Cannibalism is wrong, yes. Let's get that out of the way. But the two issues are connected, aren't they? We make these moral questions, not questions of necessity. If it were necessary for us to eat animals, including humans, to survive, then we'd be having another conversation altogether. But it's not necessary—unless you live in places such as Tibet or the Arctic.
We weren't "designed" to eat meat; through the process of natural selection, we kept the characteristics necessary for us to be able to eat meat and use it as a food source. But many animals can do this, even the ones we consider herbivores.
But this doesn't mean we need to eat meat. Just as we can eat mean, we can survive without it. We are generalists unlike any species on the planet. We have high intelligence and bodies that can adapt to many things. We aren't the most adaptable in a purely physiological sense, but we do well considering our other capabilities.
That said, this is a moral question. Given that we don't need to eat meat, that we do assumes the following:
- We have no moral objection to eating animals.
- We are ignorant to the suffering of animals.
I think it's morally wrong to eat animals based on the fact that they must suffer for us to do it. I eat meat, yes, but I'm also a moral wretch. I at one time wanted to be vegan, but I didn't have the resolve and the willpower. I at least acknowledge the flaws in my ways. I create suffering needlessly. I have moral shortcomings.
Many of us live in societies where eating animals isn't necessary. Actually, one of the best ways to reduce instances of environmental/nutritional causes of disease is to adopt a vegetarian, if not vegan, diet. Going vegan is actually good for us.
With very few (and arguably trivial) exceptions, there is nothing in meat that we cannot get from plant sources. We are far more dependent on our plant sources of food for survival than we are on meat sources.
From a moral standpoint, we should not eat meat. But we can and do. And we're all wishy-washy about it. It's okay to eat cows, pigs, and chickens, but eating dogs and cats is barbaric.
Curious beings we are.
(We should all do a TFP field trip to a slaughterhouse, if not a factory farm.)