History reveals that the healthiest people in the world were generally the most primitive people as well! Our ancestors rarely died from the diet-and lifestyle-related illnesses that kill most modern people before their time, mainly because they ate more healthfully and had more active lifestyles. (p. 32)
I don't know anything about the value of Rubin's subsequent advise on diet. And I'm not going to find out either, because this is so amazingly stupid that I won't trust a single thing I read from this point forward.
They died young. Their "lifestyle" consisted of brutal labor and frequent malnutrition. Before 1700, life expectancies were in the 30's worldwide. As recently as 1900, the life expectancy in America was 46 -- and that was the highest in the world. Certainly the many deaths in childhood, and the many deaths in childbirth cut down the average, but do the math. A life expectancy of 35 means way less than half are living to age 70.
The biblical span is mentioned as "threescore years and ten." We should not interpret that as usual, but as "the most you could reasonably hope for." The few who lived to be 80 were considered unusually blessed with long life. The myth that our ancestors, once they had survived childhood diseases, frequently lived lives of health into their 80's and 90's is simply false. Some few lived long. Visit an old cemetery once in awhile, willya?
In this book we have the nutritional myth of the benefits of the primitive lifestyle intersecting with the Christian myth that scriptural statements about food are based on our current idolatry of worshipping our own bodies. I have deep suspiciousness of the unconscious equivalence of the concepts of natural, healthful, and holy. In our current age, these are a far more dangerous heresy, because they draw us into self-centeredness and the life of the world than their opposite sins. (Yes, it is possible to err on the other side, but there isn't much spiritual danger to that in our current era.)
Update: Welcome to visitors from Dr. Sanity and Dr. Helen, two of the sites on my daily to-visit list. If you browse here, you will find that I favor short post on uh, a variety of topics.