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.

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.

If I had to limit my advice on healthier living to just one tip, it would be simply to learn how to breathe correctly.

I believe that it may be normal, healthy, and even productive to experience mild to moderate depression from time to time as part of the variable emotional spectrum, either as an appropriate response to situations or as a way of turning inward and mentally chewing over problems to find solutions.

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.

Just the attempt to learn a [new] language is like running different software through the brain.

I think it's worth trying to do something about obvious sources of stress in your life. But even more important is learning and practicing methods to neutralize the harmful effects of stress on the body and mind. There are many possibilities, anything from meditation and yoga to listening to relaxing music. My personal favorite is simple breathing techniques - they're very effective, take very little time, and they're free.