Civilization: diffusion and impact of culture

March 19, 2011 at 12:22 am (Civilization) (, , , , , )

This is part 2 of my Civilization series.

Diffusion and impact of culture

The reality of human interactions is that we fear and avoid what we don’t understand.  Most conscious thought about culture is about differences: “we” have this way of doing things, “they” do something else.  This affects all interactions in a fundamental way.  Similar cultures will mix more, trade more, share more than distant cultures.

But culture is more than a way of being – it affects the way people interact in and behave very deep ways.  Turchin’s theory of civilization says that Asibiya – the ability for group action – builds up exactly on the borders between cultures.  This is because the definition of “us” becomes very clear when contrasted to a very different “them”.  It’s a nasty fact of humanity that people can show great altruism and kindness to others, yet on an everyday level it is often nepotism – aggression towards people out of your group – that rules.  The origin of states arises from small tribes lies that form strong bonds –  which is precisely what Asibiya is designed to explain.

Culture and religion are integrally related, and religion is an aspect of culture that kingdoms have some reasonable control over.  Although switching between Christianity and Muslim faiths has been a long and painful process for many nations, religions can splinter off and yet remain fundamentally the same thing to the peasantry.  Protestantism appeared mostly as a response to Catholic domination and attempts to influence politics. Although almost the same faith, the differences create a strong “us and them” feeling in people – at least the nobles – that allows wars to be justified and alliances forged.  Yet both are “us” when compared to their more different neighbours – Muslims, or the Sikhs, or the Jews.

Differences in religion and culture in general control what is acceptable and unacceptable in war, whether the enemy is just an ally with the wrong king, or an inhuman devil.  What do the populace think of the king burning an enemy city?  If there is little shared culture with the city then people will be content, possibly even happy to see the influx of “free” goods and slaves.  But if people know people of the persecuted culture, trade there, visit there on pilgrimage or have a religious empathy for them, then they will object, strongly.  In ancient times, warfare often resulted in the burning of cities and the taking of slaves.  Conversely, during the late middle ages (and most civil wars) the European nobility fight each other – and people do die – but cities go on much as they always had because nobody would benefit from harming the people.

So how does cultural difference arise?  It seems natural to expect that prehistoric states varied greatly more than we see today – the same is certainly true of African, Papuan, American and other tribal societies, which also support a great deal more genetic diversity.  Culture goes back millions of years, to before our split with he great apes, and has perhaps appeared in limited form in many species. From this very diverse state, culture has “diffused“, so that ideas are shared.  Where some ideas lead to (or are simply associated with) success, they tend to dominate and spread to wide areas.  Because of this association with success, culture often spreads where people spread: farming, metal working, and other highly succesful strategies are clearly visible in the genetic record.

Since culture moves with people, and people do not move homogeneously but in waves, displacing those who have gone before them.  On the front of this wave is always a new technology or way of life, and with it associated a very different way of being from those on the other side of the divide.  Further (more historical) examples are the Roman expansion into the barbarian lands, the American conquest, the formation of Russia and of Australia, and of China (during multiple periods).  These waves do not grow forever, but they do leave cultural borders at which Asibiya can grow due to the added pressures of living in proximity to a strange and dangerous culture.

Living on a cultural border is both a very dangerous, and potentially very rewarding.  Almost all great empires are formed there, and the mixture of cultures allows each to take on a form very distinct from its origins.  Examples abound, and counterexamples are hard to find – Egypt, China, Greece, Rome, the Islamic empire, Russia, Britain, America – all were forged on the borders of the strongest empires of the previous era, and most often on the border at which the largest cultural differences occurred.

Culture is also important as a way of spreading change within established groups, not just in forming nations.  Money, writing, mapmaking, shipbuilding, architecture – all these and more ideas can be exported through the movement of people that use them.  It also shapes how people interact and function in everyday lives.  Successful ideas spread on the back of cultural diffusion, and to take them in, an empire must also import the aspects of culture associated with them.  Just look at how American business – and in parallel it’s culture – exported throughout the world today.

Relation to civilization

This leads to a clear dynamic for culture in civ interactions: the magnitude of trade and other agreements depends on the degree of similarity between the two cultures.  It really is better to be at war with distant heathens than your neighbours because of the lost revenue, and the disapproval of your subjects.

An important dynamic can be that the presence of a very different other on the border will unite people to a degree – they have more motivation to be united.  But the same force can quickly flip to work in reverse – if an empire is very large and unstable, then a  new and dynamic culture may form from the fusion of two very dissimilar ones, rebelling from their host empires and – if initially successful – able to gather momentum at a pace that will lead to their rapid ascension as the new power.

Cultures that interact will be exchanging people, culture and ideas, and will become similar according to how strongly this occurs.  The deliberate adoption of an imported technology will come at the cost of imported culture – a dynamic that enables cultural victory by exporting your nations ideas to the world.  And conversely, the collapse of an empire that has already exported much culture is not so catastrophic because in its ashes lie the shared cultural bonds that will enable the pieces to be picked up, and will find itself in a far more familiar world.

As before, this needs to be implemented as a genuine dynamic that can form part of a player’s strategy.  It will probably correspond to the creation of a new cultural group – the fusion between the two original groups – that can pick and choose the cultural traits that are most suitable for the current times.  In a sense, it is more likely that religion be created from such a succession than a religious movement will cause a succession to happen – the historical examples of Christianity and Islam both indicate that a lot of similar thought was around in the time period.  They both found success by exporting cultural values that were successful.

Essential reading for this section:

*P. Turchin: “Historical Dynamics :Why states rise and fall” (2003) (this is needed for all sections…)

Hamon & Loh 2010: “The Index of Cultural Diversity A New Quantitative Measure of Trends in the Status of the World’s Languages”.  Language Documentation & Conservation.

Battaglia et al 2009: “Y-chromosomal evidence of the cultural diffusion of agriculture in southeast Europe”.  European Journal of Human Genetics (2009) 17, 820–830.

Wen et al 2004: “Genetic evidence supports demic diffusion of Han culture”.  Nature 431, 302-305 (2004).

Byrne 2007: “Culture in great apes: using intricate complexity in feeding skills to trace the evolutionary origin of human technical prowess”. PRSB.

This series:

Back to “rise and fall”

Civilization index


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Civilization: rise and fall

March 3, 2011 at 12:19 am (Civilization) (, , , , , , , )

This is part 1 of my Civilization series.

Rise and fall

Successful civilisations throughout history have grown rapidly, appearing unstoppable.  Some (like Rome, and Han China) existed stably for hundreds of years.  Others, like Alexander the Great‘s Asian Empire did not.  But in every kingdom, empire and state that has ever existed (excluding the few surviving today, which are probably not as eternal as we’d like to think), something has eventually changed.  Once great empires are defeated by a smaller rival (e.g. Sassanid Persia), and others crumble all by themself.  Changing fortunes are one of the clearest signals in history.

Yet we have no mechanistic understanding for the collapse phenomenon.  It is entirely absent from “Vanilla” Civilization, which assumes that growth gives power and power allows further growth,  with the result that empires grow at an “exponential” rate. This is a good first approximation: over time, population has grown exponentially as more people plant more food which feeds more people.  The same applies to technology, and social development.  Yet these trends clearly do not apply to states and empires, even though it is often within the largest states that population density, technology and social development are highest.  So why do empires fall?

There are many mechanisms in history that may cause the strong to become weak.  Perhaps their strength was illusory.  Since success at war pays well in the short term, winners of scuffles can hire more soldiers and thus will get greater military strength. But if the infrastructure for effective taxation, trade and public works to support the empire is not in place, when the expansionist wars stop (as they must) the empire will be overstretched.  Warlords from within or without the empire can take over distant provinces and the empire collapses.  Conversely, smaller civilisations are more efficient and competitive per person, people are more involved in the state, greater mobilisation is possible and they have unity of purpose.

Yet these stories are just that – stories.  When does the first apply, leading to large states conquering small, and when do the small states gain an upper hand?

Modifications to Civilization such as “Revolution” and “Rhys and Fall of civilisation” both make a good attempt at adding this dynamic. The basic idea is that civilizations that are large (relative to what their infrastructure and governmental system can handle) will experience both inefficiency and stability problems.  This is basically correct – but is added as a fudge, entirely without a mechanism.  Some large empires (China for example) have managed to avoid internal strife (or at least, it hasn’t lasted all that long).  Yet other, similarly sized empires collapsed almost without trace.  What is the difference?

Peter Turchin has some ideas – he says that societies have “asabiya” – a unity of purpose that allows for collective action.  Groups of people that live together in strife (such as desert nomads) – and particularly those on cultural divides – develop strong bonds and are able to commit very strongly to struggles.  This allows these small groups to conquer much larger states, because the groups with such states defect and bicker and are not willing to die for their cause.

Once in power, the asibiya of such a group declines as the need for collective action decreases, and the lure of luxuries increases.  The powerful state weakens to be eventually taken over by a smaller, more dedicated group.  See his book  “Historical Dynamics: Why States Rise and Fall” and his later books and his webpage for ideas, which stem from the works of the 15th century Arabic scholar Ibn Khaldun.

There is clearly something to this theory, but it is incomplete as it stands.  Did 18th century England have higher asabiya than 18th century Venice (or Germany for that matter)?  It is impossible to tell.  Clearly, England was on the rise in a way that Venice wasn’t, but we can’t measure asabiya.  The small nomadic groups described by asabiya are not in play here; there are more standard, more economic and sociological forces.  What are they?

Essentially, we don’t know yet.  I’ve been involved in some modelling, where we show that treating a state as a number of semi-independent groups can lead to this dynamic.  Each group is coerced into the state, but gains benefits from being a part of it.  Whilst everyone is on board, everything is fine – culture and development increase, and great achievements are made by the elite.  But the groups at the bottom of the pile get a worse and worse deal – because they have less political power, and political power tends to lead to more political power.  When one group rebels, the benefit to the rest is reduced, and it can set off a chain reaction leading to state collapse.

The model allows groups to act in an entirely selfish way – there is no fluffy concept of asabiya, but asabiya arises as a natural result of within-group competition.  It is nice for several reasons.  Empires that look strongest from the outside – those with high development and culture – are exactly the least stable. Collapse can be triggered internally, or by external stresses such as war.  These problems can all be overcome by continual growth of the state, so that everyone is getting a better deal… but no growth is forever.

Unfortunately, the only reference for this is a Masters Student thesis.  But watch this space…

Relation to civilization

The implication for the modelling of artificial societies is that group dynamics matter. Giving people a shared identity leads to greater capacity for action – but this shared identity is eroded by distance in culture, status, religion, nationality, money and power.  Each new realisation of a state can form its identity on new grounds – by language, or religion, or race, or ideology, shared suffering or shared experience.  This is why modern states have had to be more inclusive, to create a shared identity amongst people who in other circumstances would see themselves as very  different.

This implies that there is a natural lifecycle to states.  It is not necessary for a state to collapse and be rebuilt, but the people must find a new way of feeling unified.  The natural dynamic in a game is to have groups with identities that are shared to a greater or lesser extent, and that have different desires based on these.  Weaker groups will be less able to bargain for their desires and therefore will want to rebel… leaders have the option of silencing them, but at the cost of alienating further groups.  It is not a long term strategy to kill your own citizens, and eventually, the state must be restructured, perhaps smaller, to create a new shared identity and (most importantly) a more even distribution of power.  The greater the change, the more dramatic the collapse will be.  Making demands of citizens – such as drafting for war – or not protecting them adequately will result in rebellion of some groups, leading to the rebellion of more.

It is important to make this a dynamic that is visible, rather than spawning random rebellions that just happen because some counter got too high.  The groups within the empire should be visible, broken down by town, and each one should be unique in some way.  Groups can be absorbed when their needs coincide strongly, which will be most common during rebellions or redefining of statehood.  They cause trouble only when their needs are not met – be they financial, political, or religious.  They can be eliminated by force – at the cost of scaring other groups – or be brought in line through education or incentives.  Left alone, strong groups will get stronger and weak ones weaker, at a rate that depends on the degree of accountability in the society.  Therefore different types of government will have a different ability to cope with differing needs.

Differences between groups are defined in terms of differences within the state versus differences without.  If there is a clear enemy, people will remain united.  Diasporas will lead to shared demands over multiple states, but also lead to shared bonds and greater trade of both goods, knowledge and cultural values.  Multiple cultures within a state lead to less focus but greater rates of innovation and cultural growth.

Adding this one feature will in one swipe unite the process of cultural diffusion (to be dealt with later) with the internal process that causes collapse.  “All” that remains to be done is to implement the mechanic in a balanced way that is interesting to engage with and produces realistic effects…

Essential reading for this section

*P. Turchin: “Historical Dynamics :Why states rise and fall” (2003) (A must read!)

P. Turchin: “War and peace and war” (2005)

Kandler and Levand: An investigation of the relationship between innovation and cultural diversity (2009)

Kogel and Prskawetz: “Agricultural productivity growth and escape from the Malthusian trap” (2000)

Kohler: “Simulating ancient societies” (2005)

Read: “A multitrajectory, competition model of emergent complexity in human social organization” (2002)

Neeraj Oak (and Daniel Lawson) “Explaining the collapse of political states” (Masters Thesis, 2011)

This series:

Forward to “diffusion and impact of culture

Civilization index

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Rise and Fall of Civilization: Index

March 3, 2011 at 12:18 am (Civilization) (, , , , , , , , , )

I need to make two confessions.  Firstly, in my “youth” I have been just a little addicted to the “Sid Meier’s Civilization” series of games.  Secondly, I have since been thinking very deeply about history – deep enough that I have supervised a Master’s Project studying the processes that allow civilisations to rise, and fall.  Over the next few weeks, I’m going to write several posts distilling my thoughts, with each split into:

  1. Some aspect of history that has an interesting and dynamic pattern;
  2. How this might relate to “simulations of history”, i.e. civilization.  This part of the post will mostly only be of interest for those also needing a visit to Civilization Anonymous (after just one more turn!).

This is an introduction and index; I will update each topic below with the correct link when they are published.  The posts will start out well researched with academic references at the bottom and web links in the text; towards the end of the series my “expert knowledge” will wane.


It has been claimed that history is just “one damn thing after another“.  Certainly history is extremely complex, and there are almost  no examples where there is a simple cause and effect for large-scale events.  But that does not mean that there are no patterns to be found.  Broad generalisations about the human psyche are possible when modern experimental psychology, sociology, and human geography are combined with game theory, mathematical modelling* and computer simulation.  Resting only on the assumption that people everywhere, at all times, were just people – with the same set of biological drives –  we can hope to apply the full scientific method to the study of history.  Combined with quantified historical and archeological evidence, there is the glimmering of a new renaissance in the study of history.

Across the intellectual divide,  Civilization 4 (with some modifications) is the most complete simulation we have for the processes that have shaped history.  Although its remit is to be “just” a game, by exploring how the game unfolds we might learn something about how history itself could have unfolded. And we learn that we don’t understand all of the rules it followed.  It is of great interest to understand a simulation model for the world that replays history as accurately as we can manage, without having to add too many of the specifics ourselves.

I first discussed these ideas when I decided to take the plunge and do some real research on the subject.  Although I will link a lot to Wikipedia, most of the ideas are fully fleshed out in the references at the bottom.


  1. Rise and fall
  2. Diffusion of Impact and Culture

Essential reading for this section

A. Toynbee: “A Study of History (1961).

*P. Turchin: “Historical Dynamics :Why states rise and fall” (2003) (A must read!)

E. Rasmusen: “Games and Information: An Introduction to Game Theory” (2009). (or similar)

Fotheringham et al. “Quantitative geography: perspectives on spatial data analysis” (2000).  (or similar)

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