Nobody was arguing that it was ok to make cows and pigs suffer. That wasn't the point.
ETA: And humans are omnivores, not pure herbivores or pure carnivores. My point about false dichotomies making life more convenient may be relevant here.
Nope. We don’t anatomically match up with omnivorous animals anymore than we do with carnivorous ones. Omnivores are more similar to carnivores than they are to herbivores.
See the table I pointed to before.
http://www.tierversuchsgegner.org/wiki/index.php?title=TaxonomyView the table of our characteristics against omnivores.
That site goes on to say:
The Opportunistic Feeder TheoryVarious folk promote the opportunistic feeder theory which suggests that because man can or has fed on meat, eggs, insects and other animal matter, then man is an opportunistic omnivore. This theory also counters the conclusions of taxonomy presented above, suggesting it is misleading and that species have individual feeding habits and cannot be pigeonholed as taxonomy suggests. The basis of this argument is that animal behaviour and adaptability indicates dietary suitability.
This theory is false and unscientific. Of course tradition is not scientific, and the practice of humans eating meat is old, but has nothing to do with what we are biologicaly equipped to feed upon. We ate meat to survive, now we eat it out of habit and not need.
Another quasi-scientific theory is associated with the opportunistic feeder theory. This can be called the biochemical individuality theory which is often seen in far eastern "medicines" such as Traditional Chinese Medicine, and the Ayurvedic systems. This theory suggests that since we are biochemically individual we should all eat individual diets suited to our moods, illnesses and other contrived indicators.
The logic behind biochemical individuality theory is fallacious, for although we are all unique biochemical beings, we are predominantly the same biochemical system, with low level variations. At the molecular level we differ, at the system level we are alike. If anyone imagines they can adjust their diet according to these individual metabolic variations, they are fooling themselves.
By picking only the low level system differences to indicate information about dietary choices, or moods, yin and yang and so forth, and extrapolating to the whole, we produce a gross misrepresentation of the facts. As far as we know, all cattle graze, all lions eat raw flesh, all chimps eat a diet of mainly raw fruit and vegetation and all chickens peck for grubs and grains. No animal on earth, that we know of, cooks its food before eating it, except humans. Only human behaviour breaks the taxonomic definition that that science defines for it. Humans prefer culture and technology over nature, and since our natural role is as a raw food herbivore, and because our bodies are only suited to that role, any significant perversion of it must, and does, lead to ill health. One cannot choose what to eat healthily, based on cultural imperitives since one will most likely present the wrong kind and quantity of precursor molecules, as well as introducing poisons to the body. A healthy human body cannot be operated on the wrong chemical inputs. "Garbage in equals garbage out"!
Our anatomy is clearly unsuited to deal with animal matter in the diet, however our digestive chemistry can deal with animal tissues and obtain some nutrition. But this does not indicate biological suitability or desirability. Cattle, which are herbivorous ruminents may eat many insects while they feed, chimps may occassionally kill and eat a small monkey. A pet cat may eat bread and margarine. So what? Are cattle to be defined as insectivores or omnivores, or opportunistic feeders? Is the pet cat an opportunistic feeder? Certainly, and the chimp an opportunistic feeder? Why not. None of this distorts taxonomy or suprises the biologist. All herbivores will be able to process animal protein to some degree or other since all protein is biochemically related. It is possible with modern processing methods to produce a "cat food" derived solely from plant material and non-animal matter that will keep a cat alive. Is this a herbivorous cat? No, it is a domestic animal eating an industrial diet. Higher lifeforms display a broader range of behaviours, and feeding behaviour simply reflects this, but does not reflect our true biological feeding requirements.
The opportunistic feeder theory is based on circular logic, "I do therefore I am" and is hard to falsify*, since at a molecular level, food is chemically similar, because all animal tissues are made up of broken down plant tissues.
The fact that opportunistic feeding theory is circular and hard to falsify make it unscientific, and useless in any discussion of what humans should eat. Taxonomy is accurate, logical but not exact. Since there are exceptions it is falsifiable.