Are human beings herbivores, carnivores or omnivores?

One of the main objections I get once people learn that I am a vegan is that eating a plant based diet is not natural and eliminating meat and dairy from one's diet would make that person deficient in certain minerals and micro nutrients. I'm sure most of you were taught in school like I was that human beings are omnivores and thus never questioned your diet.

It is very important for a living species to consume a diet it is physiologically designed to eat and when it comes to humans, even though most of us behave like omnivores, the human anatomy does not seem to be designed for this behavior when we take a closer look at our biology.

Dr. Williams C. Roberts from the National Institutes of Health and Baylor University sums it up this way:

“Although most of us conduct our lives as omnivores, in that we eat flesh as well as vegetables and fruits, human beings have characteristics of herbivores, not carnivores. The appendages of carnivores are claws; those of herbivores are hands or hooves. The teeth of carnivores are sharp; those of herbivores are mainly flat (for grinding). The intestinal tract of carnivores is short (3 times body length); that of herbivores, long (12 times body length). Body cooling of carnivores is done by panting; herbivores, by sweating. Carnivores drink fluids by lapping; herbivores, by sipping. Carnivores produce their own vitamin C, whereas herbivores obtain it from their diet. Thus, humans have characteristics of herbivores, not carnivores.”

I am of the opinion that animal products are incompatible with the human body and after struggling with my health for a long time, this quote by Dr. Roberts is what won me over. We do not have the physical characteristics to conduct ourselves as omnivores/carnivores, this is why we have to cook our food as our teeth are not designed to tear into raw flesh and our stomach does not have the gastric acid to digest it.

If your concern is whether or not a plant-based diet is natural, how do you reckon human beings survived before the discovery of fire? Without the ability to cook anything, I come to the conclusion that the most natural diet for humans to have is a raw food plant based diet. I'd love to know your thoughts in the comments.