Inbreeding and matrimonial structure in a Pyrenean community (Ansó, Huesca, Spain), 1712-1982.

Using data from parish records from 1712 to 1982 in a Spanish Pyrenean village, Ansó, the effects of the raw nuptiality, the types of consanguineous marriages and the rate and evolution of inbreeding on the mating structure have been studied. This structure has been modified in the course of time mostly through the secular variations in the frequency of consanguineous marriages. Recent inbreeding decrease in Ansó is related to the population diminution and cultural changes associated with isolate breakdown.