Samuel García-Vargas

Genetic evidence for patrilocal mating behavior among Neandertal groups

The remains of 12 Neandertal individuals have been found at the El Sidrón site (Asturias, Spain), consisting of six adults, three adolescents, two juveniles, and one infant. Archaeological, paleontological, and geological evidence indicates that these individuals represent all or part of a contemporaneous social group of Neandertals, who died at around the same time and later were buried together as a result of a collapse of an underground karst. We sequenced phylogenetically informative positions of mtDNA hypervariable regions 1 and 2 from each of the remains. Our results show that the 12 individuals stem from three different maternal lineages, accounting for seven, four, and one individual(s), respectively. Using a Y-chromosome assay to confirm the morphological determination of sex for each individual, we found that, although the three adult males carried the same mtDNA lineage, each of the three adult females carried different mtDNA lineages. These findings provide evidence to indicate that Neandertal groups not only were small and characterized by low genetic diversity but also were likely to have practiced patrilocal mating behavior.

Brief Communication: Subvertical Grooves on Interproximal Wear Facets From the El Sidron (Asturias, Spain) Neandertal Dental Sample

The distribution of subvertical grooves on interproximal wear dental facets from the El Sidrón (Asturias, Spain) Neandertals is described and analyzed. Out of 93 teeth, 64.5% present subvertical grooves, including a high frequency (50%) on the anterior dentition. Contrary to some studies, subvertical grooves from adjacent facets perfectly overlap each other and do not interdigitate, probably forming small channels. Both the facet and the groove surface share the same polished appearance, suggesting a common origin. Statistical analyses reveal that the number of grooves is neither dependent on the degree of occlusal wear, nor on the position on the tooth or the individuals age. However, facet width is an important factor determining the number of subvertical grooves. The etiology of subvertical grooves formation on Neandertal teeth remains unclear.

Bone remodelling in Neanderthal mandibles from the El Sidron site (Asturias, Spain)

Skull morphology results from the bone remodelling mechanism that underlies the specific bone growth dynamics. Histological study of the bone surface from Neanderthal mandible specimens of El Sidrón (Spain) provides information about the distribution of the remodelling fields (bone remodelling patterns or BRP) indicative of the bone growth directions. In comparison with other primate species, BRP shows that Neanderthal mandibles from the El Sidrón (Spain) sample present a specific BRP. The interpretation of this map allows inferences concerning the growth directions that explain specific morphological traits of the Neanderthal mandible, such as its quadrangular shape and the posterior location of the mental foramen.

Remodeling Patterns of Occipital Growth: A Preliminary Report

Occipital growth depends on coordinated deposition and resorption on the external and internal surface and includes interrelated processes of movement: cortical drift, displacement, and relocation. The current work aspires to map patterns of remodeling activity on the endocranial surface of the occipital bone from childhood to adulthood using a larger study sample compared with previous studies. The study sample consists of 5 adult and 10 immature (2¼ to 8 years old) occipital bones from skeletal remains from the eighteenth and nineteenth century. Preparation of the samples includes the elaboration of negative impressions, positive replicas coated with gold, and observed with the reflected light microscope. Cerebellar fossae are typically resorptive in both immature and adult specimens. Cerebral fossae, on the other hand, exhibit a resorptive surface in early childhood and turn into depository around the age of 7 years, which places this transition within the age interval of the completion of cerebral development. Depository fields are also observed in adult cerebral fossae. The remodeling map presented here is consistent with the results of Mowbray (Anat Rec B New Anat 2005;283B:14–22) and differs from cellular patterns described by Enlow. Future research implicating more elements of the neurocapsule can shed light on the factors affecting and driving occipital growth. Anat Rec, 2009.