Searching for longevity determinants : following survival of newborns in a in-land village in Sardinia (1866-2006)

Abstract

The scientific debate on longevity and its determinants is lively and involves researchers from different disciplines. Finding a clear cut explanation for why some people live longer than others is not an easy task as longevity proves to be connected to more than one factor. Moreover, variables that are shown to be significant for longer survival in certain populations are not always relevant to individuals of other populations. Recently, researchers have identified in Sardinia the Blue Zone (BZ), thus denominated due to the significant number of cases of centenarians recorded as well as a low sex ratio value. This points to an exceptional favourable longevity of males when compared with the expected values in developed countries. A village located in this area was selected for the carrying out of a more detailed analysis at individual level and socio-demographic determinants of longevity were examined. A family reconstructed database was created using a multi-source approach, as this data collection strategy allowed for careful cross-checking of the data, thus guaranteeing data of high quality as well as an exceptionally high level of coverage of known survival. Historical data was therefore used to study today’s population, establishing a unique bridge between historical demography and the current level of longevity. The study focused on survival of newborns in the selected village during a period of 50 years – from 1866 to 1915 – and also took into consideration information on related family members. Each individual included in the database was followed from birth to death, as he/she went through marriage and family formation. Complete survival of all newborns was observed until the present. Based on careful review of the existing literature, the empirical model considered factors such as sex differential, the contribution of familial transmission both in terms of genes, biological, and shared environment, and the role played by environment operationalised considering early-life conditions. Concepts were organized into a life-course approach for survival analysis. The analysis of the data enabled to the estimation of mortality trajectories, which in turn confirmed the exceptional longevity of the population understudy and in particular of males. The investigation of differential survival among members of the same community brought to light the relevance of certain familial variables on survival, which are not exclusively genetic. The results achieved open the way to further studies.(DEMO 3) -- UCL, 200