During Biblical times, it was possible for people to live up to 900 years old if they didn't die from accident, murder, etc etc.
The Bible proclaims that there was a canopy of water that used to be above the firmament. The fermament being the earth's atmosphere. The canopy of water was either in the form of gas, liquid, or ice. I believe it was in the form of gas because of the clouds.
Genesis 1:7
"And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so."
The purpose of the canopy was to pressurize oxygen creating a global oxygen tank. Keep in mind, oxygen is VERY important to our health.
"Insufficient oxygen means insufficient biological energy that can result in anything from mild fatigue to life threatening disease." www.oxygengiveslife.com. So much for evolving if our oxygen is insufficient.
Anyways, God punished the world by flood
Water came from the springs of the earth, and it rained.
Genesis 7:11-12
"In the six hundreth year of Noah's life, in the second month, the seventeenth day of the month, the same day were all the fountains of the deep broken up, and the windows of heaven were opened. And the rain was upon the earth forty days and forty nights."
The lifespan of people started going down. Very few reached 900 yrs old because the world was corrupt.
Noah lived 950 yrs old
Shem lived 600 yrs old
Arphaxad lived 438 yrs old
Salah lived 433 yrs old
Eber lived 464 yrs old
Peleg lived 239 yrs old
Reu lived 239 yrs old
Serug live 230 yrs old
Shorter lifespan and loss of oxygen is proof that the flood happened.