This is quite the interesting theory.

The author is proposing that the age numbers before the flood contain an interesting mistranslation: the last digit is always 0,2,5, or 7 until we get to Noah himself, who ends in an 8.

The gist of the theory is this:

• The ancient Sumerians used a numeric system similar to the Roman system – lots of digits appended to each other
• The last digit always being one of those 4 could very well be a marker for 0, 1/4, 1/2, 3/4
• Suddenly the age of everyone becomes quite normal
• The archeological recovered record for Sumerian kings makes almost the same mistake pre- and post- flood: the Sumerians after the flood record their pre- flood kings as having lived thousands of years, but it’s easy to spot how they misinterpreted their own recovered records.
• Noah would be different because he made it through the flood.

I’ll have to think about this one, but it is intriguing. And in Genesis 6:3, God doesn’t say man was living longer than 120 years, only that he won’t.

I don’t think I buy the author’s later theory that Adam was a pre-flood Sumerian priest.