Annals of Human Biology, May–June 2006; 33(3): 330–341 ORIGINAL ARTICLE Reproductive pattern in consanguineous and non-consanguineous marriages in La Cabrera, Spain M. J. BLANCO VILLEGAS 1 & V. FUSTER 2 1 Departamento de Biologı´a Animal, Universidad de Salamanca, and 2 Departamento de Zoologı´a y Antropologı´a Fı´sica, Universidad Complutense de Madrid, Spain (Received 21 July 2005; revised 20 December 2005; accepted 24 January 2006) Abstract Background: Among determinants of the structure of human populations, consanguineous marriages can be useful in determining to what extent they influence the genetic structure of the population. This knowledge may be gained by comparing the reproductive performance of related and non-related couples. The population studied, La Cabrera, is a mountainous region in the Leon province (north- western Spain). It includes four neighbouring municipalities with similar geographic, climatic and ecological features with 37 parishes occupying an area of 784.2 km 2 , of which only 1.5% is arable. The number of inhabitants remained stable from 1887 (9526 inhabitants) to 1960 (8984), when due to emigration it began to decrease. The average inbreeding coefficient () for the period 1880–1989 (up to third degree) was 4.82  10 3 . Aim: The objective of this analysis was to evaluate the possible factors determining the differences between consanguineous and non-consanguineous families residing in La Cabrera during the period 1880–1959. Subjects and methods: To study the structure and dynamics of each couple, families were reconstituted for the period 1880–1959 using demographic data corresponding to births, deaths and marriages obtained from parish registers. This procedure provided information on each couple’s reproductive history through information concerning the mates’ deaths as well as their offspring’s births and deaths. Principal component analysis revealed the existence of three factors that together explained 57% of the reproductive pattern variability of La Cabrera. Results: The first component (eigenvalue: 3.56) correlated positively with the number of live births and with the duration of the reproductive period. Component II (eigenvalue: 1.54) had a positive correlation with variables describing the beginning of the marital union, and with those indicating its ending. Finally, component III (eigenvalue: 1.13) reflected a negative association with the two variables that described neonatal and post-neonatal mortality. The above demographic variables represented the reproductive process in La Cabrera adequately. Fertility was the variable that offered the best explanation of the reproductive pattern (32%), followed by the marital structure (13%) and the infant mortality (12%). Conclusion: In the La Cabrera population, consanguinity appears as a socio-cultural process that affects the reproductive dynamic. Consanguinity modifies the marital structure and alters the reproductive Correspondence: M a Jose ´ Blanco Villegas, Departamento de Biologı ´a Animal (Antropologı ´a Fı ´sica), Facultad de Biologı ´a, Universidad de Salamanca, Campus Universitario Miguel de Unamuno, 37071 Salamanca, Spain. E-mail: mache@usal.es ISSN 0301–4460 print/ISSN 1464–5033 online ß 2006 Informa UK Ltd. DOI: 10.1080/03014460600627529 Ann Hum Biol Downloaded from informahealthcare.com by Dr V. Fuster on 10/22/14 For personal use only.