La gran chapuza

Uno de los argumentos más importantes esgrimidos por Darwin para probar la realidad del hecho evolutivo, frente a la idea de la creación directa, es la presencia de imperfecciones en los seres vivos. Quizá la más notable de todas esas imperfecciones se encuentre anidada en el seno de uno de los procesos más importantes de la materia viva, la fotosíntesis, y en el funcionamiento de la enzima más abundante de la Naturaleza: la ribulosa 1,5 difosfato carboxilasa-oxigenasa, generalmente abreviada como Rubisc

The earliest evidence of true lambdoid craniosynostosis: the case of “Benjamina”, a Homo heidelbergensis child

Background The authors report the morphological and neuroimaging findings of an immature human fossil (Cranium 14) diagnosed with left lambdoid synostosis. Discussion The skull was recovered at the Sima de los Huesos site in Atapuerca (Burgos, Spain). Since the human fossil remains from this site have been dated to a minimum age of 530,000 years, this skull represents the earliest evidence of craniosynostosis occurring in a hominid. A brief historical review of craniosynostosis and cranial deformation is provided

The Bañolas human mandible revisited (Gerona, Spain)

La mandíbula de Bañolas, descubierta en 1887 en Bañolas (Gerona, España), es un fósil humano sobre cuya asignación taxonómica no hay aún consenso. En diferentes estudios ha sido incluida dentro de Homo neanderthalensis {King, 1864} (Hernández-Pacheco & Obermaier, 1915; Sánchez, 1993), dentro de los ante-neandertales (de Lumley, 1971-72) y dentro de los ante-würmienses (Roth & Simon, 1993). Recientemente, Daura y colaboradores (Daura et al., 2005), en su artículo sobre la mandíbula fósil de la Cova del Gegant, sugieren que la mandíbula de Bañolas no presenta caracteres neandertales y que, dada su cronología, podría haber pertenecido a un Homo sapiens {Linneo, 1758}. Este estudio trata de arrojar luz sobre la cuestión de la asignación taxonómica de la mandíbula de Bañolas. Para ello se han utilizado caracteres morfológicos discretos que permiten discriminar entre las especies H. heidelbergensis {Schoetensack, 1908}, H. neanderthalensis y H. sapiens. La conclusión del trabajo es que los estados de los caracteres que presenta la mandíbula de Bañolas son, en su mayor parte, más frecuentes en H. sapiens que en las otras dos especies tenidas en cuenta.Since the discovery of a fossil human mandible in 1887 near the city of Bañolas (Gerona, Spain), there has been considerable disagreement among scholars as to its taxonomic allocation. In different studies the specimen has been included within Homo neanderthalensis {King, 1864} (Hernández-Pacheco & Obermaier, 1915; Sánchez, 1993), ante-Neandertals (de Lumley, 1971-72) or an ante-würmian (Roth & Simon, 1993) species. More recently, the Bañolas mandible has been argued to lack derived Neandertal traits (Daura et al., 2005). Although the mandible was found in a quarry of travertine, its exact location is unknown. Some patches of travertine adhered to the specimen have provided a geochronological age range between 17,6 to 110 kyr (Berger & Libby, 1966¸ Yokoyama et al., 1987; Julià & Bischoff, 1991; Grün et al., 2006). The only direct dating of the mandible yielded an age of 66 ± 7 kyr B.P. (Grün et al., 2006). After a recent examination of the original specimen, a number of morphological traits of this mandible has been described and compared with information from the literature regarding H. heidelbergensis {Schoetensack, 1908}, H. neanderthalensis and both fossil and extant H. sapiens {Linneo, 1758} mandibles. These characters have been considered to be of taxonomical significance to discriminate between these three species (see below for references). Despite the fragmentary condition of the Bañolas mandible, a considerable number of morphological traits can be evaluated: presence/absence of the mental trigone (Schwartz & Tattersall , 2000), shape of the anterior basal corpus (Quam & Smith, 1998), position of the digastric fossa (de Lumley, 1973), number, size and location of the mental foramen (Trinkaus, 1993), presence/absence of the retromolar space and inclination of the retromolar triangle (Franciscus & Trinkaus, 1995; Rosas, 2001), shape of the mandibular foramen (Smith, 1978), size and shape of the medial pterygoid tubercle (Antón, 1996), relative position between the condyle and the ascending ramus plane (Rosas, 2001; Nicholson & Harvati, 2006; Trinkaus, 2006), dimensions of the submental incisure (Mounier et al., 2009), location and trajectory of the mylohyoid line (Mounier et al., 2009), size of the alveolar plane (Mounier et al., 2009), shape of the gonion (Creed-Miles et al., 1996) and relative position of the lateral prominence to the dentition (Rosas, 2001; Mounier et al., 2009). The state of these characters in the Bañolas mandible is as follow: absence of mental trigone (but slight evidences of a possible mental fossa and a possible central keel) (Fig. 1), triangular anterior basal corpus shape (Figs. 1 and 3), disgastric fossa located in the posterior face of the symphysis (Figs. 1 and 3 ), a single small mental foramen placed in the upper half of the corpus and below the P4 (Fig. 2), absence of retromolar space and an oblique retromolar triangle relative to the alveolar margin (Figs. 2 and 6), small and not lib-shaped medial pteriogoid tubercle (Fig. 5), medially placed condyle relative to the ascending ramus plane (Fig. 4), large dimensions of the submental incisure (Fig. 2), mylohyoid line that starts near the M3 and follows obliquely to the alveolar margin (Fig. 4), not large (wide) alveolar plane (Fig. 6), rounded (not truncated) gonion (Figs. 2 and 4) and anteriorly placed lateral prominence (M2 and M2/ M3 septum) (Fig. 2). Regarding the mandibular foramen, it seems to present a lingula, it could confirm the presence of a normal mandibular foramen type and it would discard the possibility of an H-O mandibular foramen type (Smith, 1978) (Fig. 5). Except for the large submental incisure and the absence of mental trigone, the state of all these characters is more frequent in Homo sapiens specimens (de Lumley, 1973; Smith, 1978; Trinkaus, 1993; Franciscus & Trinkaus, 1995; Antón, 1996; Creed-Miles et al., 1996; Quam & Smith, 1998; Rosas, 2001; Nicholson & Harvati, 2006; Trinkaus, 2006; Mounier et al., 2009). The large submental incisure is a characteristic trait of Homo heidelbergensis and the absence of mental trigone is a plesiomophic character shared by Homo neanderthalensis, Homo heidelbergensis and some upper Pleistocene Homo sapiens individuals (Schwartz & Tattersall , 2000). On the view of this work our conclusion is that the Bañolas mandible shows neither derived Neandertal traits nor clear affinities to H. heidelbergensis. On the contrary, this specimen bears a greater resemblance to the H. sapiens mandibles.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

The Neandertal nature of the Atapuerca Sima de los Huesos mandibles

The recovery of additional mandibular fossils from the Atapuerca Sima de los Huesos (SH) site provides new insights into the evolutionary significance of this sample. In particular, morphological descriptions of the new adult specimens are provided, along with standardized metric data and phylogenetically relevant morphological features for the expanded adult sample. The new and more complete specimens extend the known range of variation in the Atapuerca (SH) mandibles in some metric and morphological details. In other aspects, the addition of new specimens has made it possible to confirm previous observations based on more limited evidence. Pairwise comparisons of individual metric variables revealed the only significant difference between the Atapuerca (SH) hominins and Neandertals was a more vertical symphysis in the latter. Similarly, principal components analysis of size-adjusted variables showed a strong similarity between the Atapuerca (SH) hominins and Neandertals. Morphologically, the Atapuerca (SH) mandibles show nearly the full complement of Neandertal-derived features. Nevertheless, the Neandertals differ from the Atapuerca (SH) mandibles in showing a high frequency of the H/O mandibular foramen, a truncated, thinned and inverted gonial margin, a high placement of the mylohyoid line at the level of the M3, a more vertical symphysis and somewhat more pronounced expression of the chin structures. Size-related morphological variation in the SH hominins includes larger retromolar spaces, more posterior placement of the lateral corpus structures, and stronger markings associated with the muscles of mastication in larger specimens. However, phylogenetically relevant features in the SH sample are fairly stable and do not vary with the overall size of the mandible. Direct comparison of the enlarged mandibular sample from Atapuerca (SH) with the Mauer mandible, the type specimen of H. heidelbergensis, reveals important differences from the SH hominins, and there is no morphological counterpart of Mauer within the SH sample, suggesting the SH fossils should not be assigned to this taxon. The Atapuerca (SH) mandibles show a greater number of derived Neandertal features, particularly those related to midfacial prognathism and in the configuration of the superior ramus, than other European middle Pleistocene specimens. This suggests that more than one evolutionary lineage co-existed in the middle Pleistocene, and, broadly speaking, it appears possible to separate the European middle Pleistocene mandibular remains into two distinct groupings. One group shows a suite of derived Neandertal features and includes specimens from the sites of Atapuerca (SH), Payre, l'Aubesier and Ehringsdorf. The other group includes specimens that generally lack derived Neandertal features and includes the mandibles from the sites of Mauer, Mala Balanica, Montmaurin and (probably) Visogliano. The two published Arago mandibles differ strongly from one another, with Arago 2 probably belonging to this former group, and Neandertal affinities being more difficult to identify in Arago 13. Outside of the SH sample, derived Neandertal features in the mandible only become more common during the second half of the middle Pleistocene. Acceptance of a cladogenetic pattern of evolution during the European middle Pleistocene has the potential to reconcile the predictions of the accretion model and the two phases model for the appearance of Neandertal morphology. The precise taxonomic classification of the SH hominins must contemplate features from the dentition, cranium, mandible and postcranial skeleton, all of which are preserved at the SH site. Nevertheless, the origin of the Neandertal clade may be tied to a speciation event reflected in the appearance of a suite of derived Neandertal features in the face, dentition and mandible, all of which are present in the Atapuerca (SH) hominins. This same suite of features also provides a useful anatomical basis to include other European middle Pleistocene mandibles and crania within the Neandertal clade.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEBinghamton UniversityMinisterio de Ciencia e Innovación y UniversidadesJunta de Castilla y Leónpu

Studing audition in fossil hominins: a new approach to the evolution of language?

The evolution of human language is one of the oldest questions inpaleoanthropology. Nevertheless, many previous attempts to approachthis question have not yielded informative results since they are oftenbased on anatomical features whose role in speech production in modernhumans is unclear or whose functional implications in fossil specimensare difficult to assess. We take a new approach to this question bystudying the evolution of audition. Human hearing differs from that ofchimpanzees and other primate taxa in maintaining a widened bandwidthof heightened sensitivity between 1-8 kHz, a region that contains relevantacoustic information in spoken language. Comparative analysis ofprimate audiograms suggests that this represents a unique derived featurein modern humans. Knowledge of the auditory capacities in our fossilhuman ancestors could greatly enhance the understanding of when thishuman pattern emerged during the course of our evolutionary history.Here we present a comprehensive approach to this question, onlyrarely addressed in human evolutionary studies. We have analyzed theauditory capacities in five fossil human specimens from the MiddlePleistocene site of the Sima de los Huesos (SH) in the Sierra deAtapuerca of Spain. The results demonstrate that the Atapuerca (SH)hominins resemble modern humans in showing a widened bandwidth ofheightened sensitivity between 1-5 kHz, a frequency range whichoverlaps the range of frequencies emitted during spoken language. At thesame time, both modern humans and the Atapuerca (SH) hominins differfrom chimpanzees in showing a heightened sensitivity to the highconsonant area (approximately 3-5 kHz) of the so-called "speechbanana", a frequency range associated with consonant production inhuman spoken language.The presence of a modern human auditory pattern in the Atapuercahominins suggests that these Middle Pleistocene humans alreadypossessed the anatomical features of the outer and middle ear that supportthe perception of human spoken language. Given the intuitive, butdifficult to quantify, link between sound perception and vocal productionin animals, the study of auditory capacities may have implications for theemergence of language in our fossil human ancestors. Although the studyof audition is an indirect approach to the question of speech capacity infossil specimens, the results of the present study are consistent with otherrecent suggestions for the presence of some form of spoken language inthe genus Homo prior to the appearance of our own species, Homosapiens

Reassessment of the La Ferrassie 3 Neandertal ossicular chain

The ossicular chain in La Ferrassie 3 was briefly described in the monograph on the La Ferrassie Neandertal children, but to date has not been the subject of detailed study. We provide new data on these important fossils and re-examine some previous suggestions of derived Neandertal features in the middle ear ossicles based on more limited evidence. The malleus shows a curved lateral margin of the manubrium and a relatively large head. The incus shows a tall articular facet, a depressed area on the medial surface of the body, a straight anterior border of the long process and a more closed angle between the processes. The stapes shows an asymmetrical configuration of the crura, with an anteriorly skewed head, and generally small dimensions, including a smaller and relatively wider stapedial footplate. These same features can also be seen in the few other Neandertal ear ossicles known, suggesting that a consistent anatomical pattern characterizes the Neandertal ossicular chain. While the phylogenetic polarity of many of these features remains to be clarified, the asymmetrical stapes and anteriorly skewed stapedial head appear to be derived Neandertal features. In addition, while the larger malleus head and incus articular facet in La Ferrassie 3 might reflect larger body mass in Neandertals, the larger stapes footplates in Homo sapiens cannot be explained by changes in body mass. Indeed, H. sapiens seems to depart from the general mammalian pattern in combining an increase in stapes footplate size with a decrease in body mass. Although the malleus/incus lever ratio in La Ferrassie 3 is similar to that in H. sapiens, Neandertals appear to be characterized by a slightly different spatial relationship and articulation of the ossicular chain within the tympanic cavity. While only limited inferences can be drawn regarding hearing ability based on the ossicles, the few physiologically relevant dimensions in the La Ferrassie 3 ear bones are similar to H. sapiens