You can't see it, but it's there all the same.

你看不到它，但它始終都在那裡。

If you stood on the coast of Bali and looked east to the shores of Lombok, you'd be staring right at the line's narrowest point:

如果你在峇里島向東看龍目島的海岸，你會發現你正盯著那條線最窄的地方：

a 32 km stretch of water that seems pretty unassuming.

一個32公里長的水域，似乎很不起眼。

This invisible barrier weaves its way through the entire Malay Archipelago, the largest collection of islands on the planet.

這道無形的屏障在世界最大的群島——馬來群島中交織著。

See, on the western side, the animal life is characteristic of Asia, featuring rhinos, elephants, tigers, and woodpeckers, to name a few.

請看，在西側靠近亞洲這側，動物以犀牛、大象、老虎、啄木鳥等等為特色。

But cross the line, and things suddenly change. You won't find those same species on the eastern side.

但越過這條線，情況就會突然改變。 你不會在東部地區找到這些相同的物種。

Instead, the islands have a totally different cast of ecological characters, including marsupials, Komodo dragons, cockatoos, and honeyeaters.

相反地，這些島嶼有完全不同的動物，包括有袋動物、科莫多龍、鳳頭鸚鵡和食蜜鳥。

This is what scientists call a biogeographic boundary, the meeting point of two regions of biodiversity that are highly distinct.

這就是科學家所說的生物地理學邊界，也就是兩個高度不同的生物多樣性區域的交匯點。

And this particular line, called the Wallace Line, is perhaps the sharpest and most iconic of all.

而這條被稱為「華萊士線」的線，也許是所有線路中最尖銳和最具代表性的。

So how did this invisible line come to be? Why does it shape the distribution of so many species?  

那麼，這條無形的線是如何形成的？為什麼它塑造了這麼多物種的分佈？

How did we figure out the path it takes?

我們是如何算出它的路徑的呢？

And how can it be both real and imaginary?

而它怎麼可能既是真實的又是想象的呢？

The Wallace line was first sketched out in 1859 by a guy named, wait for it, Wallace.

「華萊士線」最早是在1859年由一個叫，等等，華萊士的人勾勒出來的。

Alfred Russel Wallace to be exact, a British naturalist who you might have also heard of as the co-discoverer of natural selection.

確切地說，阿爾弗雷德·羅素·華萊士，一位英國的自然學家。你可能也聽說過他是「天擇說」的共同發現者。

That concept came to Wallace in a literal fever dream as he lay bedridden with malaria during part of his eight-year trip around the Malay Archipelago.

這個概念在華萊士的字面上的夢中出現，當時他因為瘧疾而躺在床上，這是他在馬來群島八年旅行期間的一部分。

And while he'd end up being overshadowed by Darwin on that front, the second-best idea he had on that trip was the existence of the Wallace line.

而在這一方面，他最終會被達爾文掩蓋，他在那次旅行中的第二好的想法是「華萊士線」的存在。

I mean......you know, two good ideas in one trip.

我的意思是......你知道，一次旅行想到兩個好主意。

This idea helped to forever establish him as the father of biogeography, the study of the distribution of living things.

這個想法幫助他永遠確立了生物分佈研究，也就是生物地理學之父的地位。

He had spent his voyage observing and collecting as many species as he could, hopping from island to island across almost the entire archipelago.

他在航行中觀察和收集了儘可能多的物種，從一個島跳到另一個島，幾乎貫穿整個群島。

And it was as he moved east from Bali to Lombok that he first noticed something intriguing.

當他從峇里島向東移動到龍目島時，他第一次注意到一些不尋常的地方。

Even though the islands were separated only by a narrow strait, the change in animal life wasn't gradual and subtle, it was sudden and distinct.

儘管這些島嶼只被一個狹窄的海峽分開，動物生活的變化不是漸進和微妙的，而是突然和明顯的。

Wallace saw the differences in animal life between the two as being even more striking than between England and Japan!

華萊士發現動物的生活差異，兩者之間的差異甚至比英國和日本之間的動物差異更令人震驚!

It was birds that initially caught his attention.

最初引起他注意的是鳥類。

Certain species that were plentiful on Java and Bali -

某種在爪哇島和峇里島有相當大量族群的鳥

like the yellow headed weaver, coppersmith barbet,  and the Javanese three-toed woodpecker - didn't exist at all on Lombok.

像是黃頭織布鳥、銅匠鳥和爪哇三趾啄木鳥在龍目島根本不存在。

And this abrupt shift extended to mammals and even many insects, too.

而這種突然的轉變也延伸到了哺乳動物，甚至昆蟲也是。

Almost as if an invisible barrier was separating two different worlds.

幾乎就像一個無形的屏障隔開了兩個不同的世界。

But why? And how?

但為什麼？又是如何做到的？

The biogeographic line that he drew, which others would tweak in later years, didn't just reflect the proximity of the islands.

他所畫的生物地理線，在未來的日子裡，其他人會對它進行調整，並不是只反映了這些島嶼的接近性。

In fact, some islands on opposing sides of the line are closer to each other than many islands on the same sides are to one another.

事實上，一些處於華萊士線兩側的島嶼比起位於同一側的島嶼還更接近彼此。

So Wallace realized that other, more mysterious forces must be in play. Like, say, geology.

所以華萊士意識到，一定有其他更神祕的力量在發揮作用。比如說：地質學。

He recognized that the geological past shapes the biological present.

他認識到地質的過去塑造了生物的現在。

And, because the distribution of living species today partly reflects ancient geological events,  

而且，因為今天生物物種的分佈部分地反映了古代地質事件，

he saw biogeography as a way to uncover epic chapters of the planet's history that might otherwise have been unknowable.

他把生物地理學看作是揭開地球歷史篇章的一種方式，否則可能至今仍不為人知。

These concepts are easy to take for granted today - we talk about them all the time here on Eons.

這些概念在今天很容易被認為是理所當然的，因為我們在 Eons 經常談論這些。

but they were still fairly new ideas in Wallace's day.

但在華萊士的時代，它們仍然是相當新的想法。

And by taking this perspective, he concluded that the western islands must have once all been connected to each other, and to the Asian mainland.

從這個角度出發，他得出結論，西方的島嶼肯定曾經都是彼此相連，而且是與亞洲大陸連在一塊的。

While today they are swallowed by shallow seas, this is only the result of a geologically recent rise in sea levels.

雖然如今它們被淺海所淹沒，但這只是地質上最近海平面上升的結果。

How else could the big animals of that side, like tigers and rhinos and tapirs, have ended up on the islands?

否則，那邊的大型動物，如老虎、犀牛和貘，怎麼可能會出現在這些島嶼？

Because they're now separated by expanses of water that are way too wide for those species to cross.

因為他們現在是被廣闊的水面隔開，這些水面對這些物種來說太寬了，無法穿越。

He had a similar thought about how the islands: east of Java and Borneo had formed — at least some of them were the remnants of a former Australian continent.

他對爪哇島和婆羅洲東部的島嶼有一個類似的想法形成：至少其中一些是前澳洲大陸的遺留物。

Wallace had a hunch that, throughout all of that change,

華萊士有一種預感，在所有這些變化中，

deeper waters with strong currents between the two regions

在這兩個地區之間的深水區有強大的洋流，

must have prevented many species from crossing from continent to continent when sea levels were lower.

這肯定會阻止許多物種在海平面較低時，從一個大陸穿越到另一個大陸。

And this is still preventing many species from crossing today  

而這在今天仍然阻止著許多物種的跨越，

when sea levels are higher and the continents are fragmented into neighboring groups of islands.

因為當海平面升高時，大陸會被分割成相鄰的島嶼群。

Even many flying bird and insect species obey the line, ones that are capable of crossing those stretches of open ocean.

甚至許多飛行的鳥類和昆蟲物種也服從於這一線，即便他們有能力穿越那些綿延的開闊海域。

Wallace had pulled together many pieces of the puzzle,

華萊士已將許多拼圖拼湊在一起了，

but he and other scientists at the time were missing one key idea to complete the picture: Plate tectonics.

但他和其他科學家在當時缺少一個完成的關鍵想法：板塊構造學。

The surface of the planet is not static, of course, it's dynamic.

當然，地球的表面不是靜態的，它是動態的。

It's made up of individual large sections or plates that move and collide over vast stretches of geologic time.

它是由獨立的大型部分或是板塊在漫長的地質時間中移動以及碰撞組成的。

It's yet another concept that's easy for us to take for granted,  

這又是一個容易被我們視為理所當然的概念，

but which is actually a relatively recent addition to our understanding of the world.

但這實際上是對我們理解世界的一個相對較新的補充。

In fact, plate tectonics only became widely accepted in the late 1960s – more than half a century after Wallace's death.

事實上，板塊構造學到了 1960 年代末期才被廣泛接受，此時已經是華萊士去世後半個多世紀以後了。

And also, around the time when I was born.

還有，差不多也是我出生的時候。

Which means, I'm as old as plate tectonics.

這意味著，我和板塊構造學一樣老。

We now know that plate tectonics shapes our planet in many ways,

我們現在知道，板塊構造在許多方面塑造了我們的星球，

including forming and deforming continents, raising up island chains, and building mountain ranges.

包括形成和使大陸變形，抬高島鏈，並形成山脈。

And studies have shown the Malay Archipelago to be one of the most complex tectonic regions in the world,

而研究表明，馬來群島是世界上最複雜的構造之一，

a meeting point of multiple plates all jostling for space.

他是多個互相爭奪空間的板塊的交匯點。

And this is responsible for not only the area's many volcanoes and frequent seismic activity, but also the peculiar contrasts of its animal life.

這不僅造成了該地區的許多火山、頻繁的地震活動，同時也造就動物種類的特殊對比。

Because by the 1980s, scientists were able to say with confidence that the Wallace line is, at its core, a result of plate tectonics.

因為到了 1980 年代，科學家們能夠有把握地說，華萊士線究其核心是板塊構造的結果。

Wallace had correctly identified that two former continuous land masses had existed on either side of this line in the deep past.

華萊士正確地指出有兩塊連續大陸在過去的很長一段時間裡存在在線的一側。

Today, we know them as the paleocontinents of Sunda in the west and Sahul in the east,

今天，我們知道它們是西部的巽他古大陸和東部的薩胡古大陸，

both of which existed during the ice ages when more water was locked up in ice and sea levels were lower.

兩者在冰河時期就存在的，當時更多的水被鎖在冰裡，海平面也較低。

Wallace didn't know it, but while they're pretty close now, the two partly-sunken continents used to be much, much further apart.

華萊士不知道，但雖然他們現在很接近，這兩個部分沉沒的大陸過去相距很遠很遠。

The Sahul continent of the eastern side of the line, encompassed Australia, Tasmania, New Guinea, and the Aru islands.

線的東側的薩湖古大陸涵蓋了澳洲、塔斯馬尼亞、新幾內亞和阿魯群島。

And it only approached the Asian Sunda continental shelf in the west around 20 to 25 million years ago in the late Oligocene or early Miocene epoch.

而且，它只有在大約 2,000 萬到 2,500 萬年前的漸新世晚期或中新世早期和在西面的亞洲巽他古大陸接壤。

This was a result of the Australian plate slowly drifting north over tens of millions of years after breaking away from Antarctica in the south,  

這是澳洲板塊在南方脫離南極洲大陸後緩慢向北漂移數十萬年的結果。

bringing its distinctive community of birds, reptiles, and marsupials with it.

帶來了其獨特的鳥類、爬行動物和有袋動物社群。

So even though the species of each side are neighbors now,

所以儘管雙方的物種現在是鄰居，

they'd been evolving separately for eons, their two worlds only colliding fairly recently in evolutionary terms.

但它們長久以來一直在各自進化，他們的世界只是在最近的進化過程中發生了碰撞。

And in between them, immediately east of the line,

而在它們之間，緊挨著這條線的東部，

a complex force of plate tectonics created a chain of new islands in an area of the archipelago that's now called Wallacea.

有一股複雜的板塊構造力量在該群島的一個地區創造了一連串的新島嶼，現在被稱為「華萊士區」。

These oceanic islands differ from the continental islands that flank them in that they were never connected to either of the greater land masses.

這些大洋性島嶼與兩側的大陸性島嶼不同。他們從未與任何一塊大的陸地相連。

They were ecological blank slates waiting to be filled in with whatever creatures could make it there.

他們是生態學上的白板，等待著被任何有能力的生物填補。

And those ended up being mostly species from the Australian side, seeing as the Wallace line acted as a barrier to Asian species moving east.

而最終由大多數來自澳洲側的物種填補了那塊區域，因為華萊士線成為亞洲物種向東移動的障礙。

Take, for instance, the Komodo dragon, a giant monitor lizard that today lives on a handful of islands in eastern Indonesia.

以科摩多龍為例、一種巨大的巨蜥，如今生活在印度尼西亞東部的少數幾個島嶼上。

Their fossils first appear in mainland Australia more than 3 million years ago in the Pliocene epoch,

它們的化石首次出現在 300 多萬年前上新世的澳洲大陸，

only reaching their current Indonesian island home in the Wallacea region around 1 million years ago.

但他們只在約 100 萬年前到達位於華萊士區的印尼島嶼上。

And even now, the deep waters with strong currents that weave between the two regions,  

而即使是現在，在兩個地區之間仍有交織著強大洋流的深海水域，

including the strait between Lombok and Bali, still limit the dispersal of many species across the line,

包括龍目島和巴厘島之間的海峽，仍然限制了許多物種的傳播，

keeping the differences in their evolutionary history so strikingly visible.

使它們的進化史的差異如此醒目地顯現出來。

This is what created the stark contrast bisecting the jungle of islands that Wallace first sketched out in 1859,

這就是在1859年華萊士首次勾勒出的島嶼叢林中所產生的鮮明對比，

and that still fascinates biogeographers today.

而這一點至今仍令生物地理學家們著迷。

Wallace's invisible line may not be real in a physical sense, but it shows just how loudly ancient geological events can echo through time,  

華萊士的隱形線在物理意義上可能並不真實，但它顯示了古代地質事件可以在時間中產生多麼響亮的回聲，

and how they shape the diversity and distribution of life in strange and contrasting ways.

以及它們如何以奇怪和對比的方式塑造生命的多樣性和分佈。

And while Darwin might get virtually all the credit as the guy who figured out how species came to be,

雖然達爾文可能幾乎得到了所有的榮譽，因為他發現了物種如何走到現今的地步，

Wallace is still recognized as a pioneer in figuring out how species came to be where they are.

但華萊士仍被公認為是釐清物種如何來到現在棲地的先驅者。

So plate tectonics also explains why Earth has supercontinents!

所以板塊構造也解釋了地球為什麼會有超級大陸！

You can celebrate this fact with our Saga of the Supercontinents poster that features four of these continental configurations.

你可以用我們的有著四種大陸配置的《超級大陸的傳奇》海報來慶祝這件事。

Available now at DFTBA.com.

現在可在 DFTBA.com 上購買。

And thanks to this month's top-of-the-line Eontologists!

並感謝這個月的最高級別的 Eontologists!

I'm gonna have to set up a meeting with Kallie, and me, and Joann from HR, because it's not okay that she's making me say these puns.  

我得安排與凱麗、我還有人力資源部的 Joann開個會，因為她讓我說這些雙關語是不對的。

Raphael Haase, Jake Hart, Juan M, Annie & Eric Higgins, John Davison Ng, and Melanie Lam Carnevale.

Raphael Haase, Jake Hart, Juan M, Annie & Eric Higgins, John Davison Ng, and Melanie Lam Carnevale.

Become an Eonite at patreon.com/eons and you can get fun perks like submitting a joke for me to read.

在patreon.com/eons成為Eonite，你就可以可以獲得有趣的福利，比如提一個笑話讓我講。

Here's one from Sonja.  

這裡有一個來自 Sonja 的笑話。

You can't blame barnacles for being clingy… They're just a tiny shellfish.

你不能責怪藤壺太粘人，它們只是一種小小的貝類。

Once I get...Once my lungs fill back up, I can finish that joke.

一旦我的肺重新填滿，我就可以完成這個笑話。

You can't...you can't blame barnacles for being clingy. They're just a tiny shellfish.

你不能責怪藤壺太粘人，它們只是一種小小的貝類。

Yeah...Ok...

是啊好吧。

Laugh doesn't lie.

笑聲不會說謊。

If it makes me laugh, then it must be a joke, right?

如果它能讓我笑，那他肯定是個好笑話，對吧？

And as always thanks for joining me in the Adam Lowe studio.

跟往常一樣，感謝加入我和 Adam Lowe studio。

Subscribe at youtube.com/eons for more epic epochs.

在 youtube.com/eons 訂閱以觀看更多的影片。