Population age structure, complex socio-demographic systems and resilience potential. A spatio-temporal, evenness-based approach

The present study illustrates an original approach grounded on entropy theory and complex system thinking with the aim to investigate changes over time and space in population structure by age in Italy, in light of socioeconomic resilience and post-crisis recovery potential. Assuming that population structure may reflect different levels of resilience to exogenous shocks, a Pielou J evenness index was calculated on census data made available every 10 years (1861-2011) with the aim to identify compositional homogeneity (or heterogeneity) in the age structure of the Italian population. Trends over time in the Pielou J evenness index were identified using descriptive statistics, comparison with ancillary demographic indicators and multivariate exploratory techniques including principal component analysis. The empirical results allowed the identification of multiple dimensions of demographic transition in Italy, distinguishing two phases, the former encompassing a relatively long time period between 1861 and 1936, and the latter covering a shorter period between 1936 and 2011. A spatially-explicit analysis of Pielou J evenness indices applied to the population age structure of each Italian municipality at the latest survey (2017) finally provided a comprehensive overview of the demographic characteristics likely influencing the resilience potential of local districts. The empirical evidence outlined the consolidation of a coastal-inland divide as a result of the complex linkage between demographic dynamics and local background contexts.