Stature estimation from complete long bones in the Middle Pleistocene humans from the Sima de los Huesos, Sierra de Atapuerca (Spain)

Systematic excavations at the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca (Burgos, Spain) have allowed us to reconstruct 27 complete long bones of the human species Homo heidelbergensis. The SH sample is used here, together with a sample of 39 complete Homo neanderthalensis long bones and 17 complete early Homo sapiens (Skhul/Qafzeh) long bones, to compare the stature of these three different human species. Stature is estimated for each bone using race- and sex-independent regression formulae, yielding an average stature for each bone within each taxon. The mean length of each long bone from SH is significantly greater (p < 0.05) than the corresponding mean values in the Neandertal sample. The stature has been calculated for male and female specimens separately, averaging both means to calculate a general mean. This general mean stature for the entire sample of long bones is 163.6 cm for the SH hominins, 160.6 cm for Neandertals and 177.4 cm for early modern humans. Despite some overlap in the ranges of variation, all mean values in the SH sample (whether considering isolated bones, the upper or lower limb, males or females or more complete individuals) are larger than those of Neandertals. Given the strong relationship between long bone length and stature, we conclude that SH hominins represent a slightly taller population or species than the Neandertals. However, compared with living European Mediterranean populations, neither the Sima de los Huesos hominins nor the Neandertals should be considered ‘short’ people. In fact, the average stature within the genus Homo seems to have changed little over the course of the last two million years, since the appearance of Homo ergaster in East Africa. It is only with the emergence of H. sapiens, whose earliest representatives were ‘very tall’, that a significant increase in stature can be documented.     

Luminescence chronology of cave sediments at the Atapuerca paleoanthropological site, Spain

Ascertaining the timing of the peopling of Europe, after the first out-of-Africa demographic expansion at the end of the Pliocene, is of great interest to paleoanthropologists. One of the earliest direct evidences for fossil hominins in western Europe comes from an infilled karstic cave site called Gran Dolina at Atapuerca, in a stratum approximately 1.5m below the Brunhes-Matuyama (B-M) geomagnetic boundary (780ka) within lithostratigraphic unit TD6. However, most of the meters of fossil- and tool-bearing strata at Gran Dolina have been difficult to date. Therefore, we applied both thermoluminescence (TL) and infrared-stimulated-luminescence (IRSL) multi-aliquot dating methods to fine-silt fractions from sediment samples within Gran Dolina and the nearby Galería cave site. We also applied these methods to samples from the present-day surface soils on the surrounding limestone hill slopes to test the luminescence-clock-zeroing-by-daylight assumption. Within the uppermost 4m of the cave deposits at Gran Dolina, TL and paired TL and IRSL ages range stratigraphically from 198+/-19ka to 244+/-26ka. Throughout Gran Dolina, all luminescence results are stratigraphically self-consistent and, excepting results from two stratigraphic units, are consistent with prior ESR-U-series ages from progressively deeper strata. Thermoluminescence ages culminate at 960+/-120ka approximately 1m below the 780ka B-M boundary. At Galería, with one exception, TL and IRSL ages range stratigraphically downward from 185+/-26ka to 503+/-95ka at the base of the lowermost surface-inwash facies. These results indicate that TL and (sometimes) IRSL are useful dating tools for karstic inwash sediments older than ca. 100ka, and that a more accurate chronostratigraphic correlation is now possible among the main Atapuerca sites (Gran Dolina, Galería, Sima de los Huesos). Furthermore, the oldest TL age of ca. 960ka from Gran Dolina, consistent with biostratigraphic and paleomagnetic evidence, implies a probable numeric age of 900-950ka for the oldest hominin remains ( approximately 0.8m below the TL sample). This age window suggests a correspondence to Marine Isotope Stage (MIS) 25, a relatively warm and humid interglaciation.     

A Neandertal mandible from the Cova del Gegant (Sitges, Barcelona, Spain)

A human mandible from the site of Cova del Gegant is described here for the first time and compared with other Middle and Upper Pleistocene representatives of the genus Homo from Europe and Southwest Asia. The specimen was recovered from sediments which also yielded Mousterian stone tools and Pleistocene fauna. The preserved morphology of the mandible, particularly in the region of the mental foramen, clearly aligns it with the Neandertals, making the Cova del Gegant the only known site in Catalonia documenting diagnostic human skeletal remains in association with Middle Paleolithic stone tools. This represents an important new addition to the human fossil record from the Iberian Peninsula and joins the Ba?olas mandible in documenting the course of human evolution in the northern Mediterranean region of Spain.     

Endocranial traits of the Sima de los Huesos (Atapuerca,Spain) and Petralona (Chalkidiki,Greece) Middle Pleistocene ursids. Phylogenetic and biochronological implications

A complete cranium of Ursus deningeri from Petralona (Chalkidiki, Greece) covered by a thick carbonate crust has been virtually liberated through CT scan and 3D image reconstruction, and compared with a specimen from the Sima de los Huesos, Sierra de Atapuerca (Spain) Middle Pleistocene site. X-ray computed tomography allowed for the identification of previously unrecognized and phylogenetically relevant traits. Analysis of these traits and an additional series of classically defined traits demonstrate the near identity of these specimens, thereby, confirming an early stage of the speloid “(cave bear)” condition. The replicate luminescence ages obtained for the SH deposit provide a combined minimum age estimate of 427 ± 12 ka for the underlying fossils. Based on a series of primitive and derived morphological features of these two crania, a similar age is here proposed for the Petralona and SH U. deningeri.     

Long-term climate record inferred from early-middle Pleistocene amphibian and squamate reptile assemblages at the Gran Dolina Cave, Atapuerca, Spain

The Gran Dolina cave site is famous for having delivered some of the oldest hominin remains of Western Europe (Homo antecessor, ca. 960 ka). Moreover, the evidence of lithic industries throughout the long vertical section suggests occupation on the part of hominins from the latest early Pleistocene (levels TD3/4, TD5, and TD6) to the late middle Pleistocene (level TD10). The Gran Dolina Sondeo Sur (TDS) has furnished a great number of small-vertebrate remains; among them some 40,000 bones are attributed to amphibians and squamates. Although they do not differ specifically from the extant herpetofauna of the Iberian Peninsula, the overlap of their current distribution areas (= mutual climatic range method) in Spain can provide mean annual temperatures (MAT), the mean temperatures of the coldest (MTC) and warmest (MTW) months, and mean annual precipitation (MAP) estimations for each sub-level, and their change can be studied throughout the sequence. Results from the squamate and amphibian study indicate that during hominin occupation the MAT (10-13 °C) was always slightly warmer than at present in the vicinity of the Gran Dolina Cave, and the MAP (800-1000 mm) was greater than today in the Burgos area. Climatic differences between “glacial” and “interglacial” phases are poorly marked. Summer temperatures (MTW) show stronger oscillations than winter temperatures (MTC), but seasonality remains almost unchanged throughout the sequence. These results are compared with those for large mammals, small mammals, and pollen analysis, giving a scenario for the palaeoclimatic conditions that occurred during the early to middle Pleistocene in Atapuerca, and hence a scenario for the hominins that once lived in the Sierra de Atapuerca.     

Hominin lower second premolar morphology: evolutionary inferences through geometric morphometric analysis

Mandibular premolars are increasingly used in taxon-specific diagnostic analyses of hominins. Among the principal difficulties in these evaluations is the absence of discrete, discernible, and comparable anatomical structures for rigorous quantitative assessment. Previous research has addressed either internal crown surface features (such as cusps and fossae) or the morphology of the crown outline. In the present paper, we integrate both types of information in the examination of morphological variation of lower P4s (n = 96) among various fossil hominin species with an emphasis on genus Homo. We use a set of 34 2D landmarks combining coordinate data from four classical dental landmarks on the occlusal surface and 30 sliding semilandmarks of the crown outline. Our results indicate that external shape variation is closely related to the configuration of the occlusal morphological features and influenced by dental size. The external and internal shapes of P4 are polymorphic but still useful in depicting a primitive-derived gradient. The primitive pattern seems to have been an asymmetrical contour with a mesially displaced metaconid, development of a bulging talonid, and a broad occlusal polygon. The trend toward dental reduction during the Pleistocene produced different morphological variants with a reduced occlusal polygon and decreased lingual occlusal surface in later Homo species. Homo heidelbergensis/neanderthalensis have fixed plesiomorphic traits in high percentages, whereas in modern humans a symmetrical outline with a centered metaconid and talonid reduction evolved.     

50,000 years of genetic uniformity in the critically endangered Iberian lynx

Low genetic diversity in the endangered Iberian lynx, including lack of mitochondrial control region variation, is thought to result from historical or Pleistocene/Holocene population bottlenecks, and to indicate poor long-term viability. We find no variability in control region sequences from 19 Iberian lynx remains from across the Iberian Peninsula and spanning the last 50,000 years. This is best explained by continuously small female effective population size through time. We conclude that low genetic variability in the Iberian lynx is not in itself a threat to long-term viability, and so should not preclude conservation efforts.     

A geometric morphometric analysis of hominin upper second and third molars, with particular emphasis on European Pleistocene populations

The study of dental morphology by means of geometric morphometric methods allows for a detailed and quantitative comparison of hominin species that is useful for taxonomic assignment and phylogenetic reconstruction. Upper second and third molars have been studied in a comprehensive sample of Plio- and Pleistocene hominins from African, Asian and European sites in order to complete our analysis of the upper postcanine dentition. Intraspecific variation in these two molars is high, but some interspecific trends can be identified. Both molars exhibit a strong reduction of the distal cusps in recent hominin species, namely European Homo heidelbergensis, Homo neanderthalensis and Homo sapiens, but this reduction shows specific patterns and proportions in the three groups. Second molars tend to show four well developed cusps in earlier hominin species and their morphology is only marginally affected by allometric effects. Third molars can be incipiently reduced in earlier species and they evince a significant allometric component, identified both inter- and intraspecifically. European Middle Pleistocene fossils from Sima de los Huesos (SH) show a very strong reduction of these two molars, even more marked than the reduction observed in Neanderthals and in modern human populations. The highly derived shape of SH molars points to an early acquisition of typical Neanderthal dental traits by pre-Neanderthal populations and to a deviation of this population from mean morphologies of other European Middle Pleistocene groups.