to far away planets. But there is another  

到遙遠的星球。但還有一個

incredibly vast dimension that we might  be giving too little thought to: time.

我們可能太少考慮到的令人難以置信的廣闊層面：時間。

Could it be that over the last  hundreds of millions of years,  

會不會是在過去的幾億年裡。

other civilizations existed on earth?  Indigenous technological species that  

地球上存在的其他文明？ 土生土長的科技物種，它們

rose and died out? And that they or  their artifacts are buried beneath  

崛起和消亡？而他們或他們的文物被埋在了下面

our feet? What does science have to say about  this and what are the implications for us?

我們的腳？科學對此有什麼看法，對我們有什麼影響？

Life on earth has existed for 4 billion  years, mostly as single celled organisms  

地球上的生命已經存在了40億年，大部分是單細胞生物。

until some 540 million years ago the Cambrian  explosion heralded the age of animals. A huge  

直到大約5.4億年前，寒武紀大爆炸預示著動物時代的到來。一個巨大的

time window for our indigenous aliens. Where would  we look for them and what could we hope to find?  

我們的土著外星人的時間窗口。我們將在哪裡尋找他們，我們希望能找到什麼？

Sadly we have only one  civilization to look at: Ourselves.

可悲的是，我們只有一個文明可以看。我們自己。

Anatomically modern humans emerged around  300,000 years ago and probably lived in small  

解剖學上的現代人大約在30萬年前出現，可能生活在小型的

groups of hunter gatherers, slowly spreading  around the world. Progress was slow and our  

狩獵採集者的群體，慢慢地擴散到世界各地。進展是緩慢的，我們的

lifestyle did not change much, although there  may have been local bursts of complexity.

生活方式沒有太大的變化，儘管可能有局部的複雜性的爆發。

Until about 10,000 years ago, when  the agricultural revolution changed  

直到大約1萬年前，當農業革命改變了

our lifestyle forever, enabling massive  population growth and technological progress.  

我們的生活方式永遠，使大規模的人口增長和技術進步成為可能。

Rather than just animals with culture and tools  that would have been invisible from space,  

而不僅僅是有文化和工具的動物，從太空中是看不到的。

we changed the face of the  planet, cleared forests and  

我們改變了地球的面貌，清除了森林和

constructed cities and temples for our  gods at breathtaking speeds and scales.

以驚人的速度和規模為我們的神靈建造城市和神廟。

Until about 300 years ago, we became  an industrial species and yet again  

直到大約300年前，我們成為一個工業物種，又一次

our numbers grew exponentially  as did our impact on the planet.

我們的數量成倍增長，我們對地球的影響也是如此。

We could say that our 300,000 year  long history has three phases:  

我們可以說，我們30萬年的歷史有三個階段。

We were hunter gatherers for 97%, farmers for  2.9% and industrialists for 0.1% of our history.

在我們的歷史中，我們有97%是狩獵採集者，2.9%是農民，0.1%是工業家。

And yet we are super new on earth.  

然而，我們在地球上是超級新的。

On geological timescales, even the sturdiest  things lose their durability. The oldest large  

在地質學的時間尺度上，即使是最堅固的東西也會失去其耐久性。最古老的大型

scale surface is in the Negev Desert, a meager  1.8 million years old. Everything older has been  

規模表面是在內蓋夫沙漠，只有180萬年的歷史。所有更古老的東西都已被

crushed to dust or turned over and it is either  below the ground, or covered by ice or ocean.  

粉碎成灰塵或翻轉，它要麼在地面以下，要麼被冰或海洋覆蓋。

Our age, the Anthropocene will be a layer only  a few centimeters thick in a few million years.

我們這個時代，人類世在幾百萬年後將是一個只有幾釐米厚的層。

If there were aliens before us and they  too went through these three phases,  

如果在我們之前有外星人，他們也經歷了這三個階段。

what would remain of them? What can we learn  about indegnous aliens by looking at ourselves?

他們會留下什麼？通過審視我們自己，我們能對獨立的外星人瞭解到什麼？

Hunter & Gatherer Aliens

獵人和採集者的外星人

We actually know that in the last few million  years, there were hunter gatherers aliens.  

我們實際上知道，在過去的幾百萬年裡，有狩獵採集者的外星人。

Our ancestors like Homo Erectus and cousins like  the Neanderthals or Denisovans and probably many  

我們的祖先如直立人和表親如尼安德特人或丹尼索瓦人，可能還有許多人

more that we haven't found yet or are lost to  time forever. They left fragments of their bodies,  

更多的是我們還沒有發現的，或者永遠消失在時間中的。他們留下了身體的碎片。

of weapons and tools and even art. Considering how  long they existed and how little remains of them,  

的武器和工具，甚至是藝術。考慮到他們存在的時間有多長，以及他們的遺蹟有多少。

although they lived not that far from our present  it is easy to think there have been others.

雖然他們生活在離我們現在不遠的地方，但很容易讓人想到還有其他人。

Intelligent animals like us that could talk and  use tools and fire, that had culture and art. For  

像我們這樣的智能動物，可以說話，使用工具和火，有文化和藝術。對於

the last two million years, most hominins lived as  hunter-gatherers – so if these aliens never moved  

在過去的200萬年裡，大多數人類都是以狩獵採集為生--是以，如果這些外星人從來沒有移動過

up higher on the tech tree, hundreds of different  species and cultures could have existed without  

在更高的科技樹上，數以百計的不同物種和文化可能已經存在而沒有

leaving any traces. Their artifacts lost to  biological and then geological processes.  

留下任何痕跡。他們的文物在生物和地質過程中流失。

At worst they would leave absolutely nothing  to be found after thousands of years.

在最壞的情況下，他們會在幾千年後留下絕對的東西，讓人無法發現。

But what about fossils? We talked about how  unlikely the process of fossilization is in more  

但是化石呢？我們談到了化石的過程是多麼的不可能，在更多的

detail in our dinosaur video, but in a nutshell,  per hundred thousand years of earth's history  

在我們的恐龍視頻中詳細介紹，但總的來說，地球上每十萬年的歷史

we only get a handful of good fossils. So we might  easily just miss fossils of such people – but even  

我們只得到少數幾個好的化石。所以我們可能很容易就錯過了這種人的化石--但即使是

if we had any, we would not necessarily be  able to identify them as hunter gatherers.

如果我們有的話，我們也不一定能確定他們是狩獵採集者。

Agricultural and Empire Aliens

農業和帝國的外星人

Looking at humans again, agricultural societies  left much more to be dug up and found,  

再看人類，農業社會留下了更多有待挖掘和發現的東西。

because they used more sophisticated tools made  from sturdier materials and had to feed millions,  

因為他們使用了由更堅固的材料製成的更復雜的工具，而且必須養活數百萬人。

leaving many more artifacts. Farming  allowed them to specialize and develop tech  

留下更多的人工製品。耕作使他們能夠專門化和發展技術

from writing to navigation, architecture  and government. Over thousands of years city  

從寫作到導航、建築和政府。在數千年的時間裡，城市

states became kingdoms and empires, some  existing for millennia before they fell.

國家變成了王國和帝國，一些國家在滅亡前已經存在了幾千年。

Many of the buildings or monuments  they constructed are still around  

他們建造的許多建築或紀念碑仍在。

and traces of them will exist for a few thousand  more years. Some only as outlines in the ground,  

它們的痕跡將再存在幾千年。有些只是在地面上的輪廓。

but still recognizable to future archaeologists.  The pyramids are piles of limestone so massive  

但對於未來的考古學家來說，仍然可以識別。 金字塔是由石灰石堆積而成的，其規模非常大

that they will probably be around for hundreds  of thousands of years. And because of the  

它們可能會存在幾十萬年之久。而且由於

greater numbers of humans that lived during our  farm and empire period, we can expect way more  

在我們的農場和帝國時期生活的人類數量更多，我們可以期待更多的

fossils and artifacts to be detectable, maybe  for a few million years before they vanish.

化石和人工製品可以被檢測到，也許在它們消失前的幾百萬年內。

So we can say with confidence that no such  indigenous alien civilization existed in the  

是以，我們可以有把握地說，沒有這樣的本土外星文明存在於中國。

last few million years because otherwise we  would have found something that they left.

在過去的幾百萬年裡，因為否則我們就會發現他們留下的東西。

This still leaves a window of hundreds of millions  of years, back to the emergence of complex life,  

這仍然留下了一個數億年的窗口，回到複雜生命的出現。

where we would not be able to tell. If there were  alien pre industrial societies and empires on the  

在那裡我們將無法判斷。如果有外星的前工業社會和帝國存在於

level of the ancient Romans or Chinese, they would  have likely disappeared without a trace. Their  

如果能達到古羅馬人或中國人的水準，他們很可能就會消失得無影無蹤了。他們的

tools, even advanced metals, would have rotted  away. If they dug up canals, cleared forests and  

工具，甚至先進的金屬，都會腐爛掉。如果他們開挖運河，清除森林和

built cities, their traces would be very hard to  distinguish from nature. Maybe there once was an  

建成的城市，其痕跡將很難與自然界區分開來。也許曾經有一個

empire of cephalopods occupying impressive cities  in swamps and lakes, made from wood and stone.  

頭足類動物的帝國，在沼澤和湖泊中佔有令人印象深刻的城市，由木材和石頭製成。

Their engineers flooding land to build wet cities,  their poets reciting poems in a language of  

他們的工程師將土地淹沒以建造溼潤的城市，他們的詩人用一種語言朗誦詩歌。

colors. Maybe they never industrialized – maybe  their society was too stable or not inventive  

顏色。也許他們從未實現工業化--也許他們的社會過於穩定或沒有創造力

enough or they never got a chance. A single  event like an asteroid, an epidemic or an ice age  

足夠了，否則他們就沒有機會了。像小行星、流行病或冰河時期這樣的單一事件

could just have deleted their civilization,  ground up their temples as their soft bodies  

可以直接刪除他們的文明，磨掉他們的太陽穴，因為他們柔軟的身體

rotted away. Sadly we don't have the tiniest  amount of evidence for any such civilization.

爛掉了。可悲的是，我們沒有任何關於這種文明的最少量的證據。

After a few million years at best, their  achievements would have dissolved into nothing.

最多幾百萬年後，他們的成就就會化為烏有。

Industrial Indigenous Aliens

工業化的土著外國人

What about industrial civilizations,  like humanity today? Imagine humans  

那工業文明呢，比如今天的人類？想象一下，人類

died out suddenly, through a pandemic or cosmic  rays or something like that. What would remain?

通過大流行病或宇宙射線或類似的東西突然消亡。還會剩下什麼？

Our impact on the planet is orders of  magnitude greater than that of our ancestors.  

我們對地球的影響要比我們的祖先大幾個數量級。

The fossil record will show a  great extinction of wildlife  

化石記錄將顯示野生動物的大滅絕

and an explosion of fossils from human associated  animals, like rats, cows, pigs and chickens.  

以及與人類有關的動物，如老鼠、牛、豬和雞的化石的爆炸。

Like the structures of our ancestors, skyscrapers  and streets and harddrives will basically crumble  

像我們祖先的結構一樣，摩天大樓、街道和硬盤基本上都會崩潰

into nothingness in a few millennia. But  because there were so many humans everywhere,  

在幾千年內變成虛無。但因為到處都有那麼多的人類。

for a few million years after our sudden end,  there would be clear hints of our existence.

在我們突然結束後的幾百萬年裡，會有我們存在的明確提示。

The byproducts of our industrial lifestyle might  

我們的工業生活方式的副產品可能是

actually give us away for some  hundreds of millions of years .

實際上是把我們送出了幾億年的時間。

We use massive amounts of artificial fertilizer  which redirects earth's flow of nitrogen that  

我們使用大量的人工化肥，使地球上的氮氣流向改變，而這些氮氣流向是在地球上的。

is being deposited in the soil. Mining metals  and rare Earth elements leaves long term scars  

正在沉積在土壤中。開採金屬和稀土元素會留下長期的傷痕

and depletes natural resources. We saturate  our oceans with plastics that find their way  

並耗盡了自然資源。我們的海洋中充滿了塑膠，這些塑膠找到了它們的途徑

to the ocean floor and may persist  for hundreds of millions of years.  

到洋底，並可能持續數億年之久。

There are radioactive elements and their decay,  unnatural accumulations of elements that do not  

有放射性元素和它們的衰變，非自然積累的元素，不

exist outside labs or weapons. And of course, in  our short industrial history we have changed the  

存在於實驗室或武器之外。當然，在我們短暫的工業歷史中，我們已經改變了

proportion of CO2 in the air by burning massive  amounts of fossil fuels, increasing the acidity  

通過燃燒大量的化石燃料，增加空氣中二氧化碳的比例，增加酸度

of the oceans and so on. We may already  have left a mark in the geological record.

的海洋等等。我們可能已經在地質記錄中留下了痕跡。

So far we have found no traces of  an industrial alien civilization.  

到目前為止，我們還沒有發現外星工業文明的痕跡。

No layers of weird chemicals or displaced  elements. No radioactive layer to indicate  

沒有奇怪的化學品或移位元素層。沒有放射性層來表明

that once great nations waged nuclear  war. We do see mass extinctions and  

曾經偉大的國家發動了核戰爭。我們確實看到大規模的滅絕和

massive shifts in the fossil records but no  evidence that they did not occur naturally.

化石記錄中的大規模轉變，但沒有證據表明它們不是自然發生的。

And ironically we've hit upon an interesting  problem here: If industrial societies stress the  

而具有諷刺意味的是，我們在這裡遇到了一個有趣的問題。如果工業社會強調

ecosystem enough to cause their own extinction,  they won't be around that long. But if they become  

生態系統足以導致他們自己的滅絕，他們不會存在那麼久。但如果它們成為

sustainable their imprint on the geological record  may be tiny. If past industrial civilizations were  

可持續的他們在地質記錄上的印記可能是微小的。如果過去的工業文明是

sustainable before they died out, we may have  little to no chance of ever knowing about them.

在它們消亡之前，我們可能幾乎沒有機會知道它們的存在。

In any case, over hundreds of millions  of years these signatures may become  

在任何情況下，經過數億年的時間，這些特徵可能成為

very subtle and get overlooked or interpreted as  natural. Even if an industrialized alien society  

非常微妙，被忽視或被解釋為自然。即使是一個工業化的外星社會

existed 200 million years ago and lasted  for 100,000 years, 300 times longer than  

2億年前就已存在，並持續了10萬年，是現在的300倍。

industrial humanity, it still might be  easy to miss it in the geological record.

工業化的人類，仍然可能很容易在地質記錄中錯過它。

In any case, all of this is speculation. In  the end we should not use our imagination to  

在任何情況下，所有這些都是猜測。最後，我們不應該用我們的想象力來

trick ourselves into thinking we know anything  about our blind spots. Just assuming a thing  

欺騙自己，以為我們對自己的盲點有所瞭解。只是假設一件事

happened because we don't have evidence  against it is a trap we should avoid.

因為我們沒有反對的證據而發生，這是我們應該避免的一個陷阱。

So for now, if we look at the  vastness of time it seems as  

是以，就目前而言，如果我們看一下浩瀚的時間，似乎就像

devoid of aliens as the vastness of space. Maybe  we are alone in this universe and always were.  

浩瀚的太空中沒有任何外星人。也許我們在這個宇宙中是孤獨的，而且一直是。

Maybe we'll find traces of others eventually, we  don't know. But there is one important takeaway:  

也許我們最終會發現其他人的蹤跡，我們不知道。但有一個重要的啟示。

The continuation of our civilization is  not guaranteed and if we are not careful,  

我們的文明的延續是沒有保證的，如果我們不小心的話。

we may disappear forever. Let's  hope that in a few million years,  

我們可能會永遠消失。讓我們希望，在幾百萬年後。

there won't be another civilization  studying our layer in the fossil record.

不會有另一個文明在化石記錄中研究我們這一層。

It's frustrating to know there are so  many things in our past we can't access.  

知道在我們的過去有這麼多東西我們無法進入，這很令人沮喪。

At least you can avoid that annoying feeling when  it comes to other stuff you are interested in,  

至少，當涉及到你感興趣的其他東西時，你可以避免這種惱人的感覺。

like your favorite TV shows or movies.  You can make this possible by going to  

像你喜歡的電視節目或電影。 你可以通過以下方式實現這一目標

NordVPN.com/kurzgesagt. NordVPNs service lets you  change your virtual location by choosing from over  

NordVPN.com/kurzgesagt。NordVPN的服務讓你改變你的虛擬位置，從超過

5200 fast servers in 60 countries all over the  world and access regionally blocked content or  

在全世界60個國家有5200個快速服務器，可以訪問區域封鎖的內容或

games that may not be available in your country. Secure your internet traffic with top-tier  

在你的國家可能沒有的遊戲。用頂級的互聯網流量保證你的安全

NordVPN encryption, no matter if you're  using a Computer, Tablet or Smartphone.  

NordVPN加密，無論你是使用電腦、平板電腦還是智能手機。

It's compatible with every major platform  and can be used on 6 devices at once. 

它與每個主要平臺兼容，可以同時在6個設備上使用。

If you want to make the rest of  your digital life airtight as well,  

如果你想讓你的數字生活的其他部分也變得密不透風。

NordVPN also offers the secure Password manager  NordPass and encrypted cloud storage NordLocker. 

NordVPN還提供安全的密碼管理器NordPass和加密的雲存儲NordLocker。

To explore all the games and shows you can get  your hands on, go to NordVPN.com/kurzgesagt  

要探索所有你能掌握的遊戲和節目，請到NordVPN.com/kurzgesagt

for an exclusive deal for our viewers. It's risk  free with NordVPN's 30 day money back guarantee.

為我們的觀眾提供一個獨家交易。使用NordVPN的30天退款保證是無風險的。