Three decades after the publication of the Lamendin method for adult age-at-death estimation: Methodological evolution of the procedure and interpretations.

More than three decades have passed since the publication of Lamendin et al.'s proposal in 1992. Over this time, numerous investigations have been conducted to assess the applicability of the technique in different populations with acceptable results in terms of estimation errors. The proposal by Lamendin and colleagues remains relevant today, and has made a significant contribution to adult age-at-death estimation due to its simplicity, repeatability, replicability, and high performance. Indeed, significant progress towards systematizing and strengthening the procedure has been reported in the published literature. One noteworthy advancement is the development of an international database that supports the use of Bayesian statistics for age-at-death estimation. This resource plays a crucial role in standardizing the methodology and improving the reliability for obtaining more reliable results on a global scale. The aim of this study is to investigate the historical evolution of the technique, to assess the accuracy of the results obtained by different analytic procedures, and to explore its impact in forensic applications through a systematic analysis of the specialized literature on this field. The current state of research indicates that this type of methodological research is an ongoing process, far from being completed. Many questions and challenges that require further attention to address effectively these issues remain unanswered, such as the development of non-linear regressions and probabilistic approaches, the deepening of procedures that improve global approximations, and the intensification of research focused on achieving more accurate estimations among individuals over 70 years-old. However, studies generally agree that the Lamendin technique works well for individuals between the ages of 30-60 years. It is still in force today, although the method has been significantly perfected. Despite the degree of research development in this area, further efforts are needed to improve the understanding and performance of these kinds of procedures. This will ultimately lead to an improvement in the accuracy and reliability of forensic investigation results worldwide.

Evaluación métrica de caninos permanentes para la estimación sexual en la Colección “Prof. Dr. Rómulo Lambre”, Buenos Aires, Argentina / Metric evaluation of permanent canines for sexual estimation in the Collection “Prof. Dr. Romulo Lambre”, Buenos Aires, Argentina

Introducción la estimación del sexo es un aspecto fundamental de la labor forense, ya que constituye un paso obligatorio para la identificación de restos humanos de procedencia desconocida. El análisis metodológico de la dentición como estimador sexual reviste importancia debido al elevado grado de preservación de los dientes. Considerando la necesidad de contar con información concreta respecto del potencial de la dentición en la estimación del sexo en casos locales de Argentina, el objetivo del presente estudio es evaluar la propuesta previamente desarrollada por Luna (2019) en una muestra local de restos esqueléticos humanos. Materiales y métodos se seleccionó una muestra de 152 caninos permanentes pertenecientes a 98 individuos de ambos sexos que forman parte de la colección osteológica Profesor Dr. Rómulo Lambre (La Plata, Argentina). Posteriormente se aplicó la propuesta de Luna (2019) para la estimación del sexo a partir de la métrica de la corona y del cuello de los caninos, la cual considera las medidas directas y los diferentes tipos de funciones discriminantes y regresiones logísticas. Resultados de las medidas directas consideradas, solo el diámetro mesiodistal cervical ofreció resultados aceptables (>75%) para la estimación sexual. Asimismo, únicamente la función discriminante 1 presentó probabilidades a posteriori de clasificaciones correctas superiores a 0,75 y las regresiones logísticas 1 y 3 exhibieron resultados generales satisfactorios. Conclusiones esta propuesta basada en el estudio métrico de caninos permanentes constituye una alternativa metodológica adecuada en situaciones en las cuales los elementos óseos diagnósticos del sexo se encuentran deteriorados o ausentes. (AU)

Introduction Sex estimation is a fundamental aspect of forensic work as a mandatory step for the identification of human remains of unknown origin. The methodological analysis of the dentition as a sexual estimator is important due to its high degree of preservation. Considering the need for specific information regarding the potential of dentition for sex estimation in forensic cases from Argentina, the aim of this study is to evaluate the proposal previously developed by Luna (2019) in a local sample of human skeletal remains. Materials and methods A sample of 152 permanent canines belonging to 98 individuals of both sexes was selected- The individuals belong to the Prof. Dr. Rómulo Lambre osteological collection (La Plata, Argentina). Luna's proposal (2019) was applied to estimate sex from canine crown and neck metrics, which considers direct measurements and different types of discriminant functions and logistic regressions. Results Only the cervical mesiodistal diameter showed acceptable results (>75%) for sex estimation. Moreover, discriminant function 1 showed a posteriori probabilities of correct classifications greater than 0.75 and logistic regressions 1 and 3 offered acceptable overall results. Conclusions This proposal based on the metric recording of permanent canines constitutes an adequate methodological alternative in situations in which the diagnostic bone elements of sex are deteriorated or absent. (AU)

A tooth crown morphology framework for interpreting the diversity of primate dentitions.

Variation in tooth crown morphology plays a crucial role in species diagnoses, phylogenetic inference, and the reconstruction of the evolutionary history of the primate clade. While a growing number of studies have identified developmental mechanisms linked to tooth size and cusp patterning in mammalian crown morphology, it is unclear (1) to what degree these are applicable across primates and (2) which additional developmental mechanisms should be recognized as playing important roles in odontogenesis. From detailed observations of lower molar enamel-dentine junction morphology from taxa representing the major primate clades, we outline multiple phylogenetic and developmental components responsible for crown patterning, and formulate a tooth crown morphology framework for the holistic interpretation of primate crown morphology. We suggest that adopting this framework is crucial for the characterization of tooth morphology in studies of dental development, discrete trait analysis, and systematics.

Canine Crown Sexual Dimorphism in a Sample of the Modern Croatian Population.

Sex assessment is a key part of forensic analysis to establish the identity of unknown deceased individuals. Previous studies have shown that canines are the most dimorphic teeth, but population-specific data are necessary for forensic methods. This study explores sex dimorphism in canine crown dimensions and morphology in a contemporary Croatian population. The material consisted of 302 dental casts (147 females, 155 males) of orthodontic patients and dental students (11-25 years). The distal accessory ridge (DAR) of the upper and lower canines was evaluated using the Arizona State University Dental Anthropology System. Mesiodistal (MD) and buccolingual (BL) crown dimensions were measured on 120 casts. Sex differences in MD and BL dimensions were significant (p < 0.05) for all the canines (upper and lower, left and right), while in DAR only for lower canines (p < 0.000001). When all variables were put into the model, backward stepwise discriminant function analysis isolated lower canine DAR and lower left canine MD as the two independent variables differentiating sex. Using these two variables, a discriminant function formula allowed for sex determination with an accuracy of 73.5%. This study shows that both canine crown morphology and dimensions are useful for sex determination, especially for lower canines. These methods can be applied to children, as lower canines erupt at about 9 years of age.

Root dentin translucency and age at death estimation in adults using single rooted teeth: Update of the Forensic International Dental Database.

Since the publication of Lamendin's age estimation technique, the root dentin translucency has received increasing attention as an important indicator of age. Recently, Parra and colleagues presented the Forensic International Dental Database (FIDB), a proposal to estimate age at death in adults based on Bayes theorem by applying the criteria of Lamendin's technique. The present study aims to update the procedure and to evaluate a new version of the method (named FIDBv2) using two control samples from Colombia and Greece. The performance of this new version was acceptable and suggests that the method is suitable for age at death estimation in adult individuals from different forensic contexts. The best approximations to chronological age were obtained for individuals between 30 and 60 years old, with errors less than 10 years. The age estimations calculated on control samples suggest the adequate performance of FIDBv2 on individuals from varied populations. It can be stated that the FIDBv2 constitutes a solid alternative to be used in contexts where no additional data are available. Here we reinforce the initial idea that this model for estimating age at death in adults may be generalizable to any forensic context in the world.

Primate tooth crown nomenclature revisited.

Cusp patterning on living and extinct primate molar teeth plays a crucial role in species diagnoses, phylogenetic inference, and the reconstruction of the evolutionary history of the primate clade. These studies rely on a system of nomenclature that can accurately identify and distinguish between the various structures of the crown surface. However, studies at the enamel-dentine junction (EDJ) of some primate taxa have demonstrated a greater degree of cusp variation and expression at the crown surface than current systems of nomenclature allow. In this study, we review the current nomenclature and its applicability across all the major primate clades based on investigations of mandibular crown morphology at the enamel-dentine junction revealed through microtomography. From these observations, we reveal numerous new patterns of lower molar accessory cusp expression in primates. We highlight numerous discrepancies between the expected patterns of variation inferred from the current academic literature, and the new patterns of expected variation seen in this study. Based on the current issues associated with the crown nomenclature, and an incomplete understanding of the precise developmental processes associated with each individual crown feature, we introduce these structures within a conservative, non-homologous naming scheme that focuses on simple location-based categorisations. Until there is a better insight into the developmental and phylogenetic origin of these crown features, these categorisations are the most practical way of addressing these structures. Until then, we also suggest the cautious use of accessory cusps for studies of taxonomy and phylogeny.

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.

Evaluation of Twenty Non-Metric Dental Crown Traits in Different Types of Malocclusions in a Sample from India, New Delhi Population.

Background: Dental phenotype shows variation in the form of various metric and non-metric traits, primarily due to gene-environment interplay. It gives an insight into the evolutionary trends, ancestry, and food habits. Recently, it has been explored for genetic affinity with several growth anomalies and development of craniofacial skeleton which is also responsible for dental and skeletal malocclusions. Objectives: the current study aims to investigate the non-metric dental crown traits (NDCTs) using Arizona State University Dental Anthropology system (ASUDAS) in different types of malocclusions in Delhi, National Capital Region (NCR) population. Materials and methods: The study design was observational and retrospective. The total sample comprised of 240 pairs of dental casts divided into four equal groups of 60 subjects each (30 male and 30 female), based on malocclusion. The four groups of malocclusions were: Angle's Class I, Class II division 1, Class II division 2, Class III. The investigator was blinded for patient ID and sex before recording the data. The data for cast were recorded by three observers independently in a modified malocclusion- non-metric dental crown traits (M-NDCT) anthropological variants chart and statistically analyzed for association with different malocclusions and sex. Results: Significant differences were found in the expression of several NDCTs (both in presence and scoring) in different malocclusions. Class I malocclusion showed a predominantly winging, shoveling -upper central and lateral incisor, protostylid, hypoconulid absence in lower second molar, and cusp number. Class II malocclusion showed a double shoveling, interrupted groove, tuberculum dentale, canine mesial ridge, premolar accessory cusp, Carabelli's trait, lingual cusp variation, and seventh cusp in the lower left first molar. Class III malocclusion showed the absence of hypocone in upper second molar, deflecting wrinkle, distal trigonid crest, and Y groove in left lower second molar (26.7%). Besides, sexual dimorphism was seen in shoveling -upper central and lateral incisor, canine mesial ridge, Carabelli's trait, 3-cusp in upper second molar, and cusp number. Conclusions: Significant association was found between non-metric dental traits and malocclusions (Class I, Class division 1, Class II division 2, and Class III). Significant sex-linked differences were also found. Further studies can be performed at multicenter pan-India level with a standard robust protocol and a large sample.

Patterns of variation in canal and root number in human post-canine teeth.

Descriptive morphology of tooth roots traditionally focuses on number of canals and roots. However, how or if canal and root number are related is poorly understood. While it is often assumed that canal number is concomitant with root number and morphology, in practice canal number and morphology do not always covary with external root features. To investigate the relationship between canal and root number, fully developed, adult post-canine teeth were examined and quantified from computerized tomography scans from a global sample of 945 modern humans. We tested the hypotheses that root and canal number do not follow a 1:1 ratio, that canal to root ratios differ between teeth, and that canal to root ratios differ across major human geographical groups. Results indicate that not only is root number dependent on canal number, but that this relationship becomes more variable as canal number increases, varies between individual teeth and by major geographical group, and changes as these groups increase in geographical distance from Sub-Saharan Africa. These results show that the ratio of canal number to root number is an important indicator of variation in dental phenotypes.

Comparison of the Gonial Angle With Age and Gender Using Cone-Beam Computed Tomography Images.

Introduction The mandible is one of the most important bones used in gender determination in forensic medicine and anthropology. In literature, there are many studies examining the relationship between the gonial angle on the mandible and gender. However, these studies reported different results. This study aimed to measure the gonial angle with cone-beam computed tomography (CBCT) images and investigate the relation of this angle with age and gender. Materials and methods CBCT images of 235 dentate individuals (111 males and 124 females) aged between seven and 77 years were evaluated. The individuals examined were categorized into four age groups: 7-19 years (group I), 20-39 years (group II), 40-59 years (group III), and 60-77 years (group IV). The gonial angle was measured bilaterally in all individuals. Results The mean age of the males was 41.70 ± 19.14, and the mean age of the females was 39.47 ± 17.90 years. There was no statistically significant difference between the ages based on gender (p = 0.356). It was observed that there was a statistical difference between the gonial angle and gender in groups II and III. There was no correlation between age and gonial angle in all groups. Conclusion The results obtained in this study and the comparison of these results with the literature clearly show that it is currently not possible to clearly express the relationship between the gonial angle and both age and gender. For this reason, we believe that conducting further studies evaluating both the gonial angle and the relationship between the gonial angle and other anatomical structures on a larger sample can yield more meaningful results.

Dental anthropological report: Exploring plant-based treatments through the analysis of dental calculus and sediment of dental caries in a woman from the Late Preceramic period, Peru.

Reconstructing plant-based healing treatments of past societies from a dental anthropological perspective is still challenging due to a wide range of plant species, many with both medicinal and nutritional properties, and limitations on plant-taxa identification. Starch grains and phytoliths retrieved in samples from dental calculus and sediment contained in the cavity of dental caries were examined to investigate the supply of a plant-based treatment in an individual buried in the Late Preceramic site of Huaca El Paraíso (2100-1500 BCE), whose osteological analysis reported the absence of any pathological condition at a bone tissue level. A variety of starch grains such as pumpkins, manioc, maize, and beans had an important role in the diet of the individual. The starch grains were embedded in their dental calculus, all of which, except for manioc, showed signs of cooking damage. Considering the context and characteristics of the crops, the nutritional properties of maize, pumpkins and beans are evident. However, parallel medicinal properties of manioc and maize could not be entirely denied. Phytoliths morphologically ascribed to the Asteraceae plant family, which suggest the consumption of medicinal plants of Andean vernacular use, were retrieved in the sediment of dental caries. Our results prove that the analysis of sediment obtained from dental caries is as valuable in tracing medicinal plant-based treatments as dental calculus in archaeological populations. There are still several limitations to approach this topic in dental anthropology, which are discussed in this report. The performance of both analyses -dental calculus and sediment of dental caries, is highly recommended.

Morphometric analysis of three-rooted mandibular first molars in a Slovene population: a macroscopic and cone-beam computed tomography analysis.

BACKGROUND: This study examined the root morphology of mandibular first molars (MFMs) with radix entomolaris (RE), which presents diagnostic and therapeutic challenges for clinicians. MATERIALS AND METHODS: A total of 17 three-rooted MFMs were taken from a collection of extracted teeth. Root lengths and levels of furcations were measured with a digital calliper. The pulp floor configuration, root canal systems, and RE canal curvatures were evaluated using the cone-beam computed tomography scans. RESULTS: Radix entomolaris was either located disto-lingually, with its coronal portion fixed to the distal root (n = 16) or mid-lingually (n = 1). A literature search identified four additional cases of MFMs with RE located mid-lingually. In the present study, RE was significantly (p ≤ 0.001) shorter than the distal root (DR) and the mesial root, on average by 2.04 mm and 3.15 mm, respectively. The level of the distal furcation was significantly (p = 0.003) lower than that of the mesiodistal furcation, on average by 1.39 mm. The average divergence angle formed by the cervical portions of the RE and DR canals was 53.14°. All RE canals were severely curved (> 25°) in buccolingual direction. The RE orifice was located slightly disto-lingually to considerably mesio-lingually from the DR orifice. CONCLUSIONS: The traditional assumption of a disto-lingually located RE needs to be changed, even though this is the most prevalently found variant of this anatomy. The additional variant includes the presence of a mid-lingually located RE, which has implications for the endodontic access cavity design.

Occlusal polygon area of the molars in six Colombian ethnic groups / Área del polígono oclusal de molares en seis grupos étnicos de Colombia

SUMMARY: Descriptive observational cross-sectional study to determine the AOP of the second molars (55, 65, 75, 85) and the first permanent molars (16, 26, 36 and 46) in 459 study models corresponding to six ethnic groups in Colombia, Embera indigenous of Alto Baudó (Chocó), Caucasoid mestizos of Cali (Valle del Cauca), African descent of Cali (Valle del Cauca), Misak indigenous of Silvia (Cauca), Nasa indigenous of Morales (Cauca), and indigenous of Leticia (Amazonas). There were no significant differences of AOP among the six ethnic groups except when compared to the Amazon Indians with African descent of Cali, Embera indigenous and Nasa indigenous. There was no sexual dimorphism except tooth 65 for all ethnic groups. There was bilateral symmetry except between teeth 16 and 26. The distance matrix showed that Caucasoid mestizos of Cali were grouped with microdont populations, Amazon indigenous, Embera indigenous, Misak indigenous and Nasa indigenous, and African descendants of Cali were grouped with mesodont populations. The Embera and Amazon indigenous had the highest values of OAP associated with the relative isolation and less mestizaje. Overall, there was no sexual dimorphism or bilateral asymmetry. This study coincides with the different theories about reducing the size of the teeth as evolutionary characteristic of hominids.

RESUMEN: Estudio observacional descriptivo de corte transversal en el que se determinó el APO de los segundos molars deciduos (55, 65, 75, 85) y de los primeros molares permanentes (16, 26, 36, 46) en 459 modelos de estudio correspondientes a seis grupos étnicos de Colombia: Indígenas embera del Alto Baudó (Chocó), mestizos caucasoides de Cali (Valle del Cauca), afrodescendientes de Cali (Valle del Cauca), indígenas misak de Silvia (Cauca), indígenas nasa de Morales (Cauca) e indígenas de Leticia (Amazonas). No se encontraron diferencias significativas en el APO de los seis grupos étnicos, excepto entre indígenas del Amazonas y de afrodescendientes de Cali, e indígenas embera e indígenas nasa. No se evidenció dimorfismo exual en ninguno de los seis grupos. Hubo simetría bilateral, excepto entre los dientes 16 y 26. La matriz de distancias demostró que los mestizos caucasoides de Cali se agrupan con poblaciones microdontes, indígenas del amazonas, indígenas embera, indígenas misak e indígenas nasa; mientras que los afrodescendientes de Cali se agrupan con poblaciones mesodentes. Los indígenas embera y del Amazonas presentaron altos valores del APO, asociado a su aislamiento relativo y bajo mestizaje. En términos generales, no hubo dimorfismo sexual ni asimetría bilateral. Los resultados de este estudio concuerdan con diferentes teorías sobre la reducción del tamaño dental como una característica evolutiva de los himínidos.

Dental markers of biocultural sex differences in an early modern population from Gothenburg, Sweden: caries and other oral pathologies.

BACKGROUND: With the aim to study dental pathological lesions in an early Swedish modern population, with special reference to sex variances of dental caries, the prevalence and distribution of dental caries and tooth wear were determined in complete and partial human dentitions from an early modern-time city graveyard (1500-1620) excavated in Gamlestaden, Gothenburg, Sweden. METHODS: Partial and complete dentitions were examined through visual inspection and using a dental probe. Pathologies were studied, evaluated and presented by teeth and alveoli. RESULTS: The study population consisted of 308 individuals. A total of 4,951 teeth in adults and 1,660 teeth in children were examined. Caries prevalence in the studied population was 55% and the highest prevalence of caries was found among the adults, where 68% of the individuals had at least one carious lesion. Caries experience (DMT > 0) in the entire population was 60%, and among adults caries experience was 76%. Women had significantly higher caries experience than men (p < 0.05). Caries was most prevalent in the molar teeth and least prevalent in the incisors and canines. Significant age-related increases in tooth wear were found, and a positive correlation between wear in molars and incisors (p < 0.001). Other clinical findings were signs of apical lesions, crowding of teeth, aplasia, non-erupted canines and calculus. CONCLUSIONS: Findings show that dental pathological lesions affected a majority of the studied population, and indicate that women were more predisposed to dental disease than their male counterparts. Results are discussed from a multi-factorial explanation model including dietary, physiological and cultural etiological factors.

Implicación clínica del protostílido: una mirada desde la antropología dental y la odontología no invasiva / Clinical implication of protostlylid: a point of view from dental anthropology and non-invasive dentistry

RESUMEN De acuerdo al modelo patológico multifactorial, la morfología dental ha sido asociada como uno de los factores etiológicos de la caries al favorecer el acumulo de restos alimenticios y la retención de biopelícula. Uno de los rasgos morfológicos dentales más frecuentes de la población colombiana es el punto P del protostílido, el cual se constituye en una fosa que se expresa en el surco de desarrollo vestibulomesial de los molares inferiores, región que le sigue a la superficie oclusal como uno de los sitios en donde se desarrollan con más frecuencia lesiones cariosas. Sin embargo, el desconocimiento de este rasgo morfológico por la mayoría de los odontólogos hace que el sistema morfológico del protostílido sea mal diagnosticado, lo que conlleva en muchos casos al sobretratamiento de dicha fosa con terapéuticas invasivas, las cuales, podrían ser evitadas con un conocimiento adecuado de la morfología dental y con un manejo preventivo o con técnicas no invasivas. Por tanto, el objetivo de esta revisión de tema es reconocer la expresión del punto P del protostílido y realizar una aproximación a las implicaciones clínicas del mismo y las posibilidades diagnósticas y terapéuticas conservadores que ofrece la odontología para controlar el acumulo de restos alimenticios y la retención de biopelícula.

ABSTRACT According to the multifactorial pathological model, dental morphology has been associated as one of the etiological factors of caries by favoring the accumulation of food remains and biofilm retention. One of the most frequent of non-metric dental traits of the Colombian population is the P point of the protostylid, which is constituted in a fossa that is expressed in the bucomesial development groove of the lower molars, a region that follows the occlusal surface as one of sites where carious lesions develop more frequently. However, the lack of knowledge of this morphological feature by most dentists makes the morphological system of the protostylid misdiagnosed, which in many cases leads to the overtreatment of this pit with invasive therapies, which could be avoided with a knowledge adequate dental morphology and with a preventive management or non-invasive techniques. Therefore, the aim of this review of the subject is to reconcile the expression of the P point of the protostylid and to make an approximation to the clinical implications of the same and the conservative diagnostic and therapeutic possibilities offered by dentistry to control the accumulation of food rests and retention of dental biofilm.

Tooth Enamel and its Dynamic Protein Matrix.

Tooth enamel is the outer covering of tooth crowns, the hardest material in the mammalian body, yet fracture resistant. The extremely high content of 95 wt% calcium phosphate in healthy adult teeth is achieved through mineralization of a proteinaceous matrix that changes in abundance and composition. Enamel-specific proteins and proteases are known to be critical for proper enamel formation. Recent proteomics analyses revealed many other proteins with their roles in enamel formation yet to be unraveled. Although the exact protein composition of healthy tooth enamel is still unknown, it is apparent that compromised enamel deviates in amount and composition of its organic material. Why these differences affect both the mineralization process before tooth eruption and the properties of erupted teeth will become apparent as proteomics protocols are adjusted to the variability between species, tooth size, sample size and ephemeral organic content of forming teeth. This review summarizes the current knowledge and published proteomics data of healthy and diseased tooth enamel, including advancements in forensic applications and disease models in animals. A summary and discussion of the status quo highlights how recent proteomics findings advance our understating of the complexity and temporal changes of extracellular matrix composition during tooth enamel formation.

Do dental nonmetric traits actually work as proxies for neutral genomic data? Some answers from continental- and global-level analyses.

OBJECTIVES: Crown and root traits, like those in the Arizona State University Dental Anthropology System (ASUDAS), are seemingly useful as genetic proxies. However, recent studies report mixed results concerning their heritability, and ability to assess variation to the level of genomic data. The aim is to test further if such traits can approximate genetic relatedness, among continental and global samples. MATERIALS AND METHODS: First, for 12 African populations, Mantel correlations were calculated between mean measure of divergence (MMD) distances from up to 36 ASUDAS traits, and FST distances from >350,000 single nucleotide polymorphisms (SNPs) among matched dental and genetic samples. Second, among 32 global samples, MMD and FST distances were again compared. Correlations were also calculated between them and inter-sample geographic distances to further evaluate correspondence. RESULTS: A close ASUDAS/SNP association, based on MMD and F ST correlations, is evident, with r m -values between .72 globally and .84 in Africa. The same is true concerning their association with geographic distances, from .68 for a 36-trait African MMD to .77 for F ST globally; one exception is F ST and African geographic distances, r m = 0.49. Partial MMD/F ST correlations controlling for geographic distances are strong for Africa (.78) and moderate globally (.4). DISCUSSION: Relative to prior studies, MMD/F ST correlations imply greater dental and genetic correspondence; for studies allowing direct comparison, the present correlations are markedly stronger. The implication is that ASUDAS traits are reliable proxies for genetic data-a positive conclusion, meaning they can be used with or instead of genomic markers when the latter are unavailable.

Insights on patterns of developmental disturbances from the analysis of linear enamel hypoplasia in a Neolithic sample from Liguria (northwestern Italy).

OBJECTIVE: To assess developmental disturbances through the analysis of linear enamel hypoplasia (LEH) frequency and to infer environmental stress and life history within Neolithic communities from Liguria (Italy). MATERIALS: 43 unworn/minimally worn permanent anterior teeth of 13 individuals recovered from nearby caves and dated to c. 4800-4400 cal. BCE. METHODS: LEH defects were identified with high-resolution macrophotos of dental replicas, age at LEH was calculated via perikymata counts. LEH defects matched between two or more teeth were considered as systemic disturbances. LEH frequency by age classes was analyzed via GLZ and Friedman ANOVA. RESULTS: Number of matched defects per individual range between 2-12. The mean LEH per individual was highest in the 2.5-2.99 age category, with a significant increase relative to earlier growth stages, followed by a decline. CONCLUSION: LEH may reflect life-history in the local ecology of Neolithic Liguria, where several individuals with osteoarticular tuberculosis have been recorded. Disease burden may have triggered developmental disturbances around the time of weaning. Age at first defect was negatively correlated with age at death and positively with the total number of defects, suggesting that early stress may have affected survivorship. SIGNIFICANCE: The study contributes to the reconstruction of ecological pressures among Neolithic people of Liguria, and informs on environmental challenges during the Neolithic adaptive expansion. LIMITATIONS: The visual examination of macrophotos is prone to observer error; mid-crown tends to display more visible LEH due to tooth architecture. SUGGESTIONS FOR FURTHER RESEARCH: Apply different quantitative methods to examine severity and duration of disturbances.

Rare dental trait provides morphological evidence of archaic introgression in Asian fossil record.

The recently described Denisovan hemimandible from Xiahe, China [F. Chen et al., (2019) Nature 569, 409-412], possesses an unusual dental feature: a 3-rooted lower second molar. A survey of the clinical and bioarchaeological literature demonstrates that the 3-rooted lower molar is rare (less than 3.5% occurrence) in non-Asian Homo sapiens In contrast, its presence in Asian-derived populations can exceed 40% in China and the New World. It has long been thought that the prevalence of 3-rooted lower molars in Asia is a relatively late acquisition occurring well after the origin and dispersal of H. sapiens However, the presence of a 3-rooted lower second molar in this 160,000-y-old fossil hominin suggests greater antiquity for the trait. Importantly, it also provides morphological evidence of a strong link between archaic and recent Asian H. sapiens populations. This link provides compelling evidence that modern Asian lineages acquired the 3-rooted lower molar via introgression from Denisovans.

Oral health and diet of a young Late Pleistocene woman from Quintana Roo, Mexico.

OBJECTIVES: To increase understanding of the subsistence practices of the first Americans through analysis of the near-complete dentition of a young woman dating to the terminal Pleistocene of the Yucatan Peninsula, Mexico. MATERIALS AND METHODS: The skeleton is that of "Naia" a 15 to 17-year-old female from the submerged natural trap of Hoyo Negro found in association with remains of numerous extinct species of megafauna. Superbly preserved remains included the skull with 28 teeth, which are analyzed for evidence of caries, periodontal disease, wear patterns, and malocclusion. RESULTS: Naia exhibits a high frequency of dental caries, along with aggressive periodontal disease that threatened all her teeth, particularly her incisors. Dental attrition was extremely light for a hunter-gatherer, reaching to four on the Molnar scale on only one tooth. Lack of wear is associated with severe mandibular retrognathia, and low masticatory forces. DISCUSSION: Naia's dental condition is compared with that of other northern Paleoamericans, mostly females, dating before 11,000 cal BP. These exhibit a high degree of variability in both caries and tooth wear. All, however, exhibit rapid anterior wear owing to technological use of the front teeth. Naia exhibits the highest rate of caries, similar to that of the earliest South Americans, and one of the lowest rates of attrition. This demonstrates that she had a nonabrasive diet that was at least seasonally rich in carbohydrates. This does not mean her diet was low in meat, however, because similarly light dental attrition is seen in the Arch Lake female, a Paleoamerican from a big-game hunting society.