Throughout history, people have used many methods to clean their teeth. Some ancient people chewed on frayed twigs. Others rubbed their teeth with cloth or swabbed them in vinegar. The Egyptians may have been the first people to use toothpaste when they mixed powdered pumice (a porous rock formed in volcanic eruptions) with vinegar and applied it to their teeth in the 100's B.C. Some toothpastes still contain pumice, but science has since supplied other toothpaste ingredients that the ancient Egyptians never dreamed existed.
Nobody wants to be on the receiving end of the services offered through morgues. In this quiz, you'll test your knowledge of who's doing what to your body between your death and your grave.
Atoms: the building blocks of life and the universe. We're all made of these microscopic bits of matter, but how many does it take to make a complete human being? And exactly what kinds of atoms do we have inside us?