Square sausages anyone? Scientists uncover mechanics of cubed wombat poo

Square sausages anyone? Scient...
The infamous square poop comes out of a round hole
The infamous square poop comes out of a round hole
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The infamous square poop comes out of a round hole
The infamous square poop comes out of a round hole

Wombats are the only animal in the world known to produce cubic poo. Until a few years ago it was assumed the feces was moulded into a square shape on its way out of the animal, but some robust research published in 2018 finally solved the mystery. It was revealed that wombats have a unique intestinal structure that can shape its poo into cubes before leaving the body. The resulting defecation is, quite literally, akin to squeezing a square peg through a round hole.

Now, in a newly published study in the journal Soft Matter, researchers have for the first time replicated the cubic formation process that takes place in a wombat’s intestine. The implications of the research are broad, influencing everything from manufacturing processes to digestive health diagnostics.

“Bare-nosed wombats are renowned for producing distinctive, cube-shaped poos,” explains Scott Carver, a corresponding author on the new study. “This ability to form relatively uniform, clean cut faeces is unique in the animal kingdom. They place these faeces at prominent points in their home range, such as around a rock or a log, to communicate with each other.”

The prior 2018 study, which won the researchers an Ig Nobel Prize, investigated several dissected sections of wombat intestine to establish how the animals are producing cubed poo. The new research presents the first experimental replication of that process.

Across several experimental and mathematical models the new study demonstrates how a soft intestine can produce square feces. The modeling suggests alternating stiff and soft intestinal regions leads to the creation of flat faces and sharp corners in the feces. This process was discovered to occur in the last 17 percent of a wombat’s intestine.

“Increased stiffness ratio and higher Reynolds number yield shapes that are more square,” the researchers write in the study. “The corners arise from faster contraction in the stiff regions and relatively slower movement in the center of the soft regions.”

Understanding exactly how this process works could lead to a variety of useful outcomes including novel new ways to shape soft matter in manufacturing contexts. Square sausages anyone?

Another interesting outcome from this research is a greater understanding of the relationship between the ultimate shape of feces and stiff sections in a colon. Patricia Yang, another author on the new study, suggests these findings point to novel clinical tests for digestive health.

"We know, for example, that one of the early symptoms of colon cancer is that part of the colon can become stiff,” says Yang. “It’s possible then that this forms an edge or unusual shape in the faeces and could be an early indicator about the health of the colon.”

The new research was published in the journal Soft Matter.

Source: Royal Society of Chemistry

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I am so relieved to learn we now understand this phenomena.