We all know about the dinosaurs that once roamed the planet, but long after they went extinct,
我们都知道恐龙曾经一度称霸这个星球，不过在它们灭绝很久之后，
great beasts we call the megafauna lived on every continent.
仍然有我们称之为“巨型动物”的大怪物遍布每一块大陆。
In the Americas, ground sloths the size of elephants pulled down trees with their claws.
在美洲，跟大象一般大的地獭，能用它们的爪子拉倒大树。
Saber-toothed cats the size of brown bears hunted in packs,
像棕熊一样大的剑齿虎能成群结队地狩猎，
but they were no match for short-faced bears, which stood thirteen feet on their hind legs,
不过跟巨型短面熊比起来它们都弱爆了，这些熊站起来有十三英尺高，
and are likely to have driven these cats away from their prey.
而且它们很容易就能把剑齿虎从它们的猎物旁边吓走。
There were armadillos as big as small cars, an eight foot beaver, and a bird with a 26 foot wingspan.
还有像汽车一样大的犰狳，八尺长的海狸，还有翼展为26尺的大鸟。
Almost everywhere, the world's megafauna were driven to extinction, often by human hunters.
不过几乎世界各地所有的巨型动物都已经绝种了，这通常要归咎于人类的狩猎。
Some species still survive in parts of Africa and Asia.
不过在亚洲和非洲还有一些得以幸存。
In other places, you can still see the legacy of these great beasts.
但在其他地方，你只能看到这些巨兽留下的遗迹。
Most trees are able to resprout where their trunk is broken to withstand the loss of much of their bark
大部分的树木能从树干断裂之处重新发芽生长，还能够承受失去大量的树皮，
and to survive splitting, twisting and trampling, partly because they evolved to survive attacks by elephants.
在断裂、扭曲、或被践踏后依然存活，也许这是因为树木为了经受大象的摧残而进化出来的功能。
The American pronghorn can run so fast because it evolved to escape the American cheetah.
美洲麋鹿跑得很快，因为它们得逃出美洲猎豹的魔爪。
The surviving animals live in ghost ecosystems adapted to threats from species that no longer exist.
这些得以存活的动物，生活在幽灵创造的生态系统中，因为这个生态系统是由已经灭绝的物种开创的。
Today, it may be possible to resurrect those ghosts, to bring back lost species using genetic material.
如今，我们有可能使这些幽灵复活，用基因材料让它们重归于世。
For instance, there's been research in to cloning woolly mammoths from frozen remains.
比如说，有研究已经着眼于利用猛犸象被冰封的遗体碎片复活它。
But even if it's not possible, we can still restore many of the ecosystems the world has lost.
不过就算最终难以成行，我们还是能重现当时世界上的生态系统。
How? By making use of abandoned farms.
怎么实现呢？通过利用废弃的农场。
As the market for food is globalized, infertile land becomes uncompetitive.
目前的食物市场已经全球化，贫瘠的土地已经没什么用了。
Farmers in barren places can't compete with people growing crops on better land elsewhere.
不毛之地的农民们无法和在富饶土地上耕种的农民去竞争。
As a result, farming has started to retreat from many regions, and trees have started to return.
结果就是，很多地方的农耕退化，森林重现。
One estimate claims that two-thirds of land in the US that was once forested but was cleared for farming has become forested again.
一项研究表明，美国三分之二由森林变耕地的土壤，现在又重新变回森林了。
Another estimate suggests that by 2030, an area in Europe the size of Poland will be vaccated by farmers.
另一项研究提出，可能在2030年时，一块有欧洲波兰那么大的农场可能将被荒废。
So even if we can't use DNA to bring back ground sloths and giant armadillos,
所以就算我们不能用DNA去复原那些巨型地獭和巨型犰狳，
we can restore bears, wolves, pumas lynx, moose and bison to the places where they used to live.
我们仍然可以找回熊、狼、美洲狮、山猫、驼鹿和北美野牛，让它们回到曾经生存过的地方。
Some of these animals can reshape their surroundings, creating conditions that allow other species to thrive.
这些动物会重塑它们的生存环境，创造出得以让它们种族繁衍生息的环境。
When wolves were reintroduced to the Yellowstone National Park in 1995, they quickly transformed the ecosystem.
1995年，当狼群再次出现在黄石国家公园时，它们很快地就改变了生态系统。

Where they reduced the numbers of overpopulated deer, vegetation began to recover.
它们降低了鹿过多的种群数量，植物又重新长出来了。
The height of some trees quintupled in just six years.
有一些树木的高度在六年内增长了五倍。
As forests returned, so did songbirds.
跟随森林一起回来的，还有唱歌的小鸟。
Beavers, which eat trees, multiplied in the rivers,
以树木为食的海狸，其数量在河流中成倍增长，
and their dams provided homes for otters, muskrats, ducks, frogs and fish.
它们筑起的水坝也养育了水獭、麝鼠、青蛙和鱼。
The wolves killed coyotes, allowing rabbits and mice to increase,
野狼杀死了郊狼，让兔子和老鼠的数量得以增长，
providing more food for hawks, weasels, foxes and badgers.
因此老鹰、鼬鼠、狐狸和臭鼬有了更多的食物。
Bald eagles and ravens fed on the carrion that the wolves abandoned.
秃鹫和乌鸦吃被狼遗弃了的腐肉。
So did bears, which also ate the berries on the returning shrubs.
还有也吃野果的熊又出现在复育的灌木丛间了。
Bison numbers rose as they browsed the revitalized forests. The wolves changed almost everything.
越来越多的穿梭的北美野牛让森林重现活力。狼群改变了几乎所有的东西。
This is an example of a trophic cascade,
这只是营养级联方面的一个例子而已，
a change at the top of the food chain that tumbles all the way to the bottom, affecting every level.
食物链顶端的某个改变会一路影响到食物链的最底端。
The discovery of widespread trophic cascades
这个关于营养级联的发现，
may be one of the most exciting scientific findings of the past half century.
可能是过去半个世纪里最令人兴奋地科学发现之一了。
They tell us that ecosystems that have lost just one or two species of large animals
这个发现证明了我们的生态系统其实只丢失了一两种非常不同的大型动物，
can behave in radically different ways from those that retain them.
其他的大部分行为方式其实跟现在的这些都差不多。
All over the world, new movements are trying to catalyze the restoration of nature in a process called rewilding.
世界各地都有被称为“重现荒野”的运动，催化了大自然的复苏。
This means undoing some of the damage we've caused,
这说明对于我们曾经造成的破坏进行补救，
reestablishing species which have been driven out, and then stepping back.
事实上重新唤回了曾被我们赶走的许多物种，让他们重回自然舞台。
There is no attempt to create an ideal ecosystem, to produce a heath, a rainforest or a coral reef.
这并非是尝试重建一个理想的生态系统，比如重建荒野、雨林或珊瑚礁。
Rewilding is about bringing back the species that drive dynamic processes and then letting nature take its course.
“重现荒野”只是把曾经被驱逐的物种带回来的一个动态过程，剩下的就靠大自然天然去造化了。
But it's essential that rewilding must never be used as an excuse to push people off the land.
不过重点是“重现荒野”不是一个驱逐人类的借口。
It should happen only with the consent and enthusiasm of the people who work there.
它应当得到当地人的默许和支持。
Imagine standing on a cliff in England,
想象一下，站在英格兰的海边悬崖，
watching sperm whales attacking shoals of herring as they did within sight of the shore until the 18th century.
看抹香鲸捕食鲱鱼群的景象，这是在18世纪的时候还能看到的。
By creating marine reserves in which no commerical fishing takes place, that can happen again.
通过建立不允许商业捕捞的海洋保护区，这一景象还能重现。
Imagine a European Serengeti full of the animals that used to live there: hippos, rhinos, elephants, hyenas and lions.
想象一下，欧洲草原上曾经遍布着各种各样的动物：河马、犀牛、大象、鬣狗和狮子。
What rewilding reintroduces, alongside the missing animals and plants, is that rare species called hope.
“重现荒野”带回的不仅仅是不再的动物和植物，还有一种稀有物种叫“希望”。
It tells us that ecological change need not always proceed in the same direction.
它告诉了我们生态变迁并不一定总是朝着一个方向的。
The silent spring could be followed by a wild summer.
寂静的春天之后，也可能是狂野的夏天。