I often forget that as a Physical Anthropologist I have a lot of knowledge that isn’t common. Nor is it *common* sense (or as common as common sense is nowadays). Physical Anthropology is a study of the human physical form, ranging from human evolution and the expression of bipedalism to what ancient people likely ate and how they died. Through this study, I have learned that not only are we what we eat, we are also our teeth.
Prompting for this post came from this article about a kitten who nearly died because it was fed a vegan diet. To me, it’s common sense that cats and vegetarianism don’t go together, partly because I’ve lived around cats my whole life and partly because I know their teeth.
Cats have teeth typical of carnivores. Their teeth are designed for tearing into and through meat. Their dentition is biased toward sharp canines, incisors, and sharp molars. Dogs are similar.

Cat teeth (vetmed.wsu.edu)
A typical vegetarian, like a horse or cow, has very different teeth. They have large, flat molars for grinding up vegetation. Cats and dogs don’t have these molars. Cows and horses don’t have sharp, pointy teeth either.
Humans, on the other hand, are kind of like pigs: we’re omnivores. Again, you can tell by their teeth.

Chimp, hominid, modern human teeth (left to right) (from npr.org possibly from Institute of Human Origins)
In Physical Anthropology, like biology, form usually equals function. Human and pigs have a mix of teeth to reflect their mixed diet. Cats and cows have specialized dentition to reflect their specialized diets.

Comparison of teeth: carnivore vs. herbivore (blm. gov from Thomas Burke Memorial Washington State Museum)
Related posts/websites:
Healthy Pets: Vegan Pet Food vs. What Animals Actually Need to Eat
National Geographic – Evolving to Eat Mush