The genetic-demographic approach in anthropological research. VIII. The ethnic subdivisions of the Khakass populations

Khakass families can be considered as a fundamental ethnic determinant. Based on the family subdivision the analysis of intensity and genetic effectiveness of marriage migrations has revealed the speed of formation of a new ethnic-territorial community--Khakass nationality--on the territory of the Minusinsk hollow.     

The genetic-demographic approach in anthropological research. IX. The spatial structure of Khakass populations]

The rural population of Khakassia is characterized by genetic isolation due to marital traditions and ethnic-territorial subdivisions. The type of Khakass settling limits the choice of a marital partner within the territory occupied by one ethnographic group, preventing an active migration of alleles from one population to another. Formation of local zonal anthropologic type (84% of marital couples) occurs on the territory approximately equal to the area of one administrative district.     

The genetic-demographic approach in anthropological research. X. The dynamics of the sex-age structure of Khakass populations]

Social-economic remakings in Siberia are reflected in the economy of a rural inhabitant and the sex-age structure of the Khakass populations. The age average of the population increased from 26.7 years in 1954 up to 31.2 years in 1980. It has been established that the effectively reproductive size of a population (Ne) which takes into account its historical extent serves as a satisfactory estimate of the veritable (not single, instantaneous) size of a population.     

The genetic-demographic approach in anthropological research. XI. The structure of the reproductive behavior of Khakass families]

A detailed analysis of chronological intervals typical of reproduction process has been carried out in rural Khakassian populations to reveal the mechanisms of natural selection and gene drift. It is shown that the process of reproduction is connected with cultural traditions and economical activity of a population under study. The main characteristics of reproductive family behavior (the whole number of children and sex ratio, birth interval ect.) play a very important role in family and kin relationships, age, sex and marriage-migration structure of the population.     

The genetic-demographic approach in anthropological research. VII. The influence of the social environment on the indices of the reproductive function in Khakass women

The biodemographic parameters showing the influence of social factors upon the different elements of population and family structure are considered. It has been shown that the semi-generation time interval which corresponds to the duration of the active reproductive period of the generation is worth using to reveal the mechanisms of the social adaptation of the population. It has been found that socially determined differential fertility of families and genetically determined mortality in perinatal period are now the main components of the potential selection (index Crow).     

Evaluation of the contribution of D9S1120 to anthropological studies in Native American populations

The D9S1120 locus exhibits a population-specific allele of 9 repeats (9RA) in all Native American and two Siberian populations currently studied, but it is absent in other worldwide populations. Although this feature has been used in anthropological genetic studies, its impact on the evaluation of the structure and genetic relations among Native American populations has been scarcely assessed. Consequently, the aim of this study was to evaluate the anthropological impact of D9S1120 when it was added to STR population datasets in Mexican Native American groups. We analyzed D9S1120 by PCR and capillary electrophoresis (CE) in 1117 unrelated individuals from 13 native groups from the north and west of Mexico. Additional worldwide populations previously studied with D9S1120 and/or 15 autosomal STRs (Identifier kit) were included for interpopulation analyses. We report statistical results of forensic importance for D9S1120. On average, the modal alleles were the Native American-specific allele 9RA (0.3254) and 16 (0.3362). Genetic distances between Native American and worldwide populations were estimated. When D9S1120 was included in the 15 STR population dataset, we observed improvements for admixture estimation in Mestizo populations and for representing congruent genetic relationships in dendrograms. Analysis of molecular variance (AMOVA) based on D9S1120 confirms that most of the genetic variability in the Mexican population is attributable to their Native American backgrounds, and allows the detection of significant intercontinental differentiation attributed to the exclusive presence of 9RA in America. Our findings demonstrate the contribution of D9S1120 to a better understanding of the genetic relationships and structure among Mexican Native groups.     

The roots of ethics: an anthropological approach

The roots of ethics are to be found within man's freedom and his ability to pursue values from the choices he makes. These values may be sought within the structure of the human being. Some of these values will correspond to man's vital needs (such as socializing, cooperation, family ties, etc.), yet they are not to be interpreted as being genetically determined, since they are consciously interiorized and experienced and planned at both individual and group level. Other values, such as religion, a moral sense, or art transcend those needs strictly linked with physical life. These values may be considered to be “natural universals” or ‘trans-cultural” values because they are to be found in various cultures. The fact that they offer man an advantage, does not necessarily mean that they are genetically determined or that they have been fixed through selection processes. These can be extended to include the values that have matured from the historical experience of single human beings and groups. The transcendental value of the person-man as opposed to infra-human beings, has also been confirmed as a priority criterion for value judgements and for a rational ethics, particularly within the field of bio-ethics.     

The significance of primate paleontology for anthropological studies

The correct use of taxonomic names must become widespread if a clear understanding of primate paleontology is to exist among anthropologists. Physical anthropologists are urged to acquire genuine competence in the paleontology, systematics, and taxonomy of mammals. Examples are given of improper taxonomic procedure and of the perpetuation of invalid names. The need for a stable and correct nomenclature of the primates is emphasized. The importance of examining actual fossil specimens is stressed. The taxonomy of the Hominoidea is discussed and a summary of invalid names in current use is given. Recently discovered fossils from Oligocene strata in the Egyptian Fayum are figured and the pertinence of these to the origins of higher primates is suggested.     

The use of multivariate techniques in the study of skeletal populations

A major problem in taxonomic or evolutionary studies (micro or macro) of populations through their skeletal remains is what to do about single specimens, or samples of half a dozen, or fragments of skeletons. Multivariate analysis makes possible finer distinctions of all sorts than does univariate analysis, including sex and population assignment, allowing such placement objectively when adequate samples of identified populations are available to form the multivariate context. The history and essential nature of multivariate analysis is described briefly, and examples of its application to single specimens (the Fish Hoek and Keilor skulls) are given.     

Taxonomical studies on Czechoslovak Conchostraca. III,family Leptestheriidae

Zusammenfassung Die vorliegende Arbeit befasst sich mit der Variabilität von Leptestheria variabilis, Rüppel und Eoleptestheria ticinensis, Balsamo-Crivelli aus der Tschechoslowakei. Wie bei den in den zwei vorgehenden Beiträgen angeführten Arten zeigte es sich, dass die Variabilität der von Daday und einigen anderen Autoren erwähnten Merkmale bedeutend gross ist, so dass manche Arten zu synonymisieren sind. Eine Überprüfung der Taxonomie und der geographischen Verbreitung aller mitteleuropäischen Arten weist auf Einnehmen grosser Areale, meistens an oekologisch passende Gebiete der ganzen Palaearktischen Region.Im Vergleich mit den Palaearktischen Verhältnissen wird die Valenz einer grossen Anzahl von aus anderen Regionen beschriebenen Arten, von dem taxonomischen sowie zoogeographischen Gesichtspunkte aus bezweifelt. Es wird eine Analyse der Verbreitung von Conchostraken Europa's durchgeführt, sowie ein Schlüssel für die mitteleuropäischen Arten gegeben.     

Admixture-matched case-control study: a practical approach for genetic association studies in admixed populations

Case-control genetic association studies in admixed populations are known to be susceptible to genetic confounding due to population stratification. The transmission/disequilibrium test (TDT) approach can avoid this problem. However, the TDT is expensive and impractical for late-onset diseases. Case-control study designs, in which, cases and controls are matched by admixture, can be an appealing and a suitable alternative for genetic association studies in admixed populations. In this study, we applied this matching strategy when recruiting our African American participants in the Study of African American, Asthma, Genes and Environments. Group admixture in this cohort consists of 83% African ancestry and 17% European ancestry, which was consistent with reports from other studies. By carrying out several complementary analyses, our results show that there is a substructure in the cohort, but that the admixture distributions are almost identical in cases and controls, and also in cases only. We performed association tests for asthma-related traits with ancestry, and only found that FEV(1), a measure for baseline pulmonary function, was associated with ancestry after adjusting for socio-economic and environmental risk factors (P=0.01). We did not observe an excess of type I error rate in our association tests for ancestry informative markers and asthma-related phenotypes when ancestry was not adjusted in the analyses. Furthermore, using the association tests between genetic variants in a known asthma candidate gene, beta(2) adrenergic receptor (beta(2)AR) and DeltaFEF(25-75), an asthma-related phenotype, as an example, we demonstrated population stratification was not a confounder in our genetic association. Our present work demonstrates that admixture-matched case-control strategies can efficiently control population stratification confounding in admixed populations.     

A pseudolikelihood approach to correcting for ascertainment bias in family studies.

The Cannings and Thompson approach to correcting for ascertainment bias in family studies is extended to settings with multiple ascertainment. The extension is based on maximizing a pseudolikelihood. Two approaches to computing standard errors for the maximum pseudolikelihood estimate are described. One is especially simple to compute, while the other is more generally applicable. Simulation experiments suggest that the standard-error computations can be quite accurate.     

Detection of deleterious genotypes in multigenerational studies. III. Estimation of selection components in highly selfing populations

New paradigms in genetics have increased the chance of finding genes that appear redundant but in fact may have been preserved due to a small level of positive selection potential acting during each generation. Monitoring changes in genotypic frequencies within and between generations allows the dissection of the fertility, viability and meiotic drive selection components acting on such genes in natural and experimental populations. Here, a formal maximum likelihood procedure is developed to identify and estimate these selection components in highly selfing populations by fitting the time-dependent solutions for genotypic frequencies to observed multigenerational counts. With adult census alone, we can not simultaneously estimate all three selection components considered. In such cases, we instead consider a hierarchy of 11 models with either fewer selection components, complete dominance, or multiplicative meiotic drive with a single parameter. We identify the best-fitting of these models by applying likelihood ratio tests to nested models and Akaike's Information Criterion (AIC) and the Bayesian Information Criterion (BIC) to non-nested models. With seed census, fertility and viability selection are not distinguishable and thus can only be estimated jointly. A combination of joint seed and adult census data allows us to estimate all three selection components simultaneously. Simulated data validate the estimation procedure and provide some practical guidelines for experimental design. An application to Arabidopsis data establishes that viability selection is the major selective force acting on the ACT2 actin gene in laboratory-grown Arabidopsis populations.