[maxerickson]

I think you are understating the improvements in adult life expectancy. 1000 years ago, the very wealthy (the aristocrats) were getting to their 60s. The population wasn't.

The improvements have mostly come from violence reduction and public health and dealing with disease though, I agree that those things aren't really part of a life extension technology trajectory.

[dahart]

I think you misunderstand my point. If you take away all early mortality factors, lifespan is long, and always has been. Separating the burgeoisie is actually an important piece of this argument, and it reinforces what I'm saying. Healthy adults that don't die of diseases or violence often lived as long as healthy adults today. Aristocrats a thousand years ago, on average lived to 65, but bunches of them made it to 80 and beyond. The same factors you cited lowered the lifespan a little for the entire population, even the adults. If I had data on people that only died of old age, I would use that instead, and that would (and probably still does) favor the rich.

If you solve all of these things, then lifespan is asymptotically something like 80 years. That is plain as day. We might come up with ways to increase lifespan, but we haven't yet, and none of the data Kurzweil shows are a result of increases in lifespan for people who die of old age.

[maxerickson]

I just didn't read carefully enough (missed that you were mostly speaking of potential life span).

[dahart]

All good, my beef is with Kurzweil's unscientific intentional misuse of data.

"Longevity" is the term in the social sciences for average age at death for only people that die of old age. Kurzweil used that word, he said "In the eighteenth century, we added a few days every year to human longevity; during the nineteenth century we added a couple of weeks each year; and now we’re adding almost a half a year every year."

Life expectancy increased. Longevity did not. It's somewhat common to confuse them, so he could be forgiven for a mistake, except that it wasn't a mistake, he knows the difference, and his graph is evidence. That he included numbers from the 1920s and then skipped to 2000, is impossible to do accidentally, and if you include 1940-1990, you'd see lifespan flatlines. But then he'd have to admit neither life expectancy nor longevity are on exponential growth curves. They're not linear or even sublinear either. Longevity has always been flat, and lifespan has historical dips and bumps.

[dahart]

And I regret not linking to WP on longevity earlier, it directly contradicts Kurzweil's statements. https://en.m.wikipedia.org/wiki/Longevity