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Science and technology
科學(xué)技術(shù)
Exercise and addiction
鍛煉也會上癮
Fun run
奔跑的奧秘
People, it seems, have evolved to be addicted to exercise
人類似乎在進(jìn)化過程中對鍛煉上癮了
AS THE legions of gym bunnies and jogging enthusiasts who race out into the spring sunshine every year clearly demonstrate, running can be fun.
那一大批在春日和煦的陽光中奔跑著的健身愛好者無不向我們展示著奔跑的樂趣。
More specifically, running triggers the release of brain chemicals called endocannabinoids that create a potent feeling of pleasure.
更確切地講，在奔跑時(shí)人體內(nèi)有一種化學(xué)物質(zhì)被釋放，從而使人產(chǎn)生一種強(qiáng)烈的愉悅感。
As their name suggests, these endocannabinoids work in the same way as the active ingredient of marijuana.
正如其名字的含義一般，這些endocannabinoids有著跟大麻中的有效成分一樣的效果。
From an evolutionary standpoint this surge of endocannabinoids, and the runner's high it creates, make sense.
從進(jìn)化論的觀點(diǎn)來看，人體內(nèi)endocannabinoids水平的上升及由此而生的賽跑者的亢奮對人類的發(fā)展是有意義的。
For ancient humans, remaining fit enough to run after game and away from predators and enemies was vital for survival.
那些遠(yuǎn)古時(shí)代的人類，為了能夠順利追捕到獵物并從其他獵食者的追擊中逃脫，必須將身體狀態(tài)始終維持在一個(gè)良好的水平。
Yet whether other mammals are also driven to exercise by endocannabinoids has remained a mystery.
既然人類如此，那么其他哺乳動物是否也會在endocannabinoids的內(nèi)在驅(qū)動下而進(jìn)行鍛煉呢？
Now a study led by David Raichlen of the University of Arizona has revealed that the runner's high does exist in other species, but not in all.
這仍是個(gè)未解之謎。現(xiàn)在一項(xiàng)由Arizona大學(xué)的David Raichlen博士領(lǐng)銜的研究已經(jīng)在其他哺乳動物體內(nèi)-并非全部都有-發(fā)現(xiàn)了endocannabinoids的存在。
You expect me to what?!
你猜我在干什么？！
Dr Raichlen hypothesised that endocannabinoid-driven exercise highs would be found in those mammals that gain an evolutionary benefit from being fast on their feet: antelopes, horses and wolves, for example.
Raichlen先提出了一個(gè)假設(shè)：像羚羊，馬和狼這樣一些因擁有飛毛腿而在進(jìn)化過程中受益的哺乳動物中也存在著鍛煉產(chǎn)生的興奮現(xiàn)象；
However, he also thought that they would not be present in those which are known for being quick and agile, but not for running, like ferrets.
而那些以靈動著稱，卻非憑奔跑文明的動物，如雪貂，則不會出現(xiàn)此現(xiàn)象。
To test these ideas, he and a team of colleagues devised an experiment that monitored the endocannabinoid levels of different species after they had been walking or running on a treadmill.
為了檢驗(yàn)這些猜想，Raichlen和由其同事所組成的團(tuán)隊(duì)設(shè)計(jì)了一個(gè)實(shí)驗(yàn)-對在跑步機(jī)上行走，奔跑過后的動物體內(nèi)的endocannabinoids水平進(jìn)行監(jiān)控。
The experimental animals in question were ten people, eight dogs and eight ferrets.
被考慮用來進(jìn)行實(shí)驗(yàn)的動物有以下三種：十個(gè)人，八條狗和八只雪貂。
Dr Raichlen had them run or walk on the treadmill for 30 minutes.
Raichlen博士先讓他們在跑步機(jī)上行走或奔跑30分鐘。
Since running and walking speeds differ from species to species, the speed at which the treadmill moved was varied so that it raised the heart rates of the different participants to the same level.
由于不同的動物速度不一，所以跑步機(jī)的傳送帶速度設(shè)置是以使不同動物的心率達(dá)到同一水平為依據(jù)。
Running speeds were thus set at 2.5 metres a second for people, 1.83 for dogs and 0.84 for ferrets.
這樣設(shè)置的結(jié)果便為：奔跑速度為人類2.5米/秒，狗1.83米/秒，雪貂0.84米/秒；
Walking speeds were set at 1.25 metres a second for people and 1.1 for dogs.
行走速度為人類1.25米/秒，狗1.1米/秒。
The ferrets proved too easily distracted to walk consistently on the treadmills and were thus left to sit quietly in their cages for this part of the study.
雪貂由于太易分心，沒辦法讓它持續(xù)在跑步機(jī)上行走，所以在進(jìn)行該部分實(shí)驗(yàn)時(shí)它們被留在了籠中靜靜地坐著。
Each participating animal ran for one session and walked for one other, and did so on separate days, to avoid exhaustion.
每只動物會跑一段走一段，為了避免動物們出現(xiàn)筋疲力盡的情況，實(shí)驗(yàn)是分成幾天進(jìn)行的。
Before and after each session, blood was drawn from each and the endocannabinoid levels in it were measured.
在實(shí)驗(yàn)前和試驗(yàn)后，動物們都會被抽血以檢驗(yàn)其中的endocannabinoid水平。
The researchers report in the Journal of Experimental Biology that, after 30 minutes of walking, participants' endocannabinoid levels did not rise.
研究人員在《生物學(xué)實(shí)驗(yàn)》雜志中提到，在經(jīng)過30分鐘的行走之后，參加實(shí)驗(yàn)的動物的endocannabinoid水平并沒上升。
After running, however, the average human's endocannabinoid levels rose from 2.4 picomoles per millilitre to 6.1.
然而在奔跑過后情況則有所不同：那10個(gè)人的平均endocannabinoid水平從2.4 pmol/ml上升到了6.1 pmol/ml。
Dogs showed a similar trend, with levels rising from 2.4 pmol/ml to 8.0.
狗的變化趨勢與人類似---由2.4 pmol/ml升至8.0 pmol/ml。
Ferrets were different. Although they did show an increase, from 3.0 to 3.9 pmol/ml, this was not a statistically significant rise.
唯獨(dú)雪貂例外。他們的endocannabinoid水平雖亦有所上升-3.0 至 3.9 pmol/ml，但仍處于統(tǒng)計(jì)學(xué)上可不被納入考慮的范圍內(nèi)。
These findings suggest that dogs experience a runner's high but ferrets do not.
這些發(fā)現(xiàn)表明狗中同樣存在著賽跑者的亢奮現(xiàn)象，而雪貂則沒有。
Dr Raichlen argues that it makes sense for ferrets not to have systems that reward cardiovascular activity, since such exercise consumes a lot of energy, may cause injury, and is not crucial to the stealthy hunting technique of sneaking down burrows and killing rabbits in their sleep.
看來雪貂體內(nèi)并不存在對心血管活動進(jìn)行陽性強(qiáng)化刺激的系統(tǒng)，Raichlen博士認(rèn)為這對雪貂的發(fā)展同樣是有意義的，要知道太劇烈的運(yùn)動會消耗掉過多的能量， 甚至引發(fā)受傷，且這并非是雪貂捕獵技術(shù)中的關(guān)鍵-它們一般只需偷偷溜進(jìn)兔子窩并在兔子們熟睡時(shí)將其殺死即可。
What is not clear is whether the endocannabinoid reward is an ancient mechanism that has been lost on branches of the mammalian tree that do not need it, or is something that evolves quickly in species which become active.
仍有待考證的是，究竟這種endocannabinoid刺激機(jī)制是從遠(yuǎn)古時(shí)代起即為哺乳類動物所擁有，還是從某些活躍的個(gè)別物種中進(jìn)化出來的？
Given that humanity's arboreal simian ancestors would presumably have had little need to run, it is probably the latter.
鑒于人類的祖先—類人猿是樹棲動物，據(jù)推測它們很少有奔跑的需要，因此正確結(jié)論很可能是后者。
But to be sure Dr Raichlen will need to put animals far less co-operative than ferrets on the treadmill.
但若要確認(rèn)此假設(shè)，Raichlen博士需將更多如雪貂般不太合作的動物哄上跑步機(jī)。
