Life expectancy in a western and immigrant receiving population (El Ejido, SE Spain).

This study deals with the mortality pattern of El Ejido population, an agricultural Spanish community with a sub-tropical climate, located on the western Mediterranean coast (Andalusia). Based on the incorporation of modern agrarian techniques, this region has experienced a great economic development. Its demographic consequences were relevant, such as the arrival of immigrants throughout the second half of the twentieth century.

Season of birth affects short- and long-term survival.

Recent research findings have highlighted the importance of early life conditions as risk factors for adult diseases and therefore determinants of subsequent survival. Given that individuals born during different seasons in seasonal environments experience different early-developmental conditions, an analysis of the effects of the season of birth on survival is considered an effective approach in clarifying the influence of early life conditions on survival in later life. In the present study, we analyzed the long-term effects of early developmental conditions in a historical population in which both nutritional levels and the burden of infectious diseases showed a seasonal variation.

Genetic relationships between parishes in the Ebro delta region (Spain) as estimated by migration matrix and surnames.

To determine whether there are preferential relationships among individuals from the different parishes of the Ebro River delta region, we analyzed the population relationships, taking into account both the birthplaces of the spouses and their surname frequencies. We used data from the 9,085 marriages recorded in the Ebro delta area between 1939 and 1995. Using each spouse's birthplace, we calculated the distances between the subject populations by means of the squared Euclidean distance.

Y-chromosome-Specific STR haplotype data on the Rapanui population (Easter Island).

Located in the south Pacific Ocean, Rapanui is one of the most isolated inhabited islands in the world. Cultural and biological data suggest that the initial Rapanui population originated from central Polynesia, although the presence of foreign or exotic genes in the contemporary population, as a result of admixture with Europeans and/or South Americans during the last two centuries, also has to be considered. To estimate the genetic affinities of the Rapanui population with neighboring populations, we analyzed seven microsatellite polymorphisms of the Y chromosome that recently have been indicated as useful in the study of local population structure and recent demographic history.

Inbreeding from isonymy and repeated pairs of surnames in the Ebro Delta region (Tarragona, Spain).

The aim of the study was to evaluate the levels of inbreeding calculated from isonymy with its random (Fr) and nonrandom (Fn) components, and repeated pairs of surnames (RP2) and their random component (RP2r) in the Ebro River Delta region (Tarragona, Spain). This region is made up of four parishes, and data correspond to the period 1939-1995. The global results are on the same levels as observed in other studies, but the values obtained in 3 of 4 parishes are relatively high.

Inbreeding and surnames: a projection into Easter Island's past.

The population of Easter Island is one of the most interesting extant human communities due to its unique demographic history, its geographic isolation, and the development of an incomparable culture characterized by the towering "Moais" and its enigmatic writing. Following the colonization of its population by Polynesians from the Mangarevan Islands in the 5th century AD, the island remained isolated up until the middle of the 20th century. Under these conditions, with endogamy levels fluctuating between 61.

Twin seasonality in a rural Catalonian population.

The seasonality of twinning in the Spanish populations has not been studied until now. Differences between seasonal distribution of the twin conceptions and those of the single births have been observed in other populations. The aim of this work is to explore the frequency of twinning in a rural population from Catalonia during the nineteenth century, as well as the seasonality patterns characterizing each of the twinning types.

Origin of Fueguian-Patagonians: an approach to population history and structure using R matrix and matrix permutation methods.

A complicated history of isolation between Fueguian and Patagonian groups (originated by the appearance of the Straits of Magellan) as much as differences in population structure and life strategies constitute important factors in the clustering pattern of those groups. The aim of this work was to test several hypotheses about population structure and history of Fueguian-Patagonians to propose a model that incorporates predictions for future studies. R matrix methods and matrix permutation analyses were performed upon a data matrix of craniofacial measurements of 441 skulls divided into nine samples pertaining to six Patagonian and three Fueguian populations.