A lot of proponents of new diets, e.g. Paleo, Primal, Atkins argue that grains have made people unhealthier and life expectancy was much better before the transition to agriculture.
Some research turns up statistics like this:
We can conclude that farmers were less healthy than hunters, at least until Classical to Roman times. [Due to the difficulty in disentangling all relevant factors, as Angel explains a bit earlier] [w]e cannot state exactly how much less healthy they were, however, or exactly how or why.
It's argued that people were better fed then, showing sharp drops in pelvic inlet depth index and stature. It's also argued that the rates of dental disease were 3-4 times higher, indicating poor nutrition. Even today, we still don't meet the physical size and health of our Paleolithic ancestors despite the doubling of life expectancy.
A part of this may be due to a more sedentary and crowded lifestyle of agriculture, but physical size and bone development seems like a good indicator of nutrition.
Is there another way of interpreting data such as this or counter-arguments that denote that agriculture has made people healthier? Does the depth of the pelvis actually mean anything in regards to nutrition?