Plague, influenza, coronavirus... pandemics throughout history reveal successful viruses built for destruction. Mystery often surrounds the origins of these baddies. How did they come to be? Are dangerous viruses usually created in a lab, or is nature the real mad scientist? 

Learn how scientists can tell whether newsworthy nasties (like viruses and bacteria) are natural, or D-I-Y'd by humans! Hint: tracking the genetic family tree of the most infamous examples reveals the answer.

Written and reported by Brenna Biggs.