Before revision: At their extremes, the wide spectrum of aging theories can be categorized into programmed theories - which imply that aging follows a biological timetable, and error theories - which suggest aging occurs due to cumulative damage experienced by organisms.
After revision: At their extremes, the wide spectrum of aging theories can be categorized into programmed theories – which imply that aging follows a biological timetable, and error theories – which suggest aging occurs due to cumulative damage experienced by organisms.