I wasn't going to get involved in this conversation any more, but what the hell...
Epigenetics studies the way genes are expressed (being turned on and off), and how gene expression patterns are inherited from generation to generation. The gene expression patterns of your parents, grandparents and so on set the stage for your own gene expression. Of course our gene expression is also influenced by environmental factors - food being a big one.
It has been shown that plant foods (more so than animal foods) have a direct influence on our gene expression (they can turn genes on or off, in a way the plant foods you eat are part of "formatting" your gene expression). When Jamie brings up the issue of epigenetic degradation and a loss of fertility or reproductive capacity, that is a very real issue. Already as a species we are experiencing reproductive difficulties - low sperm counts in men, loss of regular menstrual cycles in women etc. - and diet is a huge contributing factor. It is sobering to think about, because these traits can be passed on to our offspring. Maybe you will still be able to reproduce okay, but your children or your grandchildren may not be. We have to make the best choices of what we eat now, to ensure the health of future generations. Maybe you can thrive for 5 or 10 or even 20 years on a raw vegan diet, but how will your dietary choices effect your descendants? We don't really know, because veganism is such a new experiment.
I think eating quality animal products is important because they are so nutrient dense, and high in cholesterol which is an important antioxidant in our diet as well as being a critical precursor to our sex hormones. Yes, the body can make some of its own cholesterol, but from an evolutionary point of view we have been adapted to having large amounts of animal products (and cooked foods) in our diet for as long as we have been human, so its the "safe bet". When in doubt, eat what we know has worked for tens of thousands of years.
I have several friends who were (or still are) raw vegans, and after 5-7 years all of them were showing some signs of degrading health. Nervous system damage, loss of regular menstruation, candida overgrowth and a burst appendix are all things I have witnessed. Some of them decided to reintroduce animal foods - a funny story was one family who were very hesitant, but decided to try some elk liver. As soon as they started eating it, they literally couldn't stop and ate the whole thing, by the end of it they were practically high too - giggling hysterically and filled with a feeling of vitality.
Even if you eat organic, raw and vegan you are not that far removed from killing animals. Two of the most common organic fertilizers are bone meal and blood meal... guess where those come from? Everything is so interconnected, you can't really separate the plant/animal aspects of agriculture. And really, what's so different about an animal that you feel bad to kill and eat it? We all kill and eat to survive, that's the cycle of life.