by Ian W. Parker on August 5, 2009
The web site, Gravity and Levity, has a great article on the Gompertz law and the odds of surviving through your next year of life. At age 32, I’m looking at just over a 1 in 1500 chance of making it through the year.
Exponential decay is sharp, but an exponential within an exponential is so sharp that I can say with 99.999999% certainty that no human will ever live to the age of 130. (Ignoring, of course, the upward shift in the lifetime distribution that will result from future medical advances)
Surprisingly enough, 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. It’s an amazing fact, and no one understands why it’s true.
There is one important lesson, however, to be learned from Benjamin Gompertz’s mysterious observation. By looking at theories of human mortality that are clearly wrong, we can deduce that our fast-rising mortality is not the result of a dangerous environment, but of a body that has a built-in expiration date.
So, if you make it to the ripe, old age of 95,
you have the body of a 95-year-old with only a 2-in-3 chance of making it through the year.
Puts the whole idea of making the most out of every day in perspective.