Recent innovations have ignited old debates about labor and technology. In this photo, Honda's robot Asimo at the 2014 New York International Auto Show. Getty Images/Eric Thayer

Around World War II, seven workers used to man freight trains. As recently as the 1970s, five member crews were common. Now, it’s down to just two, an engineer and a conductor. Today railroads are even pushing for single-member crews.

“The old guys, they used to talk about how much things had changed,” recalls J.P. Wright, 45, a Louisville-based locomotive engineer who started in 2001. “And that’s where I’m at now.”

Wright expects fully automated freight trains to eventually dominate the railroads -- not just the yards. In that case, engineers and conductors might not be the only ones to go extinct. Wright, who’s also a songwriter, can’t help but wonder: “What are all the folk musicians gonna do when that high lonesome sound is coming from a computer?”

Wright’s lament is the result of a decades-long transformation of work on the railroads, where technical innovations have combined with cost-cutting drives from employers to drastically reduce crew-size.

One of the biggest changes he's seen in his career is the arrival of remote controlled trains in the railyards. About a decade ago, the technology started to replace on-board locomotive engineers who used to coordinate loading and switching with a pair of workers on the ground. Then, the railroads started shifting the work, in some cases, onto a single switchman, who controls everything by pressing buttons on a box that looks like an oversized video game controller.

A Brave New World?

There’s nothing new about automation. From early textile mills that destroyed the livelihoods of weavers to remote monitoring systems that displaced the caboose, technology-induced job loss has been a fixture of global capitalism. Jobs go and new ones replace them.

Some economists and policy experts, though, are beginning to doubt the latter half of the formula. The breadth and speed of recent innovations -- think robotics, synthetic biology, nanotechnology and 3D printers -- coupled with relatively high unemployment, have fueled a debate over whether humans will be permanently erased from the labor force. It's a potentially dystopian landscape that would have future workers longing for the unemployment rate seen in Friday's job figures.

“I’m really worried about this,” says Vivek Wadhwa, author and fellow at Stanford University’s Rock Center for Corporate Governance. “In the long term, I see no role for human beings.”

Wadhwa recently oversaw academic programs at Singularity University, a think tank-like group in Silicon Valley whose goal is to "educate, inspire and empower leaders to apply exponential technologies to address humanity’s grand challenges."

He says self-driving cars and trains will replace workers in the transportation industry, artificial intelligence, sensors and smartphones will eliminate the need for most doctors, nurses and surgeons--and algorithms will displace most human writers. (“I don’t mean to insult your profession,” he says.)

All of this, Wadhwa says, will happen in the next five to 15 years.

Martin Ford, too, believes “we’re on the leading edge of a major disruption” in the labor market, perhaps within the next twenty years. That’s because most jobs -- however stimulating they are -- are “routine and predictable.” Robots will soon replace blue-collar workers in fields like steel production, retail and fast food. Algorithms, meanwhile, will take the place of white-collar workers in data-driven fields of law and medicine, say, clerks and radiologists.

Employers will cheer, if not, fuel the trend, says Ford, author of Rise of the Robots: Technology and the Threat of a Jobless Future. “Humans are unreliable,” he says.

By contrast, automated systems don’t wake up and decide to quit their jobs or go on vacation -- at least not without the knowledge of the boss. Non-human workers also promise more production. They’re immune to office gossip, cigarette breaks, power naps or unpredictable urges to check the performance of their fantasy football team.

"An Ancient Debate"

Richard Wolff, an economics professor at the University of Massachusetts, Amherst, isn’t buying the hype.

“If you look at the stages of technological change in the 20th century, the 19th century, the 18th century, there were always best-sellers written in which the thesis basically was, this latest technical change is more revolutionary, more fundamental, more transformative than any of those that went before. After twenty of those, you know, it becomes hard," he says, trailing off.

Forever allured by the prospects of competitive advantage, capitalist enterprises have regularly mechanized and automated work. And yet, Wolff says, “the system has found a way to create vast numbers of new jobs so that the freedom of people from labor has always been frustrated.”

There’s an obvious economic reason: Businesses need consumers. And if there are none -- only depressed laid-off workers trying to save money -- then those 3D printing factories staffed by robots aren’t going to produce anything.

But there’s also a political reason. It makes little sense for governments, in the words of Karl Marx, to allow the capitalist system produce its own “gravediggers”: an army of unemployed people as angry at the robots who replaced them on production lines as they are at their elected representatives who sat by and let it happen.

In other words, authorities have a strong incentive to create jobs for human workers, or at the very least, help shape a labor market where humans can comfortably coexist with robots and computers.

But Who's Going To Be Replaced?

Even if humans do continue to perform work, it’s clear the kind of work they’ll be doing is changing. Undoubtedly, some jobs will disappear in the coming decades.

As part of its most recent decade-long employment projections, the Bureau of Labor Statistics considered the likely effects of automation and technological change. Researchers talked to investors and industry observers and plugged their findings into a complex model, which spat out projections by occupation.

The fields the BLS project to decline most heavily by 2022 all bear the heavy imprint of technology: Jobs for farmers, sewing machine operators, data entry keyers, word processors and typists will all decline by about a fifth. In its employment outlook for metal and plastic machine workers, a category expected to fall by 6 percent, the agency notes “workers that are able to operate computer-numerically controlled machines are expected to have the best job prospects.”

The jobs cited by BLS aren’t dramatically different from some of those named by Carl Frey and Michael Osbourne’s far gloomier study. In a 2013 paper often cited by the robots-will-replace-us camp, Frey and Osbourne posit that 47 percent of all U.S. jobs are at “high risk” for automation in the next couple of decades. At the top of the list: telemarketers, sewers, data entry keyers, cashiers, postal clerks, cooks, paralegals, butchers and locomotive engineers like J.P. Wright.

Encroaching automation on the railroad can be a little alienating, says Wright, and not just because he worries about being replaced.

“I’m being cut away from my work,” he says, “but I’m still responsible for being in control.”

While Wright relies mostly on computerized cruise control to drive his daily 187 mile route out of Louisville, he still has to remain on the lookout for any signal changes. Since the technology arrived several years ago, he says that occupational fatigue has become more of an issue.

Ultimately, though, the future of Wright’s profession -- like so many others susceptible to automation -- may be as political of a question as it is a technical one. Even if the technology is already there, current U.S. labor contracts prevent the use of single-member crews on freight trains. Likewise, it might be cheaper for the United States Postal Service to rely on sorting machines and drones instead of clerks and mail carriers, but existing labor contracts prevent layoffs. The same goes for other unionized professions that can’t easily be outsourced, like dockworkers, janitors and nurses. And for fields without collective bargaining agreements, heavy political pressure weighs on elected representatives to either save jobs or create new ones.

In spite of barriers like these, Martin Ford believes the robot age is inevitable. He acknowledges “there have been a lot of false alarms” but likens his camp to the little boy who cried wolf. “Eventually,” Ford says, “the wolf does show up.”