Scientists Say They’ve Finally Got To The Bottom Of Why Wombats Have Cube-Shaped Poop

Wombats are some of the cutest members of the animal kingdom, but one thing about them has continued to baffle experts. What’s that? Well, the cuddly creatures produce poop in the shape of a cube. After decades of confusion, though, a group of experts believe that they’ve finally found the answer as to why.

There are few mysteries in the animal world that come close to touching this bizarre enigma. Think about it – science has been able to answer so many questions regarding different creatures, yet this is the thing that stumps researchers? No one could figure it out. So the wombat’s weirdly shaped poop has gotten quite a bit of online attention down the years.

But why’s this a puzzle that needs solving? Should the shape of an animal’s feces really come under this much scrutiny? Well, the curiosity stems from the fact that no other critter on the planet leaves cubed droppings behind when they relieve themselves. Wombats are on their own in that respect.

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So could the shape of a wombat’s rear end have something to do with this, then? Not really – it’s round! Beginning to understand the fascination now? It’s all very odd. While the poop mystery sits at the top of the pile, though, there might well be a few other intriguing things that you didn’t know about the cute creatures as well.

Found in the wild in Australia, wombats are a type of marsupial that often live in hilly areas surrounded by trees. They’re expert diggers that can create burrows spanning 100 feet. You certainly can’t accuse them of laziness! On top of that, the adorable animals usually only come out of the ground in the evening.

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When the wombats climb up from the dirt after the sun’s gone down, they go looking for food. The marsupials have a particular taste for plant roots, bark, herbs and grass. The bark is also used to file down their teeth. They have to do this because a wombat’s gnashers never stop expanding while they’re alive.

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Keeping that in mind, people should be a little wary of getting too close to a wombat’s living area. These critters aren’t afraid of showing hostility towards humans, and those teeth can cause considerable damage. Wombats have a tendency to ram into perceived threats, too. The biggest of them tip the scales at nearly 80 pounds, so you’ll feel that hit.

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Anyway, here’s another tidbit to consider – were you aware that wombats are divided into three different types? The first is simply known as the “common wombat.” As the name suggests, this is the prevalent critter out in Australia. It’s got no hair on its nose, either, unlike the other two.

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Yes, the two other species are called the “southern hairy-nosed wombat” and the “northern hairy-nosed wombat.” No prizes for guessing what sets them apart from the common wombat! This pair also have bigger ears and smoother hair. Mind you, they all employ the same defense mechanism.

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You see, wombats boast particularly sturdy bottoms. That area of their body is packed with cartilage, and this comes in handy if predatory animals try to attack them in the wild. When that happens, the critters just jump into a hole, leaving only their bottoms exposed.

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Thanks to the cartilage, the attacking animals find it incredibly hard to get hold of the wombats. Sure, it’s an unconventional way to defend yourself, but it works. And speaking of unconventional, that brings us back to the mystery that’s been puzzling experts for years. Why do the cute critters produce cubic poop?

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Unsurprisingly, there’s been plenty of speculation, as one specialist told National Geographic in November 2018. “People have had all sorts of theories,” the University of Adelaide’s Mike Swinbourne acknowledged. Here’s an example to consider: could it have something to do with identifying the creatures’ homes?

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This theory suggests that wombats are physically shaping their poops after they’ve been to the toilet. Then, once they reach the desired form, the animals position the feces in a tower-like manner, placing them on top of each other. That’s one way to make your presence known! The individual droppings also won’t roll thanks to their flat sides.

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Swinbourne wasn’t too convinced by that theory, though. He believes that droppings are utilized as a marker by the wombats, yet not in that manner. “It’s not like they’re trying to build little brick pyramids,” the expert explained. “They just poop where they poop.” So does he have his own theory for this bizarre mystery?

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In Swinbourne’s mind, the lack of water in a wombat’s natural habitat might be the key. “They have to really squeeze every drop of moisture out [of their food],” he informed National Geographic. Could that internal pressure cause the unusual shape? It’s an interesting suggestion, especially when you consider the wombats found in zoos.

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Yes, according to Swinbourne, some of those zoo wombats don’t produce cube-shaped poops. The potential reason? There’s more water available in the zoos than out in the wild. Might he have a case? Well, to help untangle this peculiar enigma, another expert stepped up to the plate in 2018. Her name’s Patricia Yang.

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To give a bit more background on her profession, Yang sat down to talk with the Slate website in January 2021. “I am an expert on feces,” she explained. “My whole doctoral thesis was on urine, defecation and digestion in humans. A few years ago, I had no idea what to research for my doctoral thesis.”

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“My adviser had just started potty training his son, so we started talking and thinking about the urine system,” Yang continued. “Then the defecation system.” After that, she became a specialist in the subject, which led to a pivotal moment. You see, a simple exchange introduced her to the wombat mystery.

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“One day, I was talking about human cylindrical feces at a conference,” Yang revealed. “And afterwards, an audience member came up to me and said, ‘You have to look at wombats. They have cubed feces.’ I had no idea what they were talking about. But I Googled it, and it was so weird.”

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When an expert in poop says something like that, then you know it’s odd! “The square geometrical shape is very rare in nature,” Yang added. “I didn’t really believe it until I saw a sample myself.” And once she’d had that first-hand sighting, Yang felt compelled to launch a project to investigate the issue.

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Yang wasn’t just a poop specialist – she worked for the Georgia Institute of Technology as a mechanical engineer, too. Talk about a ranged skill set. She and some fellow analysts formed a partnership with Australia’s University of Tasmania to investigate the mystery in 2018. How would they get their answers, though?

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Simple, really: the group required wombat samples. “A wombat expert from Tasmania joined our team,” Yang told Slate. “Every time there was a road-kill wombat, he got a call, and he went to pick up the animal for us.” From there, the engineer and her colleagues zoned in on the marsupial’s intestines.

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Yang and company wanted to get a better understanding of the wombat’s intestinal walls. Specifically, how stretchy they might be. So the group conducted an experiment whereby a balloon was blown up inside the organ. For comparison, pig intestine was used as well. And at that stage, they noticed something rather odd.

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The pig’s digestive organ was fairly stretchy all the way through, yet that wasn’t the case with the wombat’s intestines. The inflated balloon showed that a couple of sections of the latter had a “ravine-like” furrow to them. Could that be the answer? Possibly, though Yang made a frank admission in January 2021.

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During email correspondence with the Gizmodo website, Yang revealed that the results had confused her team. “The ability of the wombat’s soft intestine to sculpt flat faces and sharp corners in feces is poorly understood,” she admitted. “In 2018 we found differential stiffness in the intestine, but we didn’t understand how two stiff regions make four corners.”

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Keeping that in mind, Yang authored a second study of wombat intestines for the aptly named publication Soft Matter in January 2021. On that occasion, she was joined by 13 other researchers. And in the end, a couple of additional test samples made all the difference.

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You see, after studying those wombats, Yang and her colleagues realized that the creature has two stretchy sections and a pair of firm areas in the intestine. Once that information came to light, the team drew up two-dimensional replicas on their computers. Now, the group could examine how the organ shapes the cubed poop.

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To add to that, these areas were found in the intestine’s bottom section – specifically, the final fifth of it. Still with us? Good. We know it’s a lot to take in! Anyway, one of Yang’s co-authors on this study detailed what the models told them in an email exchange with Gizmodo. His name’s David Hu.

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Like Yang, Hu’s also part of the Georgia Institute of Technology. He plies his trade as a fluid mechanics professor on campus. During his online correspondence with the website in January 2021, the academic broke down the intestine’s activity as simply as he could, drawing an interesting comparison.

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“Muscle is like a rubber band,” Hu wrote. “The stiffer the rubber, the quicker and more strongly it contracts. Now, imagine a big rubber band constructed with two stiff sections and two soft sections in an alternating ABAB pattern. When that composite band contracts, the stiff sections will contract first.”

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“The center of the stiff sections forms the first pair of corners of the square, as they are on the diagonal,” Hu continued. “Poop is hard to move because it’s so dense and stiff. The contractions are very subtle, and these corners get more and more accentuated over [the] 40,000 contractions that the feces experiences as it travels down the intestine.”

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Yang concurred with that explanation during her chat with Slate. She reiterated, “The rigid and elastic parts [of a wombat’s intestine] contract at different speeds, which creates the cube shape and corners.” Yet here’s where it gets really intriguing. These studies could actually help diagnose a certain medical condition in people.

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Referring back to the previous findings in 2018, Yang continued, “Pigs have uniform intestines, the stiffness and contraction speeds are the same, so the feces come out circular. We think this is also the case in a healthy human intestine. But if part of the human intestines becomes stiff, this is a symptom of colon cancer.”

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So if a person’s poop begins to develop edges, that could be an indication of the disease. Interesting stuff, right? And these wombat experiments also threw up another fascinating discussion point. It had nothing to do with biology or health, though. Yang believed that production companies should be paying close attention to the results.

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Why’s that? What possible connection could there be between a wombat’s intestine and the production industry? Well, it all ties back to the shape of the critter’s poop. You see, cubes aren’t the easiest things to create – constructors are restricted in how they form them. In Yang’s mind, though, a new technique was now feasible.

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Speaking to The Independent newspaper in November 2018, Yang noted, “We currently have only two methods to manufacture cubes. We mold them, or we cut them. Now we have this third method. It would be a cool method to apply to the manufacturing process – how to make a cube with soft tissue instead of just molding it.”

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Be honest with us – hands up if you saw any of this coming earlier. We certainly didn’t! Who’d have thought that the answer to this bizarre mystery could have incredible implications across different sectors? Anyway, one of the other researchers from the initial 2018 project spoke to The Independent as well.

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His name is Scott Carver, and he plied his trade as a biologist in Australia at the time. For him, the wombat analysis was valuable beyond the final results. Carver said, “There is much general interest from the public, both in Australia and internationally, about how and why wombats create cube-shaped feces.”

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“Many ideas, some more entertaining than others, have been put forward to explain [the cubed poop],” Carver told the U.K. newspaper. “But until this study, nobody had ever investigated the cause. This has been a fantastic collaboration, which shows the value of interdisciplinary research for making new scientific discoveries.”

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And that’s all thanks to a wombat’s intestines. Remarkable stuff! Yet while these findings have opened up some fascinating doors, the marsupials will be none the wiser. Instead, they’ll continue to use their weird-looking poo as a marker and a potential lure for companions without a care in the world.

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