Today is my 58th birthday, a notch closer to the end of middle age. But, having seen a few friends and many patients die young, I never focus on my age. Besides, the practice of medicine has taught me that life is fickle and that age does not always correlate with one's functional abilities. Those who adhere to a healthy lifestyle (and are fortunate enough to escape serious illness or injury) can expect to remain active and productive for most, if not all, of their life.
When man first evolved, 125,000 years ago, his life span was a third of what we anticipate today. The rigors of a nomadic life style, the dangers of hunting, exposure to the elements and, of course, a complete lack of medical care, insured a brief tour on this planet. The advent of human culture and the domestication of plants and animals had a positive impact on man's longevity but this was balanced by the rise of communicable disease and more efficient means of warfare. In recent centuries, the advance of science has led to improved sanitation, the development of vaccines, the treatment of infections and the many other benefits of modern medicine and dentistry; unfortunately, our efforts to control population growth and to eliminate warfare have been far less successful.
One might anticipate that human life expectancy, now near 80, will continue to rise as medical advances test the limits of our physiology. There's even the hope that man will learn to control (or reverse) the aging process, ending his long search for the fountain of youth. But I have my doubts; unless there is a dramatic change in human behavior, we are likely to succumb to environmental pollution and resource depletion long before we find the key to immortality.
