Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Sunday, October 28, 2018

The Seneca Rebound: why Growth is Faster after Collapse. Explaining the European World Dominance

Lisbon: the monument to the European sailors of the age of explorations, starting with the 15th century. What made Europeans so successful in the task of conquering the world? My interpretation is that it was the result of periodic "Seneca Collapses" of the European population which made it possible to accumulate resources that would then be available to propel the European expansion. It is an effect that may be called the "Seneca Rebound" that makes growth faster after a collapse.

The Middle Ages are sometimes referred to as the "Dark Ages" -- this is mostly untrue, but it is not wrong to apply this term to the early Middle Ages, called also the "Late Antiquity"(1). According to some estimates, in 650 AD the European population had shrunk to a historical minimum of some 18 million people, about half of what it had been during the high times of the Roman Empire. If you think that today the European population is estimated to be as more than 700 million people, it is almost impossible for us to imagine the Europe of the early Middle Ages: it was a minor appendage of the Eurasian continent, a poverty-stricken place, nearly empty of people, where nothing happened except for the squabbles of local warlords fighting each other.

Yet, a few centuries later, the descendants of the inhabitants of this backward peninsula of Eurasia embarked in the attempt of conquering the world and were successful at that. By the 19th century, practically all the world was under the direct or indirect control of European countries or of their American offspring, the United States. How could it happen?

The conventional explanation for the European ruling of the world has to do with factors related to the "white man's burden", a term invented by Rudyard Kipling in 1899. According to this interpretation, the European domination was a sort of manifest destiny generated by the superior qualities -- genetic or cultural -- of the European people in terms of being smarter, more laborious, better organized, driven by their Christian faith, and the like. In comparison, the populations of the rest of world were lazy, disorganized, uncultured, and in the grip of superstitions.

Maybe, but the idea that the Europeans conquered the world because they are smarter than the others is not supported by any data. Europeans may find it flattering, but it is an ad hoc interpretation that doesn't help us understand much of what led to the European world dominance. I have been scratching my head on this question for quite a while, until I stumbled into the graph below, showing two drastic "Seneca Collapses" of the European population. The term "Seneca Collapse" indicates a situation where the decline of a complex system is faster than its growth.

Graph from William E Langer, "The Black Death" Scientific American, February 1964, p. 117 -- note how growth is faster after the collapse than it was before. This is what I call the Seneca Rebound.

Note first of all that the data are uncertain and not all authors see the population drop in the European population to have been as drastic as Langer does. But there is a general agreement that a drastic collapse of the European population took place starting in mid 14th century AD. The collapse is often attributed to the spread of the "black death," a continent-wide epidemics of plague. In reality, there were several factors that led the European population to crash down so badly, including famines and a widespread economic crisis. In a complex system it always is difficult to establish a clear-cut chain of causes and effects: when the system crashes, many factors collapse together. The population crash plague that hit Europe in mid 17th century was less drastic, but also associated with a new outburst of the plague. These two Seneca Collapses followed the one I already mentioned, when the Roman Empire collapsed during the 6th-10th centuries AD.

There is a common element of these three collapse: the remarkably rapid recovery that followed. Let's describe that in more detail.

The first collapse (from the 5th to the 8th century). After the fall of the Western Roman Empire, Europe started recovering and soon it was able to mount military attacks against neighboring regions. The first crusade started in 1095 and for some three centuries successive waves of European armies attacked the region we call today the Middle East, succeeding in creating a number of European kingdoms in the area. The result was, ultimately, a failure and the European crusades and the European Middle Eastern kingdoms withered with the mid-14th century.

The Second collapse (mid-14th century). The population crash was brutal, but as soon as Europe started recovering, a new phase of expansion started: it was the age of exploration that we may consider to have started with the discovery of the island of Madeira in 1430 and then proceeding with a remarkable burst of explorations that lasted for about a century from mid 15th century to mid 6th. This burst included Columbus' travel of 1492 and the start of the gradual expansion of Europeans in Africa and in the Americas.

The Third Collapse (mid-17th century). In this case, the collapse was not so drastic as the first two and it didn't really stop Europeans from expanding. But, with the restart of population growth, Europe saw a new phase of economic growth which ushered the age of coal and, with it, the "age of divergence" when Europe truly conquered the rest of the world and started thinking of themselves as carrying the "white man's burden."

So, there is clearly a pattern here: the expansion of the European social system didn't go on smoothly, but in bursts. Over some two millennia, the European population grew from a few tens of millions up to the current 700 million people. In the process, it underwent at least three major crashes but, every time, it restarted growing. This bumpy expansion trajectory is typical of complex systems which tend to show what I call the "Seneca Effect," cycles of slow growth and fast collapse.

Europe, intended as a social system, is a complex system and it does tend to show the Seneca behavior. It is the result of the combination of resource depletion and pollution. Before the fossil fuel age, society had two main natural resources to exploit: fertile soil and forests. Both tend to be overexploited, that is destroyed faster than they can regrow. Forests are cut faster than trees can regrow and the fertile soil is eroded and washed to the sea faster than it can reform. The decline of agriculture not only puts an end to population growth, it causes it to collapse ruinously as an effect of famines and epidemics. The loss of the revenues from forests typically weakens the state and the result is internecine wars which, of course, hasten the collapse. Both wars and epidemics can be seen as forms of pollution and the final result is what I call the Seneca Effect: a decline which is much faster than growth.

But there is life after the Seneca Collapse. The disappearance of a large fraction of the population frees some previously cultivated land for forests to regrow. Then, when the population starts re-growing, people find the new forests as a near-pristine source of wood and -- once cut -- of fertile soil, and the cycle restarts. The new cycle may grow faster than the earlier one because society still remembers the social structures and the technologies of the previous cycle. This is the "Seneca Rebound" -- growth may be faster after collapse. You can see the Seneca Rebound in the curves made by Langer for Europe. Note how growth is faster after the collapses than it was before. This is because, I think, the Europeans had kept the social and technological structures they had developed before the crash -- there was no need, for instance, to re-develop their ship-making technology (3). So, they could exploit more effectively the resources that the collapse had freed.

Then, Forests are the basic resource needed to conquer the world and the Europeans exploited them effectively. Trees provide the wood for ships and the charcoal made from wood provides the material needed to make steel for weapons. Not for nothing, it was said that England had conquered an empire with ships of wood and men of iron.

But how was it that the Europeans were so much better than others at exploiting their forests? As always, success is a question of timing, opportunities, and luck. On the opposite side of the Mediterranean, the Arab civilization was socially and technologically as sophisticated as the European one - perhaps more - but their climate didn't allow forests to grow fast enough to avoid rapid overexploitation (2). The American civilizations we call "pre-Columbian" had forests, but they hadn't yet developed the technologies of steel and of oceanic ships -- they also lacked horses for transportation and as a military weapon. The Chinese, instead, had the technologies and also the forests and, indeed, they embarked in a parallel phase of explorations.

During the 12th-13th centuries an outbreak of the same plague that had affected Europe caused a decline in the Chinese population, that was followed - possibly as a consequence - by the Mongol invasion which led to the fall of the Song dynasty. When the Chinese economy experienced its own Seneca Rebound, the age treasure voyages started in the early 1400s, during the Ming dynasty, in a period when the population had restarted growing. (4)

China population trends according to a reconstruction published by Columbia University.

But the Chinese stopped their exploration phase and retreated within their borders. So, the Europeans found no competition in their worldwide expansion and that was the origin of the history we know.

These considerations are qualitative, but I think there is something in the idea of the "Seneca Rebound" as an engine that propels civilizations forward in bursts. If this is the case, if the world's civilization goes through a new Seneca Collapse, as it is likely to happen, will it restart expanding afterward?  If we manage to avoid that the coming crash is so bad that we lose the knowledge we accumulated over several centuries and that climate change doesn't erase humankind as a species, we may well restart expanding using renewable energy -- this time into space. Why not?


(1) If you are interested in the late antiquity period, and you can read Italian, you should read "L'Impero Globale" a recent book by Alessia Roberta Scopece who finds many parallels that age and our modern Globalization.

(2) The destruction of the Middle Eastern and North African forests may have been irreversible, as I note in this post of mine. (h/t Steve Kurtz)
(3) Nor there was any need to reinvent luxury and, with the rebound, Middle Ages ladies started dressing like high fashion models, as I describe in this post.

(4) Another reconstruction of the Chinese population is shown below, from an article dealing with the same question as this one -- they arrive to completely different conclusions, but it is normal. 


  1. As you've said at the end of this article Europeans didn't have to start from scratch after their collapse; knowledge and skills remained. A factor that I believe would be important to consider is the absence of regulations and controls after a collapse. A "mature" civilisation becomes burdened with regulations to the point of becoming unmanageable. This leads to a serious drag on industrial and cultural flexibility, interfering with a civilisations ability to respond to crisis.

  2. You have just articulated my worst nightmare. I fully admit that a part of me wishes for collapse so as to "stop the madness". I believe that many others do also whether or not they can allow themselves to admit it even to themselves. Obviously no one wants the inevitable pain, suffering, and death that collapse will bring but then again there is plenty of that going on right now too.

    My worst nightmare is that we collapse in such a way that allows for a rebound controlled by the same nefarious characters that are bringing us all of the wrong things...or worse.

  3. Nice stuffs, I have a couple of questions:

    Do you really think it's reasonable to suppose that in XXI century, more 2 or 3 billion of people can migrate to Mars and survive there?

    Or do you think during XXI century, it's more plausible to suppose that massive symmetric/asymmetric wars will kill billions of people because of nuclear tactic warheads, and many others billions of people will die because of famine, dryness, climate change deseases, severe wheather disasters?

    1. Naah... humans can't live on Mars. Our silicon children will live there.

    2. Whitmire's recent paper suggests that the first technologically advanced species on a a planet will destroy it's own biosphere. He's a respected academic with a solid background in astro physics who has recently retired.

    3. Don't have to be technological to destroy the biosphere. The anaerobic prokaryotes almost did that by filling the atmosphere with oxygen. Then the aerobic organisms came. And the Proterozoic was!

  4. If it takes fossil fuels to manufacture renewable energy, there can be no Rebound using them. All ores have been diffuse and high energy mined, as you wrote. And we lose that ability of extraction without the oil infrastructure. How do you move up from there? Lower EROI energy cannot sustain the existing equipment and processes. The Chinese Coal Economy might be building renewables, but they also are buying Higher Net Energy machines and fuel to supplement even hydro power, let alone solar. We couldn't travel to the stars once we reached Peak Per Capita Energy in conventional oil. How do we do it with NO conventional oil? Perhaps we could use the radioactive fuel from ocean water off of Fukishima. Hey, great article, and a concept I hadn't run across before. I just think you need to reign in that incurable optimism of yours!

    1. I don't think optimism is an ailment!

    2. Give yourself up to the cold embrace of the beautiful Goddess of Despair, who holds the mirror to Reality: because only in despair can we discover Courage.

      'Hope is born of lack of hope.' Iranian proverb.

  5. Of course, at this point one has to introduce Jared Diamonds "Guns, Germs and Steel".
    I believe, although I cannot prove it, that other cultures did have their collapses as well.
    When I think about it, the determining factor seems to be the way, a society is dealing with knowledge management. Tradition, centralization, recombination, generation and spread of knowledge is a complex feature of a society, that is developing over time. Not all societies had the notion, that knowledge management is important.
    I believe that Europe had over quite a long time, a couple of warring, competing, but at the same time stable centres, it was a truly multicentric entity. And it was this competition, this power struggle, that led to the appreciation of knowledge management.
    OTOH, we had one big asset: we had Greece. To me, it was the reception of Greek thinking, its boldness and soundness, that led to the knowledge explosion, which in turn led to european dominance. And remember: ancient Greece was also a true multicentric entity.

  6. Very good point about intense inter-state competition in Europe and knowledge management. Property rights also played a part I suspect.

    Something to bear in mind is that the expanding Europeans met cultures which were either far weaker militarily, or were themselves undergoing a collapse phase - for instance India, where the Mughal Empire was in decadence.

  7. As for Europe being sparsely populated in the early Middle Ages, so it would seem to us, but I'm currently reading 'The Alexiad' by Princess Anna Comnena describing events of the 11th century, and it seems the Byzantine rulers were horrified by the sheer numbers of the Western warriors and crusaders. They also seem to have been very well armed and armoured.

    1. Well, the 11th century is not "early middle ages"!

    2. Well, it's all relative!

      I divide the period thus: true Dark Ages - 5th to 10th centuries (utter turmoil, hundreds of petty kings, failed Empire of Charlemagne, etc); Early M A - 10th and 11th (huge number of towns founded, end of Viking disruption); Mid M A - 12th and 13th (the great cathedrals built, Troubadour culture Europe-wide, great kingdoms); High M A / Early Renaissance -14th until early 16th century. Gothic culture and way of life lasted in Northern Europe until the early 16th century.

  8. Perhaps, Professor Bardi, Diamond owes much to a previous author Hans Zinsser, who wrote a book entitled 'Rats, Lice, and History' in 1935, which is also a very interesting read.

    1. I didn't know that. Interesting, thanks!

    2. And it is another book bought on Amazon. I know that I should support the local bookstores, but....

    3. I think one can legally obtain a free pdf copy of Rats, Lice and History here:

  9. the difference between previous collapse and the coming one is resource availability.

    when previous empires collapsed, new lands we always available to invade and loot

    now the world is full. It's been picked cleaned. Therefore the next collapse will be final, though of course denial might run on for a century or so, pretending that things can restart ''if only''---but they will be false dreams.


    we will make intersting history---or at least folk myths round future campfires

    1. Denial: in the Dark Ages, lots of petty rulers stuck eagle heads on the ends of poles and called themselves 'emperor'. It didn't work like magic..... :)

    2. With enough warming, some additional resources at the poles may become available for a future civilization...

    3. About living at the poles, you may wish to read this musing of mine:

  10. After we bottom out following the upcoming collapse, there will likely be a short-term period of re-growth. But it will be short-lived, for as Norman points out above, the planet has pretty well been picked clean. There are no longer vast quantities of easily available (ie. affordable) fossil fuels left. The concentration of various metal ores has plummeted, requiring the mining and separation of large amounts of dross to obtain a shrinking percentage of useable resource.

    The idea that renewables will allow us to re-attain our current level of economy and complexity is fantasy. And the idea that renewables will propel us into space is lunacy.

    I expect that in two or three hundred years, the world will have become de-industrialized, and economically, politically and socially more resemble that of 1,000 years ago; agrarian, monarchic and feudal. And I don't see us ever advancing beyond this state because unlike forests and soil, fossil fuels and metal ores don't regenerate themselves

    Antoinetta III

    1. I can't imagine how many people said that Columbus was a lunatic before he sailed Westward!

    2. People said he had drastically underestimated the distance to Asia, and he had -- he was off by over 16,000 km. Fortunately for Columbus, there were two huge continents in the way.

      (That the Earth is round and has a circumference of about 40,000 km had been known since the time of Aristotle. That Columbus's contemporaries thought the Earth was flat is a fiction invented by Washington Irving in 1828.)

    3. After the collapse I don't think ores will be a problem at all : the population will have shrinked dramatically, and the ruins of our current "civilization" should provide all the necessary metals or even ready to use objects : just think of the amount of stainless steel knives available for instance that should last for quite a while, or the amount of copper available in all the cables and such.
      But clearly it will not be the same for energy. A key question for me is whether the remaining forests will be destroyed in the descent (as it is happening in Indonesia for palm oil for instance), or if the collapse will be too quick for it to happen.
      After the collapse, the population will be so low compared to now that wood will probably become again the main energy source for humans (besides the sun, which is always the primary energy source for life on earth), with a certain "sustainability" period.

  11. When Rome fell in this part of Britain, it was a pretty smooth transition: the Germanic mercenaries long-employed to hold back barbarian raiders just took over...... and farmed.

    One part of town which had been industrial with lots of forges became cereal fields and grazing. It disappeared so completely that it was only rediscovered few years ago when new construction started.

    Apparently,the Saxons also rummaged among Roman graves to collect coloured glass beads, which they rather fancied on themselves.

    That they were able to farm successfully shows that - unlike today - the land had not been picked clean or poisoned, but that the only the higher complex structures had collapsed. Buildings were burnt, eaten by woodworm and mould, or hacked up for building stone.

    And so,eventually, a bounce back was going to be possible based on agrarian wealth and trade.

    It is hard to see that those benign ecological conditions will apply to us and our descendants.

  12. About those 18 million people in Europe after the fall of the western Roman empire - how many of them were barbarian tribes moving in? Lots of places in Europe the local people went almost extinct.
    What was the situation in Italy, do you know? Or is that a sensitive subject for you?

    Because I remember you embraced a weird internet conspiracy theory to explain the fact the Romanians speak a romance language (quite close to italian) to protect your unique roman parentage, I guess.

    1. Weird internet conspiracy theory???? Are you sure of your memory, NB? Anyway, about your question, there is an interesting archaeological museum in the town where I live, where you can see how, during the late antiquity, the town shrunk, the people changed the way they dressed, now adopting the "northern style" with men wearing trousers rather than tunics. Clearly, the place had been taken over by Northern people -- you may call them Barbarians if you like. The cultural takeover was nearly complete. The genetic, well, it is hard to say. The Goths and the Romans mixed together, both culturally and genetically. And the result is us

    2. It makes for a fascinating study -genetics and cultural traits: for instance, the Basque-speaking peoples of the Pyrenees (many tribes - but don't tell the Nationalists of today that!)were long occupied by Rome, but it seems they were never absorbed into even Low Latin and Christian culture -so much so that when Christian missionaries approached them in the 6th and 7th centuries they couldn't find anyone to talk to in Latin.

      And these areas were fully incorporated into Rome's network of roads, military bases and towns.

      But today, if one examines objectively folk dance of the Basques, it is clear that they are almost wholly derived from Arabo-Persian culture, and that of 'Troubadour' European culture -itself derived from North Africa and Persia, and even Central Asia.

      And yet, the Arabs only ruled in the region -from Pamplona (a Roman foundation, but again don't tell the Nationalists!) for some 40 years or so. Although the Troubadour elements were clearly brought, in part, by French immigrants of the 11th and 12th centuries who built all the Basque towns up and stayed until today.

      As for dress, the famous big, floppy,'Basque beret' was actually adopted from the Scotch bonnet of Catholic Scottish exiles of the 18th century who settled mostly in France.

      How Etruscan do you feel, Prof Bardi? :)

    3. Culturally, very Etruscan. Genetically, not much, I think most of my ancestors are Southern Mediterranean -- one of these days I'll take the DNA test

    4. Why this assumption that cultural change means a new population? The Roman Senate passed law against trousers as early as the Republic. Trousers are article of dress that was typical of horse riding peoples. In the later Roman period the army became increasingly cavalry based and adopted trousers as part of military dress, the fashion then spread as civilians copied the military.

      Change of population are not required. In my lifetime I've seen skirts for women vanish with most women wearing leggings today. Or the Japanese discarding kimonos for European style clothing, there was no settlement by new peoples.

  13. As a Biologist my view is, this depends on Room to move. Either by available nascent territory - or by Evolution into Sub Species. Now we seem to be stuck, no Room to move, all territory taken and blocked against Migration, Newcomers seen as enemies...and personal debilitation, unable to evolve to another level...
    When humanity collapses, it will take down the entire Ecosphere...
    Flagrants in Soap already pollute our rivers and drinking water, Glass bottles of “mineral Water are contaminated with Micro Plastic...
    The Half Life of the pollutants exceeds our ability to eliminate it...the entire Eco Sphere will go down...for a long time...

    1. Have you seen Whitmire's paper saying the first technologically advanced species on a planet will destroy it's own biosphere?

  14. I think that collapse allowed for faster growth only in pre-industrial societies.

    Those were based on renewable energy (biomass). Once population dropped, biomass (forests, soil fertility) would regenerate and allow for further expansion at a later date.

    But our society is based on fossil fuels, not biomass. Oil and coal do not grow back after collapse. Even worse: extracting oil has become hugely energy-intensive. If the oil supply chain collapses, it will be very hard to extract more oil in a few centuries due to the sheer lack of energy.

    So maybe there will be some population growth after "the Cull", but the rate of increase will be nothing like the post-1850 population explosion, but more like the slow increases of agrarian times.

    In the best case scenario. Because in the meanwhile Westerners have unlearnt how to farm without oil, and non-Westerners will have to re-learn farming in a totally different climate.

    So sorry Prof. Bardi: if I could grade your post, it would get a big fat HOPIUM tag.

  15. In earlier phases of civilization, the peasant sub-strata might shrink, disappear from some regions for a time, but never really went away -and the skills were preserved.

    Biomass could regenerate, and the game could be set in motion once more -so it is correct to say that -historically - a Seneca Collapse need not necessarily preclude renewal.

    However, All previous rebounds were based built upon the backs of peasants and their draught animals, and the civilizations themselves were not outgrowths of a global, industrialized, fossil-fuel dependent energy-structure.

    That is indeed the crucial -and fatal - difference.

  16. Professor,

    I'd agree with you that being at the right place at the right time is crucial, but as a mostly-monocausal explanation it leaves me unsatisfied. What about different practices of Christianity and their effects on the mating patterns of Europeans ? Why was the Age of Colonization purely led by people west of the Hajnal line ? (What about Darwin ? -- but let's leave IQ out of this).

    1. I don't think that a monocausal explanation is a problem: i see it as superior to having to pile up several causes. We discuss the issue single cause vs. multiple causes here:

    2. The Hajnal line is a modern concept -- hard to say whether it existed at the time of the crusades, I'd bet not at all. Then Darwin, well, we go back to the old ideas of racial superiority of Europeans which are just that: old ideas disproved by time. The same about Christianity: it is such a polymorphic concept that it can generate people as different as Francis of Assisi and Ignacio de Loyola.

  17. I think your analysis has a lot going for it, but it’s not the driving force here. There is a lot of serendipity to get there. In the fifteenth century, admiral Zheng He expanded China’s influence all the way to Africa. Given time the Chinese would certainly have discovered America, but later emperor’s closed China from outside influence. What can’t influence you, you can’t influence.

    At the same time the Byzantine empire fell to the Ottomans, limiting Europe’s access to the Silk Road. Spain was liberated from the Moors. A wealth of ancient knowledge gushed into Europe which St. Thomas Aquinas labored to integrate with European Christianity, which was Neo Platonic. He had to merge Aristotle in there and make it ‘Christian.’ This helped jump start the Renaissance. Expeditions started down the coast of Africa to see if they would get to the far east bypassing the middle east. And one plucky individual decided to try going west. Take a look at a globe today and image that north and south America are not there. That it’s one vast ocean from Lisbon to Vladivostok. You’ll see why they thought him crazy.

    Necessity is the mother of invention. We don’t innovate unless we are forced to do it. I think that’s the point of the Seneca Rebound.


  18. @ everybody
    I'm glad to signal to you, those 3 interesting lecture ;-) quite in topic about incoming catastrophes

    Game Over for the Climate? Can we control the climate crisis in time? Updates from Permafrost Report 2017



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)