Hi Don, 
Celiac disease and gluten sensitivity are two examples of non-adaptation to
cereal grain consumption. Additionally, most cases of autoimmune disease
could well be examples of people who have not adapted to cereal grain
consumption. Hence, the remaining element of the population could be seen as
having adapted to eating grains. 

Researchers (Cavalli-Sforza for one) have mapped the distribution of certain
HLA markers in Europe. These data, if memory serves, suggest that a
significant portion of Europeans (perhaps as much as 40%)are at risk of
developing one or more of the autoimmune diseases that are triggered by
grain consumption. I know this is a sweeping generalization that could be
difficult to defend and I would not spend the time trying to defend it.
Nonetheless, that is the conclusion I drew from reading these reports and
analyzing the data. 

Similarly, in a discussion with Dr. Ken Fine, he suggested that about 42% of
the U.S. population has a genetic risk for gluten sensitivity. As I recall,
he drew his data from the Genome Project.  

I suspect that people whose genes derive from the west of Ireland, the
Scottish Highlands, Scandanavia, and much of northwestern Europe, especially
in mountainous or inhospitable regions or where cereal grain cultivation
would have been difficult, are less adapted to cereal grain consumption. 

Further, Catassi et. al. reported the highest worldwide rate of celiac
disease (so far) among the Saharawi (5.6%). This suggests that there are
other genetically naïve populations whose relatively recent exposure to
grain consumption will have a devastating impact on their genes as their
eating habits become westernized. 

The physiology of the person with celiac disease is definitely different
from individuals whose genes have adapted to eating gluten. In the U.S. and
most of Europe, the rate of celiac disease runs at about 1% of the
population.

Further, 12% has an active, measurable IgG antibody reaction to eating
gluten. Although IgG is the most common, there are four other classes of
antibodies (IgA, IgD, IgE, and IgM) each of which could be mounting a
reaction to gluten. Further, since it can damage some tissues on contact,
yet another group is susceptible to the damaging impact of grain
consumption.    

My suggestion that as much as 60% of the population may have adapted to
eating wheat, rye, barley, and oats may be entirely too optimistic.      

Ron Hoggan, Ed. D.
co-author of Dangerous Grains ISBN: 1-58333-129-8
http://www.dangerousgrains.com