I had the pleasure of accompanying my brilliant lady friend to her Phi Beta Kappa induction ceremony last night. The highlight of the evening was a keynote address by University of Chicago economist and 1993 Nobel laureate Robert Fogel, in which he provided the most explicit justification for holding an optimistic view of human potential that I have ever seen. His facts were simple, but extremely powerful.His evidence included the observation that the absolute shortest life expectancy for which the human race could continue to survive is about 20 years; any shorter than that, and the population would be in constant decline, as more people than not died before bearing children. From the thousands of years of human history up until the American Civil War, life expectancy rose by less than 20 years to just under 40 years of age. In the less than 150 years since, life expectancy has risen over 40 years to over 80 years of age.There are more statistical examples like this one, and what it has convinced Fogel of is that we may be at the very beginning of true human capabilities. He predicted that my generation could very well have an average life expectancy over 100 years. The crowd gasped at that one, but not nearly as much as they did when he told them a recent meeting of scientific and academic minds at Rockefeller University in New York had put the Earth's carrying capacity, taking into account man's technological advances, not at 25 or 30 billion but at a population of 500 billion people.As a true economist, he made no value judgments about whether or not it is right to continue to alter our way of life and the planet we inhabit. He simply stated his opinion that we are just now scratching the surface of human capabilities, and that the growth will be truly exponential.