Il collo di bottiglia dell’epidemia di peste del 1629-1630 nella popolazione di Giaglione (TO).

Epidemic crises are bottlenecks that can dramatically alter the genetic pool of a population. They reduce the genetic variability and predispose, for the effect of drift, to the affirmation or the rarefaction of certain alleles. It is possible to study the effects of a “bottleneck” analyzing the structure of surnames in correspondence with the crisis and in the following period: unaltered frequencies suggest that mortality has equally affected the population without favoring or striking particular groups of individuals more than others. If the structure of the surnames is greatly altered, it becomes interesting to understand the reasons why there were more gaps in certain strata of the population than in others . The effects of the plague of 1629-1630 at Giaglione (TO) are here analyzed. The disease was brought in Val Susa by the French troops engaged in the Thirty Years War and affected the population from the spring 1629 to the summer 1630. About 1250 of 1650 residents of Giaglione died. Registers of burials are here used as sources. The frequencies of surnames prior to the outbreak were compared with those of subsequent years in order to determine the intensity of the bottleneck, and with those of the eighteenth century to study the repopulation of the town.