This deep-sea mystery is changing our understanding of life | Karen Lloyd

譯者: Lilian Chiu 審譯者: Yuning912 陳又寧

I'm an ocean microbiologist at the University of Tennessee,

我是田納西大學的海洋微生物學家，

and I want to tell you guys about some microbes

我想和各位談的是一些微生物，

that are so strange and wonderful

它們很奇特且美妙，

that they're challenging our assumptions about what life is like on Earth.

它們甚至在挑戰我們對於 地球上生命的相關假設。

So I have a question.

問大家一個問題。

Please raise your hand if you've ever thought it would be cool

若你曾想過搭潛水艇到海底深處

to go to the bottom of the ocean in a submarine?

是一件很酷的事，請舉手。

Yes.

好。

Most of you, because the oceans are so cool.

大部分人都舉手，因為海洋很酷。

Alright, now -- please raise your hand

好，現在請再次舉手，

if the reason you raised your hand to go to the bottom of the ocean

若你想要去海底的理由是因為

is because it would get you a little bit closer

那樣你就能稍微更接近

to that exciting mud that's down there.

海洋底部那令人興奮的泥巴。

(Laughter)

（笑聲）

Nobody.

沒有人舉手。

I'm the only one in this room.

我是在場唯一的一個。

Well, I think about this all the time.

其實，我常常在想這件事。

I spend most of my waking hours

我大部分醒著的時間，

trying to determine how deep we can go into the Earth

都在研究，我們能 潛入地球多深的地方，

and still find something, anything, that's alive,

還能發現生物，發現任何生命體。

because we still don't know the answer to this very basic question

這是個關於地球上生命的基本問題，

但我們仍然不知道答案。

about life on Earth.

So in the 1980s, a scientist named John Parkes, in the UK,

在 1980 年代，有一個英國 科學家叫做約翰帕克斯，

was similarly obsessed,

和我有類似的著迷，

and he came up with a crazy idea.

他想出了一個瘋狂的點子。

He believed that there was a vast, deep, and living microbial biosphere

他相信，有一個巨大、深層， 且活生生的微生物圈，

underneath all the world's oceans

在全世界海洋的底下，

that extends hundreds of meters into the seafloor,

深入海底數百公尺。

which is cool,

這想法很酷，

but the only problem is that nobody believed him,

唯一的問題是，沒有人相信他，

and the reason that nobody believed him

而沒有人相信他的原因，

is that ocean sediments may be the most boring place on Earth.

是因為海洋沉積可能是 地球上最無聊的地方了。

(Laughter)

（笑聲）

There's no sunlight, there's no oxygen,

那裡沒有陽光、沒有氧氣，

and perhaps worst of all,

最糟糕的可能是

there's no fresh food deliveries for literally millions of years.

數百萬年來那裡沒有新鮮食物外送。

You don't have to have a PhD in biology

你不用有生物學博士學位，

to know that that is a bad place to go looking for life.

也能知道如果要尋找生命， 那地方不是個好選擇。

(Laughter)

（笑聲）

But in 2002, [Steven D'Hondt] had convinced enough people

但在 2002 年， 約翰說服了足夠的人，

that he was on to something that he actually got an expedition

相信他可能會有所發現，

讓他真的搭上「聯合果敢號」 這艘鑽探船展開考察。

on this drillship, called the JOIDES Resolution.

And he ran it along with Bo Barker Jørgensen of Denmark.

與他同行的是丹麥的波巴克尤根森。

And so they were finally able to get

終於，他們得以取得

good pristine deep subsurface samples

地表下的深層優質原始樣本，

some really without contamination from surface microbes.

沒有受到表面微生物的污染。

This drill ship is capable of drilling thousands of meters underneath the ocean,

這艘鑽探船能夠鑽到 海底下數千公尺的深度，

and the mud comes up in sequential cores, one after the other --

而泥土核依序從芯管被取出來，

long, long cores that look like this.

像這樣非常長的芯管。

This is being carried by scientists such as myself who go on these ships,

登船拿著芯管的科學家們，包括我，

and we process the cores on the ships and then we send them home

我們會在船上處理泥土核， 然後把它們送回去

to our home laboratories for further study.

家鄉的實驗室做進一步研究。

So when John and his colleagues

所以當約翰和他的同事

got these first precious deep-sea pristine samples,

拿到第一批珍貴的深海原始樣本，

they put them under the microscope,

他們把樣本放到顯微鏡下，

and they saw images that looked pretty much like this,

他們看到的影像就像是這樣，

which is actually taken from a more recent expedition

這張圖其實是來自 更近期的一次考察，

by my PhD student, Joy Buongiorno.

由我的博士生喬依邦吉歐諾進行的。

You can see the hazy stuff in the background.

你們可以看到背景有模糊的東西。

That's mud. That's deep-sea ocean mud,

那就是泥土，深海的泥土；

and the bright green dots stained with the green fluorescent dye

而帶著綠色螢光的亮綠點

are real, living microbes.

是真正的活微生物。

Now I've got to tell you something really tragic about microbes.

我要告訴各位一件 關於微生物的悲劇。

They all look the same under a microscope,

在顯微鏡下，它們看起來都一樣，

I mean, to a first approximation.

至少大致上是一樣的。

You can take the most fascinating organisms in the world,

你可以拿世界上最炫的有機體，

like a microbe that literally breathes uranium,

比如能呼吸鈾的微生物，

and another one that makes rocket fuel,

再找個製造火箭燃料的微生物，

mix them up with some ocean mud,

把它們和一些海洋泥土混合，

put them underneath a microscope,

放到顯微鏡下，

and they're just little dots.

看到的就只是小點點。

It's really annoying.

這真的很惱人。

So we can't use their looks to tell them apart.

所以我們無法從 它們的外觀來區分它們。

We have to use DNA, like a fingerprint,

我們得用 DNA，就像指紋，

to say who is who.

來判斷誰是誰。

And I'll teach you guys how to do it right now.

我現在就可以教各位怎麼做。

So I made up some data, and I'm going to show you some data that are not real.

我捏造了一些資料， 等一下看的到資料不是真實的。

This is to illustrate what it would look like

這是用來說明，如果一些物種

if a bunch of species were not related to each other at all.

彼此之間完全沒有關係， 看起來會是什麼樣子。

So you can see each species

所以，你們可以看到，每個物種

has a list of combinations of A, G, C and T,

都能列出其 A、G、C、T 的組合，

which are the four sub-units of DNA,

它們是 DNA 的四個子單位，

sort of randomly jumbled, and nothing looks like anything else,

有點算是隨機混雜在一起， 看起來都不一樣，

and these species are totally unrelated to each other.

這些物種彼此之間完全沒關聯。

But this is what real DNA looks like,

但真正的 DNA 看起來是這樣的，

from a gene that these species happen to share.

來自那些物種剛好共有的基因。

Everything lines up nearly perfectly.

一切的排列幾乎完美。

The chances of getting so many of those vertical columns

要有這麼多直行的機率，

where every species has a C or every species has a T,

對有個 C 的每種物種， 或有個 T 的每種物種，

by random chance, are infinitesimal.

在隨機的狀況下，是無限小的。

So we know that all those species had to have had a common ancestor.

所以我們知道，所有這些 物種一定有個共同的祖先。

They're all relatives of each other.

它們彼此都是親戚。

So now I'll tell you who they are.

現在，我要告訴各位它們是誰。

The top two are us and chimpanzees,

前兩種，是人類以及黑猩猩，

which y'all already knew were related, because, I mean, obviously.

你們都知道兩者有關聯， 因為…應該很明顯吧。

(Laughter)

（笑聲）

But we're also related to things that we don't look like,

但我們也和外表 不相似的物種有關聯。

like pine trees and Giardia, which is that gastrointestinal disease

比如松樹和賈第鞭毛蟲， 它就是如果你去健行時若喝下

you can get if you don't filter your water while you're hiking.

未過濾的水，就會 得到的那種胃腸病。

We're also related to bacteria like E. coli and Clostridium difficile,

我們也和細菌有關，比如 大腸桿菌和艱難梭狀芽孢杆菌，

which is a horrible, opportunistic pathogen that kills lots of people.

它是種會趁虛而入的 恐怖病原體，很致命。

But there's of course good microbes too, like Dehalococcoides ethenogenes,

當然，也有好的微生物， 像是當脫氯菌，

which cleans up our industrial waste for us.

它能幫我們清除工業廢物。

So if I take these DNA sequences,

如果我拿這些 DNA 序列，

and then I use them, the similarities and differences between them,

然後使用它們，用它們 之間的相似和差異，

to make a family tree for all of us

來為大家做個家譜樹狀圖，

so you can see who is closely related,

可以清楚看見相近的關聯性，

then this is what it looks like.

結果就會像這樣子。

So you can see clearly, at a glance,

你第一眼就可以清楚看到，

that things like us and Giardia and bunnies and pine trees

我們、賈第鞭毛蟲、 兔子，以及松樹等等，

are all, like, siblings,

都像是手足，

and then the bacteria are like our ancient cousins.

而細菌則是我們古老的表親。

But we're kin to every living thing on Earth.

但我們和地球上的 所有生物都是親戚。

So in my job, on a daily basis,

所以，我每天的工作，

I get to produce scientific evidence against existential loneliness.

就是要製造出科學證據 來駁斥存在性的孤獨。

So when we got these first DNA sequences,

所以當我們拿到第一批 DNA 序列，

from the first cruise, of pristine samples from the deep subsurface,

來自第一次航行時從地表下 很深的地方取得的原始樣本，

we wanted to know where they were.

我們想要知道它們之前在哪裡。

So the first thing that we discovered is that they were not aliens,

所以，我們最先的發現的是： 它們不是外星人，

because we could get their DNA to line up with everything else on Earth.

因為我們能將它們的 DNA 和地球上所有其他物種排列對齊。

But now check out where they go on our tree of life.

但，現在看看它們在 我們的生命之樹上的走向。

The first thing you'll notice is that there's a lot of them.

你最先會注意到的， 是它們的數量很多。

It wasn't just one little species

並不只有一個小物種

that managed to live in this horrible place.

能夠在這個糟透的地方生存。

It's kind of a lot of things.

其實有很多東西。

And the second thing that you'll notice,

你會注意到的第二件事，

hopefully, is that they're not like anything we've ever seen before.

我希望你們注意到了，就是它們 和我們以前見過的物種都不一樣。

They are as different from each other

它們彼此之間的差異程度，

as they are from anything that we've known before

就如同它們和我們過去 所知之所有物種的差異程度，

as we are from pine trees.

如同我們和松樹的差異。

So John Parkes was completely correct.

所以，約翰帕克斯完全正確。

He, and we, had discovered a completely new and highly diverse

他和我們發現地球上有個全新

極多樣化的微生物生態系統，

microbial ecosystem on Earth

that no one even knew existed before the 1980s.

在 1980 年代之前全然不為人知。

So now we were on a roll.

我們現在好運連連。

The next step was to grow these exotic species in a petri dish

下一步是要在培養皿中 繁殖這些奇特的物種，

so that we could do real experiments on them

讓我們用來做真正的實驗，

like microbiologists are supposed to do.

微生物學家應該做的那些實驗。

But no matter what we fed them,

但，不論我們餵它們什麼，

they refused to grow.

它們都不肯繁殖。

Even now, 15 years and many expeditions later,

即使現在，十五年後， 且已經經過許多次考察，

no human has ever gotten a single one of these exotic deep subsurface microbes

仍然沒有人能夠讓任何一種 從海底表下深處取得的微生物

to grow in a petri dish.

在培養皿中成長。

And it's not for lack of trying.

且那並非因為缺乏嘗試。

That may sound disappointing,

這可能聽起來讓人失望，

but I actually find it exhilarating,

但我卻覺得很振奮，

because it means there are so many tantalizing unknowns to work on.

因為那表示有好多誘人的 未知事物等待研究。

Like, my colleagues and I got what we thought was a really great idea.

比如，我和我同事 想出了一個很好的點子。

We were going to read their genes like a recipe book,

我們要把它們的基因 當作烹飪書來讀，

find out what it was they wanted to eat and put it in their petri dishes,

找出它們想要吃什麼， 把那東西放到培養皿中，

and then they would grow and be happy.

接著它們就會快樂繁殖。

But when we looked at their genes,

但我們去看它們的基因時，

it turns out that what they wanted to eat was the food we were already feeding them.

發現它們想要吃的食物就是 我們之前餵食過的食物。

So that was a total wash.

完全是白工一場。

There was something else that they wanted in their petri dishes

在培養皿中，它們 還想要其他的東西，

that we were just not giving them.

是我們還沒給它們的。

So by combining measurements from many different places

所以，我們把來自世界上 不同地方的測量值結合起來，

around the world,

my colleagues at the University of Southern California,

我在南加州大學的同事，

Doug LaRowe and Jan Amend,

道格拉洛和楊艾曼，

were able to calculate that each one of these deep-sea microbial cells

可以計算出，每一個深海微生物細胞

requires only one zeptowatt of power,

只需要 1 zepto 瓦的能量，

and before you get your phones out, a zepto is 10 to the minus 21,

不用拿手機查了，1 zepto 就是10 的負 21 次方，

because I know I would want to look that up.

換作我是你們，我也會想查。

Humans, on the other hand,

另一方面，

require about 100 watts of power.

人類需要 100 瓦的能量。

So 100 watts is basically if you take a pineapple

基本上，100 瓦的 能量就是拿個鳳梨，

and drop it from about waist height to the ground 881,632 times a day.

每天把它從腰部的高度 丟下去 881,632 次。

If you did that and then linked it up to a turbine,

如果你那樣做，並和渦輪做連結，

that would create enough power to make me happen for a day.

就會創造出足夠的 能量讓我能夠活一天。

A zeptowatt, if you put it in similar terms,

如果用類似的方式 說明 1 zepto 瓦，

is if you take just one grain of salt

就是拿一粒鹽巴，

and then you imagine a tiny, tiny, little ball

接著，想像非常非常小的球狀體，

that is one thousandth of the mass of that one grain of salt

質量只有一粒鹽巴的千分之一，

and then you drop it one nanometer,

然後把它從一奈米的高度丟下，

which is a hundred times smaller than the wavelength of visible light,

一奈米比可見光波長還要小一百倍，

once per day.

一天丟一次。

That's all it takes to make these microbes live.

只要這樣，就能讓微生物活著。

That's less energy than we ever thought would be capable of supporting life,

我們從來沒有想過這麼少的 能量也能夠維持生命，

but somehow, amazingly, beautifully,

但，不知以什麼方式， 很神奇，也很美妙，

it's enough.

它就是足以維生。

So if these deep-subsurface microbes

所以，如果這些深海微生物

have a very different relationship with energy than we previously thought,

和能量之間的關係和 我們先前所想的很不一樣，

then it follows that they'll have to have

那就表示，它們一定也會

a different relationship with time as well,

和時間有不一樣的關係，

because when you live on such tiny energy gradients,

因為當你生活中的 能量梯度那麼小的時候，

rapid growth is impossible.

不可能會快速成長。

If these things wanted to colonize our throats and make us sick,

如果這些東西想要在我們的 喉嚨中殖民，讓我們生病，

they would get muscled out by fast-growing streptococcus

它們在開始做細胞分裂之前，

before they could even initiate cell division.

就會被快速成長的鏈球菌趕出去了。

So that's why we never find them in our throats.

那就是為何我們從未 在喉嚨中找到它們。

Perhaps the fact that the deep subsurface is so boring

也許，雖然表面下的 深層地區很無聊，

is actually an asset to these microbes.

對這些微生物而言卻是一項資產。

They never get washed out by a storm.

它們永遠不會被暴風雨沖走。

They never get overgrown by weeds.

不會被過分茂密的雜草給抑制。

All they have to do is exist.

它們只需要做一件事：存在。

Maybe that thing that we were missing in our petri dishes

也許，我們的培養皿中缺少的東西，

was not food at all.

根本不是食物。

Maybe it wasn't a chemical.

也許不是化學物質。

Maybe the thing that they really want,

也許它們真正想要的東西，

the nutrient that they want, is time.

它們想要的營養物，是時間。

But time is the one thing that I'll never be able to give them.

但，時間是我永遠不可能 給予它們的東西。

So even if I have a cell culture that I pass to my PhD students,

即使我把我的細胞培養 傳給我的博士生，

who pass it to their PhD students, and so on,

他們再傳給他們的 博士生，以此類推，

we'd have to do that for thousands of years

我們得要持續傳數千年，

in order to mimic the exact conditions of the deep subsurface,

才有可能精確模仿 地面下深處的條件，

all without growing any contaminants.

而不繁殖任何污染物。

It's just not possible.

這是不可能的。

But maybe in a way we already have grown them in our petri dishes.

但，也許，我們已經以某種方式 在培養皿中繁殖它們了。

Maybe they looked at all that food we offered them and said,

也許它們看著我們 提供的各種食物，並說：

"Thanks, I'm going to speed up so much

「謝謝，我能夠加速成長，

that I'm going to make a new cell next century.

快到在下世紀就能做出一個新細胞。

Ugh.

呃。

(Laughter)

（笑聲）

So why is it that the rest of biology moves so fast?

所以，為什麼其他的 生物都進行那麼快？

Why does a cell die after a day

為什麼細胞在一天後就會死亡，

and a human dies after only a hundred years?

一個人僅在一百年後就會死亡？

These seem like really arbitrarily short limits

這些時限是非常短的，

when you think about the total amount of time in the universe.

相對於宇宙的所有時間而言。

But these are not arbitrary limits.

但它們並非隨意的時限。

They're dictated by one simple thing,

它們受到一樣很單純的東西所支配，

and that thing is the Sun.

那就是太陽。

Once life figured out how to harness the energy of the Sun

一旦生命搞懂了要 如何透過光合作用利用

through photosynthesis,

太陽的能量，

we all had to speed up and get on day and night cycles.

我們都得要加速， 開始過日夜循環的日子。

In that way, the Sun gave us both a reason to be fast

就這方面來說，太陽 給了我們加速的理由，

and the fuel to do it.

以及加速需要的燃料。

You can view most of life on Earth like a circulatory system,

你可以把地球上大部分的 生命視為是循環系統，

and the Sun is our beating heart.

而太陽就是在跳動的心臟。

But the deep subsurface is like a circulatory system

但在地表下的深處，這個循環系統

that's completely disconnected from the Sun.

完全和太陽沒有連結。

It's instead being driven by long, slow geological rhythms.

取而代之，驅動它的 是又長又慢的地理節奏。

There's currently no theoretical limit on the lifespan of one single cell.

目前，在理論上，單一細胞的 壽命長度是沒有極限的。

As long as there is at least a tiny energy gradient to exploit,

只要還有一絲絲的能量可以利用，

theoretically, a single cell could live

在理論上，單一細胞就能

for hundreds of thousands of years or more,

再活數億年甚至更久，

simply by replacing broken parts over time.

只要隨著時間把壞掉的 部分換掉即可。

To ask a microbe that lives like that to grow in our petri dishes

要讓那樣子生活的微生物， 在我們的培養皿中成長，

is to ask them to adapt to our frenetic, Sun-centric, fast way of living,

就等於是在要求它們適應我們

這種以太陽為中心 且快速瘋狂的生活方式，

and maybe they've got better things to do than that.

也許它們有別的更想做的事。

(Laughter)

（笑聲）

Imagine if we could figure out how they managed to do this.

想像一下，如果我們能夠 研究出它們如何辦到的。

What if it involves some cool, ultra-stable compounds

如果它們是利用某種 超穩定複合物，

that we could use to increase the shelf life

而若我們能將之用於 生物醫學或工業產業

in biomedical or industrial applications?

延長保存期限，這樣會如何呢？

Or maybe if we figure out the mechanism that they use

或者，假若我們能找出 它們使用的超慢速成長機制，

to grow so extraordinarily slowly,

we could mimic it in cancer cells and slow runaway cell division.

我們就能仿照這機制 來減慢癌細胞的分裂速度。

I don't know.

我不知道。

I mean, honestly, that is all speculation,

老實說，這些都是猜測，

but the only thing I know for certain

但我知道有一件事是肯定的，

is that there are a hundred billion billion billlion

有 10 的 29 次方個 活生生的微生物細胞

living microbial cells

underlying all the world's oceans.

在全世界的海洋底下。

That's 200 times more than the total biomass of humans on this planet.

那是地球上人類 生物質總量的兩百倍。

And those microbes have a fundamentally different relationship

且那些微生物與時間及能量的關係，

with time and energy than we do.

跟我們有本質上的不同。

What seems like a day to them

對它們而言是一天的時間，

might be a thousand years to us.

對我們而言可能就是一千年。

They don't care about the Sun,

它們不在乎太陽，

and they don't care about growing fast,

它們也不在乎要快速成長，

and they probably don't give a damn about my petri dishes ...

很可能它們也不在乎我的培養皿。

(Laughter)

（笑聲）

but if we can continue to find creative ways to study them,

但，如果我們能繼續尋找 有創意的方式來研究它們，

then maybe we'll finally figure out what life, all of life, is like on Earth.

也許最終我們會能了解 在地球上所有生命的樣貌。

Thank you.

謝謝。

(Applause)

（掌聲）