The future is not new. By the dawn of the 20th century science was moving so fast many people were sure humans were on the verge of tremendous change. The blogger Matt Novak collects entertainingly bad predictions at his website Paleo-Future. My favorite is a 1900 article by John Watkins that appeared in Ladies' Home Journal, offering readers a long list of predictions from leading thinkers of the day about what life would be like within the next 100 years.

"A man or woman unable to walk 10 miles at a stretch will be regarded as a weakling," Watkins wrote. "There will be no C, X or Q in our everyday alphabet."

As science advanced through the 20th century, the future morphed accordingly. When scientists figured out how to culture animal cells in the early 1900s, some claimed cultured cells would let us live forever. In the 1940s the success of antibiotics led some doctors to declare an end to the age of infectious diseases. The engineers who founded NASA were sure that within a few generations we would build cities on the moon, perhaps even Mars. And as scientists began to develop computers and the programs to run them, they began to predict that someday-someday soon-computers would gain a human intelligence.

The more science advances, the more seductive becomes its prediction. And no one is more seductive, it seems, than the computer scientist Ray Kurzweil, who has been making predictions about the future of technology in a string of best-selling books. But in the December issue of IEEE Spectrum, John Rennie shows that there's less to Kurzweil's predictions than meet the eye.

A number of Kurzweil's predictions have been just plain wrong. Others are so full of loopholes as to be meaningless. In 1990, Kurzweil predicted that in the early twenty-first century our computers would be linked to an international network. Sounds pretty visionary--until, as Rennie writes, you consider all the facts.

To see, in 1990, a society using networked computers for everyday tasks, you didn't need to be prophetic. You just needed to be French. France's government began issuing dumb terminals to telephone subscribers for free in 1981 to encourage use of the paid Minitel online information, or videotex, service. Minitel allowed users to look up phone numbers, purchase train and airline tickets, use message boards and databases, and purchase items through mail order.

Rennie focuses mainly on Kurzweil's predictions about technology. I've also looked into his prediction about biology, and I've found them to be even more problematic (if such a thing is possible). In his 1999 book, The Age of Spiritual Machines Kurzweil predicted that by 2009 "bioengineered treatments for cancer and heart disease will have greatly reduced the mortality from these diseases." A decade later, medicine had not lived up to his prophecy. In 2006--the most recent year for which statistics are available--829,072 people died in the United States of heart disease. It's true that the death rate from heart disease is somewhat lower now than in 1950, but that drop is due mainly to low-tech measures such as getting people to stop smoking. Deaths from cancer, meanwhile, only dropped ten percent between 1975 and 2010. Cancer claimed 562,875 lives in the United States in 2007.

As I write in my book, Brain Cuttings, these unfortunate facts haven't stopped Kurzweil from predicting a medical paradise--one that always lies just a few years over the horizon. In his 2010 book, Transcend: Nine Steps to Living Well Forever (co-authored with a doctor named Terry Grossman), he offered tips for keeping yourself alive for twenty years, so that you can take advantage of all the life-extending technology that will be invented by then, which will keep you alive for another twenty years, and so on and so on, bootstrapping yourself through the centuries.

For all the talk of transcendence, a lot of the tips in Transcend are profoundly banal. Maintain a regular exercise routine! Lose excess body weight! Transcend also advises readers to take vitamins and supplements, often relying on shaky evidence. Kurzweil recommends 500 milligrams of vitamin C a day, for example, writing that "vitamin C is a potent free-radical scavenger (anti-oxidant) that has been shown to be of value in preventing and treating cancer." As evidence, he cites a small study in 2002 on the effect of vitamin C on precancerous cells living in culture dishes.

Kurzweil doesn't mention any of the large-scale investigations of the benefits that vitamin C brings to the health of actual people. In 2009, scientists at Harvard Medical School published one such study in The Journal of the National Cancer Institute. For a decade, they tracked 7627 women. Half took 500 milligrams of vitamin C a day, and half took placebo. Vitamin C, the Harvard scientists concluded, "offers no overall benefits in the primary prevention of total cancer incidence or cancer mortality."

You won't read about findings like that in Transcend. But you can page through 66 pages of recipes, like Fiesta Omelets and Cajun Salmon Fillets. Whether you'll have to eat them for eternity, Kurzweil doesn't say.

Kurzweil's biological predictions fail, I think, because he doesn't appreciate the complexity of our bodies. Bigger computers certainly help scientists learn more about biology, but our understanding doesn't increase in steady increments with every extra terabyte. The Human Genome Project did not suddenly reveal how 20,000 genes work together to make a human, for example. In fact, its main value so far has been to reveal that we knew a lot less about the genome than we thought.

Kurzweil remains confident not only that we'll overcome diseases like cancer, but that we'll also soon understand the brain in intimate detail. In fact, we'll understand it so well that we'll be able to upload our minds into computers. In The Age of Spiritual Machines, here's how he imagined life in 2099: "The number of software-based humans vastly exceeds those still using native neuron-cell-based computation."

From the conversations I've had with neuroscientists who model the mind, this claim is pure science fiction. To prepare a computer to store your brain, it's not enough to simulate 100 billion neurons. Those neurons are linked to each other through trillions of synaptic connections, in a network that can shift its arrangement from one second to the next.

All the attention that Kurzweil and others pay to brain uploading seems to me like a way to cope with our nagging fear of death. Unfortunately, it distracts us from what the startling possibilities that many neuroscientists actually consider possible. We may never understand human brains well enough to upload them, but it's likely we'll come to understand many of the rules by which brain networks are organized. And that knowledge may make it possible to build computers that work a lot like our brains. We won't be surrounded by software-based humans, as Kurzweill predicts. Instead, we'll be surrounded by human-like software.

Whether that's a world in which we'd actually want to live forever is a question we'll have to answer when the time comes.

(Brain Cuttings: Fifteen Journeys Through the Mind is an ebook exclusive [Kindle, B&N, Mobipocket]. For more information, visit the book web site.)

[Robot image: andrealindenberg via Flickr]

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