Social structure and consanguinity in a French mountain Population (1550-1849)

Sociocultural factors play a crucial role in the variation of consanguinity in a population. The choice of specific matrimonial strategies can favor the closure or opening of the group to the outside, whereas differential fertility affects the gene flow from one generation to another. In the present study we analyzed the role of socioprofessional groups in the maintenance of endogamy and consanguinity in a French Alpine valley: Vallouise in the Briançon area. In mountain environments, where the reproductive space is limited and quickly saturated, the autochthonous families adopt diversified matrimonial strategies. These marriage practices tend to prevent fragmentation of agricultural property. We analyzed the matrimonial behavior in the two main social groups of this population (décideurs and farmers) from 1550 to 1849. To better understand the behavior of the two social groups, we considered the two components of consanguinity, close and distant. Our study showed that the two groups had similar behavior regarding consanguinity. The way to prevent fragmentation of the patrimony was to choose a consanguineous spouse. This type of strategy inevitably leads to a high percentage of endogamy, which in this region of the Alps exceeded 90% through many centuries.