科学家们表示，他们发现了袋熊是如何以及为何会拉方形便便的，这是已知的唯一一种会拉出方形便便的物种。
Scientists say they have uncovered how and why wombats produce cube-shaped poo -- the only known species to do so.
这种澳大利亚有袋动物每晚可以拉多达100块的大便，并使用这些粪堆来标记领土。
The Australian marsupial can pass up to 100 deposits of poop a night and they use the piles to mark territory.
尽管有像其他哺乳动物一样的圆形肛门，不过袋熊不会排出圆形颗粒、管状圈形或一塌塌的粪便。
Despite having round anuses like other mammals, wombats do not produce round pellets, tubular coils or messy piles.
佐治亚理工学院的帕特丽夏·杨表示：“我从未在生物学上看到这么奇怪的现象，这引起我的兴趣。这是一个谜。”
"The first thing that drove me to this is that I have never seen anything this weird in biology. That was a mystery," Georgia Institute of Technology's Patricia Yang said.
在研究了在塔斯马尼亚被汽车撞伤并安乐死后的袋熊的消化道后，由杨博士领导的一个小组在美国物理学会流体动力学部门于亚特兰大举行的年会上介绍了其研究结果。
After studying the digestive tracts of wombats put down after road accidents in Tasmania, a team led by Dr Yang presented its findings at the American Physical Society Division of Fluid Dynamics' annual meeting in Atlanta.
据《科学新闻》报道，同样来自乔治亚理工学院大卫·胡称：“我们在圣诞节期间剖开了这些肠子。”
"We opened those intestines up like it was Christmas," said co-author David Hu, also from Georgia Tech, according to Science News.
该团队通过在动物的消化道中插入一个气球，将袋熊的肠道与猪肠进行比较，看看它是如何伸展以适应气球的。
The team compared the wombat intestines to pig intestines by inserting a balloon into the animals' digestive tracts to see how it stretched to fit the balloon.
粪便在袋熊肠道最后25%的位置处从液体状态变为固态--但在最后8%的位置处，肠壁的弹性变化意味着大便会形成分离的立方体。
In wombats, the faeces changed from a liquid-like state into a solid state in the last 25% of the intestines -- but then in the final 8% a varied elasticity of the walls meant the poop would take shape as separated cubes.
科学家们解释称，这就形成了2厘米（0.8英寸）的立方形粪便，这是自然界和袋熊独有的特征。
This, the scientists explain, resulted in 2cm (0.8in) cube-shaped poops unique to wombats and the natural world.
然后这种有袋动物会堆叠这些立方体，堆得越高越好，它们通过这样的方式与其他袋熊交流并吸引其他袋熊。
The marsupial then stacks the cubes -- the higher the better so as to communicate with and attract other wombats.
杨博士表示：“我们目前只有两种制造立方体的方法：模塑或切割。现在我们有了第三种方法。”
"We currently have only two methods to manufacture cubes: We mould it, or we cut it. Now we have this third method," Dr Yang said.