Teeth are not bones; they are harder and made for chewing. Teeth are part of the digestive system, not the skeletal system. Enamel is the hardest substance in the human body and protects teeth. Teeth ...

Over a million years ago, among the chilly grasslands of the ancient Yukon, Canada’s most northwesterly territory, an unexpected beast roamed: a hyena. More lupine in appearance than its modern ...

Breakthroughs, discoveries, and DIY tips sent six days a week. Terms of Service and Privacy Policy. Your body contains the stuff of rocks: the calcium-based minerals ...