Familial and Environmental Influences on Longevity in Historical Quebec

Survival advantage of siblings and spouses of centenarians in 20th-century Quebec

“…The relationship was even stronger for women, with a corresponding difference of 4.3 years. These observations agree with those of Mazan and Gagnon (2007) which confirmed that both men and women benefit from the longevity of their spouses. For men, each additional year of life of their spouse reduced their risk of death by 0.6% (6% for 10 years), while the corresponding figure was 0.5% for women (5% for 10 years).…”

“…This study revealed greater lifespan variability for sisters than for brothers, corroborating observations from Desjardins and Charbonneau (1990) of a higher correlation in ages at death among brothers than among sisters. Mazan and Gagnon (2007) explored the same relationships for individuals born between 1625 and 1704 and also found a high dependency in ages at death among siblings, with reduction in mortality risks of 2.1% and 1.6%, respectively, for men and women, for each additional year of increase in the average age at death among their siblings. On the other hand, using hierarchical modeling, the authors found very little evidence for a strong parent-offspring association and argued that such association, at least in pre-industrial context, has been generally overemphasized and overestimated.…”

“…The inclusion of age at death of spouses allows to control for the shared environment in adulthood, because spouses who have shared many aspects of their daily life for several years are likely to benefit from the longevity of one another (Mazan and Gagnon 2007;Drefahl 2010). Nevertheless, although a few studies have stressed the importance of spouse survival on longevity, we have little information on the effect of this component at very old ages, let alone in families of centenarians.…”

“…We found 390 dates of death for the original 596 spouses, representing 65% of our spouse sample. Since our focus is on old-age mortality, and early deaths are not related to the biology of aging (Vaupel 1988;Mazan and Gagnon 2007), only individuals who survived to age 40 were included in our sample. Thus, the final sample is based on 2,954 siblings of centenarians, or 1,541 brothers and 1,413 sisters, as well as 76 wives and 314 husbands.…”

“…Siblings also share 50% of their genes on average (Gagnon et al 2005) and, to a large extent, the same environmental and social conditions during childhood. They may also influence each other's health and longevity through mutual support in old ages (Mazan and Gagnon 2007).…”