Pathless said:
I said:
We are biologically built as omnivores, and live in a natural world where animal death is simply a natural part of the order of life. We as a species have eaten of other animals since our beginnings.
I'm not a biologist, so I'm not sure about this, but I have read something that contradicts what Brian is saying. I don't think the person that wrote it is a scientist either, and I'm not sure where they get their information from, so admittedly this is not the most reliable quote. But, I'll share it nonetheless, and maybe someone who is more scientifically minded can verify or contradict the following:
"'Isn't it natural for human beings to eat meat?'
No! The diet of any animal corresponds to its physiological structure. Human physiology, bodily functions, and digestive systems are completely different from those of carnivourous animals. Animals can be divided into three dietary groups: meat eaters, grass-and-leaf eaters, and fruit eaters.
...
Human Beings
Human characteristics are in every way like the fruit eaters, very similar to the grass eaters, and very unlike the meat eaters. The human digestive system, tooth and jaw structure, and bodily functins are completely different from carnivorous animals. As in the case of the anthropoid ape, the human digestive system is twelve times the length of the body; our skin has millions of tiny pours to evaporate water and cool the body by sweating; we drink water by suction like all other vegetarian animals; our tooth and jaw structure is vegetarian; and our saliva is alkaline and contains ptyalin for predigestion of grains. Human beings clearly are not carnivores by physiology--our anatomy and digestive system show that we must have evolved for millions of years living on fruits, nuts, grains, and vegetables."
Excerpted from Food For Thought: the Vegetarian Philosophy by Avadhútiká Ananda Mitrá
There is some good and some erroneous information in the quote.
It is true that "the diet of any animal corresponds to its physiological structure. " and that the human digestive physiology is similar to that of our evolutionary cousins, the hominids (which she calls by the earlier term "anthropoid apes".)
However, she doesn't mention that apes are omnivorous. In addition to plants, they eat insects and sometimes small rodents or other game. Humans eat more meat than apes, and our adaptation to getting a larger share of our diet from meat is shown in the differences in dentition between the two groups. Apes have retained more massive grinding molars for their more heavily vegetarian diet. Indeed, one of the reasons we can still accommodate grains and vegetable matter in our diet is that we cook our food. If we did not, we would have a much more difficult time with a strictly vegetarian diet.
She is also incorrect in saying our digestive system is "very similar to the grass eaters". It most certainly is not, and neither is that of the apes. Apes live in arboreal jungle environments and their diets certainly include fruit, nuts, seeds and leaves, but not a lot of grasses. Animals which do depend primarily on grasses have quite different digestive systems to cope with the high proportion of cellulose (such as the four-chambered stomach of ruminants, the fore-stomach of elephants and the enlarged cecum of rabbits).
The confusion comes, perhaps, from the fact that we do rely heavily on grains i.e. the seeds of grasses. But we do not generally eat the grass stalks and our physiology is not suited for that. Even with grains, we generally make them more digestible by soaking and cooking them.
The best conclusion, both from the eating habits of our nearest animal relatives, those of the most primitive human societies and from our physiology is that we are natural omnivores. We are not true carnivores, and a purely meat diet tends to be harmful. We are not true herbivores either, but can adjust to a mostly or even fully vegetarian diet.
With the exception of B12 we can derive all needed nutrients from vegetable sources, including protein and calcium.