Kebara 2 Neanderthal pelvis: first look at a complete inlet

The renewed excavations at the Kebara Cave revealed a Neanderthal skeleton dated at about 50-55,000 years B.P. The pelvis of this individual is the most intact Neanderthal pelvis yet discovered, presenting for the first time a complete inlet. Although the superior pubic ramus is extremely long, as typically seen in the Neanderthals, the size of the pelvic inlet is comparable to that of modern Homo sapiens. The length of the superior pubic ramus is found to stem from a more externally rotated innominate bone and not, as generally assumed, from the larger pelvic inlet. It is suggested that the uniqueness of the Neanderthal pelvis may be attributable to locomotion and posture-related biomechanics rather than to obstetric requirements.     

On the differences between two pelvises of Mousterian context from the Qafzeh and Kebara caves, Israel

Two pelvises from a similar archaeological context have been discovered in recent years in two different caves in Israel. The pelvis from the Qafzeh cave (Qafzeh 9) was dated by means of thermoluminescence at approximately 95 kyr BP. All available measurement values, the most significant being those of the diagnostic obturator region, fall within those of the modern range. The other pelvis emanates from the Kebara cave and differs fundamentally from modern pelvises and from the Qafzeh specimen, although the Kebara pelvis is 30,000 years younger than the latter. As in other remains of Neandertal pelvises, the superior pubic ramus of the Kebara hominid is extremely long and slender and exhibits a cross section unlike that of modern humans. The absolute height of the obturator region is very small. It is these measurements and proportions that set the Kebara pelvis apart from both modern pelvises and the specimen from Qafzeh. The morphological differences and the chronological relationship between the two fossil pelvises support the concept of two distinct evolutionary lineages for these hominids.     

Bite force production capability and efficiency in Neandertals and modern humans

Although there is consensus that Neandertal craniofacial morphology is unique in the genus Homo, debate continues regarding the precise anatomical basis for this uniqueness and the evolutionary mechanism that produced it. In recent years, biomechanical explanations have received the most attention. Some proponents of the "anterior dental loading hypothesis" (ADLH) maintain that Neandertal facial anatomy was an adaptive response to high-magnitude forces resulting from both masticatory and paramasticatory activity. However, while many have argued that Neandertal facial structure was well-adapted to dissipate heavy occlusal loads, few have considered, much less demonstrated, the ability of the Neandertal masticatory system to generate these presumably heavy loads. In fact, the Neandertal masticatory configuration has often been simultaneously interpreted as being disadvantageous for producing large bite forces. With rare exception, analyses that attempted to resolve this conflict were qualitative rather than quantitative. Using a three-dimensional digitizer, we recorded a sequence of points on the cranium and associated mandible of the Amud 1, La Chapelle-aux-Saints, and La Ferrassie 1 Neandertals, and a sample of early and recent modern humans (n = 29), including a subsample with heavy dental wear and documented paramasticatory behavior. From these points, we calculated measures of force-production capability (i.e., magnitudes of muscle force, bite force, and condylar reaction force), measures of force production efficiency (i.e., ratios of force magnitudes and muscle mechanical advantages), and a measure of overall size (i.e., the geometric mean of all linear craniofacial measurements taken). In contrast to the expectations set forth by the ADLH, the primary dichotomy in force-production capability was not between Neandertal and modern specimens, but rather between large (robust) and small (gracile) specimens overall. Our results further suggest that the masticatory system in the genus Homo scales such that a certain level of force-production efficiency is maintained across a considerable range of size and robusticity. Natural selection was probably not acting on Neandertal facial architecture in terms of peak bite force dissipation, but rather on large tooth size to better resist wear and abrasion from submaximal (but more frequent) biting and grinding forces. We conclude that masticatory biomechanical adaptation does not underlie variation in the facial skeleton of later Pleistocene Homo in general, and that continued exploration of alternative explanations for Neandertal facial architecture (e.g., climatic, respiratory, developmental, and/or stochastic mechanisms) seems warranted.     

Differences between Neandertal and modern human infant and child growth models

Studying the emergence of distinctive human growth patterns is essential to understanding the evolution of our species. The large number of Neandertal fossils makes this species the best candidate for a comparative study of growth patterns in archaic and modern humans. Here, Neandertal height growth during infancy and early childhood is described using a mathematical model. Height growth velocities for individuals five years old or younger are modelled as age functions based on different estimates of height and age for a set of ten Neandertal infants and children. The estimated heights of each Neandertal individual are compared with those of two modern human populations based on longitudinal and cross-sectional data. The model highlights differences in growth velocity during infancy (from the age of five months onward). We find that statural growth in Neandertal infants is much slower than that seen in modern humans, Neandertal growth is similar to modern humans at birth, but decreases around the third or fourth month. The markedly slower growth rates of Neandertal infants may be attributable to ontogenetic constraints or to metabolic stress, and contribute to short achieved adult stature relative to modern humans.     

The place of Neandertals in the evolution of hominid patterns of growth and development

This study uses the two developmental fields of dental maturation and femoral growth to determine if the pattern of growth and development in Neandertals (archaic Homo sapiens) was intermediate between that of Homo erectus and recent modern humans. Specimens used in the analysis included Neandertals and Upper Palaeolithic early modern Homo sapiens from Europe and individuals from two recent modern human populations. Ontogenetic data for the H. erectus adolescent KNM-WT 15000 and for Gorilla gorilla were included for comparison. Previous reports have indicated that H. erectus demonstrates a pattern of ontogeny characterized by earlier and more rapid linear growth than in modern humans. Results reported here demonstrate that Upper Paleolithic early modern Homo sapiens display a growth trajectory indistinguishable from that of recent modern humans. The pattern of Neandertal ontogeny is not intermediate between the pattern displayed in H. erectus and the derived pattern seen in the modern reference samples and the early modern H. sapiens sample. The Neandertal growth trajectory is consistent with either slow linear growth or advanced dental development.     

Estimation of stature from the skeletal reconstruction of an immature Neandertal from Dederiyeh cave, Syria

Skeletal reconstruction of a child Neandertal unearthed at Dederiyeh Cave, Syria in 1993, is undertaken and the acquired stature discussed. Although the skeletal remains were well preserved, the reconstruction required several assumptions to be made because of the immature status of the specimen. The assumptions were mainly concerned with distances between bones in the inter-vertebral spaces and in the joints of the hip, knee, and ankle. These were estimated from X-ray films of modern children and data from previous studies. Stature was directly measured on the reconstruction, and found to be 79.2 cm. After corrections for soft tissue thickness and shrinkage of the casts, the stature became 81.7 cm. This estimate is consistent with estimates based on regression equations of long bone lengths, especially from those of the lower extremity. In comparison with longitudinal data for white American boys, the assessment of stature for Dederiyeh varied according to the estimated age. For a younger estimated age, the stature falls in the lower half of the white American range of variation, but with an older estimated age, it falls below the lower limit of the range of variation. Other immature Neandertals including two European specimens, Roc de Marsal and La Ferrassie 6, fall below the lower limit of the 5th to 95th percentile range based on the estimated statures from their long bone lengths. More comprehensive age assessment covering both fossil and modern humans is required before accurate conclusions in relation to Neandertal growth can be drawn.     

The Vindija Neanderthal scapular glenoid fossa: comparative shape analysis suggests evo-devo changes among Neanderthals

Although the shape of the scapular glenoid fossa (SGF) may be influenced by epigenetic and developmental factors, there appears to be strong genetic control over its overall form, such that variation within and between hominin taxa in SGF shape may contain information about their evolutionary histories. Here we present the results of a geometric morphometric study of the SGF of the Neanderthal Vi-209 from Vindjia Cave (Croatia), relative to samples of Plio-Pleistocene, later Pleistocene, and recent hominins. Variation in overall SGF shape follows a chronological trend from the plesiomorphic condition seen in Australopithecus to modern humans, with pre-modern species of the genus Homo exhibiting intermediate morphologies. Change in body size across this temporal series is not linearly directional, which argues against static allometry as an explanation. However, life history and developmental rates change directionally across the series, suggesting an ontogenetic effect on the observed changes in shape (ontogenetic allometry). Within this framework, the morphospace occupied by the Neanderthals exhibits a discontinuous distribution. The Vindija SGF and those of the later Near Eastern Neanderthals (Kebara and Shanidar) approach the modern condition and are somewhat segregated from both northwestern European (Neandertal and La Ferrassie) and early Mediterranean Neanderthals (Krapina and Tabun). Although more than one scenario may account for the pattern seen in the Neanderthals, the data is consistent with palaeogenetic evidence suggesting low levels of gene flow between Neanderthals and modern humans in the Near East after ca. 120-100 ka (thousands of years ago) (with subsequent introgression of modern human alleles into eastern and central Europe). Thus, in keeping with previous analyses that document some modern human features in the Vindija Neanderthals, the Vindija G₃ sample should not be seen as representative of ‘classic’ - that is, unadmixed, pre-contact - Neanderthal morphology.     

Dental tissue proportions and enamel thickness in Neandertal and modern human molars

The thickness of dental enamel is often discussed in paleoanthropological literature, particularly with regard to differences in growth, health, and diet between Neandertals and modern humans. Paleoanthropologists employ enamel thickness in paleodietary and taxonomic studies regarding earlier hominins, but variation in enamel thickness within the genus Homo has not been thoroughly explored despite its potential to discriminate species and its relevance to studies of growth and development. Radiographic two-dimensional studies indicate that Neandertal molar enamel is thin relative to the thick enamel of modern humans, although such methods have limited accuracy. Here we show that, measured via accurate high-resolution microtomographic imaging, Neandertal molar enamel is absolutely and relatively thinner than modern human enamel at most molar positions. However, this difference relates to the ratio of coronal dentine volume to total crown volume, rather than the quantity of enamel per se. The absolute volume of Neandertal molar enamel is similar to that of modern humans, but Neandertal enamel is deposited over a larger volume of coronal dentine, resulting in lower average (and relative) enamel thickness values. Sample sizes do not permit rigorous intragroup comparisons, but Neandertal molar tissue proportions evince less variation than the modern human sample. Differences in three- and two-dimensional enamel thickness data describing Neandertal molars may be explained by dimensional reduction. Although molar tissue proportions distinguish Neanderthals from recent Homo sapiens, additional study is necessary to assess trends in tissue proportions in the genus Homo throughout the Pleistocene.     

The postcranial dimensions of the La Chapelle-aux-saints 1 Neandertal

The La Chapelle-aux-Saints 1 Neandertal has figured prominently in considerations of Neandertal body size and proportions. In this context, a reassessment of its major long bones and a reassembly of its principal pelvic elements (sacrum and right ilium) was undertaken. There are secure measurements for its humeral and radial lengths and its femoral head diameter, but the femoral and tibial lengths were almost certainly greater than previous values. The resultant humeral, femoral and tibial lengths are similar to those of other male Neandertals, its femoral head diameter is among the largest known for Middle and Late Pleistocene humans, but its radial length is relatively short. The pelvic assembly provides modest bi-iliac and inlet transverse diameters compared with the few sufficiently complete and undistorted Middle and Late Pleistocene archaic human pelves, but its dimensions are similar to those of large male early modern humans.     

Neandertal scapular glenoid morphology

Analysis of Neandertal and recent human scapular glenoid fossae reveals that the former had long, narrow, and flat glenoid articular surfaces relative to those of modern humans. Comparison of glenoid length, breadth, and curvature to humeral articular dimensions demonstrates that Neandertal glenoid length and curvature scale to proximal and distal humeral articular dimensions in the same manner as those of modern humans. The remaining contrast is in the relatively greater glenoid fossa width seen in modern humans. This difference in morphology implies differences in the habitual degree of dorsoventral glenohumeral movement between Neandertals and modern humans. This in turn may be related to contrasts in tool use, especially with respect to throwing and projectile use.     

Ontogenetic variation in the mandibular ramus of great apes and humans

Considerable variation exists in mandibular ramus form among primates, particularly great apes and humans. Recent analyses of adult ramal morphology have suggested that features on the ramus, especially the coronoid process and sigmoid notch, can be treated as phylogenetic characters that can be used to reconstruct relationships among great ape and fossil hominin taxa. Others have contended that ramal morphology is more influenced by function than phylogeny. In addition, it remains unclear how ontogeny of the ramus contributes to adult variation in great apes and humans. Specifically, it is unclear whether differences among adults appear early and are maintained throughout ontogeny, or if these differences appear, or are enhanced, during later development. To address these questions, the present study examined a broad ontogenetic sample of great apes and humans using two‐dimensional geometric morphometric analysis. Variation within and among species was summarized using principal component and thin plate spline analyses, and Procrustes distances and discriminant function analyses were used to statistically compare species and age classes. Results suggest that morphological differences among species in ramal morphology appear early in ontogeny and persist into adulthood. Morphological differences among adults are particularly pronounced in the height and angulation of the coronoid process, the depth and anteroposterior length of the sigmoid notch, and the inclination of the ramus. In all taxa, the ascending ramus of the youngest specimens is more posteriorly inclined in relation to the occlusal plane, shifting to become more upright in adults. These results suggest that, although there are likely functional influences over the form of the coronoid process and ramus, the morphology of this region can be profitably used to differentiate among great apes, modern humans, and fossil hominid taxa. J. Morphol. 275:661–677, 2014. © 2013 Wiley Periodicals, Inc.     

Probit analysis of Upper Pleistocene hominids

Probit analysis allows the testing of the normality of a sample population where curve fitting and differential weighting occur simultaneously. Probit analysis may be utilized with small samples, and is ideal for use in the study of fossil populations. It is assumed that population which are normally distributed are likely to be in genetic equilibrium, so that graphic and computational probit analysis may be used to discern the effects of evolutionary forces on human populations. Probit analysis of cranial length in a sequence of Athenian population is presented in order to verify its sensitivity to these evolutionary forces. Probit analysis and other tests of homogeneity are applied to similar variables of Upper Pleistocene European Neandertal and modern man.Despite significant differences between variable means of Neandertal and modern man, probit analyses of their combined populations showed no less deviation from normality than either group separately. This suggests that the evolutionary changes in the cranium from the Neandertal stage to the modern stage of man were effected without significantly disrupting the genetic equilibrium of these populations, i.e. that rapid changes in these populations are unlikely to have occurred.     

The premaxilla in Neandertal and early modern children: ontogeny and morphology.

This comparative study of maxillae in Neandertals, Qafzeh, and extant children examines two specific traits: the premaxillary suture (sutura incisiva) and the interincisive sinuses, proposing a new hypothesis about some features of the Neandertal mid-face. Morphologic study of the premaxillary suture at its different borders (i.e. the nasal aspect of the frontal process, nasal and palatal aspects of the palatal process of the maxilla) indicates a persistence of the suture among very young Neandertal children in comparison to the condition in extant ones. This suggests a longer independence of some parts of the premaxilla in Neandertals. To further examine this possibility, CT scans of two Neandertal children were analyzed: Roc de Marsal, estimated to be about 3 years, and Engis 2, estimated to be about 5-6 years. The results are quite different between the fossils. In the older, the premaxillary suture is represented only by a deep groove. In the younger it extends deep to the surface of the nasal process reaching the Parinaud's canal. Synostosis of the premaxillary suture was found to occur later in Neandertal children than in modern ones. Moreover, we observed the existence of two interincisive sinuses in the fossil children, whereas this is rare in modern children (present on only 2% of our sample of 0-6 year-old infants, n = 247).Persistence of an open premaxillary suture represents the potential for an extended period of growth of the Neandertal mid-face. Although no trace of the premaxillary suture remains in adult Neandertals, Neandertals present many features classically considered as consequences of this persistence. The two interincisive sinuses could be a consequence of the labio-lingual diameter of the incisors. The results presented here can be further investigated by additional studies on the cranial sutural system and by precise morphologic observations and CT scans of the mid-face of a larger sample of fossil children.     

Did the lateral enamel of Neandertal anterior teeth grow differently from that of modern humans?

The formation of lateral enamel in Neandertal anterior teeth has been the subject of recent studies. When compared to the anterior teeth of modern humans from diverse regions (Point Hope, Alaska; Newcastle upon Tyne, England; southern Africa), Neandertal anterior teeth appear to fall within the modern human range of variation for lateral enamel formation time. However, the lateral enamel growth curves of Neandertals are more linear than those of these modern human samples. Other researchers have found that the lateral enamel growth curves of Neandertals are more linear than those of Upper Paleolithic and Mesolithic modern humans as well. The statistical significance of this apparent difference between Neandertal and modern human lateral enamel growth curves is analyzed here. The more linear Neandertal enamel growth curves result from the smaller percentage of total perikymata located in the cervical halves of their teeth. The percentage of total perikymata in the cervical halves of teeth is therefore compared between the Neandertal sample (n=56 teeth) and each modern human population sample: Inuit (n=65 teeth), southern African (n=114 teeth), and northern European (n=115 teeth). There are 18 such comparisons (6 tooth types, Neandertals vs. each of the three modern human populations). Eighteen additional comparisons are made among the modern human population samples. Statistically significant differences are found for 16 of the 18 Neandertal vs. modern human comparisons but for only two of the 18 modern human comparisons. Statistical analyses repeated for subsamples of less worn teeth show a similar pattern. Because surface curvature is thought to affect perikymata spacing, we also conducted measurements to assess surface curvature in thirty teeth. Our analysis shows that surface curvature is not a factor in this lateral enamel growth difference between Neandertals and modern humans.     

Unique ramus anatomy for Neandertals?

The ramus of Neandertal mandibles is said to show a suite of uniquely Neandertal character states that demonstrate the independent course of Neandertal evolution. This is the latest of numerous attempts to define cranial and mandibular autapomorphies for Neandertals. We examine variation in the four presumably autapomorphic ramal features and show they are neither monomorhic within Neandertals (to the contrary Neandertals are at least as variable as other human samples) nor unique to Neandertals, since they regularly appear in populations predating and postdating them. Neandertals differ from other human populations, both contemporary and recent, but the question of whether this fact reflects a divergent evolutionary trajectory must be addressed by the pattern of differences. In this case, as in the other attempts to establish Neandertal autapomorphies, rather than showing restricted variation and increased specialization, the Neandertal sample shows that the range of human variation in the recent past encompasses, and in some cases exceeds, human variation today, even in the very features claimed to be autapomorphic.     

Pattern profile analysis of hominid and chimpanzee hand bones

In a study designed to complement morphological research on hominid hand bones, length and width measurements of the thumb, index, and middle rays were obtained from radiographs of modern human hands. These rays are primary in precision-gripping postures and are therefore the ones most relevant for investigating evolutionary changes in fine manipulation. Pattern profile analysis allows individuals or samples to be plotted against a reference sample in standard deviation units, or Z-scores. It provides an indication of how different measurements are from modern human averages, while taking into consideration the degree of variation present within modern human samples. A pattern profile for chimpanzees is clearly distinct from humans but quite similar to that of a bonobo, demonstrating the promise of pattern analysis. Partial pattern profiles of several of the more complete early hominid bones from Hadar, Swartkrans, and Olduvai (O.H. 7) are presented and compared. Hadar bones are long and wide at midshaft relative to articular widths; both body-size effects and functional differences are likely. Thumb distal phalanges from Swartkrans and Olduvai both have relatively small base widths, but they differ in other proportions. Two first metacarpals from Swartkrans show distinct patterns. The profiles of La Ferrassie I and Shanidar IV show the characteristically large Neanderthal distal phalanges. Profiles of Skhūl IV and P?edmost III are alike in some regions with reference to modern North American white males, though they are less similar overall than are those of the two Neanderthals. © 1995 Wiley-Liss, Inc.     

Is Central Asia the eastern outpost of the Neandertal range? A reassessment of the Teshik‐Tash child

Since its discovery in southeastern Uzbekistan in 1938, the Teshik-Tash child has been considered a Neandertal. Its affinity is important to studies of Late Pleistocene hominin growth and development as well as interpretations of the Central Asian Middle Paleolithic and the geographic distribution of Neandertals. A close examination of the original Russian monograph reveals the incompleteness of key morphologies associated with the cranial base and face and problems with the reconstruction of the Teshik-Tash cranium, making its Neandertal attribution less certain than previously assumed. This study reassesses the Neandertal status of Teshik-Tash 1 by comparing it to a sample of Neandertal, Middle and Upper Paleolithic modern humans, and recent human sub-adults. Separate examinations of the cranium and mandible are conducted using multinomial logistic regression and discriminant function analysis to assess group membership. Results of the cranial analysis group Teshik-Tash with Upper Paleolithic modern humans when variables are not size-standardized, while results of the mandibular analysis place the specimen with recent modern humans for both raw and size-standardized data. Although these results are influenced by limitations related to the incomplete nature of the comparative sample, they suggest that the morphology of Teshik-Tash 1 as expressed in craniometrics is equivocal. Although, further quantitative studies as well as additional sub-adult fossil finds from this region are needed to ascertain the morphological pattern of this specimen specifically, and Central Asian Middle Paleolithic hominins in general, these results challenge current characterizations of this territory as the eastern boundary of the Neandertal range during the Late Pleistocene.     

What molars contribute to an emerging understanding of lateral enamel formation in Neandertals vs. modern humans

Two hypotheses, based on previous work on Neandertal anterior and premolar teeth, are investigated here: (1) that estimated molar lateral enamel formation times in Neandertals are likely to fall within the range of modern human population variation, and (2) that perikymata (lateral enamel growth increments) are distributed across cervical and occlusal halves of the crown differently in Neandertals than they are in modern humans. To investigate these hypotheses, total perikymata numbers and the distribution of perikymata across deciles of crown height were compared for Neandertal, northern European, and southern African upper molar mesiobuccal (mb) cusps, lower molar mesiobuccal cusps, and the lower first molar distobuccal (db) cusp. Sample sizes range from five (Neandertal M(1)db) to 29 (southern African M(1)mb). Neandertal mean perikymata numbers were found to differ significantly from those of both modern human samples (with the Neandertal mean higher) only for the M(2)mb. Regression analysis suggests that, with the exception of the M(2)mb, the hypothesis of equivalence between Neandertal and modern human lateral enamel formation time cannot be rejected. For the M(2)mb, regression analysis strongly suggests that this cusp took longer to form in the Neandertal sample than it did in the southern African sample. Plots of perikymata numbers across deciles of crown height demonstrate that Neandertal perikymata are distributed more evenly across the cervical and occlusal halves of molar crowns than they are in the modern human samples. These results are integrated into a discussion of Neandertal and modern human lateral enamel formation across the dentition, with reference to issues of life history and enamel growth processes.