For instance, at one time the greater part of the human race conceptualized the earth as being flat. But then, as more information accrued, this view of the earth changed. People began to conceptualize the earth as being round. The final piece of information that clinched it was Magellan's circumnavigation of the globe.

The invention of the steam engine also reconfigured our concepts about many things. Prior to the steam engine, the fastest thing around was a horse. The heaviest load that could be hauled was a large wagon, using a team of horses. The introduction of the steam engine changed all that, and today we have the bullet train with speeds approaching 200 miles per hour, and loads in freight trains that run up to 200 cars or more.

Our concepts about flying have also undergone great change. People at one time knew we would never be able to fly through the air, never mind at great speed. Then came the Montgolfier brothers and their hot air balloon, and eventually the Wright brothers with that spindly contraption at Kitty Hawk. And now we have the huge Boeing 747 and the even larger Airbus A, as well as space shuttles, space stations, and rockets to the moon. Entrepreneurs are lining up to buy tickets into space!.

And so it may be in the battle against aging. What we know now will be different when we know more.

There are new advances being made virtually every day: new surgical techniques, new drugs, new treatments, new discoveries. In the past century the average human life span went from about 48 years to where today, in North America, it is now almost 80 years. And climbing all the time.

It is almost certain that the average human life span will climb up to 100, then 130, and eventually to 150 years. It may in time reach 200 years and beyond. And with the advances and discoveries made in the next few decades, and the next century, who can say what the limit is?