Endogamy among the Dogon of Boni, Mali

This paper examines factors influencing endogamy in a Dogon population in Mali. Situated in Boni district, this population of about 5000 individuals is distributed over fifteen villages located on four independent massifs. This population is strongly endogamous (only 4% of all marriages are contracted with neighbouring ethnic groups), and each massif shows high endogamy. The roles of lineage, residence in the same village, and geographical distance in mating choice are examined. These different factors are successively analysed using log-linear statistical models and the results offer a more precise interpretation of endogamy in this population.     

Ace Alu insertion polymorphism in Croatia and its isolates

Alu elements are a family of interspersed repeats in the genome propagating by retroposition into new chromosomal locations. Alu insertion in Ace gene is known to be polymorphic (presence/absence of Alu element) in worldwide populations and as such serves as marker for population structure analyses. In this study we examined the distribution of genotypes and allele frequencies of this polymorphism in general Croatian population and its two isolates (the island of Hvar and the coastal region of the Middle Dalmatia) and related them to the level of endogamy as an indicator of inbreeding in these populations. Results showed that these three population groups are different with respect to Ace Alu polymorphism. The endogamy was highest on the island of Hvar. With the increase of endogamy a decrease in heterozigosity was observed. The same trend was observed for the frequency of insertion allele. Its frequencies in the village subpopulations of two studied isolates are subject to genetic drift due to small population sizes and high levels of endogamy. This in turn causes genetic differentiation among villages that is observed to be higher on the island of Hvar than in the coastal region. In the worldwide perspective, the Ace Alu insertion allele frequency of 50.6% in the general Croatian population falls within the range of other European populations.     

Temporal trends in marital structure and isonymy in S. Paolo Albanese, Italy

In the fifteenth century, after the Turkish conquest of the Balkan area, Albanian communities migrated to Southern Italy. I investigated temporal trends in isolation from 1820 to 1982 in one of these communities, the population of S. Paolo Albanese, Basilicata, which still uses the original language and religious rites. Marital structure is characterized by a high average frequency of village endogamy (75.2%). Among the exogamous marriages there is a preference for mates from Italo-Albanian settlements, with higher values in the 1800s. The distribution of marital distances reflects the positive assortative mating by ethnic community. The mean frequency of isonymous marriages was 9.01% from 1820 to 1982. These results indicate that total inbreeding from isonymy is a reliable indicator of isolation, showing temporal trends related to changes in endogamy. Fr accounts for the greater percentage of Ft in relation to the small population size and regularly decreases with time. The breakdown of isolation, as documented by the decrease in population size, endogamy, and inbreeding, is a recent feature (since 1960).     

Population and demographic study of the Turkmen Tekke

Genetical and demographic studies of typical rural population of Turkomen teke in Yangi-Kala village of the Ashkhabad region (about 5.000 inhabitants) were performed through the examination of a sample of 3528 persons. The population is characterised by intensive growth (mean number of children per one woman is 6.17), a high level of endogamy (the total coefficient of inbreeding being 0.010912), preserving the traditional marriage system (91.9 and 8.1% of intrageneric and intergeneric marriages, respectively). Migration does not significantly influence endogamy, because it takes place among kin families.     

Evolution of marital structure in 20 Sardinian villages from 1800 to 1974

This paper reports the data for endogamy, exogamy and consanguinity in 20 Sardinian villages from 1800 to 1974, divided into generational periods (25 years). The data are taken from the records of 48,262 marriages celebrated in the parishes of 20 Sardinian villages. The results for Spearman's rank correlation coefficient indicate significant positive correlations of endogamy with consanguinity (r(s) = 0.6551, percentage of consanguineous marriages; r(s) = 0.5477, Bernstein's alpha), with altitude (r(s) = 0.6386), with population size (r(s) = 0.2519), as well as a significant negative correlation of endogamy with time (r(s) = -0.4210). In addition, consanguinity shows a significant positive correlation with altitude (r(s) = 0.5717, percentage of consanguineous marriages; r(s) = 0.6295, Bernstein's alpha) and a significant negative correlation with time (r(s) = -0.2363, percentage of consanguineous marriages); the negative correlation between the mean level of consanguinity (alpha) and time is statistically not significant. In the single parishes, the levels of endogamy and consanguinity are generally higher in the mountain villages than in those situated in the hill and plain areas. Finally, it is hypothesized that, in the time period considered, the level of consanguinity and especially of endogamy were largely determined by isolation.     

Russians of the Karachay-Cherkess Republic: Population Genetic Portrait

To describe the population-genetic structure of the Russian population of Karachay-Cherkessia, the database of Compulsory Medical Insurance and marriage records for 1990–2000 were used. The Russian population is characterized by a low birth rate, low endogamy, low inbreeding, and a high level of miscegenation.     

Endogamy index and its changes with time in some populations of the Volga-Ural region

Data on several populations of Russia have been used to demonstrate that the change in the endogamy index detected in the second half of the 20th century is not global. Migration activity remains high in populations with relatively low endogamy indices, and their endogamy does not change with time. In regions with medium and high endogamy indices, these values also tend to remain stable. The endogamy indices of urban populations are increasing, and those of rural populations are decreasing.     

Inbreeding as measured by isonymy in two Venezuelan populations and its relationship to other variables

Isonymy is a useful approach to the study of population structure and thus can be utilized to detect deviations from random mating. In this study we give the results of an analysis of inbreeding levels and relate such variables as mean marital distance, surnames repeated in isonymous couples, and percentage of people using only maternal surnames to inbreeding and endogamy in two Venezuelan populations of black ancestry, Birongo and La Sabana. These populations differ in their sociocultural development and degree of isolation. We estimated inbreeding through isonymy and directly from genealogy. The most important findings are that the Ft values are higher than the a's, that the Fn component of Ft is higher than the Fr component, and that there is higher endogamy, inbreeding, and isolation in Birongo than in La Sabana. These results are in agreement with the sociocultural and historical background and development of each population. Nevertheless, both populations show similar temporal trends in almost all the variables analyzed. The use of isonymy as a complementary tool to study population structure is proposed, especially for Ibero-American populations.     

Endogamy index and its changes with time in some populations of the Volga-Ural region

Data on several populations of Russia have been used to demonstrate that the change in the endogamy index detected in the second half of the 20th century is not global. Migration activity remains high in populations with relatively low endogamy indices, and their endogamy does not change with time. In regions with medium and high endogamy indices, these values also tend to remain stable. The endogamy indices of urban populations are increasing, and those of rural populations are decreasing.     

Class endogamy, inbreeding and migration during the Argentinean colonial period: analysis based on individuals of European ancestry

During the Spanish colonial period, Córdoba was an important town due to its location suitable for controlling communication throughout a wide region of Argentina. As a typical colonial society, where individuals belonged to a well established social class, marriages among Whites were the result of strict norms and prejudices founded on nets of kinship, friendship and neighbouring. The objective of this paper is to determine, whether the elevated class endogamy among Whites during the colonial period resulted in high consanguinity and whether a process of selection of surnames was present in 1813. In both cases the interaction with the migratory flow was taken into account. It is concluded that (a) Although an endogamy of "class" existed among Whites, there is no evidence of the consequences on the biological structure of the population through preferential mating between relatives, as deduced from the low level of inbreeding from isonymy. (b) There was no differential reproduction reflecting the selection of families carrying certain surnames; therefore surnames followed a "neutral" model. (c) The diversity of surnames and the gene flow deduced from them were of a magnitude similar to present populations; this fact could have balanced the effect of the "class" endogamy. (d) Finally, the congruence between information derived from the population age distribution and historic data and the quantification of migration from surnames allowed the detection of mistakes in the census data file regarding the number of foreigners, thus validating the use of surnames as biological markers of the population structure.     

Is the Central Valley of Costa Rica a genetic isolate?

In the last decade, the Costa Rican Central Valley population (CRCV), has received considerable scientific attention, attributed in part to a particularly interesting population structure. Two different and contradictory explanations have emerged: (1) An European-Amerindian-African admixed population, with some regional genetic heterocigosity and moderate degrees of consanguinity, similar to other Latin-American populations. (2) A genetic isolate, with a recent founder effect of European origin, genetically homogeneous, with a high intermarriage rate, and with a high degree of consanguinity. Extensive civil and religious documentation, since the settlement of the current population, allows wide genealogy and isonymy studies useful in the analysis of both hypotheses. This paper reviews temporal and spatial aspects of endogamy and consanguinity in the CRCV as a key to understand population history. The average inbreeding coefficients (a) between 1860 and 1969 show a general decrease within time. The consanguinity in the CRCV population is not homogeneous, and it is related to a variable geographic pattern. Results indicate that the endogamy frequencies are high but in general it was not correlated with a values. The general tendency shows a consanguinity decrease in time, and from rural to urban communities, repeating the tendencies observed in other countries with the same degree of development, and follows the general Western World tendency. Few human areas or communities in the world can be considered true genetic isolates. As shown, during last century, the CRCV population has had consanguinity values that definitively do not match those of true genetic isolates. A clear knowledge of the Costa Rican population genetic structure is needed to explain the origin of genetic diseases and its implications to the health system.     

Prevalence and distribution of genetic diseases in Quebec: impact of the past on the present

The prevalence and distribution of genetic diseases in the province of Quebec has been influenced by its population history. The current French Canadian population stems from 8,500 pioneers who left France for Nouvelle-France between 1608 and 1759. After the English conquest of Nouvelle-France in 1759, the French Canadian population remained mostly genetically isolated, for linguistic, cultural, and religious reasons. The migration of a small number of French individuals to Nouvelle-France created a founder effect. Subsequent migrations inland have created smaller regional founder effects. The limited size of the population favoured genetic drift, and the social context encouraged endogamy, i.e. unions between French Canadians with little admixture with English and other immigrants. Founder effects, genetic drift, and endogamy have all played a role in the current prevalence and distribution of genetic diseases now found in Quebec. The prevalence and distribution of genetic diseases in Quebec need to be taken into account in clinical practice. When clinicians are knowledgeable about the genetic diseases prevalent in the population they treat, they know to consider these diseases in differential diagnoses when appropriate and prioritize investigations accordingly. When developing a new diagnostic test for a genetic disease, the prevalence of the disease and the nature of the mutations found in the target population need to be taken into account. The performance of the test will depend on how well it accounts for the particularities of the disease in that population. In other words, how well does it detect the mutations found in that population? Interpretation of individual genetic test results will also depend on how well the test is expected to perform in the individual's population.     

The gene pool of the Belgorod oblast population: changes in the endogamy indices of district populations with time

Changes in the endogamy indices of district populations of the Central Chernozem region of Russia during the past 100 years were studied. The size of an elementary population in this region increased from that of a rural municipality in the mid-20th century to that of an administrative district in the late 20th century.     

Primate population structure: evaluation of models

Genetic markers among macaques on Cayo Santiago island were analyzed in an attempt to infer aspects of mating structure. Several models that included high levels of gene flow among groups could not be distinguished, but the data are clearly incompatible with group endogamy and with high variance in male fitness. Drift effective size is approximately one half census size in this population.     

Medical genetic research on the Khanty population of the Ovgort rural district of the Yamal-Nenets Autonomous territory

The results of medico-genetical studies of the Khanty from the Lower Ob river carried out by Tomsk Department of Institute of Medical Genetics of Academy of Medical Sciences of the USSR are presented. The population is characterized by a relatively high index of endogamy (0.54) and a low inbreeding coefficient (0.0011). Diseases of the polygenic mode of inheritance predominate among nosological forms of hereditary pathology.     

Social structure and consanguinity in a French mountain Population (1550-1849)

Sociocultural factors play a crucial role in the variation of consanguinity in a population. The choice of specific matrimonial strategies can favor the closure or opening of the group to the outside, whereas differential fertility affects the gene flow from one generation to another. In the present study we analyzed the role of socioprofessional groups in the maintenance of endogamy and consanguinity in a French Alpine valley: Vallouise in the Brian?on area. In mountain environments, where the reproductive space is limited and quickly saturated, the autochthonous families adopt diversified matrimonial strategies. These marriage practices tend to prevent fragmentation of agricultural property. We analyzed the matrimonial behavior in the two main social groups of this population (décideurs and farmers) from 1550 to 1849. To better understand the behavior of the two social groups, we considered the two components of consanguinity, close and distant. Our study showed that the two groups had similar behavior regarding consanguinity. The way to prevent fragmentation of the patrimony was to choose a consanguineous spouse. This type of strategy inevitably leads to a high percentage of endogamy, which in this region of the Alps exceeded 90% through many centuries.     

Genetic demographic characteristics of the rural population of the Tuva Republic: marriage structure and inbreeding]

Marriage structure was studied in three rural populations of the Tuva Republic: the Shinaan population and the populations of Todzhinskii and Bai-Taiginskii raions (districts). The Shinaan and Bai-Taiginskii populations had high levels of endogamy (0.6704 and 0.6050, respectively). In the Todzhinskii population, which was characterized by a mixed ethnic composition, endogamy was 0.3779 for the total population and 0.4626 for Tuvinians; interethnic marriages in this population were rare. The values of marriage assortativeness with respect to birthplace were 19.38, 40.75, 75.87, and 41.87% in the Shinaan, Bai-Taiginskii, all the Todzhinskii populations, and Tuvinian monoethnic marriages in the Todzhinskii raion, respectively. High marriage assortativeness with respect to ethnicity was found. Its values (A') were 91.85 and 93.49% in Tuvinians and Russians, respectively. Tuvinian populations were characterized by high inbreeding. The total (F(it)), random (Fst), and nonrandom inbreeding (Fis) estimated by isonymy were 0.004237, 0.002298, and 0.001944 in the Shinaan population, 0.007292, 0.009448, and -0.002177 in the Bai-Taiginskii population, and 0.003846, 0.004152, and -0.000307 in the Todzhinskii population, respectively (in the latter populations, the F(it), Fst, and Fis values for Tuvinian marriages alone were 0.005000, 0.007222, and -0.002238, respectively). The results obtained indicate that individual territorial groups of Tuvinians retain a high degree of genetic isolation from one another.     

The gene pool of the belgorod oblast population: Changes in the endogamy indices of district populations with time

Changes in the endogamy indices of district populations of the Central Chernozem region of Russia during the past 100 years were studied. The size of an elementary population in this region increased from that of a rural municipality in the mid-20th century to that of an administrative district in the late 20th century.     

Marriage and migratory characteristics of the urban population of Karachay-Cherkessia (End of the 20th century)

As part of systematic research carried out by the Laboratory of Genetic Epidemiology of the Research Center for Medical Genetics, the marriage and migratory structure of the urban population of Karachay-Cherkessia was studied. Numerical estimates of the population-genetic parameters were obtained from 11346 marriage records for 1990–2000. The endogamy, ethnic assortativeness, miscegenation and local inbreeding intensities, and mean-square migration for the four cities Cherkessk, Karachayevsk, UstDzheguta, and Teberda were estimated. It is shown that the autochthonic urban population is highly miscegenated, despite the traditional preference for monoethnic marriages. Half of the Russian urban population is migrant; the autochthonic urban population is substantially formed of Karachay-Cherkessia natives of.     

Isonymic analysis of population structure in Gredos, Spain

For the period 1875-1975 an isonymic analysis was made based on 41,696 marriages celebrated in three valleys (Tormes, Alberche and Tietar) from Gredos (Spain). Total inbreeding (Ft) was lower in the Tietar valley (0.0103- 0.0136), followed by the Tormes (0.0125-0.0255) and the Alberche (0.0153-0.0200). In the latter, random inbreeding (Fr) surpassed non random (Fn). Correlation coefficients were obtained to confirm an association of inbreeding from isonymy with valley and village endogamy rates, locality census, altitude, and alpha inbreeding. Fn correlated positively with average valley endogamy and village endogamy and with altitude, but inversely with census size. Contrarily, Fr related significantly to village endogamy. The non-random component from isonymy related positively to inbreeding from dispensations. Except for village endogamy, both variables show the same relationships to variables, such as altitude, which reflect limitations to mobility; or valley endogamy indicating the disposability of potential mates which in turn depends on the census size.