Many people today discount the lifespans of those listed in Genesis, saying that its impossible that people actually lived that long. However, if the years in Genesis 5 are really shorter concerning men’s ages, then the days in Genesis 1 and 2 must be shorter as well, concerning the Creation account. Contrarily, if the days in Genesis 1 and 2 are actually thousands or millions of years, then the years of men’s ages in Genesis 5 must be thousands or millions of years!
Other ancient genealogies other than the Bible show long lifespans as well, during that time. The Sumerian Kings list mentions 3 kings that are said to have reigned 72,000 years each. Now, that is obviously exaggerated, but that very exaggeration makes more sense if people did live long lifespans back then. If they merely lived 70 or so years, such an exaggeration would make far less sense.
Genesis 7:4 says, “Seven days from now I will send rain on the earth for forty days and forty nights, and I will wipe from the face of the earth every living creature I have made.” If days were actually thousands or millions of years in Genesis, then it must have rained without letup for millions of years! That would mean that Noah was afloat in the ark with the animals for millions of years! On the other hand, if a 900 year genealogy is actually more like 90 years, then 40 days and 40 nights must only be a few minutes or less. This would mean that God flooded the entire world in just a few minutes!
Gen. 8:3,4 says, “The water receded steadily from the earth. At the end of the hundred and fifty days the water had gone down, and on the seventeenth day of the seventh month the ark came to rest on the mountains of Ararat.” How could they be so precise and exact with time periods HERE, yet be so imprecise when reporting people’s ages, or the days of Creation, in earlier chapters? In other chapters, very exact measurements are given, as well. It’s ridiculous to think that they could be so particular and exact with dates, measures, etc., yet be so imprecise and inaccurate when notating the number of years that people lived, or how long the period of Creation took.
If the recorded ages of some of the people in Genesis reflects a longer span than the years they actually lived (i.e., Adam lived 930 years; Seth lived 912 years; Enosh lived 905 years; Kenan lived 910 years; Mahalalel lived 895 years; Jared lived 962 years; Enoch lived 365 years; Methuselah lived 969 years; Lamech lived 777 years; Noah lived 950 years), then why is it that after the Flood, when God announces that man's lifespan will be shorter from now on, the lifespan of people begin to be (eventually and somewhat progressively) more 'normal' as they are today?
Gen. 11:10,11 says, "Two years after the flood, when Shem was 100 years old, he became the father of Arphaxad. And after he became the father of Arphaxad, Shem lived 500 years and had other sons and daughters."
OK, lets say that 500 years was an exaggeration of, say, 5 times the actual years that Shem lived, meaning that he actually lived to be 100, and he actually had Arphaxad when he was 20 years old.
However, in verse 12, the next verse, it says, "When Arphaxad had lived 35 years, he became the father of Shelah." Verse 13 continues, "And after he became the father of Shelah, Arphaxad lived 403 years and had other sons and daughters."
So, if you apply that 1/5 argument, Arphaxad must have become the father of Shelah when Arphaxad was 7 years old!
The same thing applies to the verses after that. Shelah became a dad at 30 years of age and lived to be 403. Eber became a dad at age 34 and lived to be 430. Peleg became a dad at age 30 and lived to be 209. Reu became a dad at 32 and lived to be 207. Serug became a dad at age 30 and lived to be 200. Nahor became a dad at 29 and lived to be 119.
If those ages of their lifespan were actually much shorter, then the ages they became a dad must have been much younger. So again, they must have fathered children when they were not even 10 years old yet!
Not only that, but notice that, in general, the lifespans become progressively shorter and shorter.