Abstract
The analysis of 26 longevity curves of different populations of inbred (Fischer 344) and outbred (Sprague-Dawley) rats highlighted a remarkable between-populations variability in survival parameters. This variability is independent of the breeding characteristics of the strain. The two strains differed in the slope of the survival curves, with Fischer 344 rats showing a higher survival over the second year of life as well as a lower interindividual variability. A model-free approach based on principal component analysis allowed us to quantify these differences and to high-light some limitations of the classical Gompertzian approach.