Human beings and plants have co-evolved for millions of years, so it makes perfect sense that our complex bodies would be adapted to absorb needed, beneficial compounds from complex plants and ignore the rest.

I tried to change the conventional paradigm, for example, by insisting on the reality of mind-body interaction, by stressing the importance of natural therapies, by focusing attention on lifestyle issues, by looking at worthwhile aspects of alternative medicine. Many people have been threatened by that. Doctors especially tend to think that they know everything about the human body, and don't realize that medical education has really omitted many very important subjects.

Each day as I travel through downtown Tucson, I am amazed at how quickly the most ancient of human behaviors have changed. For as long as there have been Homo sapiens - roughly 200,000 years - people have filled their lives principally with two activities: talking directly with other people, and doing physical things.

In Europe, when tobacco was first introduced, it was immediately banned. In Turkey, if you got caught with tobacco, you had your nose slit. China and Russia imposed the death penalty for possession of tobacco.

Whenever the immune system deals successfully with an infection, it emerges from the experience stronger and better able to confront similar threats in the future. Our immune system develops in combat. If, at the first sign of infection, you always jump in with antibiotics, you do not give the immune system a chance to grow stronger.

Routines may include taking a warm bath or a relaxing walk in the evening, or practicing meditation/relaxation exercises. Psychologically, the completion of such a practice tells your mind and body that the day's work is over and you are free to relax and sleep.

Technology has a shadow side. It accounts for real progress in medicine, but has also hurt it in many ways, making it more impersonal, expensive and dangerous. The false belief that a safety net of sophisticated drugs and machines stretches below us, permitting risky or lazy lifestyle choices, has undermined our spirit of self-reliance.