Physics of poop explained: It takes 12 seconds for all mammals including humans to defecate

Have you ever thought how much time it takes you to defecate? Well, that’s indeed a weird question but a new study has revealed that all mammals including humans, cats and elephants, take same amount of time – about 12 seconds – to defecate. The physics of poop has thus been explained by the scientists.

You must be thinking given the fact that the length of their rectums varies widely how is it possible for them to take same amount of time, but researchers have an answer. An elephant’s rectum is 10 times the length of a cat’s (40 centimeters vs. four).

But why is the time consistent? The study says it is because of the mucus. For small animals, the substance that covers the large intestine is very thin, while its vice versa in case of large animals. The study further says that the mucus lets feces to move through the intestine “like a sled sliding through a chute.”

Larger animals defecate at higher speeds compared to smaller animals because of the extra fluid. However, to relieve themselves, both use the same amount of pressure. This mucus layer was previously not known and researchers say defecation might not be possible without it.
The length of the feces is double than the rectum hence both the rectum and the colon store feces, the research said.

A new study led by researchers in the George W. Woodruff School of Mechanical Engineering

The study, “Hydrodynamics of defecation,” led by researchers in the George W. Woodruff School of Mechanical Engineering has been published in the journal Soft Matter.

This topic hasn’t been vastly researched within the scientific community. The lead authors of the study are Professor David Hu (also in the School of Biological Sciences) and his mechanical engineering student Patricia Yang, while co-authors are Daniel Chu, an assistant professor and colorectal surgeon at the University of Alabama at Birmingham. Georgia Tech spoke with each of them about their findings.