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1. Patterns of heritability across the human diphyodont dental complex: Crown morphology of Australian twins and families

   https://doi.org/10.1002/ajpa.24019  

   Paul, Kathleen_S ; Stojanowski, Christopher_M ; Hughes, Toby_E ; Brook, Alan_H ; Townsend, Grant_C ( February 2020 , American Journal of Physical Anthropology)

   This study generates a series of narrow‐sense heritability estimates for crown morphology of the deciduous and permanent dentition with two overarching aims. The first is to test the hypothesis that deciduous teeth provide a more faithful reflection of genetic information than their permanent successors. The second is to use quantitative genetic methods to evaluate assumptions underlying common data collection and analysis practices in biodistance research.

   Dental morphology data were collected from longitudinal dental casts representing Australian twins and families using Arizona State Dental Anthropology System standards. Polygenic models and estimates of narrow‐sense heritability were generated using SOLAR v.8.1.1. Each model considered age, sex, and age/sex interaction as covariates.

   Heritability estimates significantly differed from zero for the majority of morphological crown characters. Most estimates fell within the 0.4–0.8 range typically observed for crown morphology. Mean heritability was stable across the dental complex, but for paired homologues, permanent traits often yielded higher estimates than their deciduous counterparts. Results indicate directional asymmetry in environmental influence for crown morphology and inform biodistance “best practices” related to data collection and treatment.

   Overall, results for this sample support the use of crown morphology as a proxy for genetic variation in evolutionary research. This includes the deciduous dentition, which justifies the expansion of efforts to incorporate subadults into reconstructions of past microevolutionary processes. Results do not indicate that deciduous phenotypes more closely approximate underlying genotype, at least for deciduous/permanent homologues.

    

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2. Sex and ancestry patterning of residual correlations in human dental development: Cooperative genetic interaction and phenotypic plasticity

   https://doi.org/10.1002/ajpa.24908  

   Sgheiza, Valerie ( February 2024 , American Journal of Biological Anthropology)

   Most research in human dental age estimation has focused on point estimates of age, and most research on dental development theories has focused on morphology or eruption. Correlations between developing teeth using ordinal staging have received less attention. The effect of demographic variables on these correlations is unknown. I tested the effect of reference sample demographic variables on the residual correlation matrix using the lens of cooperative genetic interaction (CGI).

   The sample consisted of Moorrees et al.,Journal of Dental Research, 1963, 42, 1490–1502, scores of left mandibular permanent teeth from panoramic radiographs of 880 London children 3–22.99 years of age stratified by year of age, sex, and Bangladeshi or European ancestry. A multivariate cumulative probit model was fit to each sex/ancestry group (n = 220), each sex or ancestry (n = 440), and all individuals (n = 880). Residual correlation matrices from nine reference sample configurations were compared using Bartlett's tests of between‐sample difference matrices against the identity matrix, hierarchical cluster analysis, and dendrogram cophenetic correlations.

   Bartlett's test results were inconclusive. Cluster analysis showed clustering by tooth class, position within class, and developmental timing. Clustering patterns and dendrogram correlations showed similarity by sex but not ancestry.

   Expectations of CGI were supported for developmental staging. This supports using CGI as a model for explaining patterns of variation within the dentition. Sex was found to produce consistent patterns of dental correlations, whereas ancestry did not. Clustering by timing of development supports phenotypic plasticity in the dentition and suggests shared environment over genetic ancestry to explain population differences.

    

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3. Quantitative genetic analyses of postcanine morphological crown variation

   https://doi.org/10.1002/ajpa.23778  

   Stojanowski, Christopher_M ; Paul, Kathleen_S ; Seidel, Andrew_C ; Duncan, William_N ; Guatelli‐Steinberg, Debbie ( February 2019 , American Journal of Physical Anthropology)

   This article presents estimates of narrow‐sense heritability and bivariate genetic correlation for 14 tooth crown morphological variants scored on permanent premolars, first molars, and second molars. The objective is to inform data collection and analytical practices in dental biodistance and to provide insights on the development of molar crowns as integrated structures.

   African American dental casts from the Menegaz‐Bock collection were recorded for the Arizona State University Dental Anthropology System. Estimates of narrow‐sense heritability and genetic correlation were generated using SOLAR v.8.1.1, which included assessment of age, sex, and birth year as covariates. Both continuous scale and dichotomized estimates are provided.

   Heritability estimates were nonsignificant for the majority of variables; however, for variables yielding significant estimates, values were moderate to high in magnitude and comparable to previous studies. Comparing left and right‐side heritability estimates suggests directional asymmetry in the expression of environmental variance, something not seen in anterior tooth traits. Genetic correlations were moderate among antimeres and metameres and low for different traits scored on the same tooth crown. Although several negative correlations were noted, few reached statistical significance. Results affirm some of the current data cleaning and analytical practices in dental biodistance, but others are called into question. These include the pooling of males and females and combining left and right‐side data into a single dataset.

   In comparison to anterior tooth crown traits, postcanine heritabilities were more often non‐significant; however, those traits with significant heritability also tended to produce higher estimates. Genetic correlations were unremarkable, in part, because they were underpowered. However, M1 results may provide insight into the complex relationship between genes, environment, and development in determining ultimate crown form.

    

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4. Pubertal timing and adolescent outcomes: investigating explanations for associations with a genetically informed design

   https://doi.org/10.1111/jcpp.13808  

   Padrutt, Emily R. ; Harper, Jeremy ; Schaefer, Jonathan D. ; Nelson, Kayla M. ; McGue, Matt ; Iacono, William G. ; Wilson, Sylia ( April 2023 , Journal of Child Psychology and Psychiatry)

   Psychopathology and risky behaviors increase during adolescence, and understanding which adolescents are most at risk informs prevention and intervention efforts. Pubertal timing relative to same‐sex, same‐age peers is a known correlate of adolescent outcomes among both boys and girls. However, it remains unclear whether this relation is better explained by a plausible causal process or unobserved familial liability.

   We extended previous research by examining associations between pubertal timing in early adolescence (age 14) and outcomes in later adolescence (age 17) in a community sample of 2,510 twins (49% boys, 51% girls).

   Earlier pubertal timing was associated with more substance use, risk behavior, internalizing and externalizing problems, and peer problems in later adolescence; these effects were small, consistent with previous literature. Follow‐up co‐twin control analyses indicated that within‐twin‐pair differences in pubertal timing were not associated with within‐twin‐pair differences in most adolescent outcomes after accounting for shared familial liability, suggesting that earlier pubertal timing and adolescent outcomes both reflect familial risk factors. Biometric models indicated that associations between earlier pubertal timing and negative adolescent outcomes were largely attributable to shared genetic liability.

   Although earlier pubertal timing was associated with negative adolescent outcomes, our results suggests that these associations did not appear to be caused by earlier pubertal timing but were likely caused by shared genetic influences.

    

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5. The intersections of industrialization: Variation in skeletal indicators of frailty by age, sex, and socioeconomic status in 18th‐ and 19th‐century England

   https://doi.org/10.1002/ajpa.23881  

   Yaussy, Samantha L. ( June 2019 , American Journal of Physical Anthropology)

   Intersectionality theory argues that various categories of identity and forms of systemic oppression interact and produce inequalities in resource access, economic opportunities, and health outcomes. However, there has been little explicit engagement with this theory by bioarchaeologists examining disparate health outcomes in the past. This study examines the associations among frailty, age at death, sex, and socioeconomic status (SES) in 18th‐ and 19th‐century England.

   The sample for this study comes from four industrial‐era cemeteries from England, ca. 1711–1857. The associations among adult age (18+ years), SES, sex, and three skeletal indicators of stress (dental enamel hypoplasia [DEH,n= 293], cribra orbitalia [CO,n= 457], periosteal lesions [PNB,n= 436]) are examined using hierarchical log‐linear analysis.

   Significant interactions existed among the variables examined for two skeletal indicators: high SES females had lower frequencies of CO relative to other groups and males between ages 30–45 years exhibited higher frequencies of PNB compared to females or males of older or younger ages, regardless of SES. Additionally, sex and SES were consistently associated with age at death.

   These results suggest that patterns of stress indicators cannot be examined solely across unilateral axes of age, SES, or sex. Intersecting axes of privilege, marginalization, and structural oppression may have buffered high SES females from some negative health outcomes (CO) while predisposing them to others (risk of maternal mortality). Likewise, the hazardous working conditions relegated to adult males may have heightened the risk of injury, infection, and death for middle‐aged men in industrial‐era England.

    

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