Hobbes once described the life of man as “solitary, poor, nasty, brutish, and short.” Not anymore, at least not in wealthy nations such as ours.

Americans are living longer—we added 30 years to our life expectancy in the last century—and we have the capacity to be just as productive after “retirement” as before. And that’s a good thing. As Dr. Robert Butler, one of the world’s leading experts on aging issues and president of the International Longevity Center-USA, recently observed, longevity is not the problem. “Shortgevity,” as he calls it, is the problem.

If the word doesn’t roll off the tongue just yet, don’t be surprised if “shortgevity” becomes part of our vocabulary. Butler has coined several other terms and concepts over the last four decades, including ageism, productive aging, and life review.

“Health and longevity create wealth,” according to Butler, who recently keynoted the University of Indianapolis Center for Aging and Community’s (CAC) annual conference on Managing the 21st Century Workplace. Nations characterized by “shortgevity”—nations with low life-expectancy rates—are impoverished, unproductive, and unstable. They drain the world economy. Nations characterized by high life expectancies, however, are wealthy, highly productive, and stable. They fuel the world economy.

The doomsayers would do well to consider this as they fret about America’s aging population and aging workforce. A century ago, they worried about short life expectancy, about the toll of disease and a lifetime of manual labor on the body. Today they worry about science, healthcare, and the lack of back-breaking labor extending life indefinitely.

In truth, the “problem” of longevity is the solution to a range of other problems—if only we come to grips with the changing nature of work, retirement, and age.

Justin Heet, an associate fellow at Sagamore Institute for Policy Research who has written extensively about aging and demographics, notes that there are already some 50 million Americans between the ages of 50 and 74. And over the next 15 years, according to Heet, “the size of this population is projected to grow by more than 24 million people.” The number of Americans between the ages of 25 and 54, by way of comparison, will increase by just 3 million over that same timeframe.

That’s significant because of how we currently view work and retirement: As Heet observes, our most productive years are supposed to fall within that 25-54 period, before leveling and falling off in the next twenty.

But why is that? Isn’t this notion of checking out and (if you are blessed enough to do so) cashing in at 60 or 65 an anachronism, an aberration of the 20th century? Prior to the emergence of the social-safety nets of the Depression era, retirement was an oddity. It was much more common for people to work until they died. And most worked much more physically demanding jobs than today—in the fields, on the factory line, on the docks.

As Dr. Barry Spiker, a senior fellow at CAC, observes, “Today’s 65-year-old man is a different person than was the 65-year-old in 1942. He’s different because of healthcare and the type of work he does.”

In other words, thanks to medicine, most of us are healthier—or at least have the capacity to be healthier. And thanks to the technology-powered service economy of today, most of us work jobs that require little in the way of physical labor. Rather than moving heavy machinery, livestock, or pieces of earth, we move ideas with Word documents, numbers via Excel spreadsheets, pictures and concepts in PDF, inventory by BlackBerry and cell phone. Our value is in what we know and how we apply it—not in how much we can lift or push or pull. Even those of us who earn our living the old-fashioned way now have the opportunity to launch third or fourth careers (or fifth or sixth) in our twilight years, thanks to technology.

So one would expect this New Economy to value a lifetime of connections, ideas, and experience in the same way the Old Economy valued youthful vigor, muscle power, and endurance. If this is true, then a person’s most productive years should come later in life.

This intuitive conclusion seems to jibe with reality, although employers usually fail to recognize the value of their most seasoned workers until they are gone. Spiker notes that smart companies capture some of this knowledge and wisdom by pairing younger workers with older workers before they retire. But smarter companies, according Spiker, “allow senior staff to begin exploring for a couple months the next phase of life—a pre-retirement sabbatical. That enables people to decide whether they want to retire and puts the power in their hands.”

This “bridge to retirement” can be very effective in giving both employer and employee a sense of what they are losing—or perhaps better said, what we are losing: Butler’s research shows that 50 percent of federal workers will be eligible to retire by 2008. The nuclear-power industry expects to lose 28 percent of its workers to retirement within five years. Half of today’s nurses will reach retirement within 15 years. And the list goes on.

Of course, most employers don’t have pre-retirement sabbaticals or inventories. Hence, they don’t always realize what is walking out the door. And those that do usually come to that realization long after the high-valued seasoned employee has moved on. It’s not just knowledge that walks out the door when such an employee retires or is forced to retire. Butler reports that these workers are generally more dependable, more experienced, and less prone to absenteeism than their younger counterparts. (And as someone who has trained both younger and older workers, I can report that neither group is more teachable than the other.)

Of course, employers are only half the problem. After decades in the rat race, many seasoned employees want to quit as soon as they cross those invisible finish lines of 55 or 62 or 65 or 67.

But there is good reason for employees to keep working. First, there’s a lot of life left—even after 65 or 70. Work keeps the mind and body active. Indeed, it may even stave off the onset of certain diseases that come with a decrease in mental activity.

On a much less personal level, our economy and retirement system need people to work longer. When the magical and arbitrary “retirement age” of 65 was set with the creation of Social Security in 1935, the average American male lived until he was 57. His wife lived to 63. Today, the typical American man lives to 74, the typical American woman to 79. And a person who has already reached 65 today can expect to live well into his or her 80s.

In other words, the retirement-to-death gap is getting bigger and is straining the Social Security and Medicare systems. A PBS report found that simply raising the Social Security retirement age (currently set between 65 and 67, depending on when you were born) to 71 by 2040, and to 75 by 2070, would save enough money to cover the looming shortfalls.

So an aging workforce could be a win-win-win: Employers benefit from retained know-how. Employees benefit from larger nest eggs and better health. And the American taxpayer benefits from a wiser pool of labor; a richer, more stable economy; and perhaps even a smaller entitlement liability.