Every dog owner knows that personality changes over time, but these changes occur unevenly during the dogs' life, and each trait follows a distinct age trajectory, according to a new study. Human personality is characterized by a peculiar dualism: it is both stable and malleable, depending on the point of reference. If we compare ourselves to our peers, it is stable as our personality rankings relative to others remain consistent over time. However, personality changes became obvious if we compare ourselves across time, as people become more conscientious, more emotionally stable, and more agreeable as they get older.