It’s a pretty safe assumption that people have been born with birthmarks since humanity began, and between then and now we’ve come up with some wacky, even dangerous, explanations for them – even a few that survive still today. Learn all about them in this classic episode.

The Stuff You Should Know Doin’ Science Playlist: How Chaos Theory Changed the Universe
55:00

The Stuff You Should Know Doin’ Science Playlist: How Global Warming Works
1:00:10

The Stuff You Should Know Doin’ Science Playlist: How X-Rays Work
38:44