Sternal human variability and population affinity: Frequency of discrete traits and their relationship with sex and age

2021 ◽  
Author(s):  
Catherine Villoria Rojas ◽  
Javier Irurita Olivares ◽  
Pilar Mata Tutor ◽  
Alexandra Muñoz García ◽  
María Benito Sánchez
Keyword(s):  
Discrete Traits ◽  
Population Affinity

Self-Reported Ancestry and Craniofacial SNPs

2021 ◽  
Author(s):  
Kamar Afra ◽  
Michelle Hamilton ◽  
Bridget Algee-Hewitt
Keyword(s):  
Latin American ◽  
Tissue Expression ◽  
European Ancestry ◽  
Craniofacial Skeleton ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide ◽  
Model Based Clustering ◽  
The Face ◽  
White Sample ◽  
Population Affinity

Genotype-phenotype studies increasingly link single nucleotide polymorphism (SNPs) to the dimensions of the face for presumed homogeneous populations. To appreciate the significance of these findings, it is essential to investigate how these results differ between the genetic and phenotypic profiles of individuals. In prior work, we investigated the connection between SNPs previously identified as informative of soft tissue expression and measurements of the craniofacial skeleton. Using matched genetic and skeletal information on 17 individuals who self-identified as White with presumed common continental ancestry (European), we obtained significant Spearman correlations for 11 SNPs. In the present study, we looked at self-identified ancestry to understand the intersectional background of the individual’s phenotype and genotype. We integrated our samples within a diverse dataset of 2,242 modern Americans and applied an unsupervised model-based clustering routine to 13 craniometrics. We generated a mean estimate of 69.65% (±SD = 18%) European ancestry for the White sample under an unsupervised cluster model. We estimated higher quantities of European ancestry, 88.5%–93%, for our subset of 17 individuals. These elevated estimates were of interest with respect to the distribution of population-informative SNPs; we found, for example, that one of our sampled self-identified White individuals displayed SNPs commonly associated with Latin American populations. These results underscore the complex interrelationship between environment and genetics, and the need for continued research into connections between population affinity, social identity, and morphogenetic expression.

Assumed Differences; Unquestioned Typologies

2021 ◽  
Author(s):  
Sean Tallman ◽  
Nicolette Parr ◽  
Allysha Winburn
Keyword(s):  
Key Words ◽  
Peer Review ◽  
Forensic Anthropology ◽  
Biological Variation ◽  
Population Variation ◽  
Biological Profile ◽  
Social Inequity ◽  
Population Affinity ◽  
Do So

Forensic anthropologists traditionally estimate “race” or “ancestry” as part of the biological profile. While practitioners may have changed the terms used to describe regionally patterned human skeletal variation, the degree to which they have altered their typological approaches remains unclear. This study analyzed 119 peer-reviewed forensic anthropology articles published in four relevant journals (1966–2020) by matching combination(s) of the key words “race,” “ancestry,” “ethnicity,” and/or “population affinity.” Results indicated that while “ancestry” has supplanted “race,” this change has not brought concurrent modifications in approach, nor deeper scrutiny of underlying concepts. “Race” and “ancestry” were infrequently defined in 13% and 12% of sampled articles, respectively, and a plethora of social, geographic, and pseudoscientific terms persisted. Forensic anthropologists increasingly engaged with questions addressing the forces patterning human biological variation: 65% of studies postdating 1999 discussed population histories/structures and microevolution; 38% between 1966–1999. Fewer studies contextualized or critiqued approaches to analyzing population variation (32% of studies postdating 1999; 4% from 1966–1999), and virtually no studies considered the possibility that skeletal variation reflected embodied social inequity (5% of studies postdating 1999; 0% from 1966–1999). This lack of interrogation and clarity contributes to the faulty notion that all forensic anthropologists share similar definitions and leads to an oversimplification of complex biocultural processes. While the lack ofdefinitions and biocultural engagement may be partly due to editorial and peer-review pressures, it is likely that many forensic anthropologists have not interrogated their own perspectives. This article holds that it is essential for us to do so.

Cross-sexual Transfer

2003 ◽  
Author(s):  
Mary Jane West-Eberhard
Keyword(s):  
Sex Determination ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Alternative Phenotypes ◽  
Opposite Sex ◽  
Critical Age ◽  
Sexual Traits ◽  
Discrete Traits ◽  
Dimorphic Species ◽  
Determination Mechanism

Distinctive male and female traits are perhaps the most familiar of all divergent specializations within species. In cross-sexual transfer, discrete traits that are expressed exclusively in one sex in an ancestral species appear in the opposite sex of descendants. An example is the expression of brood care by males in a lineage where ancestral females are the exclusive caretakers of the young, as in some voles (Thomas and Birney, 1979). Despite the prominence of sexual dimorphism and sex reversals in nature, and an early explicit treatment by Darwin, discussed in the next section, cross-sexual transfer is not often recognized as a major factor in the evolution of novelty (but see, on animals, Mayr, 1963, pp. 435-439; Mayr, 1970, p. 254; on plants, Iltis, 1983). When more widely investigated, cross-sexual transfer may prove to rival heterochrony and duplication as an important source of novelties in sexually dimorphic lineages. For this reason, I devote more attention here to cross-sexual transfer than to these other, well-established general patterns of change. The male and female of a sexually dimorphic species may be so different that it is easy to forget that each individual carries most or all of the genes necessary to produce the phenotype of the opposite sex. Sex determination, like caste determination and other switches between alternative phenotypes, depends on only a few genetic loci or, in many species, environmental factors (Bull, 1983). There is considerable flexibility in sex determination and facultative reversal in some taxa. Among fish, for example, there is even a species wherein sex is determined by juvenile size at a critical age (Francis and Barlow, 1993). The sex determination mechanism, whatever its nature, leads to a series of sex-limited responses, often coordinated by hormones and not necessarily all occurring at once. A distinguishing aspect of sexually dimorphic traits in adults is that there is often a close homology between the secondary sexual traits that are differently modified in the two sexes.

scholarly journals Testing the utility of dental morphological trait combinations for inferring human neutral genetic variation

2020 ◽  
Vol 117 (20) ◽  
pp. 10769-10777 ◽  
Author(s):  
Hannes Rathmann ◽  
Hugo Reyes-Centeno
Keyword(s):  
Modern Human ◽  
Genomic Variation ◽  
Future Research ◽  
Human Populations ◽  
Dental Morphology ◽  
Genomic Signatures ◽  
Neutral Genetic Variation ◽  
Tooth Form ◽  
Dental Traits ◽  
Population Affinity

Researchers commonly rely on human dental morphological features in order to reconstruct genetic affinities among past individuals and populations, particularly since teeth are often the best preserved part of a human skeleton. Tooth form is considered to be highly heritable and selectively neutral and, therefore, to be an excellent proxy for DNA when none is available. However, until today, it remains poorly understood whether certain dental traits or trait combinations preserve neutral genomic signatures to a greater degree than others. Here, we address this long-standing research gap by systematically testing the utility of 27 common dental traits and >134 million possible trait combinations in reflecting neutral genomic variation in a worldwide sample of modern human populations. Our analyses reveal that not all traits are equally well-suited for reconstructing population affinities. Whereas some traits largely reflect neutral variation and therefore evolved primarily as a result of genetic drift, others can be linked to nonstochastic processes such as natural selection or hominin admixture. We also demonstrate that reconstructions of population affinity based on many traits are not necessarily more reliable than those based on only a few traits. Importantly, we find a set of highly diagnostic trait combinations that preserve neutral genetic signals best (up to x∼r = 0.580; 95% r range = 0.293 to 0.758; P = 0.001). We propose that these trait combinations should be prioritized in future research, as they allow for more accurate inferences about past human population dynamics when using dental morphology as a proxy for DNA.

Endostructural morphology in hominoid mandibular third premolars: Discrete traits at the enamel-dentine junction

2019 ◽  
Vol 136 ◽  
pp. 102670 ◽  
Author(s):  
Thomas W. Davies ◽  
Lucas K. Delezene ◽  
Philipp Gunz ◽  
Jean-Jacques Hublin ◽  
Matthew M. Skinner
Keyword(s):  
Discrete Traits

Interaction, Change, and the Role of the Historical in Validation: The Case of L2 Dynamic Assessment

2018 ◽  
Vol 17 (1) ◽  
pp. 28-46
Author(s):  
Matthew E. Poehner ◽  
Rémi A. van Compernolle
Keyword(s):  
Language Learners ◽  
Second Language Learners ◽  
Dynamic Assessment ◽  
Standard View ◽  
Learner Participation ◽  
Internal Relations ◽  
Discrete Traits ◽  
Changes Over Time ◽  
Interaction Change

This article examines the implications of argument-based validity for the continued development of dynamic assessment (DA) research and practice. We propose that the move toward validation as a process of interpretation and evidence-based argument is commensurable with DA but that fundamental ontological differences with conventional approaches to measurement must be recognized. Following Ollman’s (2003) explication of dialectical thinking, and in particular the distinction between philosophies of external and internal relations, we submit that the standard view of abilities as discrete traits is untenable in DA. Instead, abilities must be understood in a manner that takes account of (a) available forms of mediation and (b) change that occurs over the course of DA. To illustrate how a process of validation might be undertaken in DA, we present findings from recent DA studies involving second language learners. Our discussion brings into focus both learner participation in DA interactions and score changes over time.

Cremated Human Remains from Point of Pines, Arizona: A New Approach

1967 ◽  
Vol 32 (4) ◽  
pp. 498-506 ◽  
Author(s):  
Charles F. Merbs
Keyword(s):  
Human Remains ◽  
Human Populations ◽  
New Approach ◽  
Human Osteology ◽  
Skeletal Anomalies ◽  
Biological Studies ◽  
The Future ◽  
Discrete Traits ◽  
Traditional Approaches ◽  
And Storage

AbstractThe traditional approaches of comparative human osteology have proven largely unsatisfactory in attempts to determine biological relationships among human populations which cremated their dead. However, one category of information, that of discrete traits or skeletal anomalies, has been largely ignored. Cremations from Point of Pines, Arizona, were analyzed to determine if this kind of information, along with that usually sought from skeletal material, could be obtained in sufficient quantity to make comparative biological studies feasible. The results were encouraging, but they indicate that extraordinary care will be required in the future excavation and storage of cremated material.

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