Model of Tooth Morphogenesis Predicts Carabelli Cusp Expression, Size, and Symmetry in Humans

The patterning cascade model of tooth morphogenesis accounts for shape development through the interaction of a small number of genes. In the model, gene expression both directs development and is controlled by the shape of developing teeth. Enamel knots (zones of nonproliferating epithelium) mark the future sites of cusps. In order to form, a new enamel knot must escape the inhibitory fields surrounding other enamel knots before crown components become spatially fixed as morphogenesis ceases. Because cusp location on a fully formed tooth reflects enamel knot placement and tooth size is limited by the cessation of morphogenesis, the model predicts that cusp expression varies with intercusp spacing relative to tooth size. Although previous studies in humans have supported the model's implications, here we directly test the model's predictions for the expression, size, and symmetry of Carabelli cusp, a variation present in many human populations.In a dental cast sample of upper first molars (M1s) (187 rights, 189 lefts, and 185 antimeric pairs), we measured tooth area and intercusp distances with a Hirox digital microscope. We assessed Carabelli expression quantitatively as an area in a subsample and qualitatively using two typological schemes in the full sample. As predicted, low relative intercusp distance is associated with Carabelli expression in both right and left samples using either qualitative or quantitative measures. Furthermore, asymmetry in Carabelli area is associated with asymmetry in relative intercusp spacing.These findings support the model's predictions for Carabelli cusp expression both across and within individuals. By comparing right-left pairs of the same individual, our data show that small variations in developmental timing or spacing of enamel knots can influence cusp pattern independently of genotype. Our findings suggest that during evolution new cusps may first appear as a result of small changes in the spacing of enamel knots relative to crown size

The Interrelationship of Status and Health in the Tellico Reservoir: A Biocultural Analysis

Anthropologists have been interested in the interaction of health and status in prehistoric populations for many years. Utilizing a biocultural perspective, this paper will investigate how social stratification affected health at sites from the Tellico Reservoir in eastern Tennessee. These sites, Citico (40MR7), Toqua (40MR6), and Tomotley (40MR5), were occupied in the late Mississippian period in Tennessee, during the Dallas phase (A.D. 1300-1600) (Schroedl, 1998). Skeletal indicators of stress were used to determine the health of the people interred at the three sites, and burial location was utilized to establish the status of these people. Intra-site and inter-site analyses were conducted on the data collected from 649 skeletal remains from the three sites. The intra-site analysis compared the occurrence of stress markers between mound burials and village burials at Citico and at Toqua, while the inter-site analysis compared stress indicator incidence between the two mounds, among the three villages, and between combined mound data and combined village data. A comparison of stress marker occurrence was also performed between males and females to determine whether gender differences affected the amount of stress endured. The determination of status was another area of focus for this paper. Analyses were conducted in order to ascertain whether classes of burial goods based on raw material were correlated in any manner with the stress indicators. Positive and negative correlations could then be used to establish the status of an individual. Correlation tests were also used to analyze the association between periostitis and anemia. The two are thought to have a synergistic relationship, in which the presence of one stress increases the susceptibility to the other stress. The results of these various analyses indicate that there are differences in the incidence of stress markers based on status; individuals buried in mounds were less affected than individuals buried in villages. This outcome is probably due to differential distribution of food. Individuals in the Toqua mound were more stressed than those in the Citico mound, which may be the result of population size, and, therefore, food availability. Toqua village had the most stress of the three villages, which is possibly a function of political structure and food distribution. The results of the gender analysis suggest that both females and males were comparably stressed. The correlation tests reveal that no significant relationship exists between stress markers and the classes of burial goods. As a result, the class of burial goods based on raw material cannot be used to determine the status of an individual. Finally, the correlation tests indicate that there is, indeed, a synergistic relationship between anemia and periostitis

Post-Cranial Traumatic Injury Patterns in Two Medieval Polish Populations: The Effects of Lifestyle Differences.

Traumatic injuries can be used as general indicators of activity patterns in past populations. This study tests the hypothesis that contemporaneous (10th-12th century) rural and urban populations in medieval Poland will have a significantly different prevalence of non-violent fractures. Traumatic injuries to the post-cranial skeleton were recorded for 180 adults from rural Giecz and for 96 adults from urban Poznań-Śródka. They were statistically analyzed by body region and individual skeletal element. Results reveal that Giecz had a significantly higher rate of trunk fractures than Poznań-Śródka (Fisher's exact, p<0.05). In particular, rib and vertebral fractures were more common in Giecz males and females than in their Poznań-Śródka counterparts. Traumatic injuries in the extremities were comparable between the two samples, suggesting similar risks of trauma to these regions. These results indicate that in early medieval Poland, activities associated with a rural lifestyle resulted in more injuries. These stress or accidental fractures, which are related to a high-risk setting, were not consistent with an urban lifestyle. Overall, agricultural populations like Giecz were engaged in a laborious lifestyle, reflected in a variety of injuries related to repetitive, high-risk activities. Although urban populations like Poznań engaged in craft specialization participated in repetitive activities, their lifestyle resulted in lesser fracture-risk

Apotropaic practices and the undead: a biogeochemical assessment of deviant burials in post-medieval poland.

Apotropaic observances-traditional practices intended to prevent evil-were not uncommon in post-medieval Poland, and included specific treatment of the dead for those considered at risk for becoming vampires. Excavations at the Drawsko 1 cemetery (17th-18th c. AD) have revealed multiple examples (n = 6) of such deviant burials amidst hundreds of normative interments. While historic records describe the many potential reasons why some were more susceptible to vampirism than others, no study has attempted to discern differences in social identity between individuals within standard and deviant burials using biogeochemical analyses of human skeletal remains. The hypothesis that the individuals selected for apotropaic burial rites were non-local immigrants whose geographic origins differed from the local community was tested using radiogenic strontium isotope ratios from archaeological dental enamel. 87Sr/86Sr ratios ( = 0.7112±0.0006, 1σ) from the permanent molars of 60 individuals reflect a predominantly local population, with all individuals interred as potential vampires exhibiting local strontium isotope ratios. These data indicate that those targeted for apotropaic practices were not migrants to the region, but instead, represented local individuals whose social identity or manner of death marked them with suspicion in some other way. Cholera epidemics that swept across much of Eastern Europe during the 17th century may provide one alternate explanation as to the reason behind these apotropaic mortuary customs, as the first person to die from an infectious disease outbreak was presumed more likely to return from the dead as a vampire

Vertebral trauma in Giecz: compression.

<p>Spine segment (T12-L2) illustrating representative examples of vertebral compression fractures in T12 (moderate anterior wedging) and L2 (severe anterior wedging and complete collapse) vertebrae of an older adult female from the Giecz Collection. Scale is in cm.</p

Medieval map of Wielkopolska, Poland.

<p>The map is based on Magocsi [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0129458#pone.0129458.ref013" target="_blank">13</a>], showing locations of 4 major centers.</p

Vertebral trauma in Giecz: spondylolysis.

<p>L4 vertebrae illustrating bilateral fractures of the pars interarticularis of a middle adult female from the Giecz Collection. Scale is in cm.</p

Individual 49/2012 (30–39 year old female) with a sickle placed across the neck.

<p>Individual 49/2012 (30–39 year old female) with a sickle placed across the neck.</p

Strontium isotope ratios from human dental enamel at Drawsko, with a local baseline now derived from human, and not faunal, ⁸⁷Sr/⁸⁶Sr values.

<p>Strontium isotope ratios from human dental enamel at Drawsko, with a local baseline now derived from human, and not faunal, ⁸⁷Sr/⁸⁶Sr values.</p

Demographic profile for the Drawsko 1 site.

<p>Demographic profile for the Drawsko 1 site.</p