When you poop, why do some feces float while others sink to the bottom of the toilet bowl? Researchers from the esteemed Mayo Clinic have just published a scientific paper answering this question. Apparently it was long thought that the secret was the amount of fat inside the particular sample. Nope! In the 1970s, scientists determined that it's the amount of gas trapped inside the turd. Since then though, the mystery has been around why some poop contains more gas. The scientists were studying the gut microbiome of mice when they realized those mice whose guts were sterilized to be germ-free only pooped feces that sunk. From Phys.org:
That suggested that floating fecal matter was related to the makeup of the gut microbiome. The researchers then collected stool samples from healthy mice that were not part of the original study, but who produced floaters, and injected the material into the guts of the sterile mice. They found that all of the test mice began producing floaters. This, the researchers contend, suggests that the reason some fecal matter floats is due to the nature of the bacteria in the gut—some produce more gas than others.
The researchers were not able to isolate the bacteria that produced more gas, but did note that Bacteroides ovatus has previously been found to produce more flatulence in human patients.