PITTSBURGH -- When Edward Gerjuoy started teaching at the University of Pittsburgh in 1964, the Beatles had invaded America, boys played with a new G.I. Joe action figure and a generation reared on the make-believe of television faced harsh Cold War realities.
Almost five decades later, Gerjuoy, 94, of Oakland has no thoughts of retiring.
"What would I do? I want to be creative, productive," he said from his office in Old Engineering Hall that he visits seven days a week. "I think being active is healthy."
Workers who spend decades at the same shop are exceedingly rare these days.
"This is a dying breed," said Kerry Hannon, an author, journalist and authority on career transitions and retirement. "We 50-somethings may be the last to ride that wave."
Just 1 percent of the workforce -- about 1.5 million people, including almost 53,000 Pennsylvanians -- stayed with employers for 40 or more years, according to the Center for Workforce Information and Analysis at the Pennsylvania Department of Labor and Industry.
Once the traditional employment model, the value in staying at a company decreased, said Vera Krofchek, director of research and strategy at the Three Rivers Workforce Investment Board, which unites job seekers with companies that need them.
"Skills can become outdated really quickly today," Krofchek said. "Most people will hold 10 to 15 jobs before they're 40."
The median number of years workers stayed with an employer was 4.6 in 2012, the U.S. Bureau of Labor Statistics said, up from 4.4 years in 2010.
Regardless of whether employees stay or go, researchers say work -- even lots of it -- can be beneficial.
The keys are getting absorbed in worthwhile work, having the resources or management support to do a job well and make progress, and getting along with co-workers, according to Howard S. Friedman, distinguished professor of psychology at the University of California, Riverside, and author of The Longevity Project.
"In those circumstances, hard work is likely to help keep you healthy and happy, even after many years," he said.
Gerjuoy, who came to Pitt with a doctorate in theoretical physics from the University of California at Berkeley and received a law degree at age 59, made adjustments over the years.
A professor emeritus in Pitt's department of physics and astronomy, he embraces desktop computers and does research in quantum computing.
Cardiologist Donald Fisher has been on the job even longer than Gerjuoy: 60 years with Allegheny General Hospital.
"I was recruited from Chicago where I was earning $9,000 a year," said Fisher, 93, of Ross, who was featured in Time Magazine in 1952 for using a heart defibrillator he built to save the life of a woman undergoing heart surgery. It was one of the first defibrillators ever used in the clinical setting.
He goes to the office five days a week and wants to see his latest research project completed before thinking about retirement.
"If I can get that done, I may start thinking about playing the piano, writing an autobiography ... looking up old friends," he said.
About 60 percent of working Americans said they stick with employers for benefits and 59 percent stay for money, according to The Workforce Retention Survey by the American Psychological Association.
Workers in the public sector have almost double the median tenure of private-sector employees, partly because three in four government workers are age 35 or older, compared to three in five private-sector workers, the Bureau of Labor Statistics said.
Ed Bialobok, 62, of North Huntingdon has worked for the Department of Veterans Affairs for 32 years.
"This is kind of like an extension of the military," said Bialobok, who was wounded in the Vietnam War in 1970. "We kind of help each other."
Bialobok, who heads a team of counselors working with combat veterans at the Veterans Resource Center in White Oak, credits the work ethic of his parents for his job longevity.
"I still enjoy my work here and believe in it," he said. "The rewards are more than just a paycheck."