We all know about Donald Rumsfeld’s tough management style and no-nonsense manner. But one aspect of Rumsfeld’s tenure hasn’t gotten the attention it deserves: his call to scrap the military retirement age of 62, and the related rule under which four-star service chiefs are limited to one four-year term.

Why not? If the fit-looking guy running the war meetings every morning today is 70, why should decades of accumulated military wisdom be tossed aside when generals and admirals are in their late 50s and early 60s?

The new longevity craze isn’t limited to the military. The other night my wife and I saw “Elaine Stritch At Liberty” in its Los Angeles run, in which the Broadway legend offers a breathtaking autobiography in song. It’s hard to overstate how stunning the image is when the curtain rises and this 77-year-old woman is there in a loose shirt and black tights – meant to showcase the fact that her legs look terrific!

Stritch dazzled the audience for two and a half hours with five decades of her work. She belted out songs by composers (and pals) from Noel Coward to Stephen Sondheim with more energy than most showgirls 50 years her junior.

Look around and you’ll see it everywhere: For those blessed with health, 70 has become the new 50. Dan Rather is still hustling for scoops, like his Saddam interview, at 71. Bob Lutz, the General Motors vice chairman, is still overhauling America’s idea of sleek auto design at 71. Roy Romer, the former three-term Colorado governor and Democratic Party chairman, runs the Los Angeles public school system at 74. Leadership guru Warren Bennis is publishing some of his best work in his mid-70s.

There’s good news and bad news now that 70 is the new 50 – we’re in for more wisdom and more frustration.

Wisdom comes mostly from experience, and if we’re living and working longer, it stands to reason that the average sum of wisdom among those leading us will rise. This should bring better results in those myriad realms of human endeavor in which judgment (not raw brainpower or talent) is the most highly prized quality. I don’t know anyone who thinks their judgment has gotten worse with age.

But frustration among younger people is bound to soar as well. If you think it’s hard today for younger executives, academics, scientists or whatever to wait for leadership slots to open up above them in the large organizations that manage much of life, just wait until people reach the top job when they’re 45 or 50 – and then try to cling to it for 40 or 50 years!

In his provocative 2002 book, “Our Posthuman Future,” Francis Fukuyama speculates that if genetic breakthroughs extend human life spans into the 100s, we’re in for a world of challenges.

“There is a saying,” Fukuyama writes, citing an example from intellectual life, “that the discipline of economics makes progress one funeral at a time.” The way we think about things depends less on empirical evidence, he’s suggesting, and more “on the physical survival of people who created that paradigm … As long as they sit on top of age-graded hierarchies like peer review boards, tenure committees, and foundation boards of trustees, the basic paradigm will remain virtually unshakable.”

Fukuyama thinks this means that “political, social and intellectual change will occur much more slowly in societies with substantially longer average life spans.” I’m not sure if he’s right, but the normal progression of careers and ambitions may have to be totally retooled.

It’s easy to imagine more people drawn to entrepreneurial activity in all fields, as the only way to get out from under the stifling permanence of an ever-older Old Guard. Parents may spend more time with their children when younger, knowing they’ll still have a good 50 years to focus on their careers once they kids are grown!

It’s hard to wrap your mind around. And it’ll be our kids and grandkids, not us, who live to see this play out. But just remember: Every time Rumsfeld lectures the rest of us, and Stritch belts out another showstopper, we’re getting a preview of a longevity revolution that will alter society in ways no one can yet fathom.

Matt Miller is a syndicated columnist. His e-mail address is: [email protected].