The Speculist: Room for Improvement


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Room for Improvement

Being human, we are always trying to find a way to improve our condition. We're never satisfied with the status quo.

One very important metric for improvement is life span.

lifespan graph.gif

I found the above graph in a paper by Marvin Minsky. It shows that only about 20% of people lived to see age 45 in ancient Rome. By 1900, 20% of people lived to just above age 70. By 1960 20% made it to age 85.

Check out that last "all diseases cured" curve. If we cure all diseases (all diseases, that is, except aging itself) 20% will make it to 95. So if you're part of that lucky 1 in 5, curing all disease would give you only 10 years more than you would have had in 1960. And the maximum life span hasn't increased at all.

That really doesn't leave a lot of room for improvement. Significant improvement requires life extension. If you take away the whole aging problem, you'd get something like this:

lifespan graph life ext.GIF

Sure we'd still get hit by buses from time to time - and this graph assumes that we don't ever get any better at avoiding those risks - but at least 80% of us would make it to age 250. 20% would live 1000 years or more.

This is how we'll find room for improvement.


Two comments. First, it's not clear to me what the graph represents. It seems to be a mortality probability graph derived from a cross section of people living at a point in time. If so, the line labeled US 1960 is composed of people born from 1840 to 1960. That's a mix of life expectancies, and not really meaningful. What I'm really interested in, given the very rapid improvements in infant mortality and the treatment of some of the major causes of death, is the life expectancy at birth. If you computed that, based on actuarial forecasts, for the 1960 cohort, it would look vastly different, with the line moved out to the right at all points. So I'm not sure what the graphs really show. And I'm not sure I believe the end point, i.e., that maximum age is not also slowly creeping up.
Second, it's not just life, we need something about quality of life. As more people live longer, it's clear that we get a lot of people living longer with very poor quality of life. Dementia, physical disabilities, depression, disconnection from family and activities, etc. In one way, old age is not what it used to be when people had short retirement spans but were relatively healthy and then declined rapidly, in closer family settings. Nowadays, we retire early, live long useless, joyless, lonely lives, sometimes fading away in nursing homes, pooping in our diapers and waiting for bingo night to come around. Not a happy prospect, I think.
But what do I know, I'm a dismal economist of age 66. I have a few good quality weighted years left, I hope. After that, I dread what awaits me.

The curve furthest right, representing all diseases cured, seems unduly pessimistic. Technologically advanced democracies already have average life expectancies of around 80 years. I suspect that actually curing all diseases, besides aging itself, would move that curve much, much further to the right.

This is not a very good graph of the mortality distribution. But that aside, its cool to see the changes over time. The graph looks to support the Rectangularization hypothesis. ie, though probability of survival increases, it maxes out at 120 thus creating a rectangle.

If you want a really good look at what the future holds for life expectancy, look up the Biodemographics Trajectories of Longevity by Vaupel et al and Broken Limits of Life Expectancy by Oeppen and Vaupel. Those will paint a radically different picture of the procession of life expectancy.

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