Over the last few decades, comparative biology of aging has aimed to identify factors responsible for the huge variability in lifespan observed across the animal kingdom. While these studies have undeniably improved our understanding of the complex processes that shape lifespan, we argue that time has now come to focus on specific aging metrics (e.g., age at the onset of aging, rate of aging) rather than on lifespan. Such a shift in research programs would help decipher the fine-scale mechanisms shaping age-specific mortality profiles across the tree of life