Rodent incisors and molars are examples of rootless teeth, in which the root canal remains open and the tooth continues to grow indefinitely. Mice have four incisors, two maxillary (upper ...

PRESENTER:'If we only had incisors, we'd have to choose food that was easy to nibble into small bits, before swallowing. If we only had a mouthful of molars, we'd be no good at biting or tearing ...

And one of these newer associations pertains to the thinner incisors (the eight front teeth), found on a gene believed to have been inherited from Neanderthals interbreeding with ancient humans.