(Genesis 6:3; Psalm 90:10)
After the flood, man’s lifespan was significantly shorter. There were many factors that caused this including the tremendous change in environment. “And the Lord said, My Spirit shall not strive with man forever, for he is indeed flesh; yet his days shall be one hundred and twenty years” (Genesis 6:3 NKJV). When God said man’s time on earth should be only 120 years He was not just decreeing that He didn’t want our lives to be any longer. Given the circumstances of eating meat and eating plants that have deteriorated, our bodies (which have also deteriorated) and the devastated condition of the earth (the water canopy had been removed, the dry land had shifted and more water covered the earth than before the flood), God was telling us how long we can expect to live given the circumstances on the earth and the deterioration because of sin.
“The days of our years are threescore years and ten (seventy years) – or even, if by reason of strength, fourscore years (eighty years)” (Psalm 90:10a Amp). This sounds like a contradiction to the length of life described in Genesis 6:3 but Psalm 90 is about the Israelites in the wilderness. The footnote on this verse in the Amplified Bible says in part, “This number has often been mistaken as a set span of life for all mankind. It was not intended to refer to anyone except those Israelites under the curse during that particular forty years”. We can look at a chart of the ages of the patriarchs and see that before the flood the people lived for centuries but the deterioration of life and the devastation of the earth caused by the flood changed mankind’s lifespan dramatically.