Whatever fossil evidence they have of our diets and digestive tracts it is limited I am sure and they are making generalizations to say anything about it but besides that why would study show anything about what we should eat? Do you suppose that evolution knew we were going to be eating commercially grown animals and plants? Do you suppose evolution had any idea what was best for us? If we follow what we evolved to be eating many of us would die from parasites and malnutrtion as what likely happened to us as we evolved. Is there any science behind your idea?
Sure. There's a branch of anthropology that studies such things, called "medical anthropology". In fact, there's a specialization in medical anthropology -- evolutionary medicine -- that even more specifically deals with such stuff.
Evolutionary medicine bases its prescriptions on the idea tht rates of cultural change exceed the rates of biological change. Our hunger-gatherer physiology was shaped over millions of years, while the cultural changes leading to contemporary lifestyles have occured rapidly. ("Cultural Anthropology: The Human Challenge", Haviland, Prins, Walrath, McBride, Eleventh Edition, p. 70)
So there is a branch of science studying this stuff. Some of the names mentioned are Melvin Konner, Marjorie Shostak, George Armelagos (all anthropologists) and a physician by the name of Boyd Eaton (I mean, these are the folks listed in the sidebar in my text book that talks about evolutionary medicine).
Please bear in mind that I am not saying that we all need to go back to hunter-gatherer lifestyles, or that there is no value whatsoever to modern methods of plant & animal husbandry, farming techniques, cookery, medicine, etc. I'm simply saying that there's something to be said for doing a systematic study of such paleoanthropological information (where it can be found accurately, of course), and that I suspect that some answers to problems we have with modern diets can be found, or at least, suggested there.
Dogdoctor said:
As far as the reccomendations it comes from studies showing that people who eat high fat diets are prone to getting various cancers and people who eat lots of sugar are prone to dental disease and people who are overweight are prone to various problems etc.
Oh, no doubt there. I'm not disputing the studies. But they don't attempt to answer the question "why" -- they are simply presenting cause and effect relationships. If you can get some data as to understanding the "why" of these things --
why are high-fat diets correlated to cancer,
why do high-sugar diets lead to dental problems (and diabetes), and so forth -- then you can start making futher connections and plans as to figuring out how to have a balanced, moderate diet (and possibly also predict what new food products might be prone to causing dietary problems).
P.S. Let me add, just as a sidebar, that one of the arguments made in my Anthro book is that the development of culture has been one of humanity's most significant discoveries/developments. Culture -- as a means of social, economic, and technologic organization -- has allowed us to expand into areas in which we normally couldn't live, in numbers the land normally couldn't support. In other words, it allows us to bypass the rather lengthy process of evolution -- instead of having to wait millions of years to adapt to a cold climate, for example, we figure out a way to make clothing (and we discover fire), and through our shared culture, this idea ramifies through a large number of people and presto! you've got humans living in cold climates in practically no time at all. So that's what the book is talking about when they say things like "rates of cultural change exceed the rates of biological change."