Facial prognathism and projection are important characteristics in human evolution but their three-dimensional (3D) architectonic relationships to basicranial morphology are not clear. We used ...geometric morphometrics and measured 51 3D-landmarks in a comparative sample of modern humans (N = 78) and fossil Pleistocene hominins (N = 10) to investigate the spatial features of covariation between basicranial and facial elements. The study reveals complex morphological integration patterns in craniofacial evolution of Middle and Late Pleistocene hominins. A downwards-orientated cranial base correlates with alveolar maxillary prognathism, relatively larger faces, and relatively larger distances between the anterior cranial base and the frontal bone (projection). This upper facial projection correlates with increased overall relative size of the maxillary alveolar process. Vertical facial height is associated with tall nasal cavities and is accommodated by an elevated anterior cranial base, possibly because of relations between the cribriform and the nasal cavity in relation to body size and energetics. Variation in upper- and mid-facial projection can further be produced by basicranial topology in which the midline base and nasal cavity are shifted anteriorly relative to retracted lateral parts of the base and the face. The zygomatics and the middle cranial fossae act together as bilateral vertical systems that are either projected or retracted relative to the midline facial elements, causing either midfacial flatness or midfacial projection correspondingly. We propose that facial flatness and facial projection reflect classical principles of craniofacial growth counterparts, while facial orientation relative to the basicranium as well as facial proportions reflect the complex interplay of head-body integration in the light of encephalization and body size decrease in Middle to Late Pleistocene hominin evolution. Developmental and evolutionary patterns of integration may only partially overlap morphologically, and traditional concepts taken from research on two-dimensional (2D) lateral X-rays and sections have led to oversimplified and overly mechanistic models of basicranial evolution.
The analysis of activity-related dental wear patterns in prehistoric anatomically modern humans and modern hunter-gatherers has shown sex differences attributable to a gendered division of labor. ...Neandertals are known to have extensive anterior dental wear related to the use of their front teeth as a tool. In this study we analyze the i) cultural striations (scratches on the labial surface of the anterior teeth with a cut-mark morphology), and ii) dental chipping (ante-mortem microfracture involving enamel or both enamel and dentine) in 19 Neandertal individuals from the l'Hortus (France), Spy (Belgium), and El Sidrón (Spain) sites, and compare the characteristics of those traits with the age and sex estimation for the individuals and among samples. The study reveals that all individuals have cultural striations, but those detected on the adult females are longer than the striations found in adult males. Regarding the distribution of dental chipping, the prevalence of this trait is higher in the maxillary dentition of males whereas females have the majority of dental chipping on their mandibular teeth. The differences detected on the overall activity-related dental wear pattern denote a difference or a division of labor by age and sex in Neandertals while using the mouth as a third hand, i.e., in activities other than the provisioning of food, and provide new evidence for the lifestyle of this Pleistocene fossil human species.
El patrón de desgaste dental no masticatorio de los cazadores-recolectores prehistóricos y grupos actuales, muestra diferencias según del sexo de los individuos, reflejando una división sexual del trabajo. Los Neandertales, por su parte, tienen un gran desgaste de sus incisivos y caninos debido a que los usarían como coadyuvante o ‘tercera mano’ en numerosas tareas, como la preparación de pieles o el troceado de pedazos de carne que sujetaban con la boca. En este artículo se presenta el estudio del desgaste dental no masticatorio en 19 individuos neandertales de los yacimientos de l'Hortus (Francia), Spy (Bélgica) y El Sidrón (España). Para ello, se han analizado dos de los rasgos asociados a este tipo de desgaste dental: las estrías culturales (rayas superficiales hechas en la cara labial de la dentición anterior y que tienen la misma morfología que una marca de corte) y las melladuras del esmalte dental (fracturas producidas ante-mortem que afectan al esmalte dental o bien al esmalte y a la dentina en conjunto). Los resultados muestran que todos los individuos presentan ambos rasgos de desgaste no-masticatorio, pero se han encontrado diferencias significativas en cuanto a la longitud de las estrías, siendo más largas en las mujeres. En cuanto a la distribución de las mellas en el esmalte, los hombres tienen una mayor incidencia en la dentición maxilar, mientras que las mujeres es la mandibular. Todas las diferencias detectadas en el patrón de desgaste dental no masticatorio, aunque sutiles, parecen indicar que los Neandertales utilizaban sus dientes de manera diferente según el sexo, sugiriendo que un cierto grado de división del trabajo ya estaba presente en esta especie humana extinta.
The developed cognitive capabilities for Homo sapiens seems to be the result of a specialized and lateralized brain, and as a result of this, humans display the highest degree of manual ...specialization or handedness among the primates. Studies regarding its emergence and distribution within the genus Homo show that handedness is present very early. The mode in which it was articulated and spread across the different species during the course of human evolution could provide information about our own cognitive capacities. Here we report the manual laterality attributed to eleven 49,000 old Neandertal individuals from El Sidrón cave (Spain), through the study of instrumental or cultural striations on the anterior dentition. Our results show a predominant pattern addressed to right-handers. These results fit within the modern human handedness distribution pattern and provide indirect evidence for behavior and brain lateralization on Neandertals. They support the early establishment of handedness in our genus. Moreover, the individual identified as Juvenile 1 (6-8 years old at death), displays the same striation pattern as the adult Neandertals from the sample, and thereby the ontogenic development of manual laterality in that Neandertal population seems to be similar to that of living modern humans.
Here, we present the analysis of occlusal molar microwear textures of eight individuals from the El Sidrón Neandertal group (Spain). The aims of the study were: 1) to document potential age-, sex-, ...and maternal lineage-related differences in diet within a Neandertal familial group, and 2) to place the diet of El Sidrón individuals in the context of those of other Neandertal groups. This study also offers an interpretation of the diet of the El Sidrón Neandertals by comparing their microwear signatures to those of recent hunter-gatherer populations with diverse but known diets. The intra-group examination of the microwear signatures are consistent with the females of the El Sidrón group having had more abrasive diets or having used their teeth in more para-masticatory activities than did the males. Aside from the potential sex-related differences in diet, no additional intra-group dietary separation, such as by age group or maternal lineage, was observed. In comparison to other Neandertals, El Sidrón individuals, as a group, have microwear signatures most similar to those of other Neandertals from wooded habitats and different from those that lived in more open habitats. This result is expected based on the available paleoenvironmental reconstructions from El Sidrón Cave. The diet of the El Sidrón Neandertals, just like their Neandertal counterparts from similar wooded habitats, is interpreted as having been mixed, consisting of both meat and vegetable foods.
Ontogenetic studies help us understand the processes of evolutionary change. Previous studies on Neandertals have focused mainly on dental development and inferred an accelerated pace of general ...growth. We report on a juvenile partial skeleton (El Sidrón J1) preserving cranio-dental and postcranial remains. We used dental histology to estimate the age at death to be 7.7 years. Maturation of most elements fell within the expected range of modern humans at this age. The exceptions were the atlas and mid-thoracic vertebrae, which remained at the 5- to 6-year stage of development. Furthermore, endocranial features suggest that brain growth was not yet completed. The vertebral maturation pattern and extended brain growth most likely reflect Neandertal physiology and ontogenetic energy constraints rather than any fundamental difference in the overall pace of growth in this extinct human.
The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the ...tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ∼1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.
It is well known that the human skull achieves adult size through a superior–inferior gradient of maturation. Because the basicranium matures in size before the face, it has been suggested that the ...form of the basicranium might have ontogenetic knock‐on effects on that of the face. However, although sequential spatially organized maturation of size is well described in the cranium, the maturation of skull shape is not. Knowledge of the maturation of shape is important, nevertheless, because it is claimed that the early determination of the spatial configuration of basicranial components, where the facial skeleton attaches, is relevant in the spatio‐temporal ontogenetic cascade from basicranium to face. This paper examines the ontogeny of various components of the human skull in 28 individuals from the longitudinal Denver Growth Study. Sixty‐six landmarks and semilandmarks were digitized on 228 X‐rays and analysed using geometric morphometric methods. Bootstrapped confidence intervals for centroid size support previous studies suggesting a supero‐inferior gradient of growth maturation (size over time), while developmental maturation (shape over time) is more complex. A sequence of shape maturation is described, in which the earliest structure to mature in shape was the midline cranial base (7–8 years), followed by the lateral cranial floor (11–12), midline neurocranium (9–10) and facial and mandibular structures (15–16). The absolute ages of shape maturation of the latter three depended on the criterion of maturity used, which was not the case for the basicranial components. Additionally, ontogenetic dissociations were found between the maturation of size and shape of the midline cranial base and lateral floor, possibly underlining its role as structural ‘interface’ between brain and facial ontogeny. These findings imply potential for bidirectional developmental influences between the lateral cranial floor and the face until about 11–12 years. The findings are discussed with regard to their relevance for palaeoanthropology and especially the evolutionary and developmental bases of skull morphological variation.
When workers hear about a possible promotion, it is common for them to get training, and they can do so through education. However, there is the possibility that the worker needs to receive a salary ...according to the knowledge acquired in such training. In this study, considering a population of employed workers with incomplete secondary school, we apply game theory concepts to explore whether workers can train through study. If so, the model shows the percentage of the salary the worker is willing to invest in his education. Furthermore, the cost of studying implicitly involves an opportunity cost, deduced quantitatively in the model. In conclusion, our article defines specific thresholds to decide if the worker should study, the economic investment, and the time he would spend on it, depending on how strict the company is in auditing. The analysis does not define a Nash equilibrium since the company’s reaction is not considered.
We present the DNA sequence of 17,367 protein-coding genes in two Neandertals from Spain and Croatia and analyze them together with the genome sequence recently determined from a Neandertal from ...southern Siberia. Comparisons with present-day humans from Africa, Europe, and Asia reveal that genetic diversity among Neandertals was remarkably low, and that they carried a higher proportion of amino acid-changing (nonsynonymous) alleles inferred to alter protein structure or function than present-day humans. Thus, Neandertals across Eurasia had a smaller long-term effective population than present-day humans. We also identify amino acid substitutions in Neandertals and present-day humans that may underlie phenotypic differences between the two groups. We find that genes involved in skeletal morphology have changed more in the lineage leading to Neandertals than in the ancestral lineage common to archaic and modern humans, whereas genes involved in behavior and pigmentation have changed more on the modern human lineage.
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