Longevity can be defined as either a duration or a life span. Although the term might bring to mind the time spent by a living being in a situation, such as a job or living, the term can also be seen as much more. The length of an occurrence, or its longevity, can be measured in various ways. It can be measured in clock time, which measures all occurrences according to the same scale, such as a 24-hour day, separated into durations of equal size; or it can be measured relatively, as compared with the longevity of another event. It can be accurate according to the clock, or it can be seen in terms of perceived duration, also known as social time.

Measuring longevity, or the duration of an event or occurrence, has changed as the methods of accurately depicting the passage of time have enabled its division into smaller and smaller inter­vals. Time was once measured by passages of the sun or recurrences of events, such as seasons or the appearance of a star in the sky. Time now can be measured in increments far shorter than a second.

Measuring time in relation to another occur­rence, such as a natural event, enables one to better comprehend longevity. However, recording and communicating such a duration to others requires their awareness of the relative measuring stick. The advent of the calendar, whether cyclic or linear, solar or lunar, enabled the consistent measuring of longevity according to a predetermined scale. Once this became possible, one could accurately date to the year, as defined by that calendar, a person’s life span or the duration of an event. However, because a variety of calendric measurements coexisted, the definition of a year could vary greatly, causing inaccuracies in comparing longevities over the eons based on the generic term year.

The advent of the clock, which first determined time by the hour (the shortest interval that could then be measured with reasonable accuracy), enabled one to define the longevity of shorter events, such as meetings or the time of prayers, with the result that events could be more closely defined. However, again there was the difference in the length of hour, whether it was solar or “of the clock.” Therefore, the hour of the day would have to be defined as clock time when stating a time; this is the basis for the term o’clock, meaning “of the clock,” as opposed to a time based on another measuring system of the hours.

When examining longevity, one must look not only at the number but also the measuring system used at the time the number was created. In Biblical times, for example, longevity of life, if considered by the same time spans used today, might seem extremely long. However, when exam­ining the length of a year in the times written about, one might determine that a year’s length was much shorter than that measured today by the Gregorian calendar.

Without a standard measure, duration is notori­ously subjective. An hour spent, for example, at a baseball game can seem to be much briefer than an hour spent in a dentist chair, and thus the longev­ity of these events, while they appear the same when measured by the standard measurements, seem to differ greatly to those experiencing them

The ability, and desire, to measure longevity is an essentially human trait. By knowing how long it takes for a plant to grow, or the length of time a dog lives as compared to a fish or hamster, humans gain a degree of control over the environ­ment. A growing dependence on clock and calen­dar time has led to increased desires to measure more by these standards. Although society has benefited from a standardized method of measur­ing longevity, the existence of the method has also led to more of a dependence on such measure­ments. Actual time is becoming more important than perceived or social time.

Sara Marcus

See also Dying and Death; Fertility Cycle; Gerontology; Life Cycle; Medicine, History of; Time, Measurements of

Further Readings

Kurtzman, J., & Gordon, P. (1976). No more dying: The conquest of aging and the extension of human life. Los Angeles: J. P. Tarcher.

Newton, T. (2003). Crossing the great divide: Time, nature and the social. Sociology 37(3), 433-457.

Trivers, H. (1985). The rhythm of being: A study of temporality. New York: Philosophical Library.

Whitrow, G. J. (1972). What is time? London: Thames & Hudson.