Over the past 160 years life expectancy in the industrialized world has increased at the steady rate of a quarter year every year. At first, the change was driven by the spread of things today often taken for granted : clean water, sewage and waste disposal, better nutrition, vaccines and antibiotic.

By the late 1970s these innovation had reached the point of diminishing returns yet at almost the same time, new technology began to produce real gains in the fight against the most deadly remaining threats : cancer, heart disease and strokes. Even counting the least development countries the average person worldwide can expect to live to nearly 70 up from the mid 30s at the tum of the twentieth century. Though, the future is certainly impossible to predict many forward looking thinkers have began to broach the possibility that at some point in the next twenty years a child will be horn who will live to the now unimaginable age of one hundred forty his of her children may, in turn look forward to a world in which there exists no "Natural" limit on the age to which one might expect to live.

Baring random accident or deliberate homicide, men and women separated from us by only two generations might live indefinitely. In principle, all that is required is for technology to continue advancing faster that one ages. Such optimism must, however, be tempered with an awareness of life's social and physiocal limitations.

Today's development technology will no doubt be expensive and increasingly so at the upper ends of the age spectrum, further increasing the gap between rich and poor. As lifespan increases, was almost unknown before the 1950s primarily because, statistically speaking most people died before symptoms developed.