Changes in food processing and occlusal dental wear during the early agricultural period in northwest Mexico

Mandibular morphology and the Mesolithic-Neolithic transition in Westernmost Iberia

Neolithic farming and animal husbandry were first developed in the Near East ~ 10,000 BCE and expanded westwards, reaching westernmost Iberia no later than 5500 BCE. It resulted in major social, cultural, economic and dietary changes. Yet, the impact of this change on human mandibular morphology in Iberia is yet to be assessed, which is regrettable because mandible form is impacted by population history and diet. In this study we used Mesolithic to Chalcolithic Iberian samples to examine the impact of this transition on mandibular morphology. We also compared these samples with a Southern Levantine Chalcolithic population to assess their relationship. Lastly, we assessed dental wear to determine if the morphological differences identified were related to the material properties of the diet. We found differences between samples in mandibular shape but not size, which we attribute to contrasting population histories between Mesolithic and later populations. Some differences in the severity of dental wear were also found between Mesolithic and later Iberian samples, and smaller between the Mesolithic Iberians and southern Levantines. Little relationship was found between wear magnitude and mandibular shape. Altogether, our results show that the Mesolithic-Neolithic Iberian transition resulted in a meaningful change in mandibular morphology, which was likely driven more by population history than by dietary change.

Changes in dental wear magnitude in the last ∼8000 years in southwestern Iberia

OBJECTIVE

This study examines changes in dental wear magnitude in the past ∼8000 years, i.e., since Mesolithic until the 19th century, in southwestern Iberia. Thus, it encompasses the transition from hunting-gathering to agro-pastoralism, and then to the industrialization of food production and pre-processing.

DESIGN

Dental wear magnitude was scored in a total of 191 individuals and 1557 teeth from Mesolithic (individuals=56; teeth=643), Neolithic (individuals=35; teeth=169), Chalcolithic (individuals =35; teeth=221), Modern Age (individuals=17; teeth=209), and Late Modern Age (individuals=48; teeth=315) samples originating in southwestern Iberia (i.e., present central and southern Portugal) and according to the 8 levels ordinal scale of Smith (1984).

RESULTS

Results show a general trend for decreased wear magnitude in these two major transitions and during this timespan (although the hunting-gathering - agro-pastoralism transition had larger impact). The only meaningful differences in wear rate were found between the Late Modern Age and all remaining samples.

CONCLUSION

Dental wear generally decreased during this timespan (although wear magnitude was less impacted by the industrialization of food production and pre-processing). Our results are consistent with studies documenting skull morphological gracilization associated with reduced masticatory demands due to the adoption of softer diets.

Dental wear and oral pathology among sex determined Early Bronze-Age children from Franzhausen I, Lower Austria

The physical properties of diet and oral health throughout childhood play an important role in the development of human dentition, and differed greatly before the industrial revolution. In this study we examined dental wear and oral pathology in a sample of children from the Early Bronze-Age to investigate the physical and mechanical properties of childhood diet and related oral health. We explore cross-sectional age and sex-based variation of children in the sample. The analysis was carried out on the dentitions of 75 children, 978 teeth, excavated from the Early Bronze-Age cemetery Franzhausen I in Lower Austria. Presence of dental caries and calculus was recorded. Dental wear was measured using dentine exposure, occlusal topography, and dental microwear texture analysis. Sex determination was carried out using amelogenin peptide analysis. Caries were found in only 4 individuals (crude prevalence rate-5%, 95% CI 1% to 13%), affecting only 5 teeth (true prevalence rate-less than 1%). Dentine exposure was observed in over 70% of deciduous molars and dental wear measurements indicate a comparatively strong dental wear accumulation especially, among younger children, when compared to modern-day and later pre-industrial populations. Microwear textures presented a high complexity (Asfc > 2)/low anisotropy (epLsar < 1) profile, especially in older children. Differences between male and female children were not generally significant but increased dentine exposure was observed in the lower molars of younger female children. Our results suggest that the Early Bronze-Age children at Franzhausen I consumed a non-cariogenic diet, more abrasive and inclusive of harder/polyhedral foodstuffs than present-day children and some later Medieval children. Differences in dental wear accumulation were observed between children within the population, but with minimal variation between the sexes mostly occurring among younger children.

Testing the reliability of CT scan-based dental wear magnitude scoring

OBJECTIVES

Digital models are now frequently used in biological anthropology (bioanthropology) research. Despite several studies validating this type of research, none has examined if the assessment of dental wear magnitude based on Computerized Tomography (CT) scans is reliable. Thus, this study aims to fill this gap and assess if dental wear magnitude scoring based on CT scans provides results consistent with scoring based on direct observation of the physical specimens.

MATERIALS AND METHODS

Dental wear magnitude from 412 teeth of 35 mandibles originating from the Portuguese Muge and Sado Mesolithic shell-middens was scored. The mandibles were also CT scanned and visualized using 3D Slicer. CT scan-based scoring of dental wear magnitude was then undertaken. Two scoring rounds were undertaken for each observation method (totaling four scoring rounds) and an intra-observer error test was performed. The averaged results of the two observation methods were compared via boxplots with paired cases.

RESULTS

Intra-observer error was negligible and non-significant. Scoring results are comparable between the two observation methods. Notwithstanding, some differences were found, in which CT scan assessment generally overestimates dental wear when compared to direct observation.

DISCUSSION

Our results generally validate the use of CT scans in studies of dental wear magnitude. Notwithstanding several caveats relating to CT scanning and visualization limitations should be considered to avoid over or under-estimation of dental wear.

Dimorphism in dental tissues: Sex differences in archaeological individuals for multiple tooth types

OBJECTIVES

Dimorphism in the dentition has been observed in human populations worldwide. However, research has largely focused on traditional linear crown measurements. As imaging systems, such as micro-computed tomography (micro-CT), become increasingly more accessible, new dental measurements such as dental tissue size and proportions can be obtained. This research investigates the variation of dental tissues and proportions by sex in archaeological samples.

MATERIALS AND METHODS

Upper and lower first incisor to second premolar tooth rows were obtained from 30 individuals (n = 300), from 3 archaeological samples. The teeth were micro-CT scanned and surface area and volumetric measurements were obtained from the surface meshes extracted. Dental wear was also recorded and differences between sexes determined.

RESULTS

Enamel and crown measurements were found to be larger in females. Conversely, dentine and root measurements were larger in males.

DISCUSSION

The findings support the potential use of dental tissues to estimate sex of individuals from archaeological samples, while also indicating that individuals aged using current dental aging methods may be underaged or overaged due to sex differences in enamel thickness.

Dental microwear texture analysis of Homo sapiens sapiens: Foragers, farmers, and pastoralists

OBJECTIVES

The current study seeks to determine if a sample of foragers, farmers, and pastoralists are distinguishable based on their dental microwear texture signatures.

MATERIALS AND METHODS

The study included a sample of 719 individuals from 51 archeological sites (450 farmers, 192 foragers, 77 pastoralists). All were over age 12 and sexes were pooled. Using a Sensofar® white-light confocal profiler we collected dental microwear texture analysis (DMTA) data from a single first or second molar from each individual. We leveled and cleaned data clouds following standard procedures and analyzed the data with Sfrax® and Toothfrax® software. The DMTA variables were complexity and anisotropy. Statistics included ANOVA with partial eta squared and Hedges's g. We also performed a follow-up K-means cluster analysis.

RESULTS

We found significant differences between foragers and farmers and pastoralists for complexity and anisotropy, with foragers having greater complexity than either the farmers or the pastoralists. The farmers and pastoralists had greater anisotropy than the foragers. The Old World foragers had significantly higher anisotropy values than New World foragers. Old and New World farmers did not differ. Among the Old World farmers, those dating from the Neolithic through the Late Bronze Age had higher complexity values than those from the Iron Age through the medieval period. The cluster analysis discerned foragers and farmers but also indicated similarity between hard food foragers and hard food farmers.

DISCUSSION

Our findings reaffirm that DMTA is capable of distinguishing human diets. We found that foragers and farmers, in particular, differ in their microwear signatures across the globe. There are some exceptions, but nothing that would be unexpected given the range of human diets and food preparation techniques. This study indicates that in general DMTA is an efficacious means of paleodietary reconstruction in humans.

The physiological linkage between molar inclination and dental macrowear pattern

OBJECTIVES

Exact symmetry and perfect balance between opposite jaw halves, as well as between antagonistic teeth, is not frequently observed in natural masticatory systems. Research results show that asymmetry in our body, skull, and jaws is often related to genetic, epigenetic, environmental and individual ontogenetic factors. Our study aims to provide evidence for a significant link between masticatory asymmetry and occlusal contact between antagonist teeth by testing the hypothesis that tooth inclination is one of the mechanisms driving distribution of wear in masticatory phases in addition to dietary and cultural habits.

MATERIALS AND METHODS

The present work investigates the relationship between dental macrowear patterns and tooth inclinations on a sample of complete maxillary and mandibular 3D models of dental arches from 19 young and adult Yuendumu Aboriginal individuals. The analysis was carried out on first molars (M1) from all quadrants. Occlusal Fingerprint Analysis was used for the quantification of macrowear patterns, and 2D cross-sectional geometric analysis was carried out to investigate asymmetry in dental arches.

RESULTS

The asymmetry is highly variable on both arches, and it is associated with differences in the inclination of upper M1 crowns. Each molar has variable inclination (buccal/lingual) which influence tooth to tooth contact, producing greater or lesser variation in wear pattern. Interindividual variability of morphological variation of the occlusal relationship has to be considered in macrowear analysis.

DISCUSSION

Our results suggest that overall asymmetry in the masticatory apparatus in modern humans affects occlusal contact areas between antagonist teeth influencing macrowear and chewing efficiency during ontogeny.

Phenotypic variation of transitional forager-farmers in the Sonoran Desert

This study examines phenotypic variation and biological distances estimated using morphological traits from three Early Agricultural period (EAP) (2100 BC-AD 50) site-complexes in the Sonoran Desert of southern Arizona and northern Sonora. The hypothesis tested is that EAP forager-farmers were phenotypically homogenous as suggested by patterns in material culture and works to refine inferences regarding gene flow and biological affinity during subsistence transitions. Seven measurements from 62 EAP male and female crania were collected and used to calculate phenotypic variances, biological distances, and FST values with RMET 5.0 software. Analyses were applied to both pooled site-complex samples and to males and females separately. Results show differential variation between site-complex population samples, multiple significant biological distances, and significant FST values for the EAP regional sample that indicate widespread phenotypic heterogeneity rather than homogeneity. Significantly lower than expected variance in the Cienega Creek male sample is inferred to suggest a small closely related population present during the Cienega phase. Greater than expected male variation is attributed to higher frequencies of gene flow in the La Playa and Santa Cruz River site-complex samples. These EAP males are inferred to be more mobile across the Sonoran Desert landscape and representative of multiple biological affinities compared with females. This study provides evidence supporting the canalization of phenotypic variation when associated with human populations becoming increasingly sedentary due to transitioning subsistence practices.

Psychosocial aspects of bruxism: the most paramount factor influencing teeth grinding

In clinical practice, patients suffering from an occlusal parafunctional activity have increased. It can be observed that a negative influence of environment aggravates patient's health. The aim of this paper is to present the impact of environment and development of human civilization on the prevalence of bruxism and the correlation between them. The authors grasp the most relevant aspects of psychological and anthropological factors changing over time as well as their interactions and describe a relationship between chronic stress and bruxism. Current literature shows how contemporary lifestyle, working environment, diet, and habits influence the patient's psychoemotional situation and the way these factors affect the occluso-muscle condition.

Introduction of agriculture and its effects on women's oral health

This study explores the dynamic relationship between the introduction of agriculture and its effects on women's oral health by testing the hypothesis that female reproductive physiology contributes to an oral environment more susceptible to chronic oral disease and that, in a population undergoing the foraging to farming transition, females will exhibit a higher prevalence of oral pathology than males. This is tested by comparing the presence, location, and severity of caries lesions and antemortem tooth loss across groups of reproductive aged and postreproductive females (n = 71) against corresponding groups of males (n = 71) in an Early Agricultural period (1600 B.C.-A.D. 200) skeletal sample from northwest Mexico. Caries rates did not differ by sex across age groups in the sample; however, females were found to exhibit significantly more antemortem tooth loss than males (P > 0.01). Differences were initially minimal but increased by age cohort until postreproductive females experienced a considerable amount of tooth loss, during a life stage when the accumulation of bodily insults likely contributed to dental exfoliation. Higher caries rates in females are often cited as the result of gender differences and dietary disparities in agricultural communities. In an early farming community, with diets being relatively equal, women were found to experience similar caries expression but greater tooth loss. We believe this differential pattern of oral pathology provides new evidence in support of the interpretation that women's oral health is impacted by effects relating to reproductive biology.