The Mystery of Wombats' Cube-Shaped Poop Has Finally Been Solved

An unnamed Robert Frost character once said, “Good fences make good neighbors,” and wombats have taken this sentiment to heart. These furry little marsupials, native to Australia, are famous for building structures out of their own poop to mark their territory. It’s like an environmentally friendly version of a border wall. These walls take special perfectly cube-shaped poop to build, though, and it turns out that wombats have extremely special digestive systems to produce it.

As Inverse reported in November, researchers explored the innards of wombats for the first time in 2018, unlocking the secret of their secretions. Presenting at the American Physical Society’s Division of Fluid Dynamics 71st Annual Meeting in Atlantia, Georgia, a team of scientists outlined how it all comes down to the wombat’s intestinal walls.

“When I first heard about wombat poop, I was very, very skeptical because I didn’t think that poop could be square,” Patricia Yang, Ph.D., a postdoctoral fellow at the Georgia Institute of Technology, told Inverse in November. For those of us with cylindrical poop, it might be hard to relate to the wombat, as squares are very rare in nature. But as Yang and her colleagues found, they can occur under the right circumstances.

This is #8 on Inverse’s list of the 25 Most WTF stories of 2018.

By dissecting two wombats that had been euthanized after getting hit by cars, Yang and her team were able to actually take a look inside these unique animals. They inserted balloons into the wombats’ intestines and inflated them, using pig intestines as a more familiar point of comparison. Through this experiment and another simulation using pantyhose, they discovered that wombat poop transitions from a liquid to a solid state in the last 25 percent of the intestine and gets its signature 90-degree edges in the final 8 percent of the intestine.

This final transformation in shape is a result of the intestinal walls having varying elastic properties — stiffer in some places and stretchier in others, molding the poop into squares. But water content plays a huge role, too.

“The feces of a wombat is only about 50 percent water, while normal human feces is about 70 to 80 percent water,” Yang said. “Rabbits, deer, and goats have pellets, and these droppings are about 55 to 60 percent water — as for those pellet animals, they have an extra long colon compared to other animals of a similar size.”

This research, which isn’t yet published, represents the first systematic investigation of this mystery, one that scientists have long observed but not understood. With a better understanding of how wombats’ intestines enable them to build their famous walls, scientists have unlocked a key to their evolutionary puzzle. But which came first, the cube poop or the poop walls? Maybe they’ll find that out next.

As 2018 draws to a close, Inverse is counting down the 25 stories that made us go WTF. Some are gross, some are amazing, and some are just, well, WTF. In our ranking from least to most WTF, this has been #8. Read the original article here.

Watch the full 25 WTF countdown in the video below.