h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I enjoy speculating about what an animal's teeth have to say about the kinds of food the animal might have eaten. I find it interesting that you mention molars in terms of what they might do in the process of eating meat.

Mammals can be herbivorous, carnivorous, or omnivorous. There may be shade of gray even within these categories, but usually I assume that if an animal (a horse, for example) has more molars than a human, I assume it's more likely that the animal will make plants the mainstay of its diet. If an animal (here I'm choosing a cat) has more canines than a human, I assume that the animal will mostly be carnivorous. Humans' teeth seem to be located toward the middle of the spectrum. Those of you on vegan or macrobiotic diets might wish to argue why I am off-base. Those who subscribe tot he Paleo Diet may want to persuade me that, as Willem has pointed out, an animal with molars may well use them for eating meat, so they don't really count as indicators of herbivorousness.

There may be something I can learn from any discussions that ensue. I'm aware that the molars in a "carnivore" may be somewhat sharper than those in an herbivore. There may be much I have yet to learn.

Hello! Actually the factor of molars determining degree of herbivory, tends to be the size and depth of the teeth rather than the number. Grass-eating animals have the deepest molars. An elephant, which is largely grass-eating, has very deep molars, but only use a single functioning pair in each jaw at a time. New molars come into use by shifting forward from the back of the jaw as the old molars fall out.

Canine teeth, now … all mammals have either a single pair of canine teeth per jaw, or none. Canines are typically long, curved and pointed in carnivorous animals, but there are many herbivores that also have similar canines.

The front teeth or incisors differ between species; some carnivorous animals have sharp 'grabbing' incisors, but not all, and in some carnivores like cats they're not really significant. (Although some prehistoric saber-toothed cats had impressively curved and sharp incisors.)

Now, the molars of carnivores are special and called 'carnassials'. Instead of flat, grinding surfaces, the carnassials have pointed peaks and ridges that make 'cutting' surfaces where the upper and lower carnassials meet. This cutting or shearing is used to cut through skin and muscles.

Human molars are intermediate between those of herbivores and carnivores. They're not as deep as those of pure herbivores, with some cusps that can contribute to shredding meat. Ancient hominids like the robust Australopithecines, though in body much smaller than us modern humans, nevertheless had much larger and deeper molars, and consequently are thought to have been mostly herbivorous, eating tough plant foods like on the one hand nuts and seeds, or on the other, grass and plant roots.

Thank you!

I thought that cats had more actual canines than humans do.
Actually, I just checked and found that both cats and humans have four canines each. It might not have been cats I was thinking of, though.

I will look further.

Here's something:
" Most herbivores are missing canines entirely, and those that do possess them usually have very small or reduced canines that are not very important for chewing food"
http://www.mainstreetsmiles.com/dental-and-skull-anatomy-of-carnivores-herbivores-and-omnivores/

Horses have 12 premolars. Humans have 8.