Some argue that the Bible cannot be true because it is ridiculous to believe that people lived hundreds of years in Genesis, which is what Genesis 5:31 records. However, there is a reasonable explanation for why this could be possible, which eliminates any necessity that the Bible is untrue about what it records in Genesis 5:1-31.
1 This is the book of the generations of Adam. When God created man, he made him in the likeness of God. 2 Male and female he created them, and he blessed them and named them Man when they were created. 3 When Adam had lived 130 years, he fathered a son in his own likeness, after his image, and named him Seth. 4 The days of Adam after he fathered Seth were 800 years; and he had other sons and daughters. 5 Thus all the days that Adam lived were 930 years, and he died.
6 When Seth had lived 105 years, he fathered Enosh. 7 Seth lived after he fathered Enosh 807 years and had other sons and daughters. 8 Thus all the days of Seth were 912 years, and he died.
9 When Enosh had lived 90 years, he fathered Kenan. 10 Enosh lived after he fathered Kenan 815 years and had other sons and daughters. 11 Thus all the days of Enosh were 905 years, and he died.
12 When Kenan had lived 70 years, he fathered Mahalalel. 13 Kenan lived after he fathered Mahalalel 840 years and had other sons and daughters. 14 Thus all the days of Kenan were 910 years, and he died.
15 When Mahalalel had lived 65 years, he fathered Jared. 16 Mahalalel lived after he fathered Jared 830 years and had other sons and daughters. 17 Thus all the days of Mahalalel were 895 years, and he died.
18 When Jared had lived 162 years, he fathered Enoch. 19 Jared lived after he fathered Enoch 800 years and had other sons and daughters. 20 Thus all the days of Jared were 962 years, and he died.
21 When Enoch had lived 65 years, he fathered Methuselah. 22 Enoch walked with God after he fathered Methuselah 300 years and had other sons and daughters. 23 Thus all the days of Enoch were 365 years. 24 Enoch walked with God, and he was not, for God took him.
25 When Methuselah had lived 187 years, he fathered Lamech. 26 Methuselah lived after he fathered Lamech 782 years and had other sons and daughters. 27 Thus all the days of Methuselah were 969 years, and he died.
28 When Lamech had lived 182 years, he fathered a son 29 and called his name Noah, saying, “Out of the ground that the Lord has cursed, this one shall bring us relief from our work and from the painful toil of our hands.” 30 Lamech lived after he fathered Noah 595 years and had other sons and daughters. 31 Thus all the days of Lamech were 777 years, and he died.Genesis 5:1-31
First, it is important to note that scientific and historical studies do not provide certainty concerning events that occurred this long ago (about 6,000 years). There are theories and hypotheses, but ultimately, these theories and hypotheses are not certain.
The most likely reason for why people lived so long during this time period is that they lived right after the fall from perfection. It is reasonable to assume that before the fall, Adam and Eve’s genetics were perfect, and that as time progressed after the fall, the gene pool became more and more corrupted.
If this is the case, then we could expect people who lived during the time period closer to the fall to live longer, since their genes were not as corrupted.
At some point in time, God explicitly limits the number of years that humans would live, in Genesis 6:3.
Then the Lord said, “My Spirit shall not abide in man forever, for he is flesh: his days shall be 120 years.”Genesis 6:3
So, there is a reasonable explanation for how humans could live for such long periods of time during this particular time period. The reason why people do not live this long anymore is because 1) the gene pool has become corrupted over time, and 2) at some point in history, God set a limit to the number of years humans would live.
There are some foundational principles that apply to all alleged and apparent contradictions in the Bible. To read more, see Bible Difficulties: Foundational Principles.
To read more answers to alleged and apparent contradictions in the Bible, see “Contradictions” in the Bible Answered.
These books are also excellent resources: