Methuselah was 969 years old when he died (see Gen. 5:27), Noah was 950 (see Gen. 9:29), and Adam was 930 (see Gen. 5:5). Why did these and other ancient patriarchs who lived before the Flood live so long?
It is important to consider three points before attempting to answer why. First, modern revelation supports the scriptural indication that many Old Testament patriarchs lived incredibly long lives (see Moses 8:1–13; D&C 107:41–53). Second, early prophets of this dispensation understood these scriptural references to be literal (see Brigham Young, in Journal of Discourses, 12:37; Wilford Woodruff, in Messages of the First Presidency, edited by James R. Clark, 6 volumes [1965–75], 3:253). And third, early historians took these statements literally. The first-century historian Josephus tells us, for example, “Let no one, upon comparing the lives of the ancients with our lives, and with the few years which we now live, think that what we have said of them is false; or make the shortness of our lives at present an argument that neither did they attain to so long a duration of life” (Antiquities of the Jews, book 1, chapter 3, paragraph 9).
The question is not completely resolved in scripture, but several possible answers are implied. Some have interpreted 2 Nephi 2:21 [2 Ne. 2:21] as referring to those living before the Flood: “The days of the children of men were prolonged, according to the will of God, that they might repent while in the flesh.” Others have suggested that it was righteousness that increased the length of their lives. Josephus asserted that “God afforded [the ancients] a longer time of life on account of their virtue, and the good use they made of it in astronomical and geometrical discoveries, which would not have afforded the time of foretelling [the periods of the stars] unless they had lived six hundred years” (Antiquities of the Jews, book 1, chapter 3, paragraph 9).
President Brigham Young likewise attributed the patriarchs’ longevity to their obedience to the “laws of life.” He urged the early Saints to cease “wasting their lives and the lives of their fellow-beings, and the precious time God has given us to improve our minds and bodies … , so that the longevity of the human family may begin to return” (in Journal of Discourses, 14:89). A passage in the Book of Mormon supports the idea that the Lord will “lengthen out” the days of the righteous (Hel. 7:24).
Others have suggested that the earth’s environment may have changed radically at the time of the Flood and that this accounts for the decrease in longevity immediately thereafter (see Moses 8:17).
Among other possible purposes for the prolonged life span of the ancient patriarchs was the Lord’s need to establish truth through his law of witnesses. In Lectures on Faith, we read: “It is easily to be seen, not only how the knowledge of God came into the world, but upon what principle it was preserved; that from the time it was first communicated, it was retained in the minds of righteous men, who taught not only their own posterity but the world; so that there was no need of a new revelation to man, after Adam’s creation to Noah, to give them the first idea or notion of the existence of … the true and living God” (Joseph Smith, compiler , 20).
All these factors are feasible explanations. They are not mutually exclusive, nor do they exhaust the possibilities.