Human bodies buried in bogs can retain some features -- like perfectly preserved skin, right down to forehead wrinkles -- for thousands of years. Learn how this natural mummification process works in today's classic episode of BrainStuff.

Where Do Butternut Squash Come From?
10:07

How Did the Great Stink of London Work?
12:10

BrainStuff Classics: How Do Blue Whales Work?
08:41