Hey - thanks for bringing this topic up again! I have energy for it - let's go.
In response to your first argument - that the production of grains kills innocent animals and therefore veganism is illogical - is itself illogical. Veganism is about living nonviolently, but also practically we can't not eat. Eating meat and other animal products kills far far far many more animals, since farm animals eat grains too. It's about avoiding suffering so far as it's practical. Cement and books have products that come from dead food animals in them, but we can't not walk down the street or not read. I'm really baked right now; I'll try to find a source that articulates that better than I.
"There has been much dissension among scientists regarding the topic of human physiology and diet, and opinions have spanned the continuum from one end to the other. The fact is, human physiology does not fit neatly into any of the three major categories of mammalian diets: carnivorous, herbivorous, or omnivorous. We have a few traits from each of these classifications, which makes it easy for researchers to "prove" their position merely by pointing out those characteristics that suit their particular opinion.
It is often suggested that specific features of human anatomy or physiology dictate our behavior. However, from the perspective of diet, our physical makeup only prescribes our nutritional requirements, not how specific nutrients must be obtained. For instance, although we have a nutritional need for iron, there are many dietary sources of iron. Nutritionally speaking, it is irrelevant whether we get our iron from plant or animal sources; what matters is simply that we get it.
The argument that "biology is destiny" is typically used to justify a particular eating style. In that light, we must acknowledge that humans are the only species on Earth that appears to have no idea what its ideal diet should be. We are also the only species that has self-inflicted diet-related diseases, caused extensive environmental destruction through basic food production, and created pathogenic infestations that widely infect our food supply.
This type of reasoning also blatantly ignores a critical element of human evolution -- the aspect of choice. The arguments that "humans are meant to eat meat" or " humans have always eaten meat" are certainly no rational defenses for its continuation. If we were to accept this type of twisted logic, we would also have to say that humans have always murdered, raped, enslaved, and committed other heinous acts that our culture today finds reprehensible. Unlike most other animals, humans can choose what foods to eat. Sadly, our poor choices in the past have ravaged our land; fouled our air and waterways; heaped immeasurable suffering upon other species; and undermined our own health.
Our ability to digest a wide variety of foods undoubtedly contributed to our species' survival throughout history. Today, however, our dietary choices have more to do with tradition, culture, economics, politics, and availability than with some predetermined fate. It is time for our species to behave responsibly and select those foods that best sustain the Earth, the animals, and ourselves. Only then can we truly say we that humans have evolved in body, spirit, and wisdom."
whatever caro says goes for me too, cause i probably won't be posting on this subject again.