Agree that there are plenty of coherent smart people but you also have to think about the workload, my dad is in his 80s and is perfectly sharp on any issues you care to discuss but he also stays in bed until after 9 and enjoys a few naps during the day.

As I said in a post above, I resemble that remark--at least sleeping in, once in a while a nap. But I tend to stay awake until close to midnight. (I'm also not in my 80s, at least not yet--just hoping to get there.)

> Who knows how old we can be in the future

Read as "who knows how much more entrenched future politicians will be able to be? who knows how many more favors they will owe, how many more donors will have their ear?"

Civilization progresses one funeral at a time, but maybe if we knew we would live to four hundred we would take up longer term thinking and work for projects that took 100 years. Nod to Kim Stanley Robinson.