Have you ever wondered what's going on in your poop? Perhaps not. But this is precisely what we think about every day at the American Gut Project, the world's largest microbiome citizen science effort ...

Scientists are deep-freezing human poop in a "doomsday" vault in Switzerland that already contains more than 1,000 fecal samples, and the researchers now say they want to amass 10,000 samples by 2029.