[WalterBright]

> But I see little reason that somebody over 70 at the oldest should be allowed to vote at all (let alone do something even more serious like hold public office!)

On the other hand, someone over 70 might be more likely to vote for the general good rather than their selfish interests.

Evolutionarilly speaking, the reason humans have old people at all is that they contribute wisdom. Otherwise, people would tend to die soon after their children reach adulthood. There's no incentive for evolution to favor useless organisms that aren't able to reproduce - so old people aren't useless.