I'm no expert but I have done some reading on this recently. Particularly pertaining to the Paleo Diet. Based on the 3 books I've read our ancestors did in fact eat meat, and a fair amount of it. There are two primary differences between what we eat and what they ate.
1. Much of our meat has been raised with a goal towards building fat content and with herbicides, pesticides, and hormones all in their environment.
2. Our ancestors ate nearly the entire animal, to include bones, intestine, blood, brains, eyes, really just about anything that we throw away today.
One of the books I read made a really big deal out of these "organs and other nasty bits." In particular Dr. Shanahan suggests sticking to what she calls the
Originally Posted By: Dr. Shanahan
Four Pillars:
1. meat on the bone
2. fermented and sprouted foods
3. organs and other “nasty bits”
4. fresh, unadulterated plant and animal products.

Shanahan MD, Catherine (2011-04-22). Deep Nutrition: Why Your Genes Need Traditional Food (Kindle Locations 1935-1936). Big Box Books. Kindle Edition.


I'm much more likely to take the advice of someone who is advocating sensible changes to diet and exercise based on studies done by medical doctors, archeology and paleontology experts and other experts, than I am to take advice from someone who is advocating severe and drastic change based on a small amount of data, confined to a couple of studies. If you want to know what kind of detrimental impact that can have you should do a little research on why we use margarine and vegetable oils, with all of their negative impacts on health, instead of butter and animal fats (look up Ancel Keys). Or, look into the pasteurization of milk, what the process does to molecular bonds of the proteins, and how a snake oil salesman named Charles North propagated a myth about deaths from natural milk.

We didn't start eating meat yesterday. We've been eating it for something like 100,000 years. If you want to find a food that contributes to cancer and other detrimental diseases, you should look at something we only recently (relatively speaking) started eating, like grain. Its also worth mentioning that the bread we eat today is nothing like the bread our ancestors first made from grains, where the grain had to be sprouted in order to get at the good stuff inside. Today we just grind the shit out of it and the casing (nature's little protective coating that keeps animals from eating the grain) and everything gets process together.

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