that once roamed the planet

曾在這個地球各處遊走

but long after they went extinct,

但，他們在多年之後絕跡了

great beasts we call the megafauna lived on every continent.

我們所稱之為的巨大型動物，則接著居住在各個大洲

In the Americas, ground sloths the size of elephants

在美國，大如大象的巨爪地懶

pulled down trees with their claws.

能用他們的爪子把樹木給折斷

Saber-toothed cats the size of brown bears

相較於棕熊體積的劍齒虎

hunted in packs,

成群獵食

but they were no match for short-faced bears,

但，他們仍無法匹敵巨型的短面熊

which stood thirteen feet on their hind legs,

短面熊站起來可高達十三英尺

and are likely to have driven these cats away from their prey.

可用來驅逐劍齒虎，來防衛自己的獵物

There were armadillos as big as small cars,

還有跟小型車一樣大的犰狳

an eight foot beaver,

身長八英尺的海狸

and a bird with a 26 foot wingspan.

和一隻寬達二十六英尺展翼的鳥

Almost everywhere, the world's megafauna were driven to extinction,

但是，在現今，這些巨型動物都已絕跡

often by human hunters.

主要都是因為人類的扼殺

Some species still survive in parts of Africa and Asia.

仍然有一些物種存在於部分非洲與亞洲中

In other places, you can still see the legacy of these great beasts.

在其他地方，你們可以看到這些巨型動物所遺留下的遺跡

Most trees are able to resprout where their trunk is broken

像是，大部分的樹木可以從樹幹的斷裂處長出新芽

to withstand the loss of much of their bark

來彌補之前所失去的樹皮

and to survive splitting, twisting and trampling,

而能在裂開、曲折、或蹂躪下，仍然存活下來

partly because they evolved to survive attacks by elephants.

他們這樣的自我進化，部分原因是能夠降低受到大象的傷害

The American pronghorn can run so fast

美國羚羊跑得很快

because it evolved to escape the American cheetah.

也是因為他的自我進化，為了來躲過北美獵豹的追殺

The surviving animals live in ghost ecosystems

倖存下來的動物們則歸屬於幽靈生態

adapted to threats from species that no longer exist.

雖然威脅他們的物種不再，但他們已經演化成能適應那時的環境

Today, it may be possible to resurrect those ghosts,

現今，這些絕跡的物種可能可以復活

to bring back lost species using genetic material.

運用他們的基因物質，來讓這些絕跡物種復活

For instance, there's been research in to

例如，有個研究就是

cloning woolly mammoths from frozen remains.

利用冰凍的長毛象遺骸來複製

But even if it's not possible,

但，就算我們沒辦法成功讓這些動物復活

we can still restore many of the ecosystems the world has lost.

我們仍然能有辦法重建許多已經消失的生態環境

How? By making use of abandoned farms.

但，要怎麼做呢？可以利用廢棄的農場

As the market for food is globalized,

在食物市場的全球化下

infertile land becomes uncompetitive.

貧脊的土地沒競爭力

Farmers in barren places can't compete with people growing crops on better land elsewhere.

在這樣貧脊的土地上，農夫們無法與其他豐收的農夫們互相匹敵

As a result, farming has started to retreat from many regions,

就因為如此，農業開始從許多地方消逝

and trees have started to return.

而樹木們則因此開始蓬勃生長

One estimate claims that two-thirds of land in the US

有個估計指出三分之二的美國土地

that was once forested but was cleared for farming

曾經是森林。但，之後卻因為農業則被砍除

has become forested again.

不過，之後森林又再次重生

Another estimate suggests that by 2030,

另外的估計顯示出，在二零三零年

an area in Europe the size of Poland will be vacated by farmers.

在歐洲會出現跟波蘭一樣大的休耕土地

So even if we can't use DNA to bring back ground sloths and giant armadillos,

所以，即使我們無法運用DNA的方式，來讓巨爪地懶和巨型犰狳起死回生

we can restore bears, wolves, pumas

我們仍可以重新讓這些熊群們、狼群們、美洲獅們、

lynx, moose and bison

山貓、麋鹿、和野牛

to the places where they used to live.

回到他們原始的生活型態

Some of these animals can reshape their surroundings,

這其中有些動物能夠重新塑造他們的所處的生態環境

creating conditions that allow other species to thrive.

也能幫助其他物種的蓬勃成長

When wolves were reintroduced to the Yellowstone National Park in 1995,

在一九九五年，當狼群們再次被放回黃石國家公園時

they quickly transformed the ecosystem.

他們很快的改變了該有的生態系統

Where they reduced the numbers of overpopulated deer,

他們減少了原本過剩的鹿支數量

vegetation began to recover.

植物則開始滋長

The height of some trees quintupled in just six years.

在短短六年，有些樹的高度則長高了五倍

As forests returned, so did songbirds.

森林復甦之後，鳴鳥也跟著回來了

Beavers, which eat trees, multiplied in the rivers,

以樹為食的海狸，因而在河裡多了好幾倍

and their dams provided homes for otters, muskrats, ducks, frogs and fish.

另外他們的水壩則成了水獺、麝鼠、鴨子、青蛙、及魚的住處

The wolves killed coyotes, allowing rabbits and mice to increase,

狼群們以土狼為食，而使得兔子和老鼠的數量增加

providing more food for hawks, weasels, foxes and badgers.

同時也提供鷹、鼬鼠、狐狸及獾更多的食物

Bald eagles and ravens fed on the carrion that the wolves abandoned.

禿鷹和烏鴉吃狼群吃剩的腐肉

So did bears, which also ate the berries on the returning shrubs.

也因為灌木叢的增加，以漿果為食的熊也蓬勃發展

Bison numbers rose as they browsed the revitalized forests.

有著這樣復甦的森林，以草為食的野牛，數量也因而提升

The wolves changed almost everything.

狼群們幾乎改變了在黃石國家公園中的整個生態系統

This is an example of a trophic cascade,

這是一個營養級聯的例子

a change at the top of the food chain

一個在食物鏈上層的改變

that tumbles all the way to the bottom,

帶動了到最下層的食物鏈的改變

affecting every level.

影響了所有的食物鏈階層

The discovery of widespread trophic cascades

這樣的營養級聯充斥在食物鏈中

may be one of the most exciting scientific findings of the past half century.

這個科學發現可能是近半世紀以來最另人開心的

They tell us that ecosystems

他們讓我們知道生態系中

have lost just one or two species of large animals

只要失去一種或是兩種的巨型動物物種

can behave in radically different ways from those that retain them.

會因而造成食物鏈中的巨大變化

All over the world, new movements are trying

在世界各地，幾個新運動正試圖要

to catalyze the restoration of nature in a process called rewilding.

促使大自然的自癒能力，透過所謂的野化（促成生態的自然發展，吸引野生動植物進駐）

This means undoing some of the damage we've caused,

意思是修正一些我們所造成的破壞

reestablishing species which have been driven out,

重新復育被我們趕走的物種

and then stepping back.

然後，我們不再干預他們

There is no attempt to create an ideal ecosystem,

沒有必要為了建立出一個完美的生態系

to produce a heath, a rainforest or a coral reef.

來促進一片荒地、雨林、或是珊瑚礁

Rewilding is about bringing back the species

野化是要吸引物種進駐

that drive dynamic processes

促進生態的發展

and then letting nature take its course.

同時也讓大自然自然發展

But it's essential that rewilding must never be used

但是，這樣的野化必須不能被

as an excuse to push people off the land.

視為一個規定，來藉此驅逐人類

It should happen only

這樣的野化的實施，必須只能

with the consent and enthusiasm of the people who work there.

受到當地人們熱忱地同意

Imagine standing on a cliff in England,

想像一下，站在英國的一處懸崖邊

watching sperm whales attacking shoals of herring

欣賞著抹香鯨緊追、攻擊著鯡魚群

as they did within sight of the shore until the 18th century.

這樣歷歷在目的場景，猶如就是在十八世紀

By creating marine reserves in which no commerical fishing takes place,

設置海洋保護區，禁止任何捕魚的商業情形

that can happen again.

那這樣的場景就能再現

Imagine a European Serengeti

想像一下，一個歐洲形式的塞倫格提（位於東非坦尚尼亞和肯亞之間的生態區域，稱之為「無邊無際的平原」）

full of the animals that used to live there:

有著多樣化的動物曾經住在那裡，像是

hippos, rhinos, elephants, hyenas and lions.

河馬、犀牛、大象、土狼、和獅子

What rewilding reintroduces,

野化的不僅能吸引

alongside the missing animals and plants,

原本消失的動植物

is that rare species called hope.

他還會帶來一個名為「希望」的稀有物種

It tells us that ecological change

他讓我們了解到生態的變遷

need not always proceed in the same direction.

不會都是往絕跡的方向發展

The silent spring could be followed by a wild summer.

寂靜的春天後，仍然會接著狂野的夏天