We keep hearing about our presumed longevity, as a population, and our extended health and vitality. And it leads to silly statements such as “40 is the new 30” and “50 is the new 40.” And so on. Perhaps 100 is the “new” 80, for all I know.

Print journalism has not embraced that concept, however. If anything, it’s going in the other direction, and accelerating by the minute.

If you work at a newspaper, 40 is the new 50. And 50 is the new 70.

Age is more than just a number, in a newsroom. It is a profound liability — if a person’s age begins with anything other than a 2 or a 3.

I have known for decades that newspapers loathe “old” people on their payrolls. But the ageism is getting downright overt as the national meltdown of the print industry continues.

The Washington Post last week reported that more than 100 of its newsroom staffers have taken a buyout. A buyout offered only to staffers over the age of 50.

Other major metros have made similar offers — directed at senior staff by calling for long service before an employee is eligible … or by making the buyouts particularly attractive to long-term employees (more weeks of severance for longer service) … and in some cases suggesting — strongly — that certain older employees take the buyouts. If they know what’s good for them.

And that is the metros.

The suburbans (and smaller) newspapers long have had little use for anyone over the age of 40.

I had this bred into me during 23 years with Gannett Co. Inc, a company which specialized in medium-sized newspapers (and smaller).

In Gannett, the rule of thumb was, if you weren’t a managing editor by age 40 you never would be … and that the only people of that age the chain wanted around were senior management.

I remember one of my first editors, a Gannett guy, telling me that reporters reach their performance peak in their third year as professionals. After that, they begin to fade, he maintained, and after five years he hoped they were gone. (I was probably 27, myself, at the time, and had just become a sports editor, and certainly was sitting there doing the math on whether I had already passed my peak, by that editor’s standards.)

The non-metros have reinforced their resistance to age by paying modestly, or badly, prompting those annoying old people to move up to the metros, who might actually want them and could pay them a living wage, or out of the business entirely.

If you looked around any newspaper newsroom over the last 25 years, at least, the number of employees over 40 was always massively outstripped by those under the big four-oh. Even as Baby Boomers crossed the great divide from their 30s to their 40s.

Why might that be?

For several good reasons, most of them having nothing to do with journalism’s nuts and bolts.

1. Older journalists tend to make more money, through sheer longevity. If you can get two old journos out of a room, you’ve probably saved enough money to hire three kids out of college — or, these days, maybe just two kids, and probably just one.

2. Older journalists are harder to intimidate, manipulate or take advantage of. They know what their rights are, they have been around the block and are far more likely to “just say no” to some unreasonable or even illegal (newsrooms don’t much recognize labor laws) request.

3. Older journalists have a fairly good chance of having more public recognition than do their managers. Their bylines have been appearing for years. Managers don’t like it when their staffs are better known than they are. It’s human nature, I suppose.

4. Older people are more likely to use their health insurance, more likely to use sick days, and we can’t have that. Expense without production? Newspapers have never liked that, and they loathe it now.

To be sure, there are occasional upsides to getting younger. Sometimes tapping into youth and inexperience can be a plus for a newspaper when sheer energy might compensate for shaky fundamentals. Newspapers interested in quantity over quality are well-served with kids on the payroll. Nearly all weeklies and small dailies fit this profile.

(The on-line news magazine “Slate” recently did a piece that argued that clearing out the gray clutter is, essentially, good. Read that ageist rant here.)

Kids are less likely to need a real salary because they probably are unmarried and have no kids; less likely to complain, less likely to hold a newspaper to some former standard of competence (never mind excellence) and, if we confront the reality of diminished newspapers covering fewer stories with less newshole … you don’t really need those hoary veterans reminding managers that “this was how we used to do it” in the good old days.

Since I was fired, nearly three months ago, I have assumed I wouldn’t be going back to newspapers. It was just there, in my head. For weeks, I didn’t even bother to examine why I thought that.

When I did analyze my pessimism, it was easy to explain: Newspapers are extremely unlikely to hire anyone over the age of 40. Unlikely to hire someone over 30, even. I already knew that, of course.

There are winners in this meltdown. The Generation X and Y journos who were sick of their careers seemingly blocked by that horde of Boomers already on the best beats and holding most of the titles. That younger generation almost certainly is enjoying a sudden jump in titles and responsibilities as Boomers are hustled out to the street.

But there are losers, too, and I’m not thinking just of the journalists.

At every newspaper where the scythe is cutting down the veterans by the score, enormous amounts of expertise are being lost. There is, in fact, wisdom in age. The ability to fit items into context, and to see broader trends are almost the exclusive province of veterans. Most journalists become better writers and editors with more experience. It’s not like baseball, where you can’t hit the high hard one, when you hit 40.

Removing those people from the newsroom diminishes the product. It makes it sloppier, less informed, less attuned with its community (as well as its best readers, who tend to skew older), usually less erudite. It makes it a poorer newspaper, less apt to serve its high-minded function as a First Amendment watch dog for the community.

Apologists for the industry might also argue that these old people are unwilling or unable to get on board with all the web intiatives newspapers are so fond of. But, actually, many of the veterans are fine with the new technology. At my old job, for instance, I posted more blog items than anyone on the staff and also got more traffic than any other single employee.

Anyway, this is a bad time for journalists.

It is a brutal time for “old” journalists.

I’m waiting for the first big “ageism” suit. It will come, because newspapers’ targeting of old folks is getting just so damn obvious. Somebody is going to make money at the expense of sloppy management. As well they should.