Patterns of evolution in Middle Pleistocene hominids

This paper reviews the chronology and morphological variability of Middle Pleistocene H. erectus. specimens. Functional complexes are delineated within the skull and dentition, and their total morphological patterns quantified using univariate and multivariate statistical analysis. Statistical distances are calculated between H. erectus and other hominid samples for each complex, compared to illustrate patterns of mosaic evolution within the skull and dentition of middle Quaternary hominids, and estimated evolution rates are derived. An attempt is made to relate the observed morphological patterns to ecological shifts by early hominid communities, and to assess their significance for hominid taxonomy.     

Dental size variation in the Atapuerca-SH Middle Pleistocene hominids

The Middle Pleistocene Atapuerca-Sima de los Huesos (SH) site in Spain has yielded the largest sample of fossil hominids so far found from a single site and belonging to the same biological population. The SH dental sample includes a total of 452 permanent and deciduous teeth, representing a minimum of 27 individuals. We present a study of the dental size variation in these hominids, based on the analysis of the mandibular permanent dentition: lateral incisors, n=29; canines, n=27; third premolars, n=30; fourth premolars, n=34; first molars, n=38; second molars, n=38. We have obtained the buccolingual diameter and the crown area (measured on occlusal photographs) of these teeth, and used the bootstrap method to assess the amount of variation in the SH sample compared with the variation of a modern human sample from the Museu Antropologico of the Universidade of Coimbra (Portugal). The SH hominids have, in general terms, a dental size variation higher than that of the modern human sample. The analysis is especially conclusive for the canines. Furthermore, we have estimated the degree of sexual dimorphism of the SH sample by obtaining male and female dental subsamples by means of sexing the large sample of SH mandibular specimens. We obtained the index of sexual dimorphism (ISD=male mean/female mean) and the values were compared with those obtained from the sexed modern human sample from Coimbra, and with data found in the literature concerning several recent human populations. In all tooth classes the ISD of the SH hominids was higher than that of modern humans, but the differences were generally modest, except for the canines, thus suggesting that canine size sexual dimorphism in Homo heidelbergensis was probably greater than that of modern humans. Since the approach of sexing fossil specimens has some obvious limitations, these results should be assessed with caution. Additional data from SH and other European Middle Pleistocene sites would be necessary to test this hypothesis.     

Cranial remains of Middle Pleistocene European hominids

Cranial remains of the Middle Pleistocene European hominids are reviewed in a historical context. Swanscombe and Steinheim, the earliest specimens to be discovered, are compared with each other. Following this, the more recently discovered specimens from Vértesszöllös, Petralona and Bilzingsleben are compared. Finally, Riss remains from La Chaise, Biache and Arago are discussed in the context provided by the above specimens. It is suggested that while phyletic evolution may play a role in the observed differences, a marked degree of sexual dimorphism contributes to the variation expressed by these specimens.     

More than blades. Early Middle Palaeolithic of the Levant

The Early Middle Palaeolithic (EMP) in the Levant dated between 250 and 150 ka is a unique period characterised by the systematic production of elongated blanks using different reduction strategies: Levallois, Laminar and core on flake are involved. The hallmark of the EMP blade industries is different types of retouched points but the production of other blanks categories as bladelets, small flakes and triangular flakes is also evident. Such a broad-based approach to lithic resources of foragers relocating through the Levant during the EMP could reflect the behavioural adaptations of hominins and adjustments in their subsistence strategies as well as management of time and division of special activities, consequently leading to a marked anticipation of needs. The techno-typological diversity is visible in the mode of production but at the same time, it reflects the narrow variation that is shared among all known EMP sites. This seems to indicate that at this time the demographic organisation in the region may be closely linked within a cohesive geographical and chronological framework.     

Enamel hypoplasia in the Middle Pleistocene hominids from Atapuerca (Spain)

The prevalence and chronology of enamel hypoplasias were studied in a hominid dental sample from the Sima de los Huesos (SH) Middle Pleistocene site at the Sierra de Atapuerca (Burgos, northern Spain). A total of 89 permanent maxillary teeth, 143 permanent mandibular teeth, and one deciduous lower canine, belonging to a minimum of 29 individuals, were examined. Excluding the antimeres (16 maxillary and 37 mandibular cases) from the sample, the prevalence of hypoplasias in the permanent dentition is 12.8% (23/179), whereas the deciduous tooth also showed an enamel defect. No statistically significant differences were found between both arcades and between the anterior and postcanine teeth for the prevalence of hypoplasias. In both the maxilla and the mandible the highest frequency of enamel hypoplasias was recorded in the canines. Only one tooth (a permanent upper canine) showed two different enamel defects, and most of the hypoplasias were expressed as faint linear horizontal defects. Taking into account the limitations that the incompleteness of virtually all permanent dentitions imposes, we have estimated that the frequency by individual in the SH hominid sample was not greater than 40%. Most of the hypoplasias occurred between birth and 7 years (N = 18, X = 3.5, SD = 1.3). Both the prevalence and severity of the hypoplasias of the SH hominid sample are significantly less than those of a large Neandertal sample. Furthermore, prehistoric hunter-gatherers and historic agricultural and industrial populations exhibit a prevalence of hypoplasias generally higher than that of the SH hominids. Implications for the survival strategies and life quality of the SH hominids are also discussed. © 1995 Wiley-Liss, Inc.     

Senescence in European Middle Pleistocene hominids: The Atapuerca evidence

The mandibular specimens AT-250 and AT-793 (individual IV) and AT-888 (individual XXI) from the Atapuerca Middle Pleistocene sample show a combination of traits interpreted as evidence of senescence. In order to explore age-related mandibular changes relevant to the interpretation of the Atapuerca hominids, the sample of known age and sex from Spitalfields (London) and the Neolithic sample from Abu Hureyra (Syria) were used as a baseline. Results obtained indicate that the occurrence of an enlarged and posteriorly located mental foramen, in association with high alveolar resorption in AT-250 and AT-888, support the hypothesis of senescence in individuals IV and XXI from the Atapuerca sample. The findings suggest that European Middle Pleistocene populations lived long enough to reach senescence. The age at death for Middle Pleistocene hominids and Neanderthals has previously been estimated at around 40–45 years in the oldest specimens. The appearance of senescence processes before this age is indicative of higher rates of morphological aging in the clade which gave rise to Neanderthals. The anatomical significance of ageing features when considered in the context of craniofacial remodelling can help in the understanding of the taxonomic status of these morphological traits.     

The fragmented character of Middle Palaeolithic stone tool technology

The importance of the transport of stone artefacts in structuring Neandertal lithic assemblages has often been addressed, but the degree to which this led to fragmentation of lithic reduction over Middle Palaeolithic landscapes has not been explicitly studied thus far. Large-scale excavations of Middle Palaeolithic open-air sites and refitting studies of the retrieved assemblages have yielded new, high-resolution data on the mobile aspects of Neandertal stone tool technology. In this paper, we integrate lithic technology and raw material data from recent studies of Middle Palaeolithic open-air and rock shelter sites in Western Europe. We demonstrate that the results of a variety of typological, technological (especially refitting), and lithological studies have important consequences for our knowledge of the acquisition of raw materials and subsequent production, usage and discard of stone artefacts in the Middle Palaeolithic. Neandertal production and use of stone tools was fragmented in three domains: the spatial, the temporal and the social domain. We show that this versatile segmentation of stone artefact handling strategies is a main determinant of the character of the Neandertal archaeological record. Our data testify to ubiquitous and continuous transport of stone artefacts of a wide variety of forms, picked by Neandertals using selection criteria that were sometimes far removed from what archaeologists have traditionally considered, and to some degree still consider, to be desired end products of knapping activities. The data presented here testify to the variability and versatility of Middle Palaeolithic stone tool technology, whose fragmented character created very heterogeneous archaeological assemblages, usually the product of a wide variety of independent import, use, discard and/or subsequent transport events.     

Resource selection of lithic raw materials in the Middle Palaeolithic in southern France

The work reported here uses several approaches to examine the costs and benefits associated with exploiting potential sources of lithic raw material in the Vaucluse, southern France, and then tests the results against the proportions of raw materials from various sources found in the lithic assemblage of a Middle Palaeolithic site, the Bau de l’Aubesier. A previously published equation designed to quantify the attractiveness of each source proves to be significantly correlated with source use, but the results show that it can be improved. We then individually test the components of the attractiveness equation (raw material quality, source extent, terrain difficulty, and the size and abundance of raw material pieces at the source) and additional variables (Calories expended to get from the source to the site using a straight-line route, Calories expended using a least-cost path, surface distance of the source from the site, and distance to the closest used source) using generalized linear models. Since very similar raw materials can be found at more than one source, we combine such similar sources into source areas, and test the area of the source area (AOSA) and the total area of sources within the source area (AOSISA), as two additional independent variables. The best model shows that raw material quality, source extent, abundance of large and very large rocks, and AOSISA, are positively correlated with use of sources, while terrain difficulty, abundance of small and medium rocks, Calories, and AOSA, are negatively correlated with source use. This shows that the hominins at the Bau de l’Aubesier optimized their raw material procurement to get the most good quality material that they could, while minimizing the time and energy spent getting and using it.     

Ontogenetic approach to variation in Middle Pleistocene hominids. Evidence from the Atapuerca-SH mandibles

The ontogenetic processes underlying the variation detected in the European Middle Pleistocene hominids are explored. Regulation of growth parameters of the ontogenetic trajectory of these hominid is discussed in the context of heterochrony schemes. The sample of mandibles coming from the Atauuerca-SH site is used as a study case. The variability shown by these mandibles can be arranged along a morphological gradient, and study of growth directions has shown that the remodelling patterns are in line with the existence of a single morphogenetic pattern controlling the process. In addition, the spectrum of morphology detected in the Atapuerca sample virtually encompasses the entire range of variability detected in European Middle Pleistocene samples. From a morphological viewpoint, a hypermorphic pattern seems to be the responsible for the individual variation detected in the sample. Yet, when this information is related to mandibular growth and craniofacial interactions, evidence of an interindividual gradient of somatic development for the Atapuerca hominids is provided. Several hypotheses concerning growth parameters, however, may account for this gradient. Time and rate hypermorphosis hypothesis are discussed. Coincidence of the gradient of variation detected in this sample and the general mandibular growth trajectory of living species, support the hypothesis that is “time of maturation” of the organism the key factor.     

An anatomical basis for prognosis of malignant melanoma.

Clinical observations during surgery have led us to speculate that an anatomic basis may in fact exist for the poor prognosis associated with malignant melanoma arising in certain recognized "high-risk" areas. In our study we have treated and followed 45 patients with primary malignant melanoma for over 5 years. During the course of treatment, we identified variations in anatomic characteristics at the tumor sites. Criteria were established for high- and low-risk locations by the neurovascular structure encountered. We speculate that these sites that have neurovascular windows provide a readily accessible vascular pathway for the dissemination of malignant cells to deeper visceral structures and may account for the poor prognosis associated with primary lesions in these locations. Thirty patients were classified as being at high risk for developing metastasis, whereas 13 were classified as being at low risk; 2 patients were in a special-risk category. To date, 12 of the 30 patients with "high-risk" melanoma have gone on to develop metastatic disease, which represents 40 percent of that group, whereas none of the patients classified as "low risk" have developed metastases during the same period.     

Biophysical basis for principles of universality of speech perception

There is increasing evidence that the synergistic interaction of the objectively accepted low-frequency rhythm and the subjectively accepted high-frequency sound is a source of speech "sense". The lack of one of these components or of their synergistic interaction results in the loss of "sense" of the acoustic signal being perceived. As for the universality of perception of the sound component of speech, there is a model of sound perception, which ensures this universality. This model describes the dynamics of audition using the synchronization model of oscillations in the Ruell-Takens scenario of transition to chaos. The oscillations are described by Hopf bifurcations known to be structurally stable, which just provides the universality of sound perception. However, up till now, nothing was known about the mechanism of rhythm. It was shown in our study that the mechanism of rhythm is described by the Feigenbaum scenario of transition to chaos. Upon transition from oscillations to chaos, this scenario incorporates a critical point near which the dynamics of the system is described in an universal way.     

The Early Middle Palaeolithic lithic industry of Dederiyeh Cave,Northwest Syria

The Lower-to-Middle Paleolithic transition of the Levant has attracted much attention, particularly because the early Middle Paleolithic is the period when the earliest anatomically modern humans fossils known to date in Eurasia have been attested in that part of Asia . The associated lithic assemblages are a significant source of information for investigating the cultural landscape of this important transition. This paper presents a new dataset from the 2003–2009 excavations at Dederiyeh Cave, northwest of Syria. A techno-typological analysis of the lithic industry reveals a common practice of blade blank production, which corroborates the other known early Middle Paleolithic assemblages of the Levant. However, its strong emphasis on Levallois core reduction and sidescraper manufacturing is noteworthy. The significance of this finding deserves further research from multiple viewpoints, including the functional and spatio-temporal variability of hominin activities in this period. It will be also important to interpret the techno-typological diagnostics of the early Middle Paleolithic assemblage of Dederiyeh considering its geographic location at the northern end of the Levant, distant from the previously known sites in the central and southern Levant.