Inbreeding and demographic transition in the Orozco Valley (Basque Country, Spain)

Abstract

Inbreeding in the Orozco Valley (Basque Country, Spain) between the 18th and 20th centuries was investigated on the basis of ecclesiastical dispensations and surname lists. The variations over time are very similar to those observed elsewhere in Europe, with a major increase in the coefficient of inbreeding in the late 19th and early 20th centuries. This is due mainly to an increase in marriages between first cousins. A highly marked decrease in inbreeding is observed during the 20th century. The secular trends described by the coefficient calculated on the basis of dispensations and by that calculated on isonymy are very similar. The nonrandom component of isonymy reveals a selective search for a related spouse during the period of maximum inbreeding. These results are associated with the process of demographic transition which affected European populations as a whole in the 19th century, resulting in a greater availability of kin among potential mates and thus enabling inbreeding to increase to levels far higher than those observed for earlier centuries.

Secular trends in the relationship between surnames in a population: Study of a border town

“…The F r component is related to census size as well as to the exogamy rate, as it only depends on the distribution of surnames in the population and is independent of preferential mating or population subdivision (Abade et al, 1986;Peña et al, 2002;Robinson, 1983). The smaller the population, the greater the expected F r and the probability of two individuals sharing the same surname will increase.…”

Inbreeding levels and consanguinity structure in the Basque province of Guipúzcoa (1862-1980)

“…In contrast to this pattern, mean inbreeding levels registered over a long time span in the Spanish Basque Country are not particularly high, except for some local populations (Abelson, 1978;Zudaire, 1981;Alfonso-Sá nchez et al, 1997;Peñ a et al, 2002). The most consanguineous regions in Spain lie in the area of Submeseta Norte, which includes the provinces of León, Zamora, Palencia, and Soria (Blanco, 1998).…”

Temporal Trends in Sexual Behaviors and Sexually Transmitted Disease History Among 18- to 39-Year-Old Seattle, Washington, Residents: Results of Random Digit-Dial Surveys

“…1 These changes, termed "the second demographic transition," 2 include declines in first marriages and remarriages, increases in divorce rates, increases in proportions of women gainfully employed outside the home, decreases in proportions of couples with children and increases in proportions of childless couples, delays in age at first marriage and age at first childbirth, as well as the average age of childbirth. [3][4][5][6][7] In the United States, the percentage of adults ages 15 and older who were married declined from 69.3% and 65.9% in 1960 to 57.1% and 54% in 2003 for men and women, respectively. 8 Conversely, over the same time period, percentage of adults ages 15 and older who were divorced increased from 1.8% and 2.6% in 1960 to 8.3% and 10.9% in 2003 among men and women, respectively.…”