How does hibernation work? - Sheena Lee Faherty

譯者: Marssi Draw 審譯者: Regina Chu

Onboard the spacecraft, the astronauts preset the timer,

太空人在太空船上預設定時器

enclose themselves in capsules,

把自己關進太空艙裡

and fall into a deep hibernation

然後陷入沉睡的冬眠狀態

that’ll carry them several hundred years into the future.

將他們帶到未來數百年後

This is a familiar scene in many sci-fi films,

這是在科幻電影裡常見的場景

but could humans ever actually hibernate in real life?

但人真的可以在現實生活中冬眠嗎？

Researchers interested in this question turn to the animal kingdom,

對這個問題感興趣的科學家 轉而研究動物王國

where hibernation is commonplace,

冬眠在動物界很普遍

occurring in over 200 species that we know of.

我們已知約有兩百種物種會冬眠

Take the Arctic ground squirrel.

以北極地松鼠為例

Native to the North American tundra and northern Russia,

牠們是北美凍原和北俄原生種

this animal burrows beneath the permafrost

這種動物會挖地洞到永凍層之下潛伏

and slips into a state of suspended animation,

陷入暫停生命的狀態

its body temperature plummeting to a frigid -2.9 degrees Celsius.

體溫降至極低的攝氏 -2.9 度

Others, like the female black bear, can multitask,

另外像是母黑熊可以同時進行多種任務

giving birth and lactating while they’re hibernating through the winter.

在冬眠時產子並哺乳

The fat-tailed dwarf lemur prepares for its long dormancy

粗尾侏儒狐猴準備冬眠的方式是

by gorging on food and storing the majority of its fat reserves in its tail,

狂吃東西並將大多脂肪儲存在尾巴裡

doubling its body weight.

重量比身體還多一倍

After hibernation, it emerges looking as svelte as ever.

冬眠之後，牠們又會變得纖細苗條

So why do these animals go to such extremes?

為什麼這些動物 會採取如此極端的行為？

Hibernation is a necessity,

對牠們而言，冬眠是必要的

a survival tactic for making it through the harsh winter months

是一種求生技能 好讓自己度過長達數月的嚴冬

when dwindling food and water reserves threaten survival.

因為飲食減少受限時 性命就會受到威脅

For many years, experts believed hibernation happened

許多年來，專家相信冬眠只會出現在

only in arctic and temperate environments.

北極和溫帶地區

But more recently, they’ve discovered animals hibernating

但最近他們發現

動物也會在乾燥的沙漠 和熱帶雨林冬眠

even in arid deserts and tropical rainforests.

As hibernation kicks in,

動物一開始冬眠

animals’ heartbeats usually slow to about 1 to 3% of their original speed,

心跳通常就會減緩至 原來的 1% 到 3%

like the dwarf lemur’s,

像是侏儒狐猴

which drops from its usual roughly 180 beats per minute

原本心跳每分鐘約 180 下

to just around four.

冬眠時會減至每分鐘四下

Breathing also declines dramatically

呼吸也會大幅減少

to just one breath every 10 to 21 minutes in the lemur’s case.

到每 10 到 21 分鐘呼吸一次

And black bears, like most hibernators,

黑熊跟大部分的冬眠動物一樣

don’t urinate or defecate the entire hibernation season.

整個冬眠期都不泌尿或排泄

Hibernating animals appear to stay alive

冬眠動物維持生命

by having just enough blood and oxygen moving around their bodies.

只仰賴足夠的血液和氧氣 在身體裡流動

And scans of hibernating animals reveal that their brain activity

透過掃描冬眠動物發現 牠們的腦部活動

has just about flat-lined.

幾乎是靜止不動

But hibernation isn’t a long winter’s nap.

但冬眠並非漫長的冬日午覺

As far as researchers know,

就研究人員所知

in lemurs and ground squirrels anyway,

狐猴和地松鼠

the animals aren’t even sleeping for most of it.

幾乎大部分的時間都沒睡

Hibernation is actually made up of regular bouts of reduced metabolic rate

冬眠其實是由間歇性的 降低代謝率和體溫組成

and body temperature known as torpor.

此現象稱為蟄伏

Animals can be in torpor for a few days to five weeks,

動物蟄伏可長達五天到五個星期之久

after which they resume normal metabolic rate and body temperature

之後牠們恢復正常的代謝率和體溫

for about 24 hours,

大約 24 小時

before going back into torpor again.

然後再次進入蟄伏

The phenomenon is known as an interbout arousal,

這種現象稱為短暫覺醒期

and why it occurs is still a mystery.

成因仍是個謎

The behaviors inherent in hibernation,

冬眠時的行為

like going five weeks without sleep,

像是五週不睡覺

or dropping to near-freezing body temperatures

或體溫降至冰點

would be potentially fatal to non-hibernating species like us.

對我們這種不冬眠的物種來說 可能會致命

To find out how hibernators are able to do this,

研究員為了找出動物為何能冬眠

researchers turned their attention to those animal’s genomes.

將焦點轉向動物的基因組

So far, they’ve discovered that hibernation is controlled by genes

到目前為止，他們發現 冬眠是受基因控制

that turn off and on in unique patterns throughout the year,

該基因整年會用 特殊形式來關閉和開啟

fine-tuning the hibernator’s physiology and behavior.

微調冬眠動物的生理機能和行為

For example, ground squirrel, bear and dwarf lemur studies

例如地松鼠、熊和侏儒狐猴的研究

have revealed that these animals are able to turn on the genes

顯示這些動物能夠開啟基因

that control fat metabolism

控制脂肪代謝

precisely when they need to use their fat stores

精準地在牠們需要運用儲存的脂肪

as fuel to survive long periods of fasting.

做為燃料時，讓牠們度過漫長的禁食期

And the genes in question are present in all mammals,

這個基因存在所有哺乳動物中

which means that researchers could study hibernating mammals

意味著研究員可以 調查冬眠的哺乳動物

to see how their unique control of physiology might help humans.

看牠們獨特的生理機能控制 是否能幫助人類

Understanding how hibernators deal with reduced blood flow

了解冬眠動物如何應付減緩的血流

could lead to better treatments for protecting the brain during a stroke.

也許能幫助人類在治療中風時保護腦部

Figuring out how these animals avoid muscle deterioration

理解這些動物如何避免肌肉退化

might improve the lives of bedridden patients.

或許能幫助長期臥病在床患者的生活

And studying how hibernating animals control their weight with ease

研究冬眠動物如何輕鬆控制體重

could illuminate the relationship between metabolism and weight gain in humans.

也許能幫助了解人類 新陳代謝和增重之間的關係

And yes, more research in this area

當然，越多這個領域的研究

might someday make human hibernation a real possibility.

也許某一天就能讓人類冬眠實現

Imagine our surprise if the key to intergalactic travel

想像我們會有多訝異 發現銀河之旅的關鍵

turns out to be ground squirrels, black bears, and dwarf lemurs.

掌握在地松鼠、黑熊和侏儒狐猴手中