The Chapel - Rediscovering God Changes Everything.

The Old Testament indeed has accounts of incredibly long life spans, but it's not a calendar issue. Judaism had its arguments about which calendar to follow, but they didn't arise until around 200 B.C. or so. Some insisted on a lunar calendar, in which festival and holy days fell on different days of the week from year to year. Others preferred the solar calendar, in which the days never varied. (We have the same kind of issues, which usually get resolved by someone saying, “Columbus Day is the second Monday in October, period.”) The longevity issue is not related to any calendar because, no matter what kind you're using, a year is a year — one cycle of the seasons, from harvest to harvest.

So, what about those long life spans? The first thing to notice is that the really long ones are only found in Genesis and gradually fade out after the flood. Those who were alive before it still lived long lives like their ancestors. Those born after have increasingly diminished spans. In Genesis 11 the spans drop to the 200s, the high 100s by chapter 25, then continuing to drop through the rest of the books of Moses. Moses himself, incidentally, lived to see 120 (Deuteronomy 34:7).

Why this is so is anyone’s guess. Some commentators speculate that the spans are just exaggeration, which is possible, but why the gradual trend to stop exaggerating? Others guess that the years were quicker, but that fails for too many reasons to even list. Still others suppose there was a canopy of water vapor covering the planet (Genesis 1:6-7) that presumably filtered out harmful radiation. A 40-day downpour brought a devastating flood but also removed the filter. As the rays shone more brightly, life spans faded. Probably the most straightforward explanation deals with the effects of sin. We simply degenerated as a race.

This is precisely the trend that salvation reverses. The potential for eternal life was short circuited by sin. Death will have its reign until the Lord's return. Those who belong to him have already breathed the air of heaven, and will live so long as to make anything in Genesis look like a blink of an eye.

For more information on this topic, please refer to comments on Genesis 5:5 in G.J. Wenham’s volume on Genesis in the New Bible Commentary, and K. A. Mathews’ in The New American Commentary.