我們終于知道為什么袋熊會拉完美的立方體了

我們終于知道為什么袋熊會拉完美的立方體了

Like other herbivores, wombats poop a lot, but unlike any other known species, their droppings are almost cubic, the size and shape of dice. Biologists have long had an explanation for why this is, but have now mostly explained the how.

和其他食草動物一樣，袋熊也會大量排便，但與其他已知物種不同的是，它們的糞便幾乎是立方體的，大小和形狀都像骰子。長期以來，生物學家們一直對這一現(xiàn)象有一個解釋，但現(xiàn)在主要解釋的是如何發(fā)生的。

Anything practiced by one animal species alone among all the millions on Earth is interesting, and biologists have long been intrigued by wombats' distinctive droppings. Moreover, even world leaders in animal preservation recognize wombats' special excellence. The shape is thought to help wombats mark their territory, by allowing them to produce tall piles that don't roll down the often steep hillsides of their habitat.

在地球上數(shù)百萬種動物中，只有一種動物的行為是有趣的，生物學家長期以來一直對袋熊獨特的糞便感興趣。此外，即使是世界動物保護領袖也承認袋熊的特殊優(yōu)點。人們認為，這個形狀可以幫助袋熊標記自己的領地，因為它們可以堆出高高的堆，而不會從棲息地陡峭的山坡上滾下來。

However, many other species use dung to mark their territory, and have never come up with this useful innovation, for the simple reason it isn't easy to construct a digestive system that produces cubic, rather than broadly cylindrical, shapes. Now the wombat's secret has finally been revealed and published in the journal Soft Matter.

然而，許多其他物種用糞便來標記自己的領地，而且從來沒有發(fā)明過這種有用的創(chuàng)新，原因很簡單，要構建一個只能產(chǎn)生立方體而不是圓柱形的消化系統(tǒng)并不容易。現(xiàn)在袋熊的秘密終于被揭開，并發(fā)表在《軟物質》雜志上。

Stephen Luntz

The work was led by Dr Patricia Yang of the Georgia Institute of Technology, proving wombat-love is truly a universal language. "The first thing that drove me to this is that I have never seen anything this weird in biology. That was a mystery," Yang said in a statement. "I didn't even believe it was true at the beginning. I Googled it and saw a lot about cube-shaped wombat poop, but I was skeptical."

這項工作由喬治亞理工學院的Patricia Yang博士領導，證明了袋熊的愛確實是一種通用語言。“驅使我這么做的第一件事是，我在生物學上從未見過這么奇怪的事情。這是一個謎，”楊在一份聲明中說。“一開始我甚至不相信這是真的。我在谷歌上搜索了一下，看到了很多關于袋熊的方形糞便的信息，但我對此持懷疑態(tài)度。”

So Yang, who studies fluid dynamics within the body, did the appropriately scientific thing. She obtained digestive systems of wombats tragically killed by cars and inflated their intestines. The widespread assumption wombat anuses must be square has long been debunked, and Yang also contradicted the previous theory that the cubic shape is formed at the top of the intestine.

所以，研究人體流體動力學的楊做了一件恰當?shù)目茖W事情。她獲得了不幸被汽車撞死的袋熊的消化系統(tǒng)，并使它們的腸道充氣。人們普遍認為袋熊的肛門一定是方形的，但這一假設早已被推翻，楊教授也反駁了先前的立方體是在腸道頂部形成的理論。

Instead, the digested wombat food comes down the gut in a semi-liquid state, only to solidify in the last 8 percent of the intestine, something Yang and colleagues attribute to alternating rigid and flexible stretches of the intestine walls. These apply very different strains to the cubes' corners and edges to produce the cubic shapes.

相反，袋熊消化后的食物會以半液態(tài)的狀態(tài)進入腸道，只會在最后8%的腸道中凝固，楊及其同事認為這是由于腸道壁的剛性和柔性交替拉伸造成的。它們對立方體的邊角施加了非常不同的張力，從而產(chǎn)生了立方體的形狀。

Because you'd probably rather look at wombats than their droppings. Paul Looyen/Shutterstock

Curiosity-inspired research always attracts allegations of wasting tax-payer funds, but Yang thinks there could be practical outcomes besides the satisfaction the results bring. "We currently have only two methods to manufacture cubes: We mold it, or we cut it. Now we have this third method," she said. Whether replica wombat intestines will prove advantageous in producing industrial parts remains to be seen, but it's possible future manufacturing revolutions could be inspired by the wombat's gut.

出于好奇的研究總是會引來浪費納稅人資金的指控，但楊認為，除了結果帶來的滿足感外，還可能有實際的結果。“我們目前只有兩種制造立方體的方法:模塑或切割。現(xiàn)在我們有了第三種方法，”她說。仿制袋熊腸子在生產(chǎn)工業(yè)部件方面是否有優(yōu)勢還有待觀察，但未來的制造業(yè)革命可能會受到袋熊腸子的啟發(fā)。

One thing Yang hasn't solved, however, is the old question of how painful it is for wombats to be constantly shitting (small) bricks.

然而，楊還沒有解決的一個老問題是，袋熊不斷拉小磚塊有多痛苦。

A version of this article was first published on 19 November 2018.

本文首次發(fā)表于2018年11月19日。