Vicente Fuster

Use of Surname Models in Human Population Biology: A Review of Recent Developments

Since 1985, when a bibliography concerning studies on surnames and genetic structure appeared, the number of publications on this subject has increased a thousandfold. New topics and uses have been added, but largegaps in knowledge remain. Only studies on isonymy in cities of nation states for recent times are well covered, and most studies are on populations that were selected because they are isolated and not because they are typical. This review, although not exhaustive, covers the literature published since 1985.

Causes of neonatal mortality in Spain (1975–98): Influence of sex, rural–urban residence and age at death

Neonatal mortality during the first week of life, corresponding to the years 1975-1998, was studied in Spain. The first week of life is the time in which the highest number of deaths occur. The temporal decrease of the neonatal mortality rate (NMR) was modelled according to log10(NMR+1)= 2.784 - 0.023 per year. This decline cannot be explained by an increase in the mean birth weight (MBW=23440.835 - 10.107 g per year). From the most frequent of the causes of death to the least were: congenital anomalies, preterm born or low birth weight, respiratory problems, pregnancy difficulties, hypoxaemia/asphyxia, delivery difficulties and infectious diseases. This sequence changed when the specific age at death was considered. The NMR descended evenly for both sexes for the causes indicated above, except for preterm born or low birth weight, in which the male mortality decrease was greater since its rate was more elevated at the beginning of the period studied. For all the causes listed, NMR was more elevated both in urban areas and for males. Early neonatal mortality (first 24 hours) was higher for pregnancy difficulties, preterm born or low birth weight, congenital anomalies and hypoxaemia/asphyxia.

Population relationships in the Mediterranean revealed by autosomal genetic data (Alu and Alu/STR compound systems).

The variation of 18 Alu polymorphisms and 3 linked STRs was determined in 1,831 individuals from 15 Mediterranean populations to analyze the relationships between human groups in this geographical region and provide a complementary perspective to information from studies based on uniparental markers. Patterns of population diversity revealed by the two kinds of markers examined were different from one another, likely in relation to their different mutation rates. Therefore, while the Alu biallelic variation underlies general heterogeneity throughout the whole Mediterranean region, the combined use of Alu and STR points to a considerable genetic differentiation between the two Mediterranean shores, presumably strengthened by a considerable sub-Saharan African genetic contribution in North Africa (around 13% calculated from Alu markers). Gene flow analysis confirms the permeability of the Sahara to human passage along with the existence of trans-Mediterranean interchanges. Two specific Alu/STR combinations-CD4 110(-) and DM 107(-)-detected in all North African samples, the Iberian Peninsula, Greece, Turkey, and some Mediterranean islands suggest an ancient genetic background of current Mediterranean peoples.

Factors associated with recent increase of multiple births in Spain.

The increased incidence of multiple deliveries in Spain, in addition to changes in age at maternity and parity, is attributed to assisted reproductive treatments, but the relative contribution of the latter to this rise remains uncertain, due to the scarce information provided by clinics practicing those treatments. Population based data (1984-2004), including information on mothers age, nationality, marital status, date of delivery, and the characteristics of each (parity, single or multiple), and sex of newborns were provided by the Spanish Institute of Statistics. Twinning and triplet deliveries relate to maternal age, parity, and nationality. For younger ages (<or= 19, 20-24, 25-29) rates remained constant over time, but for older women (30-34, 35-39, >or= 40) rates increased after 1994. From 1984 to 2004 the percentage of twins of opposite sex increased from 24.31 to 36.58 per cent. Since 1997, Spanish and non-Spanish mothers differentiate with respect to multiple maternity at ages over 30. In addition to unmarried Spanish women, immigrants constitute a reliable reference group that determines the convenience of segregating information on multiple deliveries respecting origin. The proportion of twins and triplets of opposite sex, maternal age, and parity patterns observed are concordant with a differential access to reproductive treatments depending on the womans age. The present norm regulating the maximum number of fertilizations per cycle and the demand for these treatments explain the high incidence of multiple deliveries in Spain. A modified logistic curve predicts a stabilization of multiple deliveries, which will probably continue to be high in Spain.

Consanguinity in Spain: Socioeconomic, Demographic, and Geographic Influences

Information on consanguinity in Spain was reanalyzed in order to obtain a more complete picture of consanguinity patterns by considering temporal, geographical, demographic, and economic factors. To obtain data on consanguineous marriages, we reviewed 106 published references. Only populations with homogeneous geographical characteristics, economic activities, transportation facilities, and the like, were considered. Two-way analysis of variance (ANOVA) provided highly significant differences (p < 0.001) for a both for time periods and for urban versus rural patterns, but there was no interaction between the latter two. A regression analysis shows that for rural areas the geographic characteristics, economy, communications, and index of demographic tendency were significant predictors of the inbreeding coefficient. The results obtained indicate that urban and rural patterns differ significantly and that the temporal factor needs to be taken into account before comparing inbreeding coefficients. In urban areas the census size and altitude are included in the regression equation as significant variables, but association was not found between a and the index of demographic tendency (population increase or decrease). Instead, the absolute number of inhabitants (census size) was significant. In rural areas geographic characteristics, communications, and index of demographic tendency were significant predictors of the inbreeding coefficient.

Inbreeding pattern and reproductive success in a rural community from Galicia (Spain).

The present paper is based on information on marital patterns and reproductive performance (reconstituted families) in the rural community of Los Nogales, Galicia, Spain. Biodemographic data were used to analyse temporal changes and structure of consanguinity in the population, as well as consanguinity versus reproductive success. Of 2347 marriages celebrated between 1871 and 1977, 5.15% were between relatives (up to third degree). The populations inbreeding coefficient was above the Spanish average after 1890, and levels were high during the first part of the 20th century. A possible underestimation of inbreeding coefficients is attributed to the elevated frequency of extramarital births occurring in the Los Nogales population (13.47%). The structures of consanguineous matings, expressed as C22/C33 and C33/C44, turned out to be 0.86 and 0.82 respectively. Regarding migration, before 1920 consanguinity increased, but net migration was negative. In the period 1920-1929 consanguinity began to decrease, prior to maximum emigration. As for reproductive success, information from 1503 reconstituted families shows that complete fertility was slightly higher among consanguineous families despite a greater infant mortality. Lower infertility in consanguineous matings, as well as lower age at marriage and first maternity, could explain the above results.

Secular changes in stature and biacromial and bicristal diameters of young adult Spanish males

Measurements of stature and biacromial and bicristal diameters were obtained for two samples of young adult male university students, one from 1901 to 1919 and the other from 1989 to 1991. Means and standard deviations were calculated for each measurement and for three indices. Significant positive trends in stature and biacromial and bicristal diameters were apparent between the two samples: 7.3 cm (4.4%), 3.6 cm (9.9%), and 3.4 cm (12.5%), respectively. The results for stature were compared with other Spanish samples from the beginning of the century to the present. These comparisons also showed positive secular changes, although the differences among samples may have been conditioned by regional variations in socioeconomic conditions, industrialization, and so on, all of which complicate the interpretation of the magnitude of changes in Spain. In summary, the results show a positive secular trend in body dimensions, and this can be related to the improvement in living conditions in Spain, especially during the last 40 years.

Socioeconomic, Demographic, and Geographic Variables Affecting the Diverse Degrees of Consanguineous Marriages in Spain

In a population the inbreeding coefficient ;ga is determined by the relative incidence of the various degrees of consanguineous marriages—uncle-niece or aunt-nephew (C12), first cousin (C22), first cousin once removed (C23), second cousin (C33)—which may be related to temporal, geographic, demographic, and economic factors. Using published information from Spain corresponding to urban and rural areas, in this article we seek to establish how each specific relationship behaves with respect to geographic, demographic, and socioeconomic factors, to determine differential urban-rural patterns, and to study whether the diverse types of consanguineous matings relate homogeneously to these factors. For this purpose we performed multiple regressions in which the dependent variables were the different degrees of consanguinity previously selected and the independent variables were geographic, demographic, and economic factors. Our results indicate that the various types of consanguineous marriages in Spain are more conditioned by geographic, demographic, and economic variables than by the inbreeding level ;ga (the coefficient of determination was between 0.22 and 0.72; the maximum for ;ga was 0.35). A regional pattern exists in Spain and corresponds to close and to remote kinship, which may be mainly related to economic and family factors. Close relationships appear to be more associated with economic variables, whereas second-cousin marriages correspond largely to rural areas of the Spanish Central Plateau.

Reproductive pattern in a rural Mediterranean population: La Alpujarra, Spain.

The reproductive pattern of a sample of nuclear families from La Alpujarra (Andalusia, Spain) is analysed. The origin of the wife or consanguinity of the couple does not influence fertility. Variability in number of pregnancies is most closely associated with marriage duration followed by the wifes year of birth. Differences in the number of births are explained more by the number of pregnancies than by the number of miscarriages. The number of survivors to the first birthday is dependent on the number of births and to a lower extent on infant mortality. Data from incomplete families show that reproductive performance of the wife below the age of 45 cannot be accepted as a reliable estimate of complete reproduction.

Factors determining the variation in birth weight in Spain (1980–2010)

Background: Low weight and premature deliveries arouse clinical interest concerning the survival of newborns. The determinants of birth weight among Spanish natives and immigrants may differ. Research which considers maternal origin and associated factors such as age and parity is important. Aim: This study analyses and models the influence of the rapid and intense arrival of immigrants in Spain on birth weight variation. Method: Data on deliveries from the Spanish National Institute for Statistics (n = 9 443 882) are analysed regarding low birth weight, premature births and other variables. The inter-relation among these variables was interpreted by means of logistic regression models. Results and conclusions: The birth weight has decreased since 1980 in Spain, but has slightly recovered in recent years. Meanwhile the percentage of foreign maternities increased to 17.3% in 2010. Logistic regression models assess the different influence of variables known to determine low birth weight (weeks of gestation, sex, etc.) and other maternal characteristics (age at delivery, professional activity, etc.). The progressively greater contribution of foreign women to total births in Spain and their differential numerical input to the various risk groups have slowed the pattern of reduction in the mean weight of newborns in this country.