But more seriously, I read some stuff on this, it was pretty interesting. Everything changed after the Flood. The canopy of water which surrounded the earth (remember, it hadn't rained until the flood) was now gone. This canopy of vapor protected the earth from certain UV rays and is what allowed things to live to a great age. This new world wasn't fit for dinosaurs and the long ages of man (some 900 years) were now down to 120 max. For what it's worth?