Figure 1. Connection between the aging of single cells and cell populations for bacteria, yeast and metazoa.

Bacteria and yeast are seeded from spores and grow in a new niche. Cells primarily undergo replicative aging in the beginning (top row) while chronological aging dominates toward the end of each population’s lifespan (bottom row). Cell members of old populations (bottom row) have increasing tendency to acquire mutations that confer growth advantage due to genomic instability. Abbreviations: ES cell is embryonic stem cell, GASP is growth advantage in stationary phase, and ADDD is age-dependent dedifferentiation.