On Soft Matter Matters

Humans and animals can do it in 12+/- 7 seconds. No kidding!

It may seem like a silly subject to study, but researchers at Georgia Tech note that their discovery is significant because the amount of time it takes to defecate was the same for all mammals — despite some having much longer rectums that others. To put that in perspective, an elephant’s rectum, at 40 centimeters long, is 10 times the length of a cat’s. Studyfinds.org

If you have read my ‘About Page’, I hope you noticed that I planned to include occasional ridiculous—some intriguing, some amusing—studies. This research group took their investigation very seriously. If you stick with me on this, I will wrap it up with their conclusions about that which will help us all to defecate quickly and comfortably. Here’s the investigators’ plan:

Animals discharge feces within a range of sizes and shapes. Such variation has long been used to track animals as well as to diagnose illnesses in both humans and animals. However, the physics by which feces are discharged remain poorly understood. In this combined experimental and theoretical study, we investigate the defecation of mammals from cats to elephants using the dimensions of large intestines and feces, videography at Zoo Atlanta, cone-on-plate rheological measurements of feces and mucus, and a mathematical model of defecation. Patricia Yang et al, Soft Matter 2017

A brief explanation about their methods:

Time spent at Zoo Atlanta speaks for itself. Interesting days for the research group, catching sight of various large zoo animals, counting the seconds to evacuation success as they meander, variably eating and defecating—the zoo animals that is. Meanwhile, all this visible data is recorded by the crew’s videographer while the team scoops various poop samples then hauled back to the lab—complete with their mucus coating—to be measured according to size and attached viscosity. Rheology is the branch of physics that deals with the deformation and flow of matter, a cone plate viscometer is an instrument for measuring the viscosity (resistance to internal flow) of a fluid, and the time taken for a given volume of fluid to flow through the viscometer opening is then recorded.

Question: How is the duty done by any animal from hippos to squirrels in the same amount of time?

Answer: Simple, it’s simply Mucus, glorious mucus from the mucous glands. The research paper better explains the process of mucus aiding feces by comparing it to “a sled sliding through a chute.” That same stuff mucus explodes with a sneeze, trickles or get stuck in the back of the throat, often causing that hacking noise best done in the privacy of one’s own car, lines the lungs, lubricates the eyes, and coats the entire intestinal tract.

These are not exotic bird feathers, but rather lab-colored photos of the microscopic finger-like projections called villi which line the lumen of the intestine in a highly folded form, thus increasing the surface area to help with food absorption, and then the slimy substance slip slides away with the picked over end-products out the ‘chute’. The pink blobs in the photo are mucus exuding from the villi.

This photo shows the popular squatty potty which changes the angle of your chute allowing for that sought after 12 second release. Certainly decreases toilet time and increases comfort more than any saucer sledding down your guts. Highly recommended by researchers and old people.

Now these are appealing little beasties. Momma wombat and her joey, cute for sure but don’t get entranced with their furry little selves.

Adult wombats are known to be aggressive, particularly if they feel threatened. A favorite technique, according to the Australian Museum, is to flee to a nearby burrow and then use their sizeable rump to crush the pursuing predator's head against the dirt roof…Unfortunately, the Wombat does not make a good pet despite its cute and cuddly appearance. In fact, it can be quite dangerous to keep in the house. https://www.theguardian.com/australia-news/2016/aug/22/woman-attacked-by-wombat-thought-she-was-going-to-die

Not so cute after all!

But here’s an interesting fact to know and tell; wombat poop comes in cubes. No shit, they really do! No info available about timing though. You can just marvel, or read this:

The bare-nosed wombat is a herbivorous, Australian marsupial, renowned for its cubic feces. However, the ability of the wombat's soft intestine to sculpt flat faces and sharp corners in feces is poorly understood. In this combined experimental and numerical study, we show one mechanism for the formation of corners in a highly damped environment. Wombat dissections show that cubes are formed within the last 17 percent of the intestine. Using histology and tensile testing, we discover that the cross-section of the intestine exhibits regions with a two-fold increase in thickness and a four-fold increase in stiffness, which we hypothesize facilitates the formation of corners by contractions of the intestine. Patricia Yang et al, Soft Matter 2017

No mention whether or not they fall into the 5-17 second norm for all the rest of us mammals.

That’s all folks!