Lifespan 1000 years to 80?

[TubbyTubby]

It is the lunar cycle from new moon to new moon.  Basically there are 12 moons per year.

Mega hoop jumping to try and rationalize the goat-herders' campfire stories. 

You can understand their need to explain these impossible bible stories to themselves. They know full well that men didn't live for hundreds of years but they cannot possibly admit that the book is a myth or else the OT just unravels. That only leaves one possible recourse - massage the myth to fit reality, in this case adjust the length of a year.