For the past two decades, scientists have been manipulating genes to grow human cells where you wouldn’t quite expect them.

Narrator: Lions have them, hippos have them, and even you and I have them: canines, those long, pointy front teeth. They're actually the longest teeth in the human mouth. So what are these long ...

Lions have them, hippos have them, and even you and I have them: canines, those long, pointy front teeth. They're actually the longest teeth in the human mouth. So what are these long, sharp teeth ...

There is a distinctive and easily recognized open-mouth expression that is the canine equivalent of a human smile, ...

Next are the canines at the corners of your mouth ... and how the variety in human teeth allows us omnivores to chew up the wide variety of food we eat. An experiment with an egg left in vinegar ...