Ana Gracia

A mitochondrial genome sequence of a hominin from Sima de los Huesos

Excavations of a complex of caves in the Sierra de Atapuerca in northern Spain have unearthed hominin fossils that range in age from the early Pleistocene to the Holocene. One of these sites, the ‘Sima de los Huesos’ (‘pit of bones’), has yielded the world’s largest assemblage of Middle Pleistocene hominin fossils, consisting of at least 28 individuals dated to over 300,000 years ago. The skeletal remains share a number of morphological features with fossils classified as Homo heidelbergensis and also display distinct Neanderthal-derived traits. Here we determine an almost complete mitochondrial genome sequence of a hominin from Sima de los Huesos and show that it is closely related to the lineage leading to mitochondrial genomes of Denisovans, an eastern Eurasian sister group to Neanderthals. Our results pave the way for DNA research on hominins from the Middle Pleistocene.

A complete human pelvis from the Middle Pleistocene of Spain

The Middle Pleistocene site of Sima de los Huesos in Sierra de Atapuerca, Spain, has yielded around 2,500 fossils from at least 33different hominid individuals. These have been dated at more than 200,000 years ago and have been classified as ancestors of Neanderthals,. An almost complete human male pelvis (labelled Pelvis 1) has been found, which we associate with two fragmentary femora. Pelvis 1 is robust and very broad with a very long superior pubic ramus, marked iliac flare, and a long femoral neck. This pattern is probably the primitive condition from which modern humans departed. A modern human newborn would pass through the birth canal of Pelvis 1 and this would be even larger in a female individual. We estimate the body mass of this individual at 95 kg or more. Using the cranial capacities of three specimens from Sima de los Huesos, the encephalization quotients are substantially smaller than in Neanderthals and modern humans.

Nuclear DNA sequences from the Middle Pleistocene Sima de los Huesos hominins

A unique assemblage of 28 hominin individuals, found in Sima de los Huesos in the Sierra de Atapuerca in Spain, has recently been dated to approximately 430,000 years ago. An interesting question is how these Middle Pleistocene hominins were related to those who lived in the Late Pleistocene epoch, in particular to Neanderthals in western Eurasia and to Denisovans, a sister group of Neanderthals so far known only from southern Siberia. While the Sima de los Huesos hominins share some derived morphological features with Neanderthals, the mitochondrial genome retrieved from one individual from Sima de los Huesos is more closely related to the mitochondrial DNA of Denisovans than to that of Neanderthals. However, since the mitochondrial DNA does not reveal the full picture of relationships among populations, we have investigated DNA preservation in several individuals found at Sima de los Huesos. Here we recover nuclear DNA sequences from two specimens, which show that the Sima de los Huesos hominins were related to Neanderthals rather than to Denisovans, indicating that the population divergence between Neanderthals and Denisovans predates 430,000 years ago. A mitochondrial DNA recovered from one of the specimens shares the previously described relationship to Denisovan mitochondrial DNAs, suggesting, among other possibilities, that the mitochondrial DNA gene pool of Neanderthals turned over later in their history.

Middle Pleistocene lower back and pelvis from an aged human individual from the Sima de los Huesos site, Spain

We report a nearly complete lumbar spine from the Middle Pleistocene site of the Sima de los Huesos (SH) that is assigned to the previously published SH male Pelvis 1 [Arsuaga JL, et al. (1999). Nature 399: 255–258]. The “SH Pelvis 1 individual” is a unique nearly complete lumbo-pelvic complex from the human Middle Pleistocene fossil record, and offers a rare glimpse into the anatomy and past lifeways of Homo heidelbergensis. A revised reconstruction of Pelvis 1, together with the current fossil evidence, confirms our previous hypothesis that the morphology of this pelvis represents the primitive pattern within the genus Homo. Here we argue that this primitive pattern is also characterized by sexual dimorphism in the pelvic canal shape, implying complicated deliveries. In addition, this individual shows signs of lumbar kyphotic deformity, spondylolisthesis, and Baastrup disease. This suite of lesions would have postural consequences and was most likely painful. As a result, the individual’s daily physical activities would have been restricted to some extent. Reexamination of the age-at-death agrees with this individual being over 45 y old, relying on the modern human pattern of changes of the articular surfaces of the os coxae. The presence of degenerative pathological lesions and the advanced age-at-death of this individual make it the most ancient postcranial evidence of an aged individual in the human fossil record. Additional nonpathological SH lumbo-pelvic remains are consistent with previous hypotheses, suggesting a less-pronounced sagittal spinal curvature in Neandertals compared with Homo sapiens.

Cranial remains and long bones from Atapuerca/Ibeas (Spain)

Abstract The cranial remains and long bones of the Sima de los Huesos site (Sierra de Atapuerca, Spain) are described and their phylogenetic affinities established. We find in the Atapuerca/Ibeas sample: (a) a number of plesiomorphic traits (namely, character states not retained by the upper Pleistocene Neandertals but present in the outgroups); (b) one apomorphy shared with Neandertals; (c) some postcranial character states shared with Neandertals but whose phylogenetic status remain uncertain. In sum, the Atapuerca/Ibeas fossils are phylogenetically related to the Neandertals but cannot be pooled with them because of the overall plesiomorphic pattern. Other European middle Pleistocene specimens show apomorphies shared with Neandertals and plesiomorphies. In our opinion these specimens do not share uniquely derived features and thus this chronological group cannot be defined. Other aspects such as cerebral lateralization and sexual dimorphism in humeri and temporal bones are investigated.

Craniosynostosis in the Middle Pleistocene human Cranium 14 from the Sima de los Huesos, Atapuerca, Spain

We report here a previously undescribed human Middle Pleistocene immature specimen, Cranium 14, recovered at the Sima de los Huesos (SH) site (Atapuerca, Spain), that constitutes the oldest evidence in human evolution of a very rare pathology in our own species, lambdoid single suture craniosynostosis (SSC). Both the ecto- and endo-cranial deformities observed in this specimen are severe. All of the evidence points out that this severity implies that the SSC occurred before birth, and that facial asymmetries, as well as motor/cognitive disorders, were likely to be associated with this condition. The analysis of the present etiological data of this specimen lead us to consider that Cranium 14 is a case of isolated SSC, probably of traumatic origin. The existence of this pathological individual among the SH sample represents also a fact to take into account when referring to sociobiological behavior in Middle Pleistocene humans.

Intrapopulational Body Size Variation and Cranial Capacity Variation in Middle Pleistocene Humans: The Sima de los Huesos Sample (Sierra de Atapuerca, Spain)

A sexual dimorphism more marked than in living humans has been claimed for European Middle Pleistocene humans, Neandertals and prehistoric modern humans. In this paper, body size and cranial capacity variation are studied in the Sima de los Huesos Middle Pleistocene sample. This is the largest sample of non-modern humans found to date from one single site, and with all skeletal elements represented. Since the techniques available to estimate the degree of sexual dimorphism in small palaeontological samples are all unsatisfactory, we have used the bootstraping method to asses the magnitude of the variation in the Sima de los Huesos sample compared to modern human intrapopulational variation. We analyze size variation without attempting to sex the specimens a priori. Anatomical regions investigated are scapular glenoid fossa; acetabulum; humeral proximal and distal epiphyses; ulnar proximal epiphysis; radial neck; proximal femur; humeral, femoral, ulnar and tibial shaft; lumbosacral joint; patella; calcaneum; and talar trochlea. In the Sima de los Huesos sample only the humeral midshaft perimeter shows an unusual high variation (only when it is expressed by the maximum ratio, not by the coefficient of variation). In spite of that the cranial capacity range at Sima de los Huesos almost spans the rest of the European and African Middle Pleistocene range. The maximum ratio is in the central part of the distribution of modern human samples. Thus, the hypothesis of a greater sexual dimorphism in Middle Pleistocene populations than in modern populations is not supported by either cranial or postcranial evidence from Sima de los Huesos.

The Atapuerca sites and the ibeas hominids

The Atapuerca railway Trench and Ibeas sites near Burgos, Spain, are cave fillings that include a series of deposits ranging from below the Matuyama/Bruhnes reversal up to the end of Middle Pleistocene. The lowest fossil-bearing bed in the Trench contains an assemblage of large and small Mammals includingMimomys savini, Pitymys gregaloides, Pliomys episcopalis, Crocuta crocuta, Dama sp. and Megacerini; the uppermost assemblage includesCanis lupus, Lynx spelaea, Panthera (Leo) fossilis, Felis sylvestris, Equus caballus steinbeimensis, E.c. germanicus, Pitymys subterraneus, Microtus arvalis agrestis, Pliomys lenki, and alsoPanthera toscana, Dicerorbinus hemitoechus, Bison schoetensacki, which are equally present in the lowest level. The biostratigraphic correlation and dates of the sites are briefly discussed, as are the paleoclimatic interpretation of the Trench sequences. Stone artifacts are found in several layers; the earliest occurrences correspond to the upper beds containingMimomys savini. A set of preserved human occupation floors has been excavated in the top fossil-bearing beds. The stone-tool assemblages of the upper levels are of upper-medial Acheulean to Charentian tradition. The rich bone breccia SH, in the Cueva Mayor-Cueva del Silo, Ibeas de Juarros, is a derived deposit, due to a mud flow that dispersed and carried the skeletons of many carnivores and humans. The taxa represented are:Ursus deningeri (largely dominant),Panthera (Leo) fossilis, Vulpes vulpes, Homo sapiens var. Several traits of both mandibular and cranial remains are summarized. Preliminary attempts at dating suggest that the Ibeas fossil man is older than the Last Interglacial, or oxygen-isotope stage 5.

The human remains from Cova Negra (Valencia, Spain) and their place in European Pleistocene human evolution

Abstract The phylogenetic and chronological positions of the Cova Negra human remains are discussed. These remains include an adult right parietal bone, a juvenile right mandibular body fragment with a deciduous second molar, and an isolated permanent upper central incisor. There are 40 levels in the Cova Negra sedimentary sequence, ranging from the Riss-Wurm to the beginning of the Wurm III. The Cova Negra A phase (Riss-Wurm) is faunally and industrially sterile. Several variants of the Mousterian (Charentian type) are known from the beginning of the Wurm (Cova Negra B phase) to the end of the sequence (Cova Negra E and F phases). All human remains are assigned to the Wurm. On the basis of the parietal bone, uni- and bivariate analyses show that the Cova Negra biparietal vault was very broad. The cluster analysis groups Cova Negra with the biggest Neandertal neurocrania (specimens generally sexed as males). Also, this parietal bone exhibits a subcircular profile in posterior view, a trait considered as a Neandertal autapomorphy. The mandibular fragment shows three foramina mentalia and a steep linea mylohyoidea. These and other traits lead us to include this specimen in the Neandertal group. The crown dimensions and the morphology of the deciduous molar are consistent with this taxonomic attribution. The comparative study of the crown and root dimensions of the permanent incisor, as well as the presence of traits such as a strong tuberculum linguale, well developed marginal ridges (shovelling), and the marked lingual inclination of the buccal face, lead us to attribute this tooth to the Neandertal group.

Analyse phylogénétique des Hominidés de la Sierra de Atapuerca (Sima de los Huesos et Gran Dolina TD-6): l'évidence crânienne

Sierra de Atapuerca (Sima de los Huesos and Gran Dolina TD-6) hominids phylogenetic analysis: the cranial evidence. The level TD6 at the Gran Dolina site, Sierra de Atapuerca (Burgos, Spain), has produced the earliest European human remains, dating from the Lower Pleistocene. The Sima de los Huesos site, also in the Sierra de Atapuerca, is currently regarded as the richest Middle Pleistocene site in human fossils. The human fossil record from both sites contains many cranial remains which allow us to study the human evolution along the Lower and the Middle Pleistocene. We have carried out a study of the endocranial volumes of Cranium 4 and Cranium 5, comparing the results obtained using classical measurement techniques with those obtained using tridimensional reconstructions with computer axial tomographies (CAT). The values found using both techniques are virtually identical and endorse the CAT techniques for the studies on fossil internal structures. On the other hand, our phylogenetical analysis shows that the Sima de los Huesos specimens present an assemblage of primitive features together with other traits which strongly relate them with the Neandertal populations. The Gran Dolina human fossils, assigned to Homo antecessor species, present a constellation of cranial features which led us to propose this species as the last common ancestor of Neandertals and modern humans.