The longest life ever recorded in the Bible was that of Methuselah, who lived to be 989 years old. This is over 13 times the average human life expectancy today. This invites us to ponder “why did people live longer back then and why don’t they live so long today? Countless theories have been proposed in attempts to answer this question, and below we have selected the ideas we believe are the most logically, scientifically, and biblically consistent.
The first theory arises from the words found in Genesis 1:6-8. It states “Let there be a vault between the waters to separate water from water.” 7 So God made the vault and separated the water under the vault from the water above it. And it was so. God called the vault “sky.” There are
many different interpretations of this verse, but one, in particular, could be the reason for longer life expectancy. Some think that before the flood, there was a water vapor canopy surrounding the earth. The sky would separate the water vapor canopy from the water below such as oceans and other bodies of water. This water vapor canopy would create a better environment for life, there would be a higher level of oxygen and harmful UV rays from space would be blocked. The water vapor canopy would create a greenhouse effect on the whole earth from pole to pole. When the flood occurred, the water vapor canopy condensed creating a flood. With the canopy’s diminishing, UV radiation would have been able to hit mankind more directly, potentially shortening lifespan as the effects of it compounded. One potential pushback to the theory of the flood canopy is a verse in Genesis 1:14. God is creating the sun, moon, and stars and said that they will be in the vault. Thus the UV rays would have not been affected if the water canopy was not there. The water canopy could have had a different effect, but the UV rays most likely did not have anything to do with life expectancy. In short, the changes within the post-flood environment are certainly contenders for why such a drastic drop in life expectancy occurred, but may need more research.
A second reason people in bible times could have lived longer is due to the lack of disease. Upon sin’s entrance into the world, diseases were birthed as well. As time went on, disease would only grow and spread, potentially taking lives earlier than what used to be the norm. Now this is admittedly not a good enough reason on its own because it would require everyone to be affected by the same life shortening disease. Still, in combination with another theory, disease could prove one of the culprits causing people to die younger.
A third theory for the decrease in life expectancy has to do with gene bottlenecking. Gene bottlenecking is the sudden limiting of the gene pool to only a small number of people. The flood did this by wiping out all of humanity except for Noah, his wife, and his three sons each of their wives. Noah had no other children after the flood, leaving only his three sons and their wives to re-populate the earth. It is stipulated that there might have been a gene mutation that skipped every other generation in Noah’s line that caused life expectancy to decrease. Noah's grandfather lived to be 977. Lamech, Noah's father, lived to be 777, and Noah lived to be 950. Noah's son, Shem, lived to be 606. There is what seems to be a pattern here, with an overall negative trend. Shem, if this theory is correct, would pass this gene to his grandchildren causing an overexposed population to a gene mutation. We do not know the ages of Shem's brothers when they died, but they could very well have the mutated gene as well. Within a matter of time that mutated gene could have spread so vastly that it caused an overarching decrease in life expectancy.
A final proposed theory we thought important to present is the differing interpretations of Genesis 6:3. “Then the Lord said, “My spirit will not contend with humans forever, for they are mortal, their days will be a hundred and twenty years.” People tend to take one of two interpretations of this verse. The first is to read it as God declaring an official age limit of 120 years. The problem with this theory is that people after this statement of God live way beyond 120 after the flood. Take a look at any one of Noah’s sons or grandsons. The other interpretation is that God is signaling a 120 year countdown to the flood. He gives this mandate directly before he commands Noah to build the ark in the context of the wickedness of his creation. We do not have exact dates, but when given the ages of people and the time it took to build the ark, we can assume that the flood happened around 120 years after God gave this command. This leaves this second interpretation as a much more likely candidate, but we still thought it important to consider both to gain an informed outlook.
Even having researched the subject deeply, it is impossible to be certain what is to blame for the drastic decrease in life expectancy. These are merely a few ideas. What we can be sure of, however, is that our uncertainties at certain biblical mysteries do not have to break our faith. We can explore these topics comfortably knowing that God’s word is true and the things in it are too. Hopefully the ideas above give you further confidence in that.
Picture Citation
“Vapor Canopy.” Genesis Park, 1999, www.genesispark.com/exhibits/early-earth/atmosphere/.