Edited to add:
Apparently, some people lack reading comprehension, and proclaimed this article to be "dumb", "irrational", and says that it makes vegetarianism look bad. Aside from the obvious projection going on, let me say this: Nowhere in this blog entry do I tell you that humans are or are not naturally herbivores. Nowhere do I say that you should become a vegetarian. It is simply a humorous way to respond to those pain-in-the-ass people who come up with silly arguments like this. If you take it as anything else, then you're reading way too much into it. If you are upset by this, then click on something else and go on with your day. There is no reason for you to be a dick to me over what you read in this article.
Edit #2: I've gotten a lot of feedback stating that hippos are omnivores. While there are occasional reports of carnivory, cannibalism, and carrion-eating, these reports are few and far between, and it is generally accepted that this is the result of abberant behavior or nutritional stress. During shortages of their preferred grasses, they typically first turn to aquatic vegetation and elephant dung as an alternative. If, during the drought season, they do eat meat, seemingly out of desperation, it can have disastrous consequences in the form of diseases such as anthrax. In zoological parks, they are fed herbivore diets, and this is the absolute healthiest diet for them; it is what their bodies are truly designed to digest. Think about it this way: Rendered meat products have been added to cattle feed for a long time now. This does NOT mean that cows are omnivores, or that it is healthy for them; it just means that most very hungry warm-blooded creatures will eat what's available if the other option is starving. It doesn't mean their bodies are designed for that; it means that they're desperate. Every available resource, including zoos and textbooks, will tell you that a hippo is an herbivore, and I agree with that.
If there's one thing I'm sick of, it's anti-vegetarians howling, "But, see, we have CANINE TEETH, and them's for eating meat!" So, let's talk teeth, and why your pathetic, flat, short little canines are barely worthy of herbivory, let alone killing animals and rending their flesh. I'm going to cover mammals, because it's irrelevant to discuss more distantly related animals, including turtles, whose beaks are the same from carnivore to herbivore to jellyfish-ivore, or carnivorous frogs, whose few teeth are designed to keep prey from escaping their enormous mouths.
First, let's talk about omnivores. Raccoons, pigs, and bears all have sharp, pointed canines that are useful for killing and tearing flesh. You probably have a good idea of what bears' teeth look like, so here are the others.
See the pointy teeth? How they're significantly longer than the rest, and that they are round, for puncturing? They are proportionately much larger and sharper than human canine teeth.
Now, let's have a peek at a chimp's skull. A Chimpanzee is one of our closest cousins. They are omnivorous, eating mostly fruit, with about 5% of their diet (and ranging anywhere from 4 to 10% with seasonal variations) comprised of animal matter. While they eat a lot of insects, especially termites (yum yum!), a major vertebrate prey species for them is the red colobus monkey. So, here's the skull:
(Image from Bone Clones, who is linked from the image)
Note the very large, round, canine teeth. Teeth that, incidentally, are not used to kill prey! They grab their prey (again, usually baby colobus monkeys) and fling them repeatedly against the ground or a tree limb until they are dead. Also, hunting in chimpanzees appears more related to impressing chicks than it does to obtaining protein.
Chimps and humans are the only great apes to eat a significant quantity of animal protein; the rest, including bonobos, gorillas, and orangutans are primarily herbivores, opportunistically eating some insects. The lesser apes (gibbons) are primarily fruit and insect eaters, with some of them taking in tree bark and leaves as well. All of the great AND lesser apes other than humans have large, pointy, rounded canines. Here's a gorilla skull with a human skull for comparison:
Now, they sure don't need those canines for killing termites, but compared to humans, their mouths are positively fierce. But, let's not just pick on our relatives, let's have a look at the very herbivorous even-toed ungulate known as the hippopotamus:
Whoa! Fierce! Rawr! Hippos have long, sharp canines! They are widely considered to be the most dangerous animal in Africa, partly because their 8000-lb bodies can reach land speeds of 18mph (faster than you), and partly because they can bite off your head and shoulders with one angry chomp. They're fiercely territorial, and they use those big nasty teeth to fight, both with one another and with potential predators.
So, there you have it. Canine teeth are present in a number of different mammals for a number of different reasons. For many herbivores, they are used to fight off predators and competitors (and they're great for tearing the flesh of FRUITS!). Most of our closest genetic relatives are omnivorous only to the extent that they eat insects, but I don't see any of these chest-beating meat-eaters clamoring to chow down on a termite colony. Compared to true omnivores and many herbivores, our own canine teeth are quite puny, not well-shaped for hunting or even defense.
So why ARE our canines so small and flat? There are a few theories on this, one of which is that we adapted mouths that could allow us to hold our breath (perhaps to dive for shellfish during a coastal phase of evolution), and to enable sucking (fruit juices, insects and seafood from their shells, that sort of thing). These changes eventually allowed us the ability to speak; if we had big canine teeth like our cousins, we would have difficulty making all the sounds we need for communication.
I'm not telling you to go vegetarian. That's up to you. I am asking that you stop pointing to your puny-ass canines and pretending that they make you a meat-eater. Also, our new house came with a termite problem, so if you're really proud of being an omnivore, this vegetarian homeowner could really use your help!