Genesis 1:1 - 31
ESV - 1 In the beginning, God created the heavens and the earth. 2 The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God was hovering over the face of the waters.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
In Genesis 6:3 When the Lord said, “My Spirit will not contend with humans forever, for they are mortal; their days will be a hundred and twenty years.”(NIV) He was not establishing a natural age for each person from that time forward or even beginning after the Flood. Genesis 6:5-13 gives the reason for this statement. God had seen man's wickedness on Earth and He vowed to destroy all mankind and the Earth. The 120 year period was to be the amount of time before the Flood that mankind was given a chance to Repent, which they never did.
Well, I think that because Adam and Eve were in the garden and they had two special trees. The tree of life which grants immortality and the tree of the knowledge of good and evil. Our Lord only forbade them from eating from the second tree. There were no restrictions against the tree of life, they could eat it all they wanted.
I think the long lifespans were a residual effect from Adam and Eve eating from the tree of life. If you'll notice these people had gradually shorter lifespans, so it can be reasonable to conclude that the immortality was gradually being bred out of them.
While Adam and Eve could have ate of the tree, scripture never says that they did. God banned them from Eden and the tree of life after they sinned.
It seems more likely that the long ages were a product of un-deteriorated genetics, coupled perhaps with the greater protection from the radiation of the sun which the pre-flood world probably had.
I often felt as though the earth was different back then as it is now. A lot changed during and after the Flood. The earth itself, spun faster. Thus making the days shorter back in biblical times. Once the oceans were filled, and the land masses were moved, the earth's rotation shifted, and slowed down dramatically, thus making the days longer. I have nothing to back my theory up, just something I just always figured happened.
The earth travels around the sun at a speed of approximately 67,000 mph, rotating at roughly 1,000 mph. If it has slowed (which I don't believe), then how fast was it revolving before?
I believe God wants us to ponder His motives, His ways. So, He created life to be eternal, with a caveat: Sin cancels the externality of life. After man sinned, instead of putting a limit on life God must have allowed for life expectancy to be reduced inherently. An eternal being, a being fashioned to last forever, would have his workmanship questioned if he went from having a gazillion-year life span, to being dead in 70 years. A naysayer would doubt if he ever had a chance at a substantially long life. But if man goes from living for 969 years (Methuselah, Gn 5:25) to living 175 years (Abraham Gn 25:7) over 12 generations (from Methuselah to Abraham), the decrease in lifetime for the species seems reasonable.
To let us know that life didn't necessarily leak out of man over a predetermined length of time, we have the story of Abel, one of Adam's sons, killed by another of his sons. We know he died before reaching 130 years old because Adam was 130 years old when Seth, Abel's replacement was born. In Genesis terms, he had a short life any way you frame it.
The lives of the early inhabitants of the earth seem long to us because our life expectancy is so much shorter. I don't think their lives seemed long to the angels, who have been around for eons. It's a matter of perspective.
What if the answer to this mystery has nothing to do with a water canopy or genetic entropy but everything to do with where these patriarchs lived?
Genesis 4 says that Cain the son of Adam was not only cast out from the land of his father, but also cast out from the presence of Yahweh. A few verses prior, we read that Cain and Abel made sacrifices to Yahweh in His presence. In Psalm 91, we learn that a millennium is as a day or one night watch to the Almighty, indicating that time flows differently when in Yahweh’s presence.
My argument is that due to the patriarch’s proximity to the Garden of Eden, the residence of Yahweh on Earth, time dilation, or a discrepancy in the flow of time compared with the rest of the planet, allowed them to live such long lives. Thus, after the Great Flood when Eden was submerged, the presence of Yahweh on Earth left and thus the lifespan of men drastically diminished.