圖像來源,GETTY IMAGES
敘利亞一座被遺棄的雕像（Credit：Getty Images）
Great civilisations are not murdered. Instead, they take their own lives.
偉大的文明不是被人類滅絕的。是它們自己結束了生命。
So concluded the historian Arnold Toynbee in his 12-volume magnum opus A Study of History. It was an exploration of the rise and fall of 28 different civilisations.
歷史學家湯因比（Arnold Toynbee）在其12卷巨著《歷史研究》（A Study of History）中這樣總結。這一著作探索了28種文明的興衰史。
He was right in some respects: civilisations are often responsible for their own decline. However, their self-destruction is usually assisted.
他在某些方面是對的：通常，造成文明衰落的是文明自身。然而，文明的自我毀滅通常是其他事物推波助瀾的結果。
The Roman Empire, for example, was the victim of many ills including overexpansion, climatic change, environmental degradation and poor leadership. But it was also brought to its knees when Rome was sacked by the Visigoths in 410 and the Vandals in 455.
比如說，羅馬帝國的衰落是過度擴張、氣候變化、環境惡化以及缺乏的領導力等多種因素造成的。但同時，讓羅馬帝國滅亡的還有公元410年入侵的西哥特人（Visigoths）以及455年入侵的汪達爾人（Vandals）。
Collapse is often quick and greatness provides no immunity. The Roman Empire covered 4.4 million sq km (1.9 million sq miles) in 390. Five years later, it had plummeted to 2 million sq km (770,000 sq miles). By 476, the empire’s reach was zero.
文明瓦解通常十分迅速，即便是宏大的事物也無法逃過一劫。公元390年，羅馬帝國佔地440萬平方公裡（190萬平方英裡）。5年後，它的面積驟然降至200萬平方公裡（77萬平方英裡）。到了公元476年，帝國已不復存在。
Our deep past is marked by recurring failure. As part of my research at the Centre for the Study of Existential Risk at the University of Cambridge, I am attempting to find out why collapse occurs through a historical autopsy. What can the rise and fall of historic civilisations tell us about our own? What are the forces that precipitate or delay a collapse? And do we see similar patterns today?
在人類的歷史中，失敗一次又一次地發生。我在劍橋大學（University of Cambridge）生存風險研究中心（Centre for the Study of Existential Risk）的研究工作之一，就是嘗試找出歷史上經常發生文明瓦解的原因。歷史上文明的興衰能夠告訴我們什麼？是哪些力量促進或者推遲文明瓦解？我們在當今世界中能看到相似的規律嗎？
The first way to look at past civilisations is to compare their longevity. This can be difficult, because there is no strict definition of civilisation, nor an overarching database of their births and deaths.
觀察過去文明的第一個方法是比較他們的持續時間。這會比較困難，因為文明並沒有明確的界定，也沒有一個記錄文明出現和消亡的資料庫。
In the graphic below, I have compared the lifespan of various civilisations, which I define as a society with agriculture, multiple cities, military dominance in its geographical region and a continuous political structure. Given this definition, all empires are civilisations, but not all civilisations are empires. The data is drawn from two studies on the growth and decline of empires (for 3000-600BC and 600BC-600), and an informal, crowd-sourced survey of ancient civilisations (which I have amended).
在下面的圖表中，我將多種文明的生命周期進行比較。其中，我對文明的定義是在其所處的地域內，有農業、有多個城市、佔軍事主導地位、有延續的政治架構的社會。根據這種定義方法，所有帝國都是文明，但所有的文明並不一定都是帝國。該數據源自兩個針對帝國興衰的研究（公元前3000年至公元前600年，以及公元前600年至公元600年）以及一個非正式、基於社群的針對古代文明的調研（我已修正這份調研）。
Collapse can be defined as a rapid and enduring loss of population, identity and socio-economic complexity. Public services crumble and disorder ensues as government loses control of its monopoly on violence.
文明瓦解可以被定義為人口持續驟減、身份丟失、社會經濟複雜性不斷下降。緊接著，隨著政府失去了對暴力的掌控，公共服務開始崩潰，社會秩序開始混亂。
Virtually all past civilisations have faced this fate. Some recovered or transformed, such as the Chinese and Egyptian. Other collapses were permanent, as was the case of Easter Island. Sometimes the cities at the epicentre of collapse are revived, as was the case with Rome. In other cases, such as the Mayan ruins, they are left abandoned as a mausoleum for future tourists.
實際上，過去所有的文明都曾面對這樣的命運。一些恢復了，一些轉型了（如中國文明以及埃及文明）。還有些文明的瓦解是永久性的，例如復活節島（Easter Island）文明。有時，在文明瓦解中心的城市可能復興，羅馬（Rome）文明正是如此。而在其他的情況下，像瑪雅（Mayan）遺址這樣的文明都是像陵墓一樣被遺棄，留給未來的旅客。
What can this tell us about the future of global modern civilisation? Are the lessons of agrarian empires applicable to our post-18th Century period of industrial capitalism?
這些能告訴我們什麼關於未來全球現代文明的事呢？農耕帝國的教訓能否適用於18世紀工業資本主義後呢？
I would argue that they are. Societies of the past and present are just complex systems composed of people and technology. The theory of 「normal accidents」 suggests that complex technological systems regularly give way to failure. So collapse may be a normal phenomenon for civilisations, regardless of their size and stage.
我認為能。過去和現在的社會均由人與技術組成。"正常事故"理論認為，複雜的技術系統常常讓位於失敗。所以文明瓦解是一個正常的現象，與文明涉及的範圍和發展階段無關。
We may be more technologically advanced now. But this gives little ground to believe that we are immune to the threats that undid our ancestors. Our newfound technological abilities even bring new, unprecedented challenges to the mix.
現代技術可能更先進。但這很難讓人相信，我們已經克服了威脅人類祖先滅亡的事情。新發現的科技能力給這複雜的情況加入了新的、前所未有的挑戰。
And while our scale may now be global, collapse appears to happen to both sprawling empires and fledgling kingdoms alike. There is no reason to believe that greater size is armour against societal dissolution. Our tightly-coupled, globalised economic system is, if anything, more likely to make crisis spread.
雖然現在人類文明是全球性的，但龐大的帝國或者剛建立的小國都一樣可能面臨文明瓦解。我們沒有理由相信規模龐大就是對抗社會瓦解的鎧甲。我們的全球化經濟系統聯繫緊密，這似乎只會讓危機蔓延。
圖像來源,GETTY IMAGES
氣候壓力越發嚴重（Credit：Getty Images）
If the fate of previous civilisations can be a roadmap to our future, what does it say? One method is to examine the trends that preceded historic collapses and see how they are unfolding today.
假如以前的文明對未來有所指引，那會指引向何方呢？一種方法是，回顧歷史上文明消亡之前的趨勢，觀察它們在當代如何演變。
While there is no single accepted theory for why collapses happen, historians, anthropologists and others have proposed various explanations, including:
儘管沒有確切的理論解釋為何出現文明瓦解，歷史學家與考古學家還是提出了多種解釋，包括：
CLIMATIC CHANGE: When climatic stability changes, the results can be disastrous, resulting in crop failure, starvation and desertification. The collapse of the Anasazi, the Tiwanaku civilisation, the Akkadians, the Mayan, the Roman Empire, and many others have all coincided with abrupt climatic changes, usually droughts.
氣候變化：氣候的穩定性發生變化時，可能造成耕種失敗、饑荒以及荒漠化等災難性後果。阿納薩吉文明（Anasazi）、蒂亞瓦納科文明（Tiwanaku）、阿卡德文明（Akkadians）、瑪雅文明（Mayan）、羅馬帝國（Roman Empire）等在滅亡時都曾經歷突發的氣候變化（通常是乾旱）。
ENVIRONMENTAL DEGRADATION: Collapse can occur when societies overshoot the carrying capacity of their environment. This ecological collapse theory, which has been the subject of bestselling books, points to excessive deforestation, water pollution, soil degradation and the loss of biodiversity as precipitating causes.
環境退化：當社會活動超過環境的承載力時，就會發生文明衰亡。曾是暢銷書主題的生態環境崩潰理論指出，過度砍伐森林、水體汙染、土壤退化以及喪失生物多樣性均是誘因。
INEQUALITY AND OLIGARCHY: Wealth and political inequality can be central drivers of social disintegration, as can oligarchy and centralisation of power among leaders. This not only causes social distress, but handicaps a society’s ability to respond to ecological, social and economic problems.
不平等以及寡頭政治：財富和政治不公可以是社會崩潰的主要驅動力，具有同等作用的還有寡頭政治以及領導者的中央集權。這不僅會引起社會貧困，還會導致社會沒有足夠能力應對生態、社會以及經濟問題。
The field of cliodynamics models how factors such as equality and demography correlate with political violence. Statistical analysis of previous societies suggests that this happens in cycles. As population increases, the supply of labour outstrips demand, workers become cheap and society becomes top-heavy. This inequality undermines collective solidarity and political turbulence follows.
歷史動力學模擬了平等、人口等因素如何與政治暴力相關聯。針對早先社會的統計分析顯示，這是周期性發生的。隨著人口增加，勞動力供大於求，人工變得廉價、社會架構變得頭重腳輕。這種不平等削弱了集體團結，接下來便是政治動蕩了。
COMPLEXITY: Collapse expert and historian Joseph Tainter has proposed that societies eventually collapse under the weight of their own accumulated complexity and bureaucracy. Societies are problem-solving collectives that grow in complexity in order to overcome new issues. However, the returns from complexity eventually reach a point of diminishing returns. After this point, collapse will eventually ensue.
複雜性：文明瓦解學專家、歷史學家泰恩特（Joseph Tainter）主張，社會最終會在其自身積累的複雜性以及官僚主義的重壓之下倒塌。社會是一個能解決問題的集體，為了解決新的問題，其複雜程度會不斷加劇。然而，這種複雜性所帶來的回報最終將達到一個臨界點，隨後會反噬這些回報。在此之後，文明瓦解便無可避免。
Another measure of increasing complexity is called Energy Return on Investment (EROI). This refers to the ratio between the amount of energy produced by a resource relative to the energy needed to obtain it. Like complexity, EROI appears to have a point of diminishing returns. In his book The Upside of Down, the political scientist Thomas Homer-Dixon observed that environmental degradation throughout the Roman Empire led to falling EROI from their staple energy source: crops of wheat and alfalfa. The empire fell alongside their EROI. Tainter also blames it as a chief culprit of collapse, including for the Mayan.
能源投資回報率（Energy Return on Investment, EROI）是衡量文明的複雜程度增加的另一個因素，指的是能源生產過程中能源產出和消耗的比值。和複雜性一樣，能源投資回報率也存在一個會降低回報的拐點。政治科學家迪克森（Thomas Homer-Dixon）在其著作《向下的好處》（The Upside of Down）中指出，羅馬帝國的環境退化導致其主要能源（小麥與紫花苜蓿）的投資回報率下降，羅馬帝國也隨之衰落。泰恩也認為，這便是瑪雅文明（the Mayan）瓦解的元兇。
EXTERNAL SHOCKS: In other words, the 「four horsemen」: war, natural disasters, famine and plagues. The Aztec Empire, for example, was brought to an end by Spanish invaders. Most early agrarian states were fleeting due to deadly epidemics. The concentration of humans and cattle in walled settlements with poor hygiene made disease outbreaks unavoidable and catastrophic. Sometimes disasters combined, as was the case with the Spanish introducing salmonella to the Americas.
外部打擊：換而言之，即「四騎士」：戰爭、自然災害、饑荒以及瘟疫。例如，阿茲特克帝國（Aztec Empire）因為受到西班牙入侵而覆滅。大多數早期農耕國家均因致命瘟疫而迅速消失。在衛生環境惡劣的圍城中，人類及牲口聚集在一起，無可避免地導致災難性的疫情爆發。有時禍不單行，西班牙入侵美洲時帶來了沙門氏菌便是如此。
RANDOMNESS/BAD LUCK: Statistical analysis on empires suggests that collapse is random and independent of age. Evolutionary biologist and data scientist Indre Zliobaite and her colleagues have observed a similar pattern in the evolutionary record of species. A common explanation of this apparent randomness is the 「Red Queen Effect」: if species are constantly fighting for survival in a changing environment with numerous competitors, extinction is a consistent possibility.
隨機性/運氣不佳：對帝國的統計分析顯示，文明瓦解是隨機的，與時代無關。進化生物學家以及數據科學家茲立巴特（Indre Zliobaite）和他的同事在物種進化中發現了相似的規律。「紅桃皇后效應」（Red Queen Effect）是對這種明顯隨機性的一種常見解釋：如果一個物種需要在變化的環境中持續不斷地與大量競爭者作鬥爭才能生存，那麼它們幾乎肯定會滅亡。
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Despite the abundance of books and articles, we don’t have a conclusive explanation as to why civilisations collapse. What we do know is this: the factors highlighted above can all contribute. Collapse is a tipping point phenomena, when compounding stressors overrun societal coping capacity.
儘管已經有了大量的書籍與文章，我們對文明瓦解的原因仍未有定論。現在知道的是：上文所列舉的因素均有影響。文化瓦解是一個臨界點現象，此時的綜合壓力已經超過了社會的承受範圍。
We can examine these indicators of danger to see if our chance of collapse is falling or rising. Here are four of those possible metrics, measured over the past few decades:
我們可以通過檢查以下危險指數來獲知，文化瓦解的概率是上升還是下降。以下是其中四個潛在指標在過去幾十年中的變化：
Temperature is a clear metric for climate change, GDP is a proxy for complexity and the ecological footprint is an indicator for environmental degradation. Each of these has been trending steeply upwards.
氣溫是對氣候變化的一個清晰的度量， GDP代表了複雜程度，而生態足跡則是反應環境變化的指標。這些指標已經開始急劇上揚。
Inequality is more difficult to calculate. The typical measurement of the Gini Index suggests that inequality has decreased slightly globally (although it is increasing within countries). However, the Gini Index can be misleading as it only measures relative changes in income. In other words, if two individuals earning $1 and $100,000 both doubled their income, the Gini would show no change. But the gap between the two would have jumped from $99,999 to $198,998.
貧富不均則更難量化。經典衡量方法基尼係數（Gini Index）顯示，貧富不均的情況在全球範圍內輕微下降（但在一些國家內上升）。然而，基尼係數（Gini Index）可能具有誤導性，因為它僅衡量收入的相對變化。換而言之，如果將兩個分別掙1美金和100,000美金的人收入翻倍，基尼係數（Gini）不會發生改變。但兩人的收入差距將從99,999美金躍升至198,998美元。
Because of this, I have also depicted the income share of the global top 1%. The 1% have increased in their share of global income from approximately 16% in 1980 to over 20% today. Importantly, wealth inequality is even worse. The share of global wealth from the 1% has swelled from 25-30% in the 1980s to approximately 40% in 2016. The reality is likely to be starker as these numbers do not capture wealth and income siphoned into overseas tax havens.
因此，我也對全球收入前1%的人的收入佔比進行了描述。1980年，收入前1%的人的收入佔全球的16%，這個數字現在上升至20%。更重要的是，財富分化變得更加嚴重。1980年，收入前1%的人佔世界25-30%的財富。到2016年，這個數字激增至40%。由於這些數據不包括來自海外避稅天堂的財富和收入，真實情況會更加嚴峻。
圖像來源,GETTY IMAGES
富人正變得更加富裕，這在過去對文明造成了額外的壓力（Credit：Getty Images）
Studies suggest that the EROI for fossil fuels has been steadily decreasing over time as the easiest to reach and richest reserves are depleted. Unfortunately, most renewable replacements, such as solar, have a markedly lower EROI, largely due to their energy density and the rare earth metals and manufacturing required to produce them.
研究表明，由於化石燃料這種最容易獲取、儲備最充沛的資源已經耗盡，其能源投資回報率正逐步下降。不幸的是，相比之下，太陽能等大多數用於替代的可再生能源的能源投資回報率低得多。這主要與它們的能源密度、稀土元素、以及所需的生產流程有關。
This has led much of the literature to discuss the possibility of an 「energy cliff」 as EROI declines to a point where current societal levels of affluence can no longer be maintained. The energy cliff need not be terminal if renewable technologies continue to improve and energy efficiency measures are speedily implemented.
這讓很多文獻開始探討，當能源投資回報率跌至在社會難以為繼的拐點時，「能源斷崖」發生的可能性。如果可再生能源技術繼續改進、能源效率能快速上升，能源斷崖才不會是終點。
Measures of resilience
復原的方法The somewhat reassuring news is that collapse metrics are not the entire picture. Societal resilience may be able to delay or prevent collapse.
令人稍感安慰的是，造成文明瓦解的因素並非全部。社會恢復能力或許可以推遲或者阻止文明的瓦解。
For example, globally 「economic diversity」 – a measurement of the diversity and sophistication of country exports – is greater today than it was in the 1960s and 1970s, as measured by the Economic Complexity Index (ECI). Nations are, on average, less reliant on single types of exports than they once were. For example, a nation that had diversified beyond only exporting agricultural products would be more likely to weather ecological degradation or the loss of trading partners. The ECI also measures the knowledge-intensity of exports. More skilled populations may have a greater capacity to respond to crises as they arise.
例如，據經濟複雜度指數（Economic Complexity Index, ECI）顯示，如今全球的「經濟多樣性」（衡量一個國家出口的發展程度和多樣性的指標）比20世紀60至70年代的更高。大致說來，國家對單一出口的依賴性比以往更低。不局限於農產品出口的國家更有可能度過生態退化以及丟失貿易夥伴的危機。經濟複雜度指數也衡量出口地人群的知識密集程度。技術更為熟練的人能更好地應對危機。
Similarly, innovation – as measured by per capita patent applications – is also rising. In theory, a civilisation might be less vulnerable to collapse if new technologies can mitigate against pressures such as climate change.
類似的情況也發生在創新領域，人均專利申請數量也在增加。理論上，如果新技術能夠緩解氣候變化等壓力，那文明在面臨瓦解時便不會那麼脆弱。
It’s also possible that 「collapse」 can happen without violent catastrophe. As Rachel Nuwer wrote on BBC Future in 2017, 「in some cases, civilisations simply fade out of existence – becoming the stuff of history not with a bang but a whimper」.
即便沒有「暴力災害」，文明也可能瓦解。努爾（Rachel Nuwer）於2017年在英國廣播公司未來欄目（BBC Future）中寫道：「在某些情況下，文明只是簡單的淡去。嗚咽一聲便成為歷史的一部分，並無巨大聲響。」
圖像來源,GETTY IMAGES
我們的技術能力有可能推遲文明的瓦解（Credit：Getty Images）
Still, when we look at all these collapse and resilience indicators as a whole, the message is clear that we should not be complacent. There are some reasons to be optimistic, thanks to our ability to innovate and diversify away from disaster. Yet the world is worsening in areas that have contributed to the collapse of previous societies. The climate is changing, the gap between the rich and poor is widening, the world is becoming increasingly complex, and our demands on the environment are outstripping planetary carrying capacity.
然而，當我們從整體來看所有這些文化瓦解及恢復的指標時，顯然不能自鳴得意。我們有創新和避免災難的多種能力，的確有理由樂觀。但是，從引起過去社會文化瓦解的各方面看來，世界正在惡化。氣候正在變化，貧富差距擴大，世界正變得日益複雜，我們對環境的需求超過了這個星球的承載能力。
The rungless ladder
沒有梯級的階梯That's not all. Worryingly, the world is now deeply interconnected and interdependent. In the past, collapse was confined to regions – it was a temporary setback, and people often could easily return to agrarian or hunter-gatherer lifestyles. For many, it was even a welcome reprieve from the oppression of early states. Moreover, the weapons available during social disorder were rudimentary: swords, arrows and occasionally guns.
這還不是全部。令人擔憂的是，現在的世界緊密關聯，又彼此獨立。過去，文明瓦解局限於某個區域之內——那樣的文明瓦解只是社會臨時退步，人們通常能輕易地回到農耕或狩獵的生活方式。對許多人來說，這甚至是一種從此前受壓迫狀態的解脫。此外，當時在社會動蕩期間流通的武器都比較基礎：比如刀劍、箭以及偶爾才會出現的槍。
Today, societal collapse is a more treacherous prospect. The weapons available to a state, and sometimes even groups, during a breakdown now range from biological agents to nuclear weapons. New instruments of violence, such as lethal autonomous weapons, may be available in the near future. People are increasingly specialised and disconnected from the production of food and basic goods. And a changing climate may irreparably damage our ability to return to simple farming practices.
如今，社會瓦解變得更危險。在此期間，生物製劑、核武器等武器都能在國家甚至是部分群體中流通。致命的自動化武器等新型暴力武器可能在不遠的未來面世。人們變得越發專業化，與食物和基本商品的生產脫節。變化的氣候可能破壞我們回到基本農耕活動的能力，讓一切無可挽回。
Think of civilisation as a poorly-built ladder. As you climb, each step that you used falls away. A fall from a height of just a few rungs is fine. Yet the higher you climb, the larger the fall. Eventually, once you reach a sufficient height, any drop from the ladder is fatal.
試著把文明想像成一個簡陋的梯子。當你向上爬的時候，你踩過的每一階都會掉落。從幾級臺階的高度摔下來尚能接受，但你爬得越高，就跌得越狠。最終，當到達一個足夠高的地方，任何一次從梯子上跌落都是致命的。
With the proliferation of nuclear weapons, we may have already reached this point of civilisational 「terminal velocity」. Any collapse – any fall from the ladder – risks being permanent. Nuclear war in itself could result in an existential risk: either the extinction of our species, or a permanent catapult back to the Stone Age.
隨著核武器湧現，我們可能已經達到文明的「終極速度」。任何一次文明瓦解——任何一次從梯子上跌落——其風險都是永恆的。核戰本身就可以對人類的存亡造成重大威脅：要麼我們的物種滅絕，要麼永遠回到石器時代（Stone Age）。
圖像來源,GETTY IMAGES
一名女性走在武裝衝突後敘利亞城鎮的廢墟裡（Credit：Getty Images）
While we are becoming more economically powerful and resilient, our technological capabilities also present unprecedented threats that no civilisation has had to contend with. For example, the climatic changes we face are of a different nature to what undid the Maya or Anazasi. They are global, human-driven, quicker, and more severe.
雖然我們在經濟上變得越發強大、具有適應能力，但我們的科技能力也展現出此前任何一個文明都沒有經歷過的威脅。舉個例子，氣候變化帶來的威脅和讓瑪雅文明及阿納薩吉文明消失的因素有本質上不同。當下的這種力量是全球性的，由人類所驅動，發生的更快、更嚴重。
Assistance in our self-imposed ruin will not come from hostile neighbors, but from our own technological powers. Collapse, in our case, would be a progress trap.
推動我們自我毀滅的並不是敵國，而是我們自己的科技能力。在這種情況下，文明的瓦解是社會發展的陷阱。
The collapse of our civilisation is not inevitable. History suggests it is likely, but we have the unique advantage of being able to learn from the wreckages of societies past.
文明的瓦解並非無法避免。歷史告訴我們，文明可能走向滅亡，但我們也有獨特的優勢，能夠吸取過去殘存的經驗教訓。
We know what needs to be done: emissions can be reduced, inequalities levelled, environmental degradation reversed, innovation unleashed and economies diversified. The policy proposals are there. Only the political will is lacking. We can also invest in recovery. There are already well-developed ideas for improving the ability of food and knowledge systems to be recuperated after catastrophe. Avoiding the creation of dangerous and widely-accessible technologies is also critical. Such steps will lessen the chance of a future collapse becoming irreversible.
我們知道要做什麼：減排、減少貧富不均、讓環境恢復到退化前的樣子、推動創新發展、讓經濟變得多元化。政策提案就在那裡，缺乏的只是政治意願。我們還可以投入發展恢復能力。現在已經有很多發展成熟的方案來提升災後對食物和知識系統的重建能力。不要創造危險而易獲得的技術也很重要。這些將阻擋文明在未來遭遇毀滅而變得不可逆轉。
We will only march into collapse if we advance blindly. We are only doomed if we are unwilling to listen to the past.
如果我們盲目推動社會前進，文明才會走向瓦解。如果我們對歷史充耳不聞，文明才註定會走向滅亡。
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