Henry Ford's world-changing assembly line began in 1913 in Highland Park, Michigan, and though it's the most famous it wasn't the first: it had its roots in the disassembly line. Henry knew a good idea when he saw one and meat packers in Chicago had been swinging carcasses at a regularized rate from man to man for years, allowing one person to stay in the same place and do the same job over and over as each chunk of "product" swung by.

The benefits of the assembly line are obvious, but so are the dangers. Faster and cheaper is the first part: within a year of the line's inception a complete Ford chassis rolled out every 93 minutes instead of every 12-hours-plus as it had previously. The price of a Model T went from $950 in 1909 to $360 seven years later, in spite of the fact that Ford changed the wage rate from under $2.50 for a nine-hour day to five bucks for doing only eight. By 1926, Ford was producing half the motor vehicles in the world.

The second part, the danger of the line, involves the seismic transition in the relationship of man to machine: the man didn't use the machinery any more; the machinery used the man. And though woebegone characters from Charlie Chaplin to Lucy Ricardo could make it look funny, the line made all the decisions and there was nothing humorous about it. The line was unforgiving and any change in its relentless rate of speed could cause terrible, hot friction between workers and the boss.

And the society in which the assembly line thrived was similar in many ways to the line itself. As the line broke the shift into discrete parts and small, infinitely repeatable functions, so were the day and the week broken down as well. The shift was for work and work paid for the rest of life, the part after the whistle, the part that belonged to the worker. No one was expected to be deeply involved in the work or to enjoy it particularly, or to feel great personal satisfaction about its results.

It was also a society in which men and women did almost completely separate jobs, a distinction that seemed as immutable as the difference between one twist on the line and another.

One good thing about the assembly line was that the worker never had to worry that it would follow him home. It was a very different way of living than experienced by, say, the farmer who lived and worked in the same place, or the storekeeper whose sitting room was separated from his business by only a curtain.

For many of us, that separation of home and factory is all gone now, now that we live on the line. Because that's what the phone-linked computer is, now that we have them in our homes and carry them around everywhere in small, darkly efficient attaché cases: an assembly line you live on.

And as its speed continues to increase, as it proves itself able to do more and more tasks, more and more quickly, those of us who are there to twist a digital bolt when it appears in front of us find ourselves working faster and faster during longer and longer shifts. There's a TV commercial for a laptop computer that brags it can allow you to cut the chains that tie you to your desk. The truth is, it's just a portable chain.

I work at home on my computer, which is connected by phone lines to the world. That's an attractive prospect when you imagine February in Canada. I don't miss the choice on a blizzarding morning between cramped public transit and half-attentive, multi-tasking drivers (more about that in a moment). In fact, there's a wry pleasure in sitting in my window watching my neighbours plodding out.

But the home office is not so attractive a proposition when you consider that work demanding immediate attention may come to me on Saturday morning when my kid wants to play Monopoly on the floor, or on Tuesday night at 10:23 when my body and brain are playing Dumb and Dumber. In the phone-and-computer world, the man who works at home sleeps in his office.

Another effect of trying to keep up with the indefatigable computer is that we've come to believe that multi-tasking is normal, the way we used to believe that breaking everything into tiny reproducible parts was normal. Part of what makes getting to the office such a trial these days is the drivers who think they're wasting precious time if they don't do something "productive" while travelling.

My 81-year-old mother has had a cellphone for several years now which she carries in case of emergency on the road. I called her number when she bought the thing to make sure it worked and, to my knowledge, it's never rung (or played the 1812 Overture as the case may be) since then. She wouldn't even consider using it while she's as engaged as an air traffic controller in the job at hand.

She's from a time when driving was instinctively seen for what it is: the most complex combination of data processing and physical response that most people will face in their lifetime – in other words, the apotheosis of multi-tasking. She knows people's lives and safety are at stake.

Many drivers apparently don't believe that any more. That doesn't reflect any increased ability to perform a life-threatening job while concentrating on something else entirely. And I hate to think it reflects their decreased care for the lives and limbs of their fellow road-users (not to mention their own). No, I think it reflects the fact that the line keeps speeding up and we each have our ways of running to catch up to it.

It's a more dangerous world – certainly a more frenzied world – for us all as more and more we live on the line.