你是怎麼來到這裡的？：英語精讀講義

You just clicked on this video, 表達脈絡

你剛剛點開了這支影片，

so you're alive.

所以你還活著。

And interestingly,

而有趣的是，

in order to understand exactly where you came from, 文法

要想弄清楚你究竟是從哪裡來的，

we must first understand what it means to be alive. 文法

我們得先了解「活著」究竟代表什麼。

Life is an organized genetic unit capable of metabolism, 片語搭配

生命是一種有組織的遺傳單位，能進行新陳代謝，

reproduction,

能夠繁殖，

and evolution.

也能演化。

It's important to remember this as we go way back in history to figure out exactly how you got here. 講解

當我們一路回溯歷史，想弄清楚你究竟是怎麼來到這裡時，務必要記住這一點。

Astronomers believe our solar system began to form 4.6 billion years ago when a star exploded and then collapsed to form the sun

天文學家認為，我們的太陽系在46億年前開始形成：當時一顆恆星爆炸，隨後坍縮成太陽，

and around 500 smaller planets collided with each other to form the inner planets we know today,

約500顆較小的行星彼此碰撞，形成了我們今天熟悉的內行星，

including your home,

其中也包括你的家園——

Earth.

地球。

For about 600 million years,

在大約6億年的時間裡，

Earth was too hot for life. 文法

地球熱得無法孕育生命。

Most of the water was evaporating into space,

大部分的水都不斷蒸發到太空中，

and even if some simple chemical reactions began to take place creating life, 講解

即使某些能創造生命的簡單化學反應已經開始發生，

the comets and meteorites hitting Earth at the time

當時撞上地球的彗星和隕石

would have brought enough heat to make the developing oceans boil, 文法

也會帶來足以讓逐漸形成的海洋沸騰的熱量，

destroying all potential life.

摧毀所有可能出現的生命。

As comets and meteorites subsided,

隨著彗星和隕石的撞擊逐漸減少，

Earth cooled and it became possible for water to remain on the surface. 文法

地球冷卻下來，水終於能留在地表。

And so,

於是，

life begins around 3.7 billion years ago.

生命大約在37億年前開始出現。

There are many theories about how exactly it began.

關於生命究竟如何起源，有許多理論。

Some believe simple life arrived from a meteorite, 表達脈絡

有些人認為，簡單生命是由一顆隕石帶到地球的，

while others think chemical evolution started with compounds reacting to heat,

另一些人則認為，化學演化始於化合物受熱產生反應，

or perhaps they were struck by lightning.

也可能是那些化合物遭到閃電擊中。

And while the exact date is difficult to pinpoint, 片語搭配

雖然確切日期很難判定，

a new study claims to have found the oldest fossil ever 文法

一項新研究聲稱，已找到迄今最古老的化石，

at 3.77 billion years old,

已有37.7億年歷史，

an ancient microbe that flourished around a hydrothermal vent on the ocean floor.

也就是一種曾在海底熱液噴口周圍繁盛的古老微生物。

It's around this time that the first simple cells began to evolve on Earth. 文法

大約就在這個時期，地球上最早的簡單細胞開始演化。

They were able to capture energy,

它們能夠捕捉能量，

replicate themselves,

自我複製，

and evolve,

並持續演化，

and became the single unit on which all life will be built, 文法

最終成為構成所有生命的基本單位，

including you.

包括你在內。

For 2 billion years,

在長達20億年的時間裡，

all organisms on Earth are unicellular,

地球上的所有生物都是單細胞生物，

and they likely lived in the oceans shielded from the hard ultraviolet light of the sun,

而且很可能生活在海洋中，躲避太陽強烈的紫外線，

but then something remarkable happened. 表達脈絡

但後來，一件非凡的事發生了。

Photosynthesis.

光合作用。

Around 2.5 billion years ago,

大約25億年前，

a random mutation occurred that was advantageous to cells,

一種對細胞有利的隨機突變出現了，

and they began using the energy of the sun to power their metabolism. 用詞

細胞開始利用太陽能，為新陳代謝提供動力。

And since oxygen or O2 is the product of photosynthesis,

而由於氧氣，也就是O2，是光合作用的產物，

our atmosphere changed,

我們的大氣也隨之改變，

eventually creating the ozone layer,

最後形成了臭氧層，

which acted to shield the Earth from the sun's deadly light.

保護地球免受太陽致命光線的傷害。

Of course,

當然，

at this point O2 is poisonous to most organisms,

在這個時候，O2對大多數生物來說是有毒的，

but over time cells evolved to tolerate it,

但細胞逐漸演化出耐受它的能力，

and because metabolic reactions using O2 were more efficient,

而且，由於使用O2的代謝反應效率更高，

cells could grow larger.

細胞得以長得更大。

Around 1 billion years later,

大約10億年後，

cells began to engulf and co-opt smaller cells, 用詞

細胞開始吞噬更小的細胞，並將它們納為己用，

increasing their abilities to live in diverse environments.

提升了自身在各種環境中生存的能力。

This selective advantage led to cells sticking together in a coordinated manner even after dividing. 文法

這種選擇優勢使細胞即使分裂後，仍會以協調一致的方式黏在一起。

And these cells eventually began exchanging genetic material,

最終，這些細胞開始交換遺傳物質，

aka, 用詞

也就是說，

they had sex.

它們開始「做愛」了。

Single-celled organisms would divide by mitosis or simple nuclear division,

單細胞生物會透過有絲分裂或簡單的細胞核分裂來增殖，

but once meiosis evolved, 文法

但減數分裂演化出來後，

genetic reorganization began to occur,

遺傳重組便開始出現，

and the rate of evolution increased as offspring were now more genetically variable,

由於後代的遺傳多樣性提高，演化速度也隨之加快，

and some of these offspring were more likely to survive and reproduce. 文法

其中一些後代也因此更有可能存活並繁殖。

And so,

於是，

the tree of life began to explode. 慣用語

生命之樹開始迅速開枝散葉。

First, 表達脈絡

首先，

there were plants,

出現了植物，

and then fungi,

接著是真菌，

corals,

珊瑚，

and then protostomes like crabs,

然後是螃蟹這類原口動物，

echinoderms like sea urchins,

海膽這類棘皮動物，

and then fish like sharks and cod,

再來是鯊魚和鱈魚這類魚類，

and then tetrapods evolved from fish and began adapting to living outside of the water part-time, 片語搭配

接著，四足動物從魚類演化而來，開始適應偶爾離開水域的生活，

initially gulping air and absorbing oxygen in the gut.

起初，牠們會大口吞入空氣，並在腸道中吸收氧氣。

As time passes,

隨著時間推移，

species would evolve lungs separate from the gut for absorbing air,

這些物種逐漸演化出與腸道分開、專門用來呼吸空氣的肺臟，

as well as a new way to walk on land.

以及在陸地上行走的新方式。

In come amphibians, 文法

接著登場的是兩棲類，

reptiles,

爬蟲類，

dinosaurs,

恐龍，

and finally,

而最後則是

mammals.

哺乳類。

In fact,

事實上，

our entire ancestry stems from a cute furry-tailed rat-like mammal, 片語搭配

我們整個祖先譜系的源頭，是一種可愛、長著毛茸茸尾巴、形似老鼠的哺乳動物，

which survived and thrived around 66 million years ago, 片語搭配

牠在大約6,600萬年前存活下來，並繁衍興盛，

just after an asteroid wiped out the dinosaurs. 片語動詞

就在一顆小行星使恐龍滅絕後不久。

And after tens of millions of years of evolution and new species emerging, 片語搭配

而經過數千萬年的演化，隨著新物種不斷出現，

one branch of the Protungulatum family tree evolved into our ape and monkey ancestors.

Protungulatum演化樹上的一個分支，演化成了我們的猿猴祖先。

And nearly 4 million years ago,

將近400萬年前，

one of the first human-like creatures arrives,

最早期的類人生物之一出現了，

Australopithecus afarensis,

阿法南方古猿，

the most famous discovered remains being that of Lucy,

其中最著名的出土遺骸就是露西，

who stood upright.

她能直立行走。

100,000 generations later,

十萬個世代後，

or 2 to 3 million years ago,

也就是約200萬至300萬年前，

the species group Homo began,

人屬這個物種群出現了，

which had a bigger brain and started using their hands for more complex activities like creating and wielding tools.

他們擁有更大的腦，並開始用雙手進行更複雜的活動，例如製作和使用工具。

This was the first step of transforming our environment to improve our lives.

這是我們改造環境、改善生活的第一步。

It was also a catalyst to switch from a vegetarian diet to one containing meat, 講解

這也促使我們從素食轉向含肉的飲食，

which is a more concentrated form of nutrition and less affected by seasonal shortages.

這種飲食的營養密度更高，也較不受季節性食物短缺影響。

These simple stone tools allowed us to rip through meat and would become the tool of choice for 2 million years. 講解

這些簡單的石器讓我們能撕開肉塊，並成為往後200萬年間的首選工具。

And around 1.8 million years ago,

大約180萬年前，

Homo erectus emerged,

直立人出現了，

the direct ancestor to our species.

也就是我們這個物種的直系祖先。

Finally,

最後，

a few hundred thousand years ago,

在幾十萬年前，

modern humans or Homo sapiens step into the light, 慣用語

現代人類，也就是智人，登上了歷史舞台，

larger,

他們的體型更大，

smarter,

更聰明，

and more capable than their predecessors.

也比先前的人類更有能力。

Interestingly,

有趣的是，

we almost didn't make it. 慣用語

我們差點沒能活下來。

A climate change event around 140,000 years ago plummeted the human population to only hundreds of people,

大約14萬年前，一場氣候變遷使人類人口驟降至僅剩數百人，

an endangered species.

因而淪為瀕危物種。

But we survived.

但我們活了下來。

As recently as 60,000 years ago,

直到距今僅僅6萬年前，

three different species of the family Homo coexisted:

人屬中仍有三個不同的物種共存：

Homo neanderthalensis,

尼安德塔人，

Homo denisova,

丹尼索瓦人，

and we Homo sapiens,

以及我們——智人，

which all lived on this planet together.

這三種人類共同生活在這顆星球上。

In fact,

事實上，

sapiens and neanderthals mated quite often,

智人和尼安德塔人經常交配，

which is why most contemporary humans, 文法

這就是為什麼大多數現代人，

including you,

包括你，

have neanderthal DNA.

都帶有尼安德塔人的DNA。

The neanderthals died out around 30,000 years ago when Homo sapiens were arriving in what is now Europe. 講解

大約3萬年前，智人抵達今日歐洲之際，尼安德塔人滅絕了。

And from this point on,

從此以後，

the Homo sapiens were the only living humans left on Earth.

智人便成為地球上唯一存活的人類。

Unlike our primate relatives, 文法

不同於我們的靈長類近親，

whose evolution favored strength,

牠們的演化偏重力量，

ours chose brain power.

我們的演化則選擇了腦力。

In fact,

事實上，

your brain weighs 2% of your body weight, 表達脈絡

你的大腦重量只占體重的2%，

but uses 20% of your caloric intake.

卻消耗了你所攝取熱量的20%。

And this brain power allowed us to survive in a variety of environments as we began to migrate around the entire world.

而當我們開始遷徙到世界各地時，這份腦力讓我們能在各種環境中生存。

Where we started as small wandering groups of less than 100,

我們起初是人數不到100、四處遷徙的小群體，

we began to settle in groups of thousands,

後來開始定居，聚集成數千人的群體，

then millions, 表達脈絡

接著是數百萬人，

and now billions.

如今則是數十億人。

You were born a Homo sapiens,

你生來就是一名智人，

and that is how you got here. 表達脈絡

而你就是這樣來到這裡的。