The human cranial remains from Gran Dolina Lower Pleistocene site (Sierra de Atapuerca, Spain).

In this article we study the cranial remains of the late Lower Pleistocene human fossils from Gran Dolina (Sierra de Atapuerca, Spain), assigned to the new species Homo antecessor. The cranial remains belong to at least five individuals, both juveniles and adults. The most outstanding feature is the totally modern human morphology of the very complete face ATD6-69, representing the earliest occurrence of the modern face in the fossil record. The Gran Dolina fossils show in the face a suite of modern human apomorphies not found in earlier hominids nor in contemporary or earlier Homo erectus fossils. There are also traits in the Gran Dolina fossils shared with both Neandertals and modern humans, which reinforce the hypothesis that Neandertals and modern humans form a clade, and that the Gran Dolina fossils are a common ancestor to both lineages.     

Right handedness of Homo heidelbergensis from Sima de los Huesos (Atapuerca, Spain) 500,000 years ago

Handedness is a product of brain specialization, which in turn seems to be responsible for the higher cognitive capabilities of humans, such as language and technology. Handedness in living humans is well established and shows the highest degree of manual specialization. Studies on hand laterality in nonhuman primates, particularly in chimpanzees, remain a matter of controversy as results tend to vary depending on factors such as the tasks performed and the environment in which the individuals live. Studies in several disciplines have attempted to determine where in the course of human evolution handedness established itself, with evidence collected from sources such as paleoneurological analyses, stone tool flaking, zooarchaeological studies and dental wear analyses, the last one of which have proven the most reliable source of information. Here we report an experimental and paleoanthropological study on hand laterality of a sample of 28 hominids from Sima de los Huesos (Atapuerca, Spain), dated at about 500,000 years ago, and compare our results with dental microwear analysis in other fossil samples such as that from Krapina (Croatia), as well as modern traditional societies. Our results indicate that European Middle Pleistocene Homo heidelbergensis was already as right-handed as modern populations.     

Restauration d’un fémur fossile humain du site de la Sima de los Huesos (Atapuerca, Espagne)

A fossil human femur of Homo heidelbergensis from the site of the Sima de los Huesos (Atapuerca, Spain) was reconstructed from two main proximal and distal portions and numerous smaller fragments from the diaphysis. The use of an evaporative process to separate the bone fragments during their restoration represents an innovative approach in restoring paleontological materials and the intervention has resulted in the reconstruction of a complete femur. To avoid excessive manipulation of the reconstructed femur, a mold (negative) and cast (positive) were made of the restored specimen. This case study provides general protocols which can be widely applied to the restoration of paleontological materials from the moment of their excavation until they are deposited in a research center.     

Right‐handed fossil humans

Fossil hominids often processed material held between their upper and lower teeth. Pulling with one hand and cutting with the other, they occasionally left impact cut marks on the lip (labial) surface of their incisors and canines. From these actions, it possible to determine the dominant hand used. The frequency of these oblique striations in an array of fossil hominins documents the typically modern pattern of 9 right‐ to 1 left‐hander. This ratio among living Homo sapiens differs from that among chimpanzees and bonobos and more distant primate relatives. Together, all studies of living people affirm that dominant right‐handedness is a uniquely modern human trait. The same pattern extends deep into our past. Thus far, the majority of inferred right‐handed fossils come from Europe, but a single maxilla from a Homo habilis, OH‐65, shows a predominance of right oblique scratches, thus extending right‐handedness into the early Pleistocene of Africa. Other studies show right‐handedness in more recent African, Chinese, and Levantine fossils, but the sample compiled for non‐European fossil specimens remains small. Fossil specimens from Sima del los Huesos and a variety of European Neandertal sites are predominately right‐handed. We argue the 9:1 handedness ratio in Neandertals and the earlier inhabitants of Europe constitutes evidence for a modern pattern of handedness well before the appearance of modern Homo sapiens.     

Twentieth anniversary of Homo antecessor (1997‐2017): a review

It has been twenty years since diagnosis and publication of the species Homo antecessor.¹ Since then, new human fossils recovered from the TD6 level of the Gran Dolina site (Sierra de Atapuerca, northern Spain) have helped to refine its taxonomic and phylogenetic position. In this paper, we present a synthesis of the most characteristic features of this species, as well as our interpretation derived from the latest investigations. We focus on the phylogenetic interpretation of Homo antecessor, taking into account the most recent paleogenetic analyses and a reassessment of the European Middle Pleistocene hominin record. We try to show that, twenty years after its publication, H. antecessor provides a good opportunity to address the morphology of the last common ancestor of Neandertals and modern humans.     

Modeling of chromosome intermingling by partially overlapping uniform random polygons

During the early phase of the cell cycle the eukaryotic genome is organized into chromosome territories. The geometry of the interface between any two chromosomes remains a matter of debate and may have important functional consequences. The Interchromosomal Network model (introduced by Branco and Pombo) proposes that territories intermingle along their periphery. In order to partially quantify this concept we here investigate the probability that two chromosomes form an unsplittable link. We use the uniform random polygon as a crude model for chromosome territories and we model the interchromosomal network as the common spatial region of two overlapping uniform random polygons. This simple model allows us to derive some rigorous mathematical results as well as to perform computer simulations easily. We find that the probability that one uniform random polygon of length n that partially overlaps a fixed polygon is bounded below by \({1-O(\frac{1}{\sqrt n})}\). We use numerical simulations to estimate the dependence of the linking probability of two uniform random polygons (of lengths n and m, respectively) on the amount of overlapping. The degree of overlapping is parametrized by a parameter \({\epsilon\in [0,1]}\) such that \({\epsilon=0}\) indicates no overlapping and \({\epsilon=1}\) indicates total overlapping. We propose that this dependence relation may be modeled as \({f(\varepsilon, m, n) =1-{\frac{a(\epsilon)}{b(\epsilon)\sqrt{mn}+c(\epsilon)}}}\). Numerical evidence shows that this model works well when \({\epsilon}\) is relatively large \({(\varepsilon \ge 0.5)}\). We then use these results to model the data published by Branco and Pombo and observe that for the amount of overlapping observed experimentally the URPs have a non-zero probability of forming an unsplittable link.     

New Luminescence Ages for the Galería Complex Archaeological Site: Resolving Chronological Uncertainties on the Acheulean Record of the Sierra de Atapuerca,Northern Spain

The archaeological karstic infill site of Galería Complex, located within the Atapuerca system (Spain), has produced a large faunal and archaeological record (Homo sp. aff. heidelbergensis fossils and Mode II lithic artefacts) belonging to the Middle Pleistocene. Extended-range luminescence dating techniques, namely post-infrared infrared stimulated luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated luminescence (TT-OSL) dating of individual quartz grains, were applied to fossil-bearing sediments at Galería. The luminescence dating results are in good agreement with published chronologies derived using alternative radiometric dating methods (i.e., ESR and U-series dating of bracketing speleothems and combined ESR/U-series dating of herbivore teeth), as well as biochronology and palaeoenvironmental reconstructions inferred from proxy records (e.g., pollen data). For the majority of samples dated, however, the new luminescence ages are significantly (∼50%) younger than previously published polymineral thermoluminescence (TL) chronologies, suggesting that the latter may have overestimated the true burial age of the Galería deposits. The luminescence ages obtained indicate that the top of the basal sterile sands (GIb) at Galería have an age of up to ∼370 thousand years (ka), while the lowermost sub-unit containing Mode II Acheulean lithics (base of unit GIIa) was deposited during MIS 9 (mean age = 313±14 ka; n = 4). The overlying units GIIb-GIV, which contain the richest archaeopalaeontological remains, were deposited during late MIS 8 or early MIS 7 (∼240 ka). Galería Complex may be correlative with other Middle Pleistocene sites from Atapuerca, such as Gran Dolina level TD10 and unit TE19 from Sima del Elefante, but the lowermost archaeological horizons are ∼100 ka younger than the hominin-bearing clay breccias at the Sima de los Huesos site. Our results suggest that both pIR-IR and single-grain TT-OSL dating are suitable for resolving Middle Pleistocene chronologies for the Sierra de Atapuerca karstic infill sequences.     

The Atapuerca human fossils

After 20 years of research, the Atapuerca sites have provided a large amount of archaeological and palaeontological remains. Human fossils have been found in three sites: Gran Dolina, galería and Sima de los Huesos. The Early Pleistocene human fossils from Gran Dolina have been ascribed to a new species,Homo antecessor, that represent the last common ancestor of Neandertals and modern humans. The Sima de los Huesos fossils and all the European Middle Pleistocene human fossils are the ancestors exclusively of the Neandertals, which evolved in Europe in conditions of geographic and genetic isolation.