If you’ve read the first several chapters of Genesis, you’ve probably noticed that people back then lived a lot longer than they do now!
After all, Adam lived to be 930, and his descendant Methuselah died at 969.
When compared to the average life span nowadays—about 70 to 80 years—that kind of old age is astounding.
How did people born before the Flood live so long?
AiG geneticist Dr. Georgia Purdom has some fascinating answers.
Average Lifespans From Adam to Abraham
The very first human being ever created lived to be 930 years old. Ten generations later, Noah lived to be 950, and his son Shem lived to see his 600th birthday.
Once the Flood happened, though, we see mankind’s average age quickly dip over a few generations and then dip again around the time of Peleg (when the Tower of Babel occurred).
From then on, the average age continues to drop. Abraham, born nine generations after Shem, lived to be 175, which Genesis 25:8 tells us was old for his time.
At this point, living past 100 seems to have still been fairly common. Abraham’s son Isaac died at 180 (and his other son, Ishmael, at 137), Jacob died at 147, and Joseph at 110.
By the time Moses was born, though, it seems the average age had decreased. In Psalm 90:10, Moses implies that the average lifespan at his time was 70 to 80 years old—quite similar to the average lifespan we see nowadays. Moses was considered very old when he died at 120.
The question is, then, how did the maximum lifespan go from 1,000 years to 120?
Climate change could very well be one of the reasons the average lifespan dropped so dramatically.
By studying the fossil record, it seems that most of the earth had a tropical environment. Then the Flood came and destroyed the surface of the earth. The mass destruction triggered an ice age that covered nearly 30% of the world with ice, mostly in the northern latitudes.
The effects on animal and plant life, as well as the atmosphere, may have had an impact on people’s lifespans.
Genetics are likely the primary culprit for shortening the average lifespan, especially genetic mutations.
A mutation is any change in the sequence of DNA, says Dr. Purdom: “All known mutations cause a loss of information. … We inherit mutations from our parents and also develop mutations of our own; subsequently, we pass a proportion of those on to our children.”
Because of that, it’s possible that in the generations from Adam to Moses, there were a large number of mutations in any individual’s DNA.
These mutations could have spread widely during what are known as genetic bottlenecks, or population bottlenecks.
This occurs when a large portion of the population dies or becomes isolated. When this happens, the mutations present in that smaller group of people have a greater effect, which impacts the population as a whole.
In other words, people lose access to other people’s versions of genes, called alleles. (Think of genes like the color red, and alleles as different shades of red.)
We see two such bottlenecks in the book of Genesis—right after the Flood and at the Tower of Babel.
Stronger Mutations, Shorter Lives
After Noah’s Flood, the human population was reduced to a mere eight people! Any genetic mutations present in Noah’s family had a stronger effect on his descendants since they could only intermarry with their relatives.
At the Tower of Babel, we see another bottleneck. After God confused the languages of the people, they broke away into smaller groups and spread around the globe. Each of those smaller populations had certain genetic mutations that impacted the average lifespan across the human race.
We see evidence for this idea in the Bible. From the Flood until the Tower of Babel, we see the average lifespan bottom out at around 450 years. Then, after the Tower of Babel (which was around the time of Peleg), we see the average lifespan drop significantly once again—this time to about 235 or so.
In each of those genetic bottlenecks, a host of alleles would have been filtered out and lost. This means a loss of genetic information that, in turn, weakened immune systems and made humans more prone to infectious diseases.
Why Do We Die?
Whether humans live to be 1,000 years old or only 80, one thing is certain—we weren’t created to die.
Dr. Purdom points out that even our cells were designed to replicate and stay young. So why do we die at all?
The Bible has an answer for that in Genesis 3. When Adam and Eve sinned and ate the forbidden fruit, they invited a curse of death and disease into our world. That curse of death can’t be cured by scientific discoveries or genetic manipulation. It can only be cured in Jesus Christ.
Jesus calls death the final enemy. One day, we’ll be free from the curse of death if we put our hope in Jesus’ death on the cross and His resurrection!
Have you done that? If not, we invite you to do so right now. Click here to learn how you can cross from death to life today!