Many omnivorous and herbivorous mammals have small canines or have lost them through evolutionary tooth reduction. Humans, as an omnivorous species, have canines that barely protrude above the level of the incisors. Premolars are positioned behind the canine teeth. Herbivores have premolars whose crowns tend to wear to flat grinding surfaces and resemble the more posterior molar teeth. Omnivorous mammals display premolars having a shape in between that of carnivores and herbivores.
Humans have only two premolars on each side of the upper and lower jaws.
The molars are the posterior-most teeth in the jaw and are the last ones to erupt. In carnivores, these teeth are much flatter and broader crowned than the premolars. Domestic dogs have three lower, but only two upper molars. Molars are designed for crushing or grinding. The table below summarizes the common premolar and molar condition in carnivorous and herbivorous placental mammals.