The names of Spain: a study of the isonymy structure of Spain

In order to estimate the isonymy structure of Spain, we studied surname distribution in 283 Spanish towns based on 3.625 million telephone users selected from 6.328 million users, downloaded from a commercial CD-ROM which contains all 13 million users in the country. Since in Spain the surname is made by the paternal and the maternal surname, it was possible to classify surnames according to parental origin. Two matrices of isonymy distances, one for paternal and one for maternal surnames, were constructed and tested for correlation with geographic distance. For the whole of Spain, Euclidean distance was significantly but weakly correlated with geographic distance both for paternal and maternal surnames, with r = 0.205 +/- 0.013 and r = 0.263 +/- 0.012, respectively. Two dendrograms of the 283 sampled towns were built from the two matrices of Euclidean distance. They are largely colinear. Four main clusters identified by the dendrograms are correlated with geography. Given the surname structure of Spain, we were able to calculate from isonymy and for each town 1). total or expressed inbreeding, 2). random or expected inbreeding, and 3). local inbreeding. Total inbreeding, F(IT), was highest in the North Atlantic regions and lowest along the Mediterranean Coast. The lowest levels were found in Andalusia, Catalunyia, Valencia, and Navarra. Random inbreeding, F(ST), had a similar geographical pattern. Local inbreeding, F(IS), was relatively uniform in the whole of Spain. In towns, random inbreeding dominates over local inbreeding. From the analysis, it emerges that the northwestern area of Spain is the most inbred.     

Namesakes or relatives? Approaches to investigating the relationship between Y chromosome haplogroups and surnames

Population genetics successfully applies surnames as quasi-genetic markers when estimating similarity between populations and calculating the level of random inbreeding. These calculations are based on the isonymy coefficient, which assumes that every surname is monophyletic, i.e., it originated from a single common ancestor and all namesakes are therefore relatives. On the other hand, there is a general opinion that a typical Russian surname is polyphyletic: it originated multiple times and most namesakes are, therefore, not related to each other. Combined studies of Y chromosomes and surnames now allow us to address this issue. This study discusses approaches to statistical evaluation of Y chromosome haplogroup frequencies in groups of people bearing the same surname (namesakes). The proposed index of accumulated haplogroup frequency eliminates the artifactual effect of a randomly increased haplogroup frequency in namesakes by subtracting its population (expected) frequency from the observed value, while the expected frequency is calculated as the weighted average of the frequencies of this haplogroup in the populations where the surname carriers come from. From the total sample (comprising 1244 persons from 13 populations of the historical Russian area), 123 individuals carrying 14 most frequent surnames were chosen. A comparison of the haplogroup frequencies in these 14 namesake groups and in 14 respective population control groups compiled from the total sample showed that accumulation of certain Y chromosome haplogroups was nonrandom even in carriers of widespread surnames. An analysis of Y-STR haplotypes rather than Y-SNP haplogroups could provide a better insight into relationships between namesakes and will be the subject of further research.     

Inbreeding avoidance in an isolated indigenous Zapotec community in the valley of Oaxaca, southern Mexico

We analyzed inbreeding using surname isonymy in an indigenous genetic isolate. The subjects were residents of a rural Zapotec-speaking community in the valley of Oaxaca, southern Mexico. The community can be classified as a genetic isolate with an average gene flow of < or = 3% per generation. Surnames were collected for individuals in each household in pedigree form using the culturally traditional patronym-matronym naming. Estimation of inbreeding from surname isonymy is facilitated by the traditional patronym-matronym name assignment among indigenous Mexican populations. A total of 2,149 individuals had valid surname patronym-matronym pairings, including 484 deceased ancestors. Surname isonymy analysis methods were used to estimate total inbreeding and to segregate it into random and nonrandom components. The surname isonymy coefficient computed from 119 isonymous surname pairings (119/2,149) was 0.0554. The estimated inbreeding coefficient from surname isonymy was 0.0138 (0.0554/4). The random and nonrandom components of inbreeding were F(r) = 0.0221 and F(n) = -0.0091, respectively. The results suggest that consanguinity is culturally avoided. Nonrandom inbreeding decreased total inbreeding by about 41%. Total estimated inbreeding by surname isonymy was 0.0138, which is similar to inbreeding estimated from a sample of pedigrees, 0.01. Socially prescribed inbreeding avoidance substantially lowered total F through negative nonrandom inbreeding. Even in the situation of genetic isolation and small effective population size (N(e)), estimated inbreeding is lower than may have otherwise occurred if inbreeding were only random. However, among the poorest individuals, socially prescribed jural rules for inbreeding avoidance failed to operate. Thus the preponderance of inbreeding appears to occur among the poor, economically disadvantaged in the community.     

Marital and migration structure and inbreeding in the Adyg population]

Endogamy and gametic indices for both Russian and Adyg populations living in the Adyg autonomous region of Krasnodar district were determined on different levels of territorial units: village, rural, community (a group of villagers) and rural region. Inbreeding coefficient was estimated for Adyg population and its structure analysed: a random component contributes mostly to the inbreeding coefficient (Fst = 0.00991), non-random component of the inbreeding coefficient being Fis = 0.010009, which testifies to negative marital assortativity among Adygs. Local inbreeding "a" and decline in the inbreeding "phi" coefficient at a distance from 0 to 500 km were calculated using the Malecot's formula: the coefficient "a" was found to be 0.00397, which is in good accordance with the Fst.     

Surnames in the Azores: analysis of the isonymy structure

Geographic isolation is a significant factor to consider when characterizing human populations. The knowledge of the genetic structure of isolated populations has been of great importance to disease-locus positioning and gene identification. To investigate the genetic structure of the Azorean population, we conducted a survey based on the frequencies of surnames listed in the 2001 telephone book. We calculated the following parameters: isonymy (I), the random component of inbreeding (F(ST)), genetic diversity according to Fisher (alpha), Karlin-McGregor's migration rate (v), and Nei's distance. For the 1,271 subscribers and 163 different surnames, Graciosa island presented the lowest value of abundance of surnames (alpha = 15.75), suggesting great genetic isolation compared to the other eight islands. Migration, calculated on the basis of the diversity of surnames within islands, ranged from 0.2747 (Corvo island) to 0.0026 (S?o Miguel island), indicating that people migrated preferentially toward the economically more developed islands. The value of the random component of inbreeding obtained for the whole population (F(ST) = 0.0039) indicates little genetic differentiation (Wright's F(ST) < 0.05). Moreover, isonymy similarity revealed using the UPGMA method shows three subclusters corresponding to the geographic distribution of the islands.     

Surnames in the Study of Human Biology

Use of surname analysis in human population biology depends on surnames being inherited like genes. In societies that meet this condition, communities with a few surnames at high frequency are the more inbred ones, and marriages between persons of the same surname can be used to estimate rates of inbreeding. Furthermore, the degree of commonality of the surnames of two communities estimates their biological relationship provided that any two persons of the same surname derived it from a common ancestor and that virilocal and uxorilocal migration is equal. Although the assumptions are only partially met, the surname method yields results which correlate with the amount of marital migration and with geographical and historical features. Rare surnames meet the assumptions better than common ones. Documents, both old and new, yield surnames of large numbers of people which can easily be analyzed to show the cumulative effect of marital migration since the establishment of surnames (in England in the Middle Ages). Surnames thus serve to delineate the breeding structure of some human populations over a longer span of time than is usually possible with pedigrees, over a more definite span of time than in genetic studies, and more easily in broad surveys than alternative methods . [isonymy, surnames, inbreeding, coefficient of relationship, England]     

Genetic structure of the Utah Mormons: isonymy analysis

Isonymy analysis is reported for a sample of 188,895 marriages extracted from the Utah Genealogical Database. Inbreeding rates estimated by isonymy are low, ranging from 0.005 for the earliest marriage cohort (1800-1809) to 0.0008 in the most recent cohort (1950-1959). The inbreeding values decrease considerably through time, but they are consistently higher than inbreeding values estimated from pedigrees. Several explanations are offered for this, including polyphyletism of surnames and the presence of Scandinavian patronyms in this population. Random isonymy between subdivisions is also compared with random kinship estimated from migration matrices. In terms of within-subdivision kinship, the two approaches yield similar results. However, the results are quite dissimilar for between-subdivision kinship. This reflects the recent and nonrandom settlement of Utah by different ethnic groups with different surname distributions. In later time periods, the correlations between the two types of kinship estimates increase, showing that migration patterns (which are strongly determined by geographic distance) exert an increasing influence on the distribution of surnames. Logistic regression is performed on a subset of marriages (n = 88,202), using isonymous vs. nonisonymous marriage as the dependent variable. The independent variables are year of marriage, geographic distance between husband's and wife's birthplaces, endogamous vs. exogamous marriage, and population sizes of husband's and wife's birthplaces. Year of marriage and geographic distance are shown to be significant independent predictors of isonymous marriage.     

Namesakes or relatives? Approaches to investigating the relationship between Y chromosomal haplogroups and surnames

Population genetics successfully applies surnames as quasi-genetic markers when estimating similarity between populations and calculating a measure of random inbreeding. These calculations are based on an isonomy coefficient which assumes that every surname is monophyletic: that it originated from single common ancestor and all namesakes are therefore relatives. On the other hand, there is a general opinion that a typical Russian surname is polyphyletic: it originated multiple times and most namesakes are therefore not related to each other. Combined studies of Y chromosomes and surnames now allow us to address this issue. In this study, we discuss approaches for statistical evaluation of Y chromosomal haplogroup frequencies in groups of people bearing the same surname (namesakes). We propose an 'Index of Accumulated Haplogroup Frequency', which allows for errors due to random (artifactual) effects increasing a haplogroup frequency in a group of namesakes by subtracting the population frequency of this haplogroup. This population frequency is calculated as the weighted average of the frequencies of this haplogroup in the populations that the carriers of this surname come from. Fom the total sample (comprising 1244 persons from 13 populations of the historical Russian area) we chose 123 persons carrying 14 surnames which were the most frequent in the total sample. Haplogroup frequencies in these 14 "surname" groups were compared with the respective 14 "population" control groups compiled from the total sample as described above. We found that even these widespread surnames exhibit non-random accumulation of specific Y chromosomal haplogroups. More detailed analyses of the relationships between namesakes could be carried out using Y-STR haplotypes rather than Y-SNP haplogroups, and will be the subject of a future study.     

Trends in inbreeding, isonymy, and repeated pairs of surnames in the Valserine Valley, French Jura, 1763-1972

The estimates of inbreeding derived from pedigrees and frequency of isonymous marriages (i.e., between persons of the same surname) are compared using genealogical and isonymic information from 4,899 marriages recorded between 1763 and 1972 in 4 rural villages of the French Jura region (a mountainous area near the Swiss border). Before the second half of the 20th century, the two kinds of estimates show a different temporal evolution. The mean inbreeding coefficient based on pedigrees increases between 1763 and 1852 and reaches a maximum between 1853 and 1882 (alpha = 0.0028), with a very low percentage (< 1%) the result of remote kinship. The mean inbreeding coefficient based on isonymy is always higher, with a maximum observed between 1793 and 1822 (F = 0.0200), and it remains roughly the same between 1763 and 1882 (F = 0.0150), with a high percentage resulting from a random component (Fr), a consequence of the small population size and genetic drift. After 1883, the 2 mean coefficients decrease. This discordance is largely explained by the poor quality, for the first periods, of the genealogical data base, which ignores the more remote links of kinship, justifying the use of the model of Crow and Mange (1965) to explore consanguinity during the more ancient periods. The temporal evolution of the repeated pairs of surnames index (RP) confirms the recent evolution of the marital structure of the valley. Moreover, it appears that isonymous marriages and repeated and unique pairs of surnames constitute 3 distinct matrimonial groups characterized by both a different mean coefficient of inbreeding (alpha) and a different rate of endogamy.     

Population structure of São Miguel Island, Azores: a surname study

The knowledge of a population structure may constitute a powerful tool for mapping genes underlying susceptibility to Mendelian and complex diseases. To obtain a better understanding of the population structure of S?o Miguel Island (Azorean Archipelago, Portugal), we carried out a surname survey using the surnames listed in the most recent telephone book (2001). We identified 1315 different surnames in a total of 27,621 subscribers. The frequency of the different surnames was used to calculate the following parameters: isonymy (I), random component of inbreeding (FST), genetic diversity according to Fisher (alpha), migration rate according to Karlin-McGregor (v) and Nei's genetic distance. Eleven localities were selected, according to population size and geographic distribution, for analysis using the above parameters. Our results show that 51% of Salga's population and 52% of Sete Cidades's population are represented by six and eight surnames, respectively. These figures demonstrate the effective isolation of these two small places, which are located at opposite ends of S?o Miguel Island. Salga, Achada, and Sete Cidades present the lowest values of Fisher's alpha, indicating less genetic diversity. In contrast, the capital, Ponta Delgada, presents the highest value of alpha (78.13), indicating more genetic diversity. Our data indicate that the clustering of the localities corresponds to the geographic features of the island, where localities close together tend to share similar surnames. In conclusion, the population of S?o Miguel is relatively homogeneous and may constitute an ideal model for genetic mapping studies.     

Population structure of rural settlements of Sakha Republic (Yakutia): surname structure

The distributions of surnames have been studied in 12 rural ethnic territorial groups of Sakha Republic (Yakutia). The populations studied are characterized by considerable accumulation of individual surnames, the surname spectra of representative of different ethnic groups living in the same area substantially overlapping. The random isonymy, migration index, surname diversity, and the surname distribution redundancy index display geographic and ethnic differences. The isonymy relationship coefficients calculated for representatives of individual ethnic groups (Yakuts, Evens, and Russians) and for total populations of the settlements studied are determined by the geographic distances between the compared populations and the intensity of migrations.     

A study of contemporary levels and temporal trends in inbreeding in the Tangier Island, Virginia, population using pedigree data and isonymy

In this study we describe inbreeding in a large pedigree from Tangier Island, Virginia, in which we compare two commonly used methods to estimate inbreeding in humans: pedigree and isonymy (identical surnames of spouses). Genealogical data on 3,512 individuals dating back to 1722 were used. Using the pedigree method, we determined an average inbreeding coefficient (F) of 0.00873 for the community as a whole, and 0.018 for inbred individuals. Analysis of temporal trends showed that inbreeding began around 1800 and peaked at 0.0109 in 1824-1849 and 1875-1899. Thereafter, inbreeding steadily declined to 0.00565 in 1975-1997. Analysis of pedigree structure complexity over time showed that close consanguinity contributes to inbreeding in the earlier cohorts, and remote consanguinity accounts for much of the inbreeding in the later cohorts. The number of common ancestors increases over time, as does the number of paths connecting inbred individuals to these common ancestors. Inbreeding estimates based on the isonymy approach yielded a 2.2-fold higher value of F (0.01945) compared to the pedigree method. Total isonymy estimates over 25-year cohorts overestimated inbreeding values from pedigree data between 1. 5-8-fold. We speculate that the overestimation is probably due to the inability of our data to satisfy the method's assumption of monophyletic origin of each surname. In conclusion, inbreeding in the Tangier Island population is consistent with the isolated nature of its population, and temporal trends reflect patterns in emigration and a breakdown in isolation over time.     

Population structure of rural settlements of Sakha Republic (Yakutia): Surname structure

The distributions of surnames have been studied in 12 rural ethnic territorial groups of Sakha Republic (Yakutia). The populations studied are characterized by considerable accumulation of individual surnames, the surname spectra of representative of different ethnic groups living in the same area substantially overlapping. The random isonymy, migration index, surname diversity, and the surname distribution redundancy index display geographic and ethnic differences. The isonymy relationship coefficients calculated for representatives of individual ethnic groups (Yakuts, Evens, and Russians) and for total populations of the settlements studied are determined by the geographic distances between the compared populations and the intensity of migrations.     

A medico-genetic study of the population of Western Pamir. VI. Local genetic differentiation in the populations of Western Pamir]

The article comprises the results on the analysis of the structure of the great Pamirs' population (of a higher rank) and of one of its parts, the subpopulation of the valley of the river Bartang. Wright's F coefficient was used for the statistical treatment of the data obtained in the course of the analysis. The FST estimates were obtained from the variances of the frequencies of the genes located in 5 loci (ABO, MN, P, Rh and P.T.C.) culculated for 23 samples of the great populations of the Pamirs and for 9 samples of the population of the Bartang river valley. The general inbreeding coefficient for the Pamirs FIT=0,0323, its random component FST=0,0017 and the non-random component FIS=0.0306.     

Genetic kinship among an isolated Adi tribe of Arunachal Pradesh: isonymy in the Adi Panggi

Isolated tribes in remote areas are important for genetic studies, and one such little known subtribe of the Adi tribe, namely, the Adi Panggi (Pangi) of the Upper Siang District of Arunachal Pradesh, India, was studied for surname distribution to deduce the deviation from random mating and genetic kinship between villages. The estimates of homonymy (homozygosity) vary between villages; husbands show wider variation (0.009 to 0.23) than wives (0.005 to 0.054). The remote villages of Sumsing and Sibum and Geku Town show lower entropy among husbands' surnames than among Panggi wives. The highest equivalent surname number was found among Sibum husbands (9.9), Panggi wives (12.6), and Panggi and non-Panggi wives (13.5). The estimates of unbiased random isonymy among husbands and wives together show the smallest values in Sibum (0.05) and the highest values in Sumsing and Ramku (0.16). The random and nonrandom components of the inbreeding coefficient show avoidance of inbreeding among the Panggi villages (-0.012 to -0.27) except in Sibum (0.012). Genetic kinship between villages based on the Mij distance shows different clusters of villages among husbands and wives. Both the Panggi wives and the Panggi and non-Panggi wives show a similar pattern of clustering between villages. The wide homonymy variation between villages among the patrilocal Adi Panggi indicates differential genetic kinetics among husbands and wives, avoidance of inbreeding, and female-oriented differential gene flow with little effect on the overall intervillage genetic kinship.     

Note on estimates of the inbreeding coefficient through study of pedigrees and isonymous marriages

Crow and Mange (1965) developed a method to estimate the inbreeding coefficient (F) through an ingenious surname analysis. Such formulations assume a regularity of transmission of surnames, monophyletism, and random occurrence of consanguineous marriages. Accordingly, the ratio of isonymous partners to F of the offspring is equal to 4. Nevertheless, genealogy analyses show that the consanguineous marriages do not necessarily occur regularly. Therefore the isonymy analysis gives a misestimation of the inbreeding coefficient, depending on the prevailing form of nonrandomness. We suggest a small correction to the formulation in situations when pedigree information is available. The weighted mean of the ratio of isonymous partners to F of the known consanguineous marriages is suggested as a way to improve the formulas. The technique was applied to a northeastern Brazilian sample, and the results agree well with those of bioassays and therefore provide an apparently more realistic estimate of the inbreeding coefficient by isonymy.     

Examining population structure through the use of surname matrices: methodology for visualizing nonrandom mating

The analysis of nonrandom mating using the frequency of marital isonymy indirectly measures the degree of population structure. However, population structure is the result of all matings in a population. Difficulties with large surname matrices have resulted in data being summarized into a single statistic or collapsed into brief tables, with considerable loss of information. By using sophisticated computer graphing procedures and displays, it is possible to directly analyze the mating structure of a community. If P is a vector of proportions for each male surname i (i = 1, 2, 3, ..., n), Q a similar vector of female surnames j(j = 1, 2, 3, ...,m), then the expected frequency matrix E of each possible mating is P x Q. The difference D between the observed frequency matrix O and the expected matrix is O-E. The D matrix is graphed with the x axis containing the male surnames, the y axis the female surnames, and the z axis the difference values dij. Negative values represent negative nonrandom mating and positive values positive nonrandom mating. From 5417 marriages (1840-1963) in the Midlands of Tasmania, those between spouses having 1 of 194 core names were extracted. We analyze these marriages utilizing the new technique and examine the surface of the graph and statistical analysis of its finer structure. Among the results was the demonstration of frequency-dependent selection of surnames. This finding has significant implications for microevolution of human populations, as surnames have existed for possibly 700 years.     

Isonymy structure of USA population

The isonymy structure of the 48 states of the continental United States of America was studied using the surname distributions of 18 million telephone users, distributed in 247 towns. The shortest linear distance between nearest neighbor towns included in the sample was 12.0 km. The largest distance was 4,577 km. The number of different surnames found in the whole analysis was 899,585. Lasker's distance was found to be significantly but weakly correlated with the geographic distance, with r = 0.21 +/- 0.01. A dendrogram of the 48 states was built from the matrix of isonymy distances: it divides the US into several clusters, in general correlated with geography. A notable exception is California and New Jersey, which cluster together. Wisconsin is separated from all other states. An important cluster is formed by Texas, Colorado, New Mexico, Nevada, and Arizona, together with Illinois and Florida. It was observed that Hispanic surnames are among the most frequent in Illinois, as they are in New Jersey and California. No main distinction among the states clearly attributable to surnames of French origin was detected; however, New Hampshire, Vermont, and Maine which have a considerable number of these surnames belong to the same northeastern cluster. From the present analysis, the great mobility of the US population emerges clearly, and it seems relevant that the practical absence of isolation by distance is seen also considering only small towns. It appears that groups of different origin are well-mixed over the whole area of the United States. The values of isonymy indicate that the south-central area of the USA has the highest level of inbreeding. In fact, the heterogeneity in surname composition is greater in the coastal areas, particularly on the East Coast, than anywhere else in the USA.     

Genetic demographic description of the Ust-Aldan rural population of Sakha Republic (Yakutia): ethnic, sex, and age compositions, vital statistics, and surname structure

Information on the sex, age, and ethnic compositions; reproductive parameters; intensity of natural selection (Crow's indices); and surname diversity of three rural populations (the Byadi, Dyupsya, and Cheriktey villages) of the Ust-Aldan ulus (district) of Sakha Republic (Yakutia) has been analyzed. The rural Yakut population of the Ust-Aldan ulus is demographically young (the mean age 25-31 years) and characterized by low outbreeding, unfavorable sex ratio in both prereproductive and reproductive ages, and high fertility (3.58-5.45 children surviving until the reproductive age per woman that has completed the reproductive period), although the actual reproductively active period is shorter than half its physiological duration. In the structure of total selection, the differential-fertility component is considerably greater than the differential-mortality component (Itot = 0.625, Im = 0.093, and If = 0.487). In the villages studied, some surnames are accumulated (45-65% of the population have five most frequent surnames), which determines the low surname diversity (alpha = 11.62-25.19) and high random isonymy (Ir = 0.0391-0.0823).     

Patterned selection of mates in St. Ouen, Jersey, and the Scilly Isles examined by isonymy

Within-lineage repeated-pair isonymy is calculated as RPW = sigma [Sij(Sij - 1)]/sigma [Si(Si - 1)], in which Sij is the number of a combination of two surnames in marriages (for total RPW, in both orders, brides first and also grooms first) and Si is the corresponding number of individuals of each surname (for total RPW of both sexes). In St. Ouen the 3479 native Jersey marriages between 1634 and 1914 yield a mean total RPW of 0.03314, which can be compared with a random isonymy (Ir) of 0.02205 and a marital isonymy (Im) of 0.04942. In the most recent time periods (1830-1914) there was an increase in RPW, but the increase is small if all marriages are considered rather than only native Jersey ones. In the Scilly Isles 2827 marriages between 1725 and 1975 yield a mean total RPW of 0.05127, which compares with a mean Ir of 0.01960 and an Im of 0.05238. In each kind of isonymy there is a decline over 1850-1975 caused by increased migration to the Scilly Isles. In the Scilly Isles RPW consistently approximately equals Im, so the nonrandom component of inbreeding is fully accounted for by factors that affect marital choice in the whole lineage. In St. Ouen, however, RPW is intermediate in value between Ir and Im, so the nonrandom component of inbreeding is only partly a lineage phenomenon and is also affected by other (individual) factors in choice of spouses.