Well, I think the most obvious flaw is that it bases its conclusions on the increased meat consumption of a culture without actually taking into account the additional factors of other harmful modern dietary changes and lifestyle factors, and the fact that many other civilizations have eaten largely animal based diets without such issues of disease and degeneration. For raw paleos, its easy to dismiss the fallacy of such things, but even from the cooked paleo or low carb perspective, there is a difference eating an animal based diet that excludes modern foods and cooked grains and starches, and even a traditional diet that increases its consumption of factory meats and refined starches and chemicals. I think there was a more recent post-book argument where Campbell was trying to say grass-fed would have played no difference, or that most folks in the study were eating grass-fed or some nonsense. Not to mention that the cultures did not consume a 100% plant based diet, or near one, so I think the only fairly reasonable conclusion is those eating a largely carbohydrate diet, should not drastically increase their cooked meat consumption without addressing their starch and sugar diet. I think there are various debates between Mercola/Cordain and Campbell on the web.
