For 1,500 years after creation, men lived such long lives that most were either contemporaries of the first man, Adam, or personally knew someone who was! The ten patriarchs (excluding Enoch) who preceded the Great Flood lived an average of 912 years. Lamech died the youngest at the age of 777, and Methuselah lived to be the oldest at 969.
During the 1,000 years following the Flood, however, the Bible records a progressive decline in the life span of the patriarchs, from Noah who lived to be 950 years old until Abraham at 175. In fact, Moses was unusually old for his time (120 years) because, when he reflected on the brevity of life, he said: “The days of our lives are seventy years; and if by reason of strength they are eighty years, yet their boast is only labor and sorrow; for it is soon cut off, and we fly away”
By Dr. David Menton and Dr. Georgia Purdom
Genesis 5:27 So all the days of Methuselah were nine hundred and sixty-nine years; and he died.