in these taxa may reflect increased differentiation of the facial muscles of expression and greater utilization of the visual channel in social communication. The independent contrasts of VII volume and GLI, however, were not correlated with social group size. To examine whether the human hypoglossal motor system is specialized to control the tongue for speech, we tested human XII volume and GLI for departures from nonhuman haplorhine prediction lines. Although human XII volumes were observed above the regression line, they did not exceed prediction intervals. Of note, orang-utan XII volumes had greater residuals than humans. Human XII GLI values also did not differ from allometric prediction. In sum, these findings indicate that the cranial orofacial motor nuclei evince a mosaic of phylogenetic specializations for innervation of the facial muscles of expression in the context of a generally conservative scaling relationship with respect to medulla size.

Since Dart’s analysis of the Taung skull in1925 in Nature, there has been controversy surrounding the presence of a clearly defined lunate sulcus (LS) in the australopithecines, marking the anterior extent of primary visual cortex (PVC). An anterior position signifies that the LS is in an ape-like position, such as found in Pan troglodytes. A posterior position is a more human-like characteristic (autapomorphy). If the latter occurred in Australopithecus, then the cerebral cortex underwent some neurological reorganization prior to brain enlargement, thus occurring earlier than the emergence of the genus Homo. The endocast of the Stw 505 specimen from Sterkfontein, South Africa, shows an unmistakably posterior placement of the LS. The early hominid brain was reorganized at least by the time of Australopithecus africanus, thus vindicating Dart’s early assessment. To cite this article: R.L. Holloway, C. R. Palevol 3 (2004).

Stephen Jay Gould, the prominent evolutionary biologist and science historian, argued that “unconscious manipulation of data may be a scientific norm” because “scientists are human beings rooted in cultural contexts, not automatons directed toward external truth” [1], a view now popular in social studies of science [2]–[4]. In support of his argument Gould presented the case of Samuel George Morton, a 19th-century physician and physical anthropologist famous for his measurements of human skulls. Morton was considered the objectivist of his era, but Gould reanalyzed Morton's data and in his prize-winning book The Mismeasure of Man [5] argued that Morton skewed his data to fit his preconceptions about human variation. Morton is now viewed as a canonical example of scientific misconduct. But did Morton really fudge his data? Are studies of human variation inevitably biased, as per Gould, or are objective accounts attainable, as Morton attempted? We investigated these questions by remeasuring Morton's skulls and reexamining both Morton's and Gould's analyses. Our results resolve this historical controversy, demonstrating that Morton did not manipulate data to support his preconceptions, contra Gould. In fact, the Morton case provides an example of how the scientific method can shield results from cultural biases.

The parietal bones approximately cover the extension of the underlying parietal lobes. Although the boundaries of these two anatomical elements do not coincide, during morphogenesis the growth of the parietal bones is largely induced by the pressure exerted by the parietal lobes. Modern humans display larger parietal chords and arcs compared with non-modern human species. However, the variation of these variables have not been analyzed before according to the covariation with the general endocranial diameters. When the curvature of the parietal bones is regressed onto the main neurocranial distances, modern humans show larger relative values, suggesting not only an absolute enlargement but a definite allometric change. Taking into account the morphogenetic relationships with the parietal lobes, these results further support previous hypotheses suggesting a relative enlargement of these cortical areas in Homo sapiens, by using simple and reliable homologous neurocranial arcs. Anat Rec, 2011. © 2011 Wiley-Liss, Inc.

The gyrification indices (GI) recently compared for chimpanzee and human brains by Armstrong et al. (1991) ignores important volumetric differences in primary visual striate cortex (area 17 of Brodmann) and the lateral geniculate body which provides the optic radiation to the visual cortex. Allometric relationships for these structures are very strong in non-human primate brains based on the data of Stephan et al. (1981). In human brains, however, their observed empirical values are over 121 % less than expected for a primate of such a brain size. The regions that show the same overlap of values between chimpanzee and human cortex of the GI are not homologous given the sharp reduction in lateral extent of primary visual striate cortex in the human brain. The GI as used by these authors ignores important reorganizational changes between chimpanzee and human despite volume differences in brain size. Thus, it is doubtful that the GI can be used to assess the position of primary visual striate cortex in the Taung hominid endocast, or to argue for the primacy of brain enlargement before brain reorganization. To assess the simultaneity of volume and reorganizational changes in early hominid evolution, it will be essential to have a better understanding of the paleoneurological evidence. Although controversial, the Hadar AL 162-28 endocast of the 3 + MY Australopithecus afarensis provides evidence for morphometric reorganization of the occipital and parietal lobes of the brain prior to any dramatic increase in overall brain volume.

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. Our results do not support positive allometry for the frontal lobe's width in relation to the main endocranial diameters within modern humans (Homo sapiens). Also, the correlation between frontal width and hemispheric length is lower than the correlation between frontal width and parieto-temporal width. When compared with the australopithecines, the genus Homo could have experienced a non-allometric widening of the brain at the temporo-parietal areas, which is most evident in Neandertals. Modern humans and Neandertals also display a non-allometric widening of the anterior endocranial fossa at the Broca's cap when compared with early hominids, again more prominent in the latter group. Taking into account the contrast between the intra-specific patterns and the between-species differences, the relative widening of the anterior fossa can be interpreted as a definite evolutionary character instead of a passive consequence of brain size increase. This expansion is most likely associated with correspondent increments of the underlying neural mass, or at least with a geometrical reallocation of the frontal cortical volumes. Although different structural changes of the cranial architecture can be related to such variations, the widening of the frontal areas is nonetheless particularly interesting when some neural functions (like language or working memory, decision processing, etc.) and related fronto-parietal cortico-cortical connections are taken into account.

The anatomic pattern and left hemisphere size predominance of the planum temporale, a language area of the human brain, are also present in chimpanzees ( Pan troglodytes ). The left planum temporale was significantly larger in 94 percent (17 of 18) of chimpanzee brains examined. It is widely accepted that the planum temporale is a key component of Wernicke's receptive language area, which is also implicated in human communication-related disorders such as schizophrenia and in normal variations such as musical talent. However, anatomic hemispheric asymmetry of this cerebrocortical site is clearly not unique to humans, as is currently thought. The evolutionary origin of human language may have been founded on this basal anatomic substrate, which was already lateralized to the left hemisphere in the common ancestor of chimpanzees and humans 8 million years ago.

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 endo- casts out of rubber latex shells filled with plaster. The extent to which the method of production introduces errors in endocast replicas is unknown. We demonstrate a powerful method of comparing complex shapes in 3- dimensions (3D) that is broadly applicable to a wide range of paleoanthropological questions. Pairs of virtual endocasts (VEs) created from high-resolution CT scans of corresponding latex/plaster endocasts and their associated crania were rigidly registered (aligned) in 3D space for two Homo sapiens and two Pan troglodytes specimens. Distances between each cranial VE and its corresponding latex/plaster VE were then mapped on a voxel-by-voxel basis. The results show that between 79.7% and 91.0% of the voxels in the four latex/plaster VEs are within 2 mm of their corresponding cranial VEs surfaces. The average error is relatively small, and variation in the pattern of error across the surfaces appears to be generally random overall. However, inferior areas around the cranial base and the temporal poles were somewhat overestimated in both human and chimpanzee specimens, and the area over- laying Broca's area in humans was somewhat underesti- mated. This study gives an idea of the size of possible error inherent in latex/plaster endocasts, indicating the level of confidence we can have with studies relying on compari- sons between them and, e.g., hominid fossil endocasts. Am J Phys Anthropol 132:183-192, 2007. V C 2006 Wiley-Liss, Inc.

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. The roles of the PT in human language are well known while PP is implicated in dyslexia and communication disorders. Since posterior bifurcation of the sylvian fissure (SF) is unique to humans and great apes, we used it to determine characteristics of its posterior ascending ramus, an indicator of the PP, in chimpanzee and orangutan brains. Results showed a human-like pattern of R>L PP (P = 0.04) in chimpanzees with a nonsignificant negative correlation of L>R PT vs. R>L PP (CC = -0.3; P = 0.39). In orangutans, SF anatomy is more variable, although PP was nonsignificantly R>L in three of four brains (P = 0.17). We have now demonstrated human-like hemispheric asymmetry of a second language-related brain area in great apes. Our findings persuasively support an argument for addition of a new component to the comparative neuroanatomic complex that defines brain language or polymodal communication areas. PP strengthens the evolutionary links that living great apes may offer to better understand the origins of these progressive parts of the brain. Evidence mounts for the stable expression of a neural foundation for language in species that we recently shared a common ancestor with.

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. Because the position of the photographs varied randomly from trial to trial, sequences could not be learned by motor imitation. Both monkeys learned new sequences more rapidly after observing an expert execute those sequences than when they had to learn new sequences entirely by trial and error.

Ever since Anders Retzius' invention of the cephalic index late in the nineteenth century, legions of anthropologists armed with spreading calipers have bravely endured the apprehension of their subjects and have accumulated thousands of measurements of head lengths and breadths and divided the latter by the former to achieve that purportedly objective characterization, the cranial index, mellifluously categorized as “dolichocephalic, mesocephalic, or brachycephalic.” From this index, one could (if properly trained) hazard a guess about whether someone was from the Northwestern, the Mediterranean, or the Alpine region of Europe. There was even hope that all groups throughout the world could be characterized and classified similarly. The uses to which this index were put ranged from the beneficent to the grotesque, from simple curiosity to preventing people from being accepted as immigrants, and to the characterization of “ideal” racial types as ingredients in racial classifications. On the humorous side, Hooten (1) noted that only hat makers paid no attention to the differences in head shape. I confess that over my years of teaching human skeletal biology, I have enjoyed almost each and every head measurement that I've taken. I ordinarily managed to demonstrate that the index meant nothing in terms of defining whence came a person. I doubt that any of us practicing these arts have failed to mention the findings of Franz Boas' 1910–1913 publications (2) that the offspring of immigrants born in the United States showed a “significant” difference from their immigrant parents in this index. (I say significant because that was what we were taught.) This finding was perhaps one of the most …

The Omo L338y-6 occipital region has been recently studied by White and Falk (1999), who claim that it shows a readily identifiable enlarged left occipital-marginal sinus (O/M). These observations are contrary to the direct observations of previous investigators (Rak and Howell, 1978; Kimbel, 1984; Holloway, 1981; Holloway, 1988). White and Falk (1999) further argue that the presence of this enlarged O/M strongly suggests that the Omo L338y-6 hominid was indeed a "robust" Australopithecus. We used direct sectioning and CT scanning to analyze magnified sections of a high-quality first-generation cast of the newly cleaned original fossil. These methods fail to show any evidence of a morphological landmark that can be interpreted as an enlarged O/M, either as an eminence or a sulcus. In contrast, the same techniques used with both SK 1585 and OH5 ("robust" Australopithecus with an enlarged O/M) show extremely visible and palpable enlarged O/M's. Examination of the original Omo fossil confirms that it lacks an O/M. This evidence clearly shows that an enlarged O/M cannot be identified on either the original fossil or a first-generation cast, although this does not rule out the possibility that the Omo L338y-6 hominid was a "robust" Australopithecus. We believe that the differences between observers regarding this feature are most probably due to displacement caused by a crack and the different source materials employed, i.e., the difference between a first-generation cast of the original fossil and a third- or fourth-generation cast of the endocast made two decades ago.

This paper describes the morphology and phylogenetic significance of a well-preserved fossil human cranium found near Reilingen, Germany in 1978. The specimen consists of two complete parietals, most of the right temporal, and 70% of the occipital. The specimen displays several features characteristic of early "archaic" Homo sapiens: maximum breadth at the supramastoid crests, roughly pentagonal occipital view, an angular torus, superoinferiorly elongate/ anteroposterior shortened squamous temporal, strong mastoid, and separation of the tympanic and mastoid temporal portions. Other features align the Reilingen cranium with the "classic" Neandertals: developed suprainiac fossa, bilaterally protuberant occipital torus, strong juxtamastoid eminence, a highly convex occipital plane, and lambdoid flattening. This morphology and our cephalometric analysis support the assignment of this specimen to a Stage 2 "pre-Neandertal" group (e.g., Steinheim, Swanscombe, and Atapuerca [SH site]). Following an "Accretion Model" of European hominid evolution, Stage 2 succeeds Stage 1 European "early-pre-Neandertals" (e.g., Mauer and Petralona), and precedes both the Saale-Eem Stage 3 "early Neandertals" (e.g., Biache 1), which present greater platycephaly, a reduced mastoid process, an enlarged juxtamastoid eminence, and true "en-bombe" (parieto-occipital form), and Weichsel Stage 4 "Neandertals" (sensu stricto, i.e., "classic" Neandertals).

Endocasts provide evidence on size and shape characteristics, blood supply trajectories, and neurological features of the brain, allowing comparative analyses of fossil hominins crucial to our understanding of human brain evolution. Here, we assess the morphological features of the virtual endocast of the Cioclovina Upper Paleolithic calvarium, one of the earliest reliably dated European modern human fossils. Our study was conducted on a computed tomography (CT) scan of the original specimen. The endocranial profile was approximated via a semiautomatic segmentation of the CT data. Virtual reconstructions of the endocast were used for assessing the morphological features of the endocranium and for the estimation of the endocranial volume. Cioclovina exhibits a clockwise torque with a small anterior extension of the left frontal lobe over the right one and a protrusion of the right occipital lobe over the left, most likely due to the superior sagittal sinus coursing over the occipital pole. There is an obvious right predominance of the posterior drainage system. Interestingly, the area of the frontal sinus is occupied by dense bony tissue with small air cells corresponding probably to a natural bony loss in the diploe ¨ and to vascular spaces. An estimated endocranial volume of 1498.53 cc was calculated. The convolutional details of the third inferior frontal gyrus (Broca’s caps) are indistinguishable from those found in modern Homo sapiens, and the left occipital lobe appears wider than the right, a possible correlate of right-handedness. Our metric analysis of endocranial measurements also aligns Cioclovina with modern humans. Anat Rec, 294:1083–1092, 2011. V

Having calculated the brain volumes of several australopithecine and early Homo fossil hominid brain endocasts ([1][1]–[3][2]), I read with considerable interest the report by Glen C. Conroy et al. (12 June, p. [1730][3]) and the commentary by Dean Falk (Perspectives, Science 's Compass, 12 June

One of the more vexing problems with hominoid endocasts has been to secure reliable information that goes beyond their volumes. One method is explored here, where a large number ( N = 171) of radial distances from a homologous internal central point to the dorsal endocast surface are measured in a polar coordinate system. From two pilot studies, one with a hominoid sample of N = 64, and the other with an enlarged sample of N = 92, the following results can be mentioned tentatively: (1) there are residual data that differ taxonomically in different cortical regions once overall endocast size is corrected in allometric fashion; (2) the major cortical regions where these differences appear most strongly are in the lower parietal lobule, anterior occipital zone, and the dorsoanterior region of the frontal lobe; (3) the method shows excellent promise in objectively and quantitatively depicting taxa-specific shape differences in functionally understood cortical regions through multivariate statistical analyses.

A quantitative neuropathological necropsy study of 22 control and 22 chronic alcoholic subjects showed a statistically significant loss of brain tissue in the chronic alcoholic group. The loss of tissue appeared to be from the white matter of the cerebral hemispheres rather than the cerebral cortex. This may reflect a primary alteration in the composition or structure of the white matter or it may be secondary to loss of nerve cells from the cortex with subsequent degeneration of the axons in the white matter. Further morphometric analyses including cortical neuronal counts will be necessary to clarify this issue.

A stochastic, hierarchical model for the evolution of the advanced hominid brain is developed. The fossil and geological data date the event to 1.6-1.8 million years ago. Palaeoclimatological evidence does not suggest that it coincided with significant ecological change. The cognitive capacities of "small" hominoid brains are reviewed in the context of pongid technology and carnivory and the evidence for hominid stone tool technology prior to the Plio/Pleistocene. Calibration information suggests that small-brained gracile australopithecines represented a successful long-term adaptation to their particular African ecozones. The evolution of the advanced hominid brain is, therefore, likely the result of ongoing stochastic genetic processes that keep the eukaryotic genome in a state of genetic flux without reference to the selection pressures generated by macroscopic biotic communities. Radiometric calibration of the fossil evidence viewed in conjunction with computer simulations of macroevolutionary events...

Volumetric data are presented for 16 of the early hominids from both South and East Africa. Although the sample sizes are small, the statistical data support the conclusion that at least three taxa are represented; Australopithecus africanus, A. robustus , and Homo habilis . These data, plus certain morphological attributes, indicate that the brains of early hominids were reorganized to a human pattern, regardless of their small endocranial capacities. Some speculative suggestions are made regarding the possible relationship between brain and body weights, as well as Stephan's (1972) “progression indices”. If the speculations are correct, they provide additional support for the idea that brain reorganization occurred early in human evolution, and that concepts which regard the brain as having a more terminal role in human mosaic evolution are incorrect, as all of the fossil encephalization or “progression indices” are in the range of modern Homo sapiens .

tion. This parameter, measured in cubic centimeters, has been used as a means of taxonomic identification, behavioral complexity, and intelligence, and for discussing dissimilar rates of somatic evolution. While it is generally appreciated that this parameter is a poor one for explaining behavioral differences, there is almost no discussion in the anthropological literature regarding the reasons behind the unsuitability of this parameter for either taxonomic or behavioral correlations. The range of variation of cranial capacity for modern Homo sapiens is about 1,000 c.c., with no correlation between capacity and behavior readily demonstrable. Such a figure represents almost the total amount of increase in capacity from the Australopithecine level to that of modern man. This parameter has also been one of the major stumbling blocks for almost 40 years in the acceptance of the Australopithecines as true hominids. It has been mainly the discoveries of stone tools, as well as the postcranial material (the pelves) which have been the most weighty factors in interpreting these early fossils as true hominids. With present-day emphases on behavior and selection in primate populations both past and present, and the increasing focus upon culture as an adaptive process and ecological niche, it seems critical to have a better understanding of both the meaning of this parameter and its unsuitability with respect to behavioral differences. This paper has an exceedingly simple point to make: a comparison of forms based on cranial capacity is not a comparison of equal units. Showing just why this is the case may aid in understanding other aspects of neural organization which are of more importance in relation to behavior, and pave the way for a clearer formulation of hypotheses which can eventually be tested through experimentation. While I have provided a much more thorough presentation of this problem elsewhere (Holloway 1964), and a number of more technical manuscripts are under preparation, it has been suggested that a presentation of the basic problems in a format containing a minimum of neurological technicalities might be of value for those anthropologists interested but without the

Starting with a critique of current beliefs that maxillary canine reduction in hominids was causally related to tool-use and tool-making, the article suggests that reduction took place because selection favored a different pattern of social behavior. Sexual dimorphism and aggressive intragroup behavior tend to be related in terrestrial primates. A shift in hormonal interactions is suggested, such that selection for diminution of aggressiveness resulted in a diminution of sexual dimorphism. Tool-making is seen as one of a number of cognitive reorganizations, not as a causal factor in canine reduction.

It is argued that a number of recent writings based on primate studies and on analysis of early hominid evolution have blurred certain central issues regarding human and non-human primate behavior. The central problem of how man organizes his experience and how he interacts with his environment is seldom squarely faced. A framework is provided here which examines tool-making in terms of psychological processes. It is argued that both tool-making and language come out of the same cognitive structure. The framework attempts to provide a means by which the appearance of emergent human behavior may be gauged from the fossil record. Two attributes, arbitrary form and imposition, are defined. It is argued that these two dimensions are specific to the human psychological structure, and that stone tools made to any standardized form satisfy the requirements of emergence in cognitive structure. Tool-making is analyzed using models for language behavior, and strong parallels are shown with certain design features t...

A redetermination of endocranial volume of the original 1924 Taung australopithecine described by Dart indicates a volume of 405 cubic centimeters, rather than the 525 cubic centimeters published earlier. The adult volume is estimated to have been 440 cubic centimeters. This value, plus other redeterminations of australopithecine endocasts, lowers the average to 442 cubic centimeters, and increase the likelihood of statistically significant differences from both robust australopithecines and the Olduvai Gorge hominid No. 7.