Insights into molar-incisor hypomineralisation in past populations: A call to anthropologists.

OBJECTIVE: Molar incisor hypomineralisation (MIH) is a developmental defect of enamel affecting the first permanent molars and often the incisors and affecting approximately 13% of the current population worldwide. Here, we aim to highlight potential differential diagnoses of MIH in archaeological collections (taphonomic discoloration, amelogenesis imperfecta, fluorosis, rachitic teeth, etc.). METHODS: Causative factors of dental discolourations are identified through a literature review. RESULTS: In an archaeological context, the sediments contained in the burial soil can lead to tooth discoloration. Taphonomic staining of the dentition may have a similar appearance to enamel hypomineralisation, and thus is a confounding factor that has the potential to cause miscalculation of the true prevalence of MIH within archaeological collections. Some rare medieval cases are reported in the modern literature but without microanalysis, misdiagnosis is possible. The aetiological factors of MIH are unknown but probably follow the multifactorial model involving systemic medical and genetic factors. CONCLUSIONS: Systematic detection and diagnosis of MIH during anthropological studies is therefore of great interest. SIGNIFICANCE: The hypotheses that only contemporary agents are causative factors of MIH could be refuted by the discovery of individuals living before medication or pollutants. The identification of MIH in a group of individuals also provides information regarding the health status of a population and reflects stress occurring during the period of mineralisation of the first permanent molars after secretion of the enamel matrix. LIMITATIONS: Taphonomic alterations of archaeological remains prevent MIH diagnosis. SUGGESTIONS FOR FUTURE RESEARCH: MIH diagnosis can be difficult in archaeological series and further non-destructive methods (microtomography, elemental analyses, etc.) are required.

Non-metric dental analysis of human interactions around the Pyrenees during the Neolithic and their biological impact.

BACKGROUND: Interactions across the Pyreneans during the Middle-Neolithic (V-IV millennium BCE) have been described for a long time. Nevertheless, except for a few examples and attempts to describe them, the biological impact of these interactions on the human groups' make-up is not yet understood. The present work analyzes the biological affinities of different groups from both sides of these mountains that represent the Populations of the Middle- and Late-Neolithic by means of the dental morphology. METHODS: We present novel dental morphological data of 221 individuals from 11 archaeological sites. These data have been analyzed and compared to those from previously published twenty Iberian sites and one French site. Data were recovered following the ASUDAS protocol, and MMD biological measure was calculated between groups. RESULTS: Our results suggest that there were some differences between the analyzed populations. These differences were observed at each side of the Pyrenees, but also across them. Concretely, the coastal groups across the mountains show more affinities between each other than the inland groups. In addition, the differences between groups decreased by the end of the Neolithic. CONCLUSIONS: Therefore, our results indicate that the intense trade activities registered in the coastal area between both sides of the Pyrenees would have had the greatest biological impacts in the homogenisation of the groups. Although less intense, the across mountain network and coastal to mountain area trade networks to the south of Pyreneans, also influenced the biological make-up of the groups.

The human remains from Axlor (Dima, Biscay, northern Iberian Peninsula).

OBJECTIVES: We provide the description and comparative analysis of all the human fossil remains found at Axlor during the excavations carried out by J. M. de Barandiarán from 1967 to 1974: a cranial vault fragment and seven teeth, five of which likely belonged to the same individual, although two are currently lost. Our goal is to describe in detail all these human remains and discuss both their taxonomic attribution and their stratigraphic context. MATERIALS AND METHODS: We describe external and internal anatomy, and use classic and geometric morphometrics. The teeth from Axlor are compared to Neandertals, Upper Paleolithic, and recent modern humans. RESULTS: Two teeth (a left dm2 , a left di1 ) and the parietal fragment show morphological features consistent with a Neandertal classification, and were found in an undisturbed Mousterian context. The remaining three teeth (plus the two lost ones), initially classified as Neandertals, show morphological features and a general size that are more compatible with their classification as modern humans. DISCUSSION: A left parietal fragment (Level VIII) from a single probably adult Neandertal individual was recovered during the old excavations performed by Barandiarán. Additionally, two different Neandertal children lost deciduous teeth during the formations of levels V (left di1 ) and IV (right dm2 ). In addition, a modern human individual is represented by five remains (two currently lost) from a complex stratigraphic setting. Some of the morphological features of these remains suggest that they may represent one of the scarce examples of Upper Paleolithic modern human remains in the northern Iberian Peninsula, which should be confirmed by direct dating.

Prehistoric funerary complexity in northern Iberia studied by using dental morphology.

During the Neolithic Age and afterwards, several funerary practices coexisted in the northeast of the Iberian Peninsula from the Mediterranean to the Atlantic. According to archaeological data, there was a coexistence of sepulchral caves and megalithic monuments at the end of the Neolithic, following the dominance of open-air pit burials during the Middle Neolithic. The aim of this work is to analyze the biological relationships between individuals representing those cultures, based on their dental morphology - the first such attempt. This study presents data of 156 individuals from this period, and will allow elucidate the population dynamics including the role of migrations and other factors. The results indicate that there were no significant differences between the groups living in Atlantic and Mediterranean areas. Moreover, pairwise comparisons for each trait only show two significant results. This lack of differences could be related to trade activities between the two basins, which would contribute to individual exchanges between groups. Furthermore, according to biological affinities, trade activities along the Mediterranean Sea had a more marked influence over the Catalan populations than those from the Atlantic basin. There are no biological differences between groups representing the open-air pit culture and the sepulchral caves in each area. Finally, the megalithic groups from the Atlantic basin differ the most from the surrounding populations. This could be indicative of a slightly different biological origin of the people related to this culture.

A case of bilateral macrodontia of mandibular second premolars from a Chalcolithic context in the Iberian Peninsula.

Isolated macrodontia, consisting of the gigantism of a single tooth, is an extremely rare condition. Only 16 cases of isolated macrodontia of mandibular second premolars have been reported to date. Although the aetiology of this phenomenon remains unknown, many authors have related it to the control of the apoptotic process, leading to the patterning and size of dental cusps. There is not a clear genetic inheritance pattern since only two of those 16 cases correspond to close relatives. To our knowledge, there have been no reports of isolated macrodontia of mandibular second premolars in archaeological remains. Cova del Pantà de Foix site is a Chalcolithic sepulchral cave situated in the North-East of the Iberian Peninsula in which the remains of at least 30 individuals were recovered. Most of these individuals show several signs of environmental stressors. The current study presents the first case of isolated bilateral macrodontia of mandibular premolars from an archaeological context, corresponding to a young male individual discovered in this site. This condition could be the last consequence of environmental factors epigenetically affecting apoptosis processes in early tooth development and a possible genetic predisposition to show a shape-deviation in the dentition.