生命在於運動,老鼠也愛奔跑大綱

If an exercise wheel sits in a forest, will mice run on it?

如果把跑輪放在森林裏，小鼠會上去跑步嗎？

Every once in a while, science asks a simple question and gets a straightforward answer.

科學時常會提出一個簡單的問題，然後得到一個直截了當的答案。

In this case, yes, they will. And not only mice, but also rats, shrews, frogs and slugs.

這個問題的答案是，會。不僅小鼠會，大鼠、鼩鼱、青蛙和蛞蝓都會。

True, the frogs did not exactly run, and the slugs probably ended up on the wheel by accident, but the mice clearly enjoyed it. That, scientists said, means that wheel-running is not a neurotic behavior found only in caged mice.

當然，青蛙算不上在跑，蛞蝓可能也是偶然來到跑輪上的，但是小鼠明顯是真的喜歡跑輪。科學家表示，這說明在跑輪上跑步並不是關在籠子裏的老鼠纔有的神經性舉動。

They like the wheel.

它們喜歡跑輪。

Two researchers in the Netherlands did an experiment that it seems nobody had tried before. They placed exercise wheels outdoors in a yard garden and in an area of dunes, and Monitored the wheels with motion detectors and automatic cameras.

荷蘭的兩名研究員做了一項似乎從來沒人做過的實驗。他們在室外的院子和一塊沙地裏放置了一些跑輪，並通過運動檢測器和自動相機對這些跑輪進行監測。

They were inspired by questions from animal welfare committees at universities about whether mice were really enjoying wheel-running, an activity used in all sorts of studies, or were instead like bears pacing in a cage, stressed and neurotic. Would they run on a wheel if they were free?

他們的靈感來自一些大學的動物福利委員會所提出的問題。這些委員會質疑小鼠是否真的喜歡在輪子上跑步——所有研究都會用到這個活動，或者還是像在籠子裏踱步的熊那樣，出於壓力和緊張。如果處於自由狀態，它們還會在輪子上跑步嗎？

Now there is no doubt. Mice came to the wheels like human beings to a health club holding a spring membership sale. They made the wheels spin. They hopped on, hopped off and hopped back on.

目前，這一點毫無疑問。到跑輪上跑步的小鼠，就像來到正在舉行春季促銷的健身俱樂部的人類一樣。他們開始讓輪子轉動。它們跳上去、跳下來，然後再跳上去。

"When I saw the first mice, I was extremely happy," said Johanna H. Meijer at Leiden University Medical Center in the Netherlands. "I had to laugh about the results, but at the same time, I take it very seriously. It's funny, and it's important at the same time."

“當我看見第一隻小鼠時，我非常高興，”荷蘭萊頓大學醫學中心(Leiden University Medical Center)的約翰娜·H·梅傑(Johanna H. Meijer)說。“這些結果不能不讓我覺得可笑，但同時，我也會認真對待它。這很有趣，同時也很重要。”

Dr. Meijer's day job is as a "brain electrophysiologist" studying biological rhythms in mice. She relished the chance to get out of the laboratory and study wild animals, and in a way that no one else had.

梅傑的正職工作是研究小鼠生物節律的“腦電生理學家”。她非常享受走出實驗室，以前所未有的方式研究野生動物的機會。

She said Konrad Lorenz, the great-grandfather of animal behavior studies, once mentioned in a letter that some of his caged rats had escaped and then returned to his garden to use running wheels placed there.

她說，動物行爲研究的鼻祖康拉德·洛倫茨(Konrad Lorenz)曾在一封信中提到，有些被他關在籠子裏的大鼠逃走後，又回到他的花園，到放在那裏的跑輪上跑步。

But, Dr. Meijer said, the Lorenz observation "was one sentence."

但是，梅傑說，洛倫茨的觀察“只是一句話”。

For the experiment, the wheels were enclosed so that small animals could come and go but so that larger animals could not knock them over. Dr. Meijer set up motion sensors and automatic video cameras. Several years and 12,000 snippets of video later, she and Yuri Robbers, also a Leiden researcher, reported the results. They were released online Tuesday in the Proceedings of the Royal Society B.

爲了進行試驗，跑輪被圍了起來，這樣小動物就能來去自由，大動物則無法把它們撞翻。梅傑安放了運動傳感器和自動攝影機。她和同爲萊頓研究人員的尤里·羅伯斯(Yuri Robbers)報告稱，幾年後，他們獲得了1.2萬個視頻片段。週二，這些結果被公佈在了《英國皇家學報B》(Proceedings of the Royal Society B.)的網站上。

Gene D. Block, chancellor of the University of California, Los Angeles, was not involved with the paper but knows Dr. Meijer and had seen the wheel set up in her garden. He said the study made it clear that wheel-running is "some type of rewarding behavior" and "probably not driven by stress or anxiety."

加州大學洛杉磯分校校長吉恩·D·布洛克(Gene D. Block)與這篇論文無關，但是他認識梅傑，而且還見過她在花園裏放置的跑輪。他說，研究表明在跑輪上跑步是“一種有益的行爲”，“可能不是出於壓力或焦慮”。

Mice accounted for 88 percent of the wheel-running events, and spent one minute to 18 on the wheel. The other animals each accounted for less than 1 percent. Frogs, though there were very few, were seen to get on the wheel, get off and get back on.

在所有在跑輪上跑步的動物中，小鼠佔了88%，在跑輪上花費的時間爲1到18分鐘。其他每種動物所佔的比例不到1%。雖然數量不多，但是我們也看到青蛙爬上跑輪，爬下來，然後又爬回去。

Russell Foster, a circadian rhythm researcher at Oxford University, said he read the paper and sent it out to other scientists on behalf of the Proceedings and was delighted when peer reviews from other scientists were positive.

羅素·福斯特(Russell Foster)是牛津大學(Oxford University)的一名生理節律研究員。他說他讀過這篇論文，並代表《英國皇家學報B》把它發給了其他科學家。其他科學家都對此持肯定態度，這讓他感到高興。

Marc Bekoff, a professor of ecology and evolutionary biology at the University of Colorado who is active in the animal welfare movement, said in an email that he thought the paper did show that wheel-running could be a "voluntary activity," but that mice in labs may be doing more of it because of the stress of confinement.

馬克·貝科夫(Marc Bekoff)是科羅拉多大學(University of Colorado)的一名生態學和進化生物學教授，積極參與動物福利運動。他在電子郵件中說，他認爲這篇論文的確表明跑輪運動可能是一種“自願活動”，但是實驗室的老鼠可能會因爲禁閉的壓力而進行更多跑輪運動。

"Wild bears will often pace back and forth," he wrote, "but in captivity, the rate of doing it seems to be greatly heightened."

“野熊經常會來回踱步，”他寫道，“但是如果被關起來，他們踱步的頻率似乎就會大幅度增加。”

As to why the mice, frogs or perhaps even slugs run, or move, on the wheel, Dr. Meijer said she thought that "there is an intrinsic motivation for animals, or should I say organisms, to be active."

至於爲什麼小鼠、青蛙或者甚至連蛞蝓都會在跑輪上跑步或移動，梅傑說她認爲“動物天生具有行動的慾望，或者說保持活躍的機制”。

Huda Akil, co-director of the Molecular and Behavioral Neuroscience Institute at the University of Michigan, who has studied reward systems, said: "It's not a surprise. All you have to do is watch a bunch of little kids in a playground or a park. They run and run and run."

研究過獎勵機制的密歇根大學(University of Michigan)分子和行爲神經研究中心(Molecular and Behavioral Neuroscience Institute)主任胡達·阿基勒(Huda Akil)說：“這並不意外。你需要做的就是看一羣小孩在操場或公園裏玩耍。他們會一直跑，一直跑，一直跑。”

Dr. Akil said that in humans, running activates reward pathways in the brain, although she pointed out that there are innate differences in temperament in all sorts of animals, including humans. Rats that do not like to run can be bred. And plenty of people do all they can to avoid jogging, cycling and elliptical machines.

阿基勒說，在人類身上，跑步運動可以激活大腦裏的獎勵迴路，雖然她指出所有動物的秉性都存在固有的不同，人類也是如此。可以培育出不愛跑的大鼠。而極盡可能地避免慢跑、騎車和玩橢圓機的人類也多得是。

Presumably, the same is true of wild mice. While some were setting the wheel on fire with their exertions, others, out of camera range, may have been sprawled out on the mouse equivalent of a lounge chair, shaking their whiskers in dismay and disbelief.

大概對於野鼠而言也是如此。雖然有些老鼠正在跑輪上奮力奔跑，但是那些不在攝像機覆蓋範圍內的老鼠，可能正慵懶地躺在老鼠版的休閒椅上，在驚恐或猶疑中抖着鬍鬚。