Responding to Doug and Imyers04. Part of the problem we face is trying to navigate through the realities of the modern world while holding on to important Primal and Paleo principles.
I assume that during a lot of human evolution, meat was eaten raw. But I also assume that conditions in the wild were such that ruminants did not pass diseases back and forth to each other quite as freely as confined feedlot or small pasture cattle do. Paratuberculosis, for example, is transmitted from cow to cow when cow's explosive diarrhea, caused by the bacteria, contaminates the common feed, while they are in enclosured lots or pastures. Rather than living on the boundless open prairie.
An example of what I am talking about is Chronic Wasting Disease (CWD) in deer and elk. This nasty mad-cow-disease like disorder was apparently originally caused decades ago by some human researchers in Colorado who confined deer in a pen with sick domestic sheep, and when the deer became sick also, the researchers turned them loose rather than euthanizing them. CWD has spread geographically from there and been transmitted by farmed game also. It is so insidious. Sick elk were kept on one pasture, then they were all killed and the pasture was cleaned and unused for five years. When elk were reintroduced to it after five years, they caught the disease and became sick also. That is how hardy the pathogen is. Temperatures of 1000 degrees F won't reliably kill the pathogen and it can take many years for the brain symptoms to develop after the exposure.
There was a time when I would have considered deer and elk meat from the mountain west to be the healthiest meat available in North America. But there are now locations in Wyoming where random sampling of deer infected with CWD reveals an infection rate of 30%. So I simply don't eat deer or elk meat from anywhere with any incidence of CWD. Despite the assurances of the chambers of commerce and fish and game departments, whose funding depends on license fees and tourism, that CWD may not infect humans much.
Fortunately, most meat does not contain CWD, and is only subject to pathogens that are killed by cooking. I've little doubt that many of the disease causing pathogens in ruminants these days are from human livestock handling practices. But the genie is now out of the bottle and can't be put back. So cooking makes sense.
Avoiding meat that contains CWD is an example of how I've had to modify my Paleo preferences and practices to acknowledge modern realities. There are numerous reasons other than pathogens why I avoid dairy, but pathogens are in the mix.
I doubt that even the most pristine Primal or Paleo lifestyle will protect us from the infectious diseases that I have been addressing lately in this thread, if we expose ourselves to the pathogens.
Consider the Native Americans on the American frontier. Surely they were the ultimate hunter-gatherers, diets high in Omega 3, low in grains, etc. But they were wiped out, in many cases to the last man or woman, by infectious disease. If Paleo lifestyle would have protected anyone, it would have protected them. The best way to avoid infectious disease is to avoid exposure to the pathogens causing it.