Discussion Paper no. 05-05


Data from historical populations provide an adequate context for the examination of the familial and environmental components of longevity. We have investigated the relation between sibling survivorship and longevity through French-Canadian children of a completed fertility cohort born between 1625 and 1704. The Cox regression model was used to analyze the effects of sibling survivorship on the survival time of these early Canadian inhabitants. Other covariates such as regional variation, secular trends (i.e. period effects), parental and spousal survival were also taken into consideration. Our findings show that individuals with at least one sibling surviving beyond 85 years of age had a life-long sustained mortality advantage over the general population. The risks of death after age 50 was 55% and 60% lower for females and males, respectively, having a long-lived sibling. In comparison, the parental of origin effects were negligible. Only the mother-son association in age at death was found significant among the four possible parent-child pairs. Overall, the various models provided better fit to male than to female data. Biological as well as social explanations are explored in order to account for the various results.