A vegetarian diet is dependent on community, civilisation, and climate. To live wild and solitary, or to live in certain places, one should be prepared to eat meat.
Further: to live truly in balance with nature requires killing and eating meat.
Industrialised meat is a bad thing. Farming animals purely for the sake of killing them – ruling them not only in death but also in life – is no good. Nor is the current dependence on oil for all of our farming systems – the processing of the animals themselves, and the growing of the feed with which we fatten them for slaughter.
However, the opposite extreme – opting out of the cycle of predation completely – seems equally imbalanced. Where currently we have mastered nature so completely as to have largely tamed it, refusing to participate at all would be no more of an answer.
(Even if one could opt out entirely, which is not so easy. A vegetarian may not kill animals, but they still compete with animals for available food supplies, and in a balanced biosphere will then necessarily cause both human and animal populations to be kept in check by the cycles of supply and demand. We are unavoidably and constantly in conflict with the rest of nature.)
To live truly in harmony with nature would require living in such a way as to make the most efficient use of nature's resources, acknowledging ourselves, animals and plants all as parts of one system, and remembering that even as herbivores eat plants and carnivores (and humans) eat animals, eventually the carnivores too will die, to be eaten by plants. It's, well, the circle of life.
And more than this; nature works, succeeds, survives, because species compete, balance each other, consume excesses, and contribute to the whole. Vegetarianism is justified as a response to industrialised food chains, but in a more universal sense it seems to step outside of exactly what makes nature work, making a decision that, well, maybe isn't ours to make.
This article contains a number of not-really-backed-up assertions and a couple of outright oddities (‘Moreover, without cooking, the human brain (…) could not keep running…,’) but nonetheless contains a few points I believe important. Mainly: we can survive on a vegetarian diet, but should we be trying so hard to do so, given the inefficiencies involved?
I'm keen to hear counter-evidence, too – is a vegetarian diet truly more healthy, or is it just more healthy than the usual western crap? The macrobiotic diet contains some meat, and the Inuit diet also seems to work just fine.