Mystery of Wombat Excrement Dispelled

[Recusant]

Wombats excrete cube-shaped feces. Why and how was not properly understood up till now. A new paper explains the "how," but I'm not impressed by the "why" hypothesis mentioned in the article linked below. I'm resisting getting into a humorous take on this, leaving that to those with better abilities, should they choose to indulge. 

"Box seat: scientists solve the mystery of why wombats have cube-shaped poo" | The Guardian

How wombats produce their cube-shape poo has long been a biological puzzle but now an international study has provided the answer to this unusual natural phenomenon.

The cube shape is formed within the intestines – not at the point of exit, as previously thought – according to research published in scientific journal Soft Matter on Thursday.

The paper expands upon preliminary findings first presented at a meeting of the American Physical Society's fluid dynamics division in Georgia in 2018.

[Continues . . .]

The link in the second paragraph takes you to the abstract. The full paper is available with a free account at Royal Society of Chemistry Publishing.

Abstract for "Intestines of non-uniform stiffness mold the corners of wombat feces":

The bare-nosed wombat (Vombatus ursinus) is a fossorial, 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. Using a mathematical model, we simulate a series of azimuthal contractions of a damped elastic ring composed of alternating stiff and soft regions. Increased stiffness ratio and higher Reynolds number yield shapes that are more square. The corners arise from faster contraction in the stiff regions and relatively slower movement in the center of the soft regions. These results may have applications in manufacturing, clinical pathology, and digestive health.

[xSilverPhinx]

Asked why wombats have this feature, Carver said one theory was that wombats, with their strong sense of smell, communicate with each other via faeces and that the cube shape helps prevent the faeces from rolling away.

Indeed, sounds like wombatshit to me.

Why does there even have to be a 'why'?