Why wombats don’t cut corners: scientists discover how they produce square poo from a round hole

Squaring the circle: wombat droppings come with eight corners (Getty Images/iStockphoto)

We all have different abilities and skills to boast of at dinner parties, but the bare-nosed wombat has one that’s genuinely unique among living creatures: it produces cube-shaped poo.  

And now scientists say they have discovered how it does so from a round anus.

For years, experts had been puzzled by the animal’s particular talent, so the discovery has caused much excrement – sorry, excitement – among biologists.

Bare-nosed wombats, commonly found in the southeastern side of Australia, eats mostly grass, plants and shrub roots, producing up to 100 pellets a night. Droppings from the furry marsupials advertise their territory to others.

Scientists who dissected three dead wombats found regions of varied thickness and stiffness in the intestines, Science Magazine reported.  

The stiffer portions are “like a stiff rubber band – [they] contract faster than the soft regions,” said David Hu, of the Georgia Institute of Technology and study author.  

Softer intestinal regions squeeze slowly and mould the final corners of the cube, the team found.

“Wombat dissections show that cubes are formed within the last 17 per cent of the intestine,” the authors wrote in the aptly named journal Soft Matter.  

“The corners arise from faster contraction in the stiff regions and relatively slower movement in the centre of the soft regions.”

Contrary to what you might think, cube-shaped poo does not seem to be painful. Dr Hu said wombats in captivity had poo that was less cubic than that of those in the wild. “The squarer the poop, the healthier the wombat,” he said.