The etymology of the term 'piggyback' goes back to the 1500s, when it had nothing to do with pigs. Learn more in this episode of BrainStuff, based on this article: https://people.howstuffworks.com/piggyback-ride.htm

Could the Bird Flu Cause a Human Pandemic?
14:57

Where Do Butternut Squash Come From?
10:07

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