Summary of passage: Methuselah became the father of Lamech who was Noah’s father. Noah fathered Shem, Ham and Japheth. All lived long lives.
11) Methuselah and he was 969 years old.
12) God kept Seth’s descendants alive longer than others so they would have a chance to repent before he sent the flood (right after Methuselah died). Also, Seth’s descendants lived right after the Fall. God had intended man to live forever so because it was so close to the Fall, God kept man alive longer.
I would speculate God wanted the earth populated so he allowed man to live longer so he could procreate more.
Also, the atmosphere/environment was very different before the flood destroyed everything. Think of the differences say in the times of Dinosaurs and Ice Ages. The world was a different place. Everything was teeming with life. No pollutants or hazards in the environment. Probably little illnesses and diseases as of yet. Abundant food. We don’t hear of starvation during this time. Genetically, there probably wasn’t a lot of harmful mutations yet. God is still very, very close to His people here–physically–so they lived longer.
As more and more generations passed, more and more turning from God entered the world. Sin accumulated. Thus, I would say God decided to shorten man’s life in accordance. To lessen the evil we do to ourselves and in the world.
Ultimately, it’s God’s will and grace that determines how long we live. The rest is just speculation.
Conclusions: The only day I liked in this lesson. It shows how everything is God’s will and is in His grace. Perfect lesson for me today.