Ecosystems were hit with a double blow as massive volcanic eruptions filled the atmosphere with carbon dioxide and an asteroid roughly the size of Manhattan struck the Earth.

生態系統遭到了雙重打擊：大量的火山爆發使大氣充滿了二氧化碳，以及一顆約有曼哈頓大的小行星撞擊地球。

The dust from the impact reduced or stopped photosynthesis for many plants, starving herbivores and the carnivores that preyed on them.

撞擊所產生的塵土減少或阻礙了許多植物的光合作用，導致草食性動物及獵捕牠們的肉食性動物缺乏食物。

Within a short time span, three-quarters of the world's species disappeared forever,

在短時間內，世界上 3/4 的物種便永遠地消失了，

and the giant dinosaurs, flying pterosaurs, shelled squids, and marine reptiles that had flourished for ages faded into prehistory.

巨大的恐龍、飛翔的翼龍、帶殼的菊石，及繁盛很久的海生爬蟲類動物走下了歷史的舞台。

It may seem like the dinosaurs were especially unlucky, but extinctions of various severities have occurred throughout the Earth's history, and are still happening all around us today.

或許恐龍們看起來特別不幸，但在地球的歷史上也曾發生過其他不同程度的生物滅絕，而且仍在你我身邊繼續發生著。

Environments change, pushing some species out of their comfort zones while creating new opportunities for others.

環境轉變，迫使某些物種必須離開舒適圈，但也為其他物種製造了新的機會。

Invasive species arrive in new habitats, outcompeting the natives.

入侵物種進入新的棲地後在競爭中勝過原生物種。

And in some cases, entire species are wiped out as a result of activity by better adapted organisms.

有時候整個原生物種因適應較佳的入侵物種的活動而滅絕。

Sometimes, however, massive changes in the environment occur too quickly for most living creatures to adapt, causing thousands of species to die off in a geological instant.

有時候環境的劇變來得太快，大部分生物無法適應，導致數千物種在地質年代的瞬間相繼滅絕。

We call this a mass extinction event.

我們稱之為「大滅絕」。

And although such events may be rare, paleontologists have been able to identify several of them through dramatic changes in the fossil record,

雖然這樣的事件或許不多，古生物學家已能從化石的劇變中指認出幾次「大滅絕」事件，

where lineages that persisted through several geological layers suddenly disappear.

是根據數個地層中一直存在的動物世系的化石突然消失了。

In fact, these mass extinctions are used to divide the Earth's history into distinct periods.

事實上，這些「大滅絕」可用來將地球歷史區隔為不同時期。

Although the disappearance of the dinosaurs is the best known mass extinction event, the largest occurred long before dinosaurs ever existed.

雖然恐龍的消失是最為人所知的「大滅絕」事件，但最大的「大滅絕」遠早在恐龍存在之前。

252 million years ago, between the Permian and Triassic periods, the Earth's land masses gathered together into the single supercontinent Pangaea.

2 億 5200 萬年前，在二疊紀與三疊紀之間，地球上的陸塊聚合成一塊超級大陸，「盤古大陸」。

As it coalesced, its interior was filled with deserts, while the single coastline eliminated many of the shallow tropical seas where biodiversity thrived.

聚合後，大陸的內陸充滿了沙漠，合併為單一的海岸線消除了許多生物的熱帶淺海。

Huge volcanic eruptions occurred across Siberia, coinciding with very high temperatures, suggesting a massive greenhouse effect.

在西伯利亞發生的大規模的火山爆發，伴隨著超高溫度，造成了劇烈的溫室效應。

These catastrophes contributed to the extinction of 95% of species in the ocean,

這些天災促成了95%的海洋物種滅絕，

and on land, the strange reptiles of the Permian gave way to the ancestors of the far more familiar dinosaurs we know today.

而在陸上，二疊紀奇異的爬蟲生物被我們今日更熟悉的恐龍的祖先所取代。

But mass extinctions are not just a thing of the distant past.

但是「大滅絕」不僅僅存在於遙遠的過去。

Over the last few million years, the fluctuation of massive ice sheets at our planet's poles has caused sea levels to rise and fall, changing weather patterns and ocean currents along the way.

近數百萬年來，地球兩極巨大冰蓋的改變造成了海平面的起伏，改變了氣候模式及洋流途徑。

As the ice sheets spread, retreated, and returned, some animals were either able to adapt to the changes, or migrate to a more suitable environment.

隨著冰蓋的擴張，縮減及重塑，某些生物得以適應改變，或遷徙至更適合的環境。

Others, however, such as giant ground sloths, giant hyenas, and mammoths went extinct.

不過其他例如：大地懶、碩鬣狗以及猛瑪象就滅絕了。

The extinction of these large mammals coincides with changes in the climate and ecosystem due to the melting ice caps.

受冰冠融化影響的氣候變遷及生態改變，這些大型哺乳類動物滅絕了。

But there is also an uncomfortable overlap with the rise of a certain hominid species originating in Africa 150,000 years ago.

但有個令人不安的重疊處源於 15 萬年前在非洲原始人類的崛起。

In the course of their adaptation to the new environment, creating new tools and methods for gathering food and hunting prey,

在他們適應新環境的過程中，創造了採集食物與漁獵的新工具及方法。

humans may not have single-handedly caused the extinction of these large animals, as some were able to coexist with us for thousands of years.

人類或許並未單獨地造成大型動物的滅絕，有些動物也能與我們共存數千年。

But it's clear that today, our tools and methods have become so effective that humans are no longer reacting to the environment, but are actively changing it.

但很顯然地， 我們現代的工具及方法已變得如此強效，使人類不再是適應環境，而是主動去改變環境。

The extinction of species is a normal occurrence in the background of ecosystems.

物種的滅絕是生態系統中的常事。

But studies suggest that rates of extinction today for many organisms are hundreds to thousands of times higher than the normal background.

但研究指出如今許多生物滅絕的速度比正常情況下高出了千百倍。

But the same unique ability that makes humans capable of driving mass extinctions can also enable us to prevent them.

但人類導致物種滅絕的獨特能力也能用來防止物種的滅絕。

By learning about past extinction events, recognizing what is happening today as environments change, and using this knowledge to lessen our effect on other species,

學習過去物種的滅絕，了解環境改變下今日發生的事，並用這些知識減少我們對其他物種的影響，

we can transform humanity's impact on the world from something as destructive as a massive asteroid into a collaborative part of a biologically diverse future.

我們可以將人類對世界有如小行星般毀滅性的影響力轉化為一個使未來生物多樣化的助因。