The ages mentioned in Gen. 5:1-32 range
from almost a thousand years to Enoch's
life at 365 years. Scholars have yet to
come up with a completely satisfactory
explanation for these large numbers. Some
have suggested that the years were shorter
than ours. But the timing described in
the flood story makes it clear that a
year was about 350 days. Not much difference
there. And if the years were different,
then Adam would be less than 4000BCE.
Others claim that the list is not complete,
that many generations were missing. Perhaps,
but it states rather clearly how long
a patriarch lived after his son was born.
Then there are those who compare the lists
to those of other ancient cultures, noting
that eight Sumerian kings reigned for
a period of 241,200 years. The sum total
of the patriarchs is only about 6700 years
-- short, by those standards. To date,
scholars admit that if these numbers are
symbolic, they haven't figured out the
symbolism yet. Perhaps the numbers merely
show how being made in God's image played
out over the years. The fact is that the
patriarchs were, indeed, fruitful, and
they multiplied. And finally maybe it
was just the authors' way of indicating
it all happened a LONG time ago.
Wenham, Gordon. "Genesis 1-15."
Word Biblical Commentary, Genesis.
Waco, TX: Word Books, 1987, 133-34.