Dental agenesis data in modern and premodern sub-Saharan Africans are presented by region, West, Central, East, and South, and by sex. Beyond characterizing the anomaly, comparisons are made with ...other populations and future work is encouraged. The findings should be of use to dental clinicians and anthropologists.
Agenesis of the UI2, LI1, UP2, LP2, UM3, and LM3 was recorded in 52 discrete samples of mainly skeletal dentitions (n = 2162) from across the subcontinent. After dividing into temporal categories, regional pooling was effected for adequate sample sizes across the vast geographic area. Only adults were included to record M3 status. Analyses included 95% confidence intervals and chi-square comparisons by region and sex.
Of 1668 modern individuals 2.3% have UI2-LP2 agenesis (CI 1.6–3.1%). Regional and sex differences are non-significant, though females are most affected. For M3s it is 7.0% (5.7–8.4%), with the Central region sample differing significantly from the East and South. Females again have greater prevalence, with the difference in the West significant. UI2-LP2 agenesis affects 0.6% of 494 premodern individuals (0.1–1.8%), while M3 agenesis is 8.5% (6.1–11.5%). None of these differences are significant.
Rates are toward the low end of global ranges, including 0.0–12.6% for UI2-LP2 from case reports, and 5.3–56.0% for M3 agenesis. With exceptions, generally insignificant inter-region differences imply that rates reasonably represent sub-Saharan peoples overall. Results will be of interest to anthropologists, but those related to risk factors, patterning, and prevalence may assist clinicians in tailoring treatment, while informing patients how this anomaly differs by population ancestry.
•New dental agenesis data in premodern and modern sub-Saharan Africans.•Of 1668 modern individuals 2.3% have UI2, LI2, UP2, LP2, and 7.0% have M3 agenesis.•Of 494 premodern individuals 0.6% have UI2, LI2, UP2, LP2 and 8.5% have M3 agenesis.•Some, but mostly insignificant differences by region and sex.•Prevalence and patterning differs from many other world populations.
There are longstanding questions about the origins and ancestry of the Picts of early medieval Scotland (ca. 300-900 CE), prompted in part by exotic medieval origin myths, their enigmatic symbols and ...inscriptions, and the meagre textual evidence. The Picts, first mentioned in the late 3rd century CE resisted the Romans and went on to form a powerful kingdom that ruled over a large territory in northern Britain. In the 9th and 10th centuries Gaelic language, culture and identity became dominant, transforming the Pictish realm into Alba, the precursor to the medieval kingdom of Scotland. To date, no comprehensive analysis of Pictish genomes has been published, and questions about their biological relationships to other cultural groups living in Britain remain unanswered. Here we present two high-quality Pictish genomes (2.4 and 16.5X coverage) from central and northern Scotland dated from the 5th-7th century which we impute and co-analyse with >8,300 previously published ancient and modern genomes. Using allele frequency and haplotype-based approaches, we can firmly place the genomes within the Iron Age gene pool in Britain and demonstrate regional biological affinity. We also demonstrate the presence of population structure within Pictish groups, with Orcadian Picts being genetically distinct from their mainland contemporaries. When investigating Identity-By-Descent (IBD) with present-day genomes, we observe broad affinities between the mainland Pictish genomes and the present-day people living in western Scotland, Wales, Northern Ireland and Northumbria, but less with the rest of England, the Orkney islands and eastern Scotland-where the political centres of Pictland were located. The pre-Viking Age Orcadian Picts evidence a high degree of IBD sharing across modern Scotland, Wales, Northern Ireland, and the Orkney islands, demonstrating substantial genetic continuity in Orkney for the last ~2,000 years. Analysis of mitochondrial DNA diversity at the Pictish cemetery of Lundin Links (n = 7) reveals absence of direct common female ancestors, with implications for broader social organisation. Overall, our study provides novel insights into the genetic affinities and population structure of the Picts and direct relationships between ancient and present-day groups of the UK.
Hyperdontia data in modern and premodern sub-Saharan Africans are presented by region—West, Central, East, and South, and sex. Beyond describing the anomaly, comparisons are made with other world ...populations and future work is promoted. These findings may be useful to both dental clinicians and anthropologists.
Hyperdontia presence and patterning were recorded in 51 samples of skeletal dentitions and hardstone casts (n = 1916). Its infrequency prompted regional pooling after grouping by time. Only adults were included to record later forming fourth molars reportedly common in Africans. Quantitative analyses, including 95% confidence intervals, were conducted to characterize spatiotemporally sub-Saharan peoples.
Forty-four of 1429 modern individuals (3.08%) exhibit hyperdontia (CI 2.24–4.13%). Regional variation is significant, particularly West-Central vs. East-South, between 6.8% and 1.5%. Four of 487 premodern individuals, 0.82%, have hyperdontia (0.22–2.10%), with minimal regional differences. Males are most affected, as reported by other researchers. Other similarities with non-African research are evident regarding isomere, antimere, and form, with one key exception—a proclivity for the posterior over anterior maxilla.
3.08% is toward the upper end of published world ranges, including an oft-cited 0.1–3.6 + %. However, the regional variation argues against a single prevalence to describe collectively the subcontinental inhabitants. This variation parallels past west to east and south migrations like other biocultural indicators. Thus, beyond a health concern to clinicians or interesting anomaly to anthropologists, hyperdontia may be useful in other studies. There are no equivalent premodern ranges for comparison. Similarity in patterning overall to previous findings suggests a shared, potentially ancient genetic component in expression.
•New hyperdontia data in modern and premodern sub-Saharan Africans listed by region.•3.08% of 1429 modern individuals exhibit hyperdontia (CI 2.24–4.13%).•Regional variation is significant, ranging between 6.8% and 1.5%.•0.82% of 487 premodern individuals affected (0.22–2.10%), with little regionality.•Similarities to other world groups suggest a shared genetic component in expression.
Some researchers posit population continuity between Late Palaeolithic hunter–gatherers of the late Pleistocene and Holocene agriculturalists from Lower (northern) Nubia, in northeast Africa. ...Substantial craniodental differences in these time-successive groups are suggested to result from
in situ
evolution. Specifically, these populations are considered a model example for subsistence-related selection worldwide in the transition to agriculture. Others question continuity, with findings indicating that the largely homogeneous Holocene populations differ significantly from late Pleistocene Lower Nubians. If the latter are representative of the local populace, post-Pleistocene discontinuity is implied. So who was ancestral to the Holocene agriculturalists? Dental morphological analyses of 18 samples (1075 individuals), including one dated to the 12th millennium BCE from Al Khiday, near the Upper Nubian border, may provide an answer. It is the first Late Palaeolithic sample (
n
= 55) recovered within the region in approximately 50 years. Using the Arizona State University Dental Anthropology System to record traits and multivariate statistics to estimate biological affinities, Al Khiday is comparable to several Holocene samples, yet also highly divergent from contemporaneous Lower Nubians. Thus, population continuity is indicated after all, but with late Pleistocene Upper—rather than Lower Nubians as originally suggested—assuming dental traits are adequate proxies for ancient DNA.
Objectives
A variety of mechanical processes can result in antemortem dental chipping. In this study, chipping data in the teeth of Homo naledi are compared with those of other pertinent dental ...samples to give insight into their etiology.
Materials and methods
Permanent teeth with complete crowns evidencing occlusal wear were examined macroscopically. The location, number, and severity of fractures were recorded and compared to those found in samples of two other South African fossil hominin species and in samples of nonhuman primates (n = 3) and recent humans (n = 7).
Results
With 44% of teeth affected, H. naledi exhibits far higher rates of chipping than the other fossil hominin samples. Specifically, 50% of posterior teeth and 31% of anterior teeth display at least one chip. The maxillary teeth are more affected than the mandibular teeth (45% vs 43%, respectively), 73% of molar chipping occurs on interproximal surfaces, and right teeth are more often affected than left teeth (50% vs 38%).
Discussion
Results indicate that the teeth of H. naledi were exposed to acute trauma on a regular basis. Because interproximal areas are more affected than buccal and posterior teeth more than anterior, it is unlikely that nonmasticatory cultural behavior was the cause. A diet containing hard and resistant food, or contaminants such as grit, is more likely. The small chip size, and steep occlusal wear and cupped dentine on some molars are supportive of the latter possibility. This pattern of chipping suggests that H. naledi differed considerably—in terms of diet, environment, and/or specialized masticatory processing—relative to other African fossil hominins.
The mean measure of divergence (MMD) distance statistic has been used by researchers for nearly 50 years to assess inter-sample phenetic affinity. Its widespread and often successful use is well ...documented, especially in the study of cranial and dental nonmetric traits. However, the statistic has accumulated some undesired mathematical baggage through the years from various workers in their attempts to improve or alter its performance. Others may not fully understand how to apply the MMD or interpret its output, whereas some described a number of perceived shortcomings. As a result, the statistic and its sometimes flawed application(s) have taken several well-aimed hits; a few researchers even argued that it should no longer be utilized or, at least, that its use be reevaluated. The objective of this report is to support the MMD, and in the process: (1) provide a brief history of the statistic, (2) review its attributes and applicability relative to the often-used Mahalanobis D(2) statistic for nonmetric traits, (3) compare results from MMD and D(2) model-free analyses of previously-recorded sub-Saharan African dental samples, and (4) investigate its utility for model-bound analyses. In the latter instance, the ability of the D(2) and other squared Euclidean-based statistics to approximate a genetic relationship matrix and Sewall Wright's fixation index using phenotypic data, and the inability of the MMD to do so, is addressed. Three methods for obtaining such results with nonlinear MMD distances, as well as an assessment of the fit of the isolation-by-distance model, are presented.
We report the frequencies of linear enamel hypoplasia (LEH) and, specifically, pitting enamel hypoplasia (PEH) defects in the teeth of Paranthropus robustus, for comparison with four other South ...African hominin species and three extant nonhuman primate species. Unlike LEH, the lesser known PEH is characterized by multiple circular depression defects across a tooth crown and is often difficult to interpret in terms of developmental timing and etiology. Teeth in all samples were examined macroscopically with type, position and number of defects recorded. Frequencies of teeth with LEH vary among hominin species, but the differences in PEH are considerable. That is, P. robustus has much higher rates of pitting defects, with 47% of deciduous teeth and 14% of permanent teeth affected, relative to 6.7% and 4.3%, respectively, for all other hominin teeth combined; none of the extant primate samples evidences comparable rates. The defects on P. robustus molars are unlike those in other species, with entire crowns often covered in small circular depressions. The PEH is most consistent with modern human examples of amelogenesis imperfecta. Additionally, the defects are: 1) not found on anterior teeth, 2) uniform in shape and size, and 3) similar in appearance/severity on all molars. Therefore, this form of PEH may have been a side effect of selection on another trait that shares the same coding gene(s), i.e., these defects have a genetic origin. We discuss a possible scenario that may explain how this form of PEH evolved to become so common in the Paranthropus genus.
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