Just to widen the discussion out to include cancer....

Video lecture - How Cancer Begins
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http://www.lovehealth.org
If you're worried about getting cancer steer clear of red meat and
rich foods and avoid cigarettes. In this lecture, Dr. Robert Weinberg
exlains the scientific basis for this advice, as well as a layman's
look at the genetic, biochemical and environmental factors that make
good cells go cancerous.

He comments: "Normal cells are civic-minded, lining up together in a
precise architecture that gives structure to body tissue. When the
cell's genes are damaged, they send out faulty instructions, turning
orderly structure into a chaotic mess. This kind of injury to cells
likely comes from the outside – as many as 90% of human cancers are
due to bad diets and smoking. Weinberg discusses the specific
pathways by which carcinogens invade and do their damage in the hopes
of being able to halt the process and freeze a cancer's growth. But,
cautions Weinberg, better to count on prevention than a cure in the
fight against cancer.

He mentions that, contrary to popular opinion, cancer is not a modern
phenomenon - a result of industrialization; rather, it began 700
million years ago with the evolution of multi-cellular organisms. He
gives an interesting example, telling that cancer has also been found
in Egyptian mummies. He then goes on to explain how different forms
of cancer are found in varying frequencies depending upon the
geographical location and the existing population.