The Built-In Human Expiration Date

In the book of Genesis it notes that the human lifespan is limited to a maximum of 120 years. And since God is a mathematician, it shouldn’t be surprising that this rate of mortality is an exponential function:

What do you think are the odds that you will die during the next year?  Try to put a number to it — 1 in 100?  1 in 10,000?  Whatever it is, it will be twice as large 8 years from now.

This startling fact was first noticed by the British actuary Benjamin Gompertz in 1825 and is now called the “Gompertz Law of human mortality.”  Your probability of dying during a given year doubles every 8 years.  For me, a 25-year-old American, the probability of dying during the next year is a fairly miniscule 0.03% — about 1 in 3,000.  When I’m 33 it will be about 1 in 1,500, when I’m 42 it will be about 1 in 750, and so on.  By the time I reach age 100 (and I do plan on it) the probability of living to 101 will only be about 50%.  This is seriously fast growth — my mortality rate is increasing exponentially with age.

As the fascinating article notes, the Gompertz law holds across a large number of countries, time periods, and even different species: “While the actual average lifespan changes quite a bit from country to country and from animal to animal, the same general rule that ‘your probability of dying doubles every X years’ holds true.”

  • Truth

    So if someone lives to be 120 years and one day, Joe will admit that the Bible was wrong?

    • Derek Rishmawy

      Well, that verse really is supposed to be more a generality that would eventually kick. In fact, there are a number of places in the following chapters that the same author of Genesis notes several people living far past 120 years. After a certain point, to reach that age became as sign of prosperity and blessing. All that to say one 121 year old doesn’t falsify the general point.

      • Truth

        Good points. Too bad, I really want there to be empirically verifiable predictions based on the Bible. It’s easy to refute people who say that the world will end in 2012 – it’s much more difficult to demonstrate the error of people who make open-ended predictions. If there are still millennarian Christians around 3000 years from now, they may well think that Jesus will return in their lifetime.

    • Adam C

      Abraham lived for more than 120 years (that was after this pronouncement was made). So, no. Joe shouldn’t have to admit the Bible is wrong. Maybe there is an interpretation error (or maybe not, I could be wrong!). I think a likely interpretation is that the Flood would be in 120 years (from that point). No one would be able to reach 120 years because the Flood would destroy them by that time.

      Not quite sure if you are being sarcastic, “Truth”.

  • Barry Arrington

    Hey Truth, a man once said to Billy Sunday that he didn’t believe a single word in the Bible. Billy Sunday grabbed the man’s nose and twisted it until it bled and quoted from Proverbs where it says “the twisting of the nose brings forth blood.” Now, I assume you are a devotee of the scientific method, and of course one of the bedrock principles of that method is that one should be able to replicate experiments. Why don’t you come over to my house and we will replicate that one on your nose?

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