Tomorrow Happens by David Brin, Deb Geisler, James Burns Page B

develop. A mere two decades weren't long enough for a man or woman to amass the knowledge needed for complex culture, let alone pass that wisdom on to new generations. (In fact, chimps and other apes share some of this lifespan bonus, getting about half as many extra heartbeats.)

    So evolution rewarded those who found ways to slow the aging process. Almost any trick would have been enlisted, including all the chemical effects that researchers have recently stimulated in mice, through caloric restriction. In other words, we've probably already incorporated all the easy stuff! We're the mammalian Methuselahs and little more will be achieved by asceticism or other drastic life-style adjustments. Good diet and exercise will help you get your eighty years. But to gain a whole lot more lifespan, we're going to have to get technical.

    So what about intervention and repair ?

    Are your organs failing? Grow new ones, using a culture of your own cells!

    Are your arteries clogged? Send tiny nano-robots coursing through your bloodstream, scouring away plaque! Use tuned masers to break the excess inter-cell linkages that make flesh less flexible over time.

    Install little chemical factories to synthesize and secrete the chemicals that your own glands no longer adequately produce.

    Brace brittle bones with ceramic coatings, stronger than the real thing!

    In fact, we are already doing many of these things, in early-primitive versions. So there is no argument over whether such techniques will appear in coming decades, only how far they will take us.

    Might enough breakthroughs coalesce at the same time to let us routinely offer everybody triple-digit spans of vigorous health? Or will these complicated interventions only add more digits to the cost of medical care, while struggling vainly against the same age-barrier in a frustrating war of diminishing returns?

    I'm sure it will seem that way for the first few decades of the next century . . . until, perhaps, everything comes together in a rush. If that happens—if we suddenly find ourselves able to fix old age—there will surely be countless unforeseen consequences . . . and one outcome that's absolutely predictable.

    We'll start taking that miracle for granted, too.

    On the other hand, it may not work as planned. Many scientists suggest that attempts at intervention and repair will ultimately prove futile, because senescence and death are integral parts of our genetic nature. After all, from a purely biological point of view, we individuals are merely the grist of evolution, here to strive, compete and reproduce, if we can.

    If our australopithecine ancestors had been ageless immortals, wouldn't that have bollixed the cruelly creative process of natural selection that produced us? Biologists who believe in the intrinsic genetic clock say we should be grateful for those three billion heartbeats. After that, the best service we can do for our grandchildren is to get out of their way.

    Other experts disagree. They think the "clock" is a mere coincidence, having to do with steadily accumulating errors in our cells. In particular, they point to telomeres —little chemical caps protecting the ends of our chromosomes—which wear away with time until the sheltering layer vanishes and grave erosion starts affecting the vulnerable DNA strands, instead. This gradual chemical deterioration simulates a destiny clock, though some researchers hope it might be halted, if we learn the right medical and biochemical tricks.

    Whichever side is right about the nature and evolutionary origins of the aging clock, there are no obvious reasons why human beings can't or won't meddle with its programming, once we fully grasp how cell and genome work. Even if such tools come too late for today's generation, intervention may help our descendants to live longer, healthier lives.

    Long life may be just one of the benefits to spill from our rising pot of knowledge. Suppose we learn to emulate achievements