Very interesting thread! Definite food for thought (no pun intended). I majored in physical anthropology (only the BA level). I have not read the paleo diet, but I am familiar with the basic concepts.

It is my understanding that early homo sapiens were primarily scavengers and opportunists. While evidence for hunting is present, it is believed that most meat products were scavenged.
Early humans probably went for long periods without meat. When they found it, they stuffed themselves for days, as long as it lasted. Some even died from it, such as the populations in China that consumed toxic doses of liver, which may have been eaten raw. Many of the hunted animals were sick or disabled. I personally believe that the key here is variety. Early humans ate everything that was even remotely edible. They find evidence for this in corpolites (fossilized feces). Eggs, plants, bark, certain grasses, fruit in season, etc.

The point you bring up is a good one. Most ancient people lived until thirty if they were EXTREMELY lucky. 40 was considered very elderly. Infant mortality was over 50% in most populations and often higher. Worms and parasites were a severe problem as was malnutrition.

So, I am hesitant when we hold this up as the "way to eat". I do believe the pysical evidence is clear that our teeth and digestive systems evolved for opportunistic eating. After saying that, I do believe in the Atkins diet. I believe our modern foods, extremely processed, are making our population fatter and sicker by the day. I don't want to eat like our ancestors did. But I know that something is really wrong with fruity pebbles, cakes, and refined flour. I do believe we have a severe problem with insulin resistance in our society. I think it is gonna get worse. Great topic, Cindi.