I did a forum search and search of Mark's blog posts on "saturated fats" and couldn't really find any evidence explaining how saturated fat from sources such as butter and red meat are "okay" to eat. In other words, feel no need to replace them with better fats such as olive oil or leaner meat cuts. Many people here (including Mark) talk about how lard and animal fat are not bad. There have been many large and concrete studies that have linked diets high in saturated fat to heart disease.
First off, for those who do not know, saturated fat (main sources are whole milk, butter, cheese, red meat, chocolate, coconut oil) when compared to carbohydrates raises both LDL (bad cholesterol) and HDL (good cholesterol.) Monounsaturated fat and polyunsaturated fat (olive oil, nuts, fish) lower LDL and raise HDL.
To cite one study, in the 1956, Ancel Keys began a survey called the Seven Countries Study. His study showed a strong connection between amount of saturated fat and higher rates of heart disease. To make things clear, he did not find a connection between total amount of fat consumed and higher rates of heart disease (thus, this argument is not about fat=bad, it's about saturated fat=bad.) In fact, Crete had the highest amount of fat intake (40% of calories) and the lowest rates of heart disease. This was due to their liberal use of olive oil.
Second, in my book, "Eat, Drink and Be Healthy, the Harvard Medical School Guide to Healthy Eating" by Walter C. Willett, M.D. states that in the 50s and 60s, "dozens of carefully controlled feeding studies among small groups of volunteers showed conclusively that when saturated fat replaced carbohydrate in the diet, total cholesterol levels in the blood rose; and when polyunsaturated fat replaced carbohydrate, total cholesterol levels fell."
Not to mention the Lyon Diet Heart Study that showed heart attack survivors eating a Mediterranean-type diet (rich in unsaturated fats like olive oil and nuts and low in saturated fats such as red meat and butter)had fewer second heart attacks and deaths from heart disease than those on a low-fat, high-carbohydrate diet. The main diff. between a Mediterranean Diet and Primal are the grains, red meat and butter. Thus, according to Primal, you can't say that the grains were the influence in longer-lives in the Lyon Heart Study. It has to be, as the study showed, the lower saturated fat content.
The point is - why is the Primal Blueprint encouraging food items such as butter, lard and red meat (or saturated fats in general) when there are much healthier alternatives? There have been so many studies that link high amounts of saturated fats to heart disease.