The effects of geographical and prolonged cultural isolation on the marital behaviour of an Alpine community (Valsesia-Italy, 1618–1899)

The settlement of the “Alta Valsesia” during the XIII century by the ethnic group “Walser” coming from the Switzerland region “Vallese”, left clear historical and cultural traces. In the present study we analysed the “Alagna Valsesia” community (Piedmont). The aim of this research is to reconstruct the demographic and the matrimonial structure of this cultural and geographic isolate over three centuries and to evaluate the degree of isolation through the analysis of some biodemographic parameters calculated on the bases of parish registers, from 1618 to 1899 (1503 marriages). Data on the population dynamics highlighted an early depopulation, since 1500, than led in 1800 to a decline to population of about 60%, relating to the well known phenomenon of the leaving of mountainous isolate. The analysis of the marriages shows a low rate of endogamic mating (82%). This rate reach the highest peak 93% between 1650 and 1659, then it decreases to the minimum values 67% in the middle of 1700. The rates of consanguineous and isonymic marriages are around 20% and 4–5% respectively, reaching the maximum values during 1800; with the only exception for the period between 1700 and 1749, when the rates decreases because of a substantial migratory flow. Inbreeding coefficient stressed out — values between 0,4×10–3 and 2,4×10–3, not so different from the ones reported for other Italian mountainous isolates. The analysis of the seasonality of marriages high-lighted a strong concentration of marriages during winter months, particularly in January and February, when works were suspended because of the cold.