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A web page by Peter Turchin

What is cliodynamics?

Empires rise and fall, populations and economies boom and bust, world religions spread or wither... What are the mechanisms underlying such dynamical processes in history? Are there 'laws of history'? We do not lack hypotheses to investigate - to take just one instance, more than two hundred explanations have been proposed for why the Roman Empire fell. But we still don't know which of these hypotheses are plausible, and which should be rejected. More importantly, there is no consensus on what general mechanisms explain the collapse of historical empires. What is needed is a systematic application of the scientific method to history: verbal theories should be translated into mathematical models, precise predictions derived, and then rigorously tested on empirical material. In short, history needs to become an analytical, predictive science (see Arise cliodynamics).

Cliodynamics (from Clio, the muse of history, and dynamics, the study of temporally varying processes) is the new transdisciplinary area of research at the intersection of historical macrosociology, economic history/cliometrics, mathematical modeling of long-term social processes, and the construction and analysis of historical databases. Mathematical approaches – modeling historical processes with differential equations or agent-based simulations; sophisticated statistical approaches to data analysis – are a key ingredient in the cliodynamic research program (Why do we need mathematical history?). But ultimately the aim is to discover general principles that explain the functioning and dynamics of actual historical societies.

The community of researchers working on mathematical history and cliodynamics has been rapidly growing in recent years. We now have our own journal, Cliodynamics: the Journal of Theoretical and Mathematical History. Although this web page is primarily devoted to my personal research, I also try, as much as possible, to reflect the most significant developments in the field as a whole.

Currently my research focuses on two broad questions. The first issue is the one introduced above: what general mechanisms explain the collapse of historical empires. It turns out that such imperial (and, sometimes, civilizational) collapses generally occured during the waves of political instability that periodically affected agrarian societies. A theory explaining these waves, or cycles, is presented and empirically tested in Secular Cycles, coauthored with Sergey Nefedov. The empirical part surveys long-term oscillations in demographic, economic, social, and political structures in England, France, and Russia from medieval to early modern periods, and in the Roman Republic and Empire. While the theory does very well for past agrarian societies, the inevitable question arises, what about our times? Are we about to experience another age of political instability and social disintegration? To answer this question, I am working on a project examining the historical dynamics of the American Republic, from its inception (c.1780) to the present. First draft is expected in 2011. Stay tuned for developments.

The second research direction starts with the observation that large-scale states and empires are a relative rarity in the historical record. The most difficult question, really, is not why they collapse, but how they were possible in the first place. What were the social forces that held together huge empires, encompassing tens of millions of people spread over millions of squared kilometers of territory? I bring a variety of approaches to bear on this question: insights from the multilevel selection theory, agent-based models (in collaboration with Sergey Gavrilets), and systematic empirical surveys of global patterns of "imperiogenesis". Understanding the nature and evolution of large-scale cooperation has also practical implications for such issues as failed states and nation building (see War, Peace, and the Evolution of Social Complexity).


Recent Developments:

December 2011

Cliodynamics: Volume 2, Issue 2 published!

Turchin, Peter; Hochberg, Michael E. 2011. Editor's Column: Introducing the Social Evolution Forum. Cliodynamics 2: 215-216.

Baker, David C. 2011. The Roman Dominate from the Perspective of Demographic-Structural Theory. Cliodynamics 2: 217-251.

Fletcher, Jesse B; Apkarian, Jacob; Roberts, Anthony; Lawrence, Kirk; Chase-Dunn, Christopher; Hanneman, Robert A. 2011. War Games: Simulating Collins' Theory of Battle Victory. Cliodynamics 2: 252-275.

Korotayev, Andrey; Zinkina, Julia; Kobzeva, Svetlana; Bozhevolnov, Justislav; Khaltourina, Daria; Malkov, Artemy; Malkov, Sergey. 2011. A Trap At The Escape From The Trap? Demographic-Structural Factors of Political Instability in Modern Africa and West Asia. Cliodynamics 2: 276-303.

Pomerantz, Kenneth. 2011. How Big Should Historians Think? A Review Essay on Why the West Rules—For Now by Ian Morris. Cliodynamics 2: 304-329.

Christian, David. 2011. Expansion Cycles in Competitive Systems: A Review of Expansions by Axel Kristinsson. Cliodynamics 2: 330-332.

Manning, Joseph G. 2011. Middle Range Theory: A Review of The Origins of Political Order by Francis Fukuyama. Cliodynamics 2: 333-340.

Blanton, Richard E. 2011. Science or Ideology? A Review of The Archaeology of Politics and Power by Charles Maisels. Cliodynamics 2: 341-343.

Social Evolution Forum. Lustick, Ian S.. 2011. Institutional Rigidity and Evolutionary Theory: Trapped on a Local Maximum; with commentaries by Nettle, Daniel; Wilson, David Sloan; Kokko, Hanna; Thayer, Bradley A. Cliodynamics 2: 344-361.

December 2011

An Evolutionary Approach to the Twin Problems of Failed States and Nation-Building (Stanford University, Dec. 3-5, 2011)

Why people cooperate in constructing larger social units, and its reverse, social disintegration, have been studied intensively from the perspective of cultural and social evolution. So far, however, the insights coming from this research have not been integrated into our understanding of how to deal with failed states, or succeed in nation-building. To jump-start such a dialogue between scientists and policy makers, the Evolution Institute has organized a workshop at Stanford University on December 3-5, 2011. This workshop brought together academic experts from such diverse fields as evolutionary, social/political, and historical sciences with diplomats and policy makers. The workshop focused on a particular region where ideas on how to achieve peace are urgently needed, Afghanistan and Pakistan.

For more information see the workshop webpage

November 2011

The Social Evolution Forum: a new platform aimed at promoting communication, discussion and collaboration on diverse topics related to the evolution of human society

A central question of social evolution is elucidating the mechanisms and dynamics that resulted in the rise of large-scale complex human societies. We think that conceptual and empirical tools are now sophisticated enough to make possible dramatic breakthroughs in answering this question. The stakes are enormous – not only because of the scale of the intellectual puzzle and intrinsic interest in the emergence of states, empires and civilizations, but also because of potential application in addressing such societal problems as war and failed states, and more optimistically trust, peace and large-scale cooperation. Currently, researchers interested in these issues work in highly diverse disciplines – anthropology, economics, sociology, political science, evolutionary biology, and mathematics – with little interdisciplinary contact. Periodically scientists from these different disciplines meet at conferences or workshops, and interact intensively, but durable projects rarely emerge. There are a number of challenges to fostering interdisciplinary dialogue and collaborations, including semantics and different conceptual models and approaches. We hope that the Social Evolution Forum will help us overcome these challenges (from the SEF description).

Go to the Social Evolution Forum

May 2011

Structural-demographic causes of political instability: a talk for Symposium on Historical Analysis for Defence and Security, Portsmouth, UK; May 18-19, 2011

A useful approach to thinking about why outbreaks of political instability occur is to separate the causes into structural conditions and triggering events. Specific triggers of political upheaval, such as self-immolation of a Tunisian fruit vendor, are very hard, perhaps impossible to predict. On the other hand, structural pressures build up slowly and predictably, and are amenable to analysis and forecasting. Quantitative historical analysis reveals that complex human societies are affected by recurrent — and predictable — waves of political instability (P. Turchin and S. A. Nefedov. Secular Cycles. Princeton Univ. Press; 2009). The structural-demographic theory suggests such seemingly disparate social indicators as stagnating or declining real wages, a growing gap between rich and poor, overproduction of young graduates with advanced degrees, and exploding public debt, are actually related to each other dynamically. Historically, such developments have served as leading indicators of looming political instability. In my presentation I will describe a dynamical model based on structural-demographic theory and test it with data on economic, social, and political dynamics in the nineteenth century America, including the most violent episode of political instability in the U.S. history, the American Civil War.

Powerpoint slides here

March 2011

Cliodynamics: Volume 2, Issue 1 published!

Special Feature on History, Big History, and Metahistory (Vol 2, Iss. 1)

Krakauer, David C., John Gaddis, and Kenneth Pomeranz. 2011. Editors’ Column: An Inquiry into History, Big History and Metahistory. Cliodynamics 2: 1–5.

Christian, David. 2011. A Single Historical Continuum. Cliodynamics 2: 6–26.

Erwin, Douglas H. 2011. A Paleontological Look at History. Cliodynamics 2: 27–39.

Gaddis, John L. 2011. War, Peace, and Everything: Thoughts on Tolstoy. Cliodynamics 2: 40–51.

Gell-Mann, Murray. 2011. Regularities in Human Affairs. Cliodynamics 2: 52–70.

Harpham, Geoffrey G . 2011. Meta-History’s Dangerous Dream. Cliodynamics 2: 71–81.

Krakauer, David C. 2011. The Star Gazer and the Flesh Eater: Elements of a Theory of Metahistory. Cliodynamics 2: 82–105

McNeill, J. R. 2011. Homogeneity, Heterogeneity, Pigs and Pandas in Human History. Cliodynamics 2: 106–120.

Pomeranz, Kenneth. 2011. Labeling and Analyzing Historical Phenomena: Some Preliminary Challenges. Cliodynamics 2: 121–145.

Spier, Fred. 2011. Complexity in Big History. Cliodynamics 2: 146–166.

Turchin, Peter. 2011. Toward Cliodynamics – an Analytical, Predictive Science of History. Cliodynamics 2: 167–186.

Vermeij, Geerat J. A Historical Conspiracy: Competition, Opportunity, and the Emergence of Direction in History. Cliodynamics 2: 187–207.

West, Geoffrey B. 2011. Can there be a Quantitative Theory for the History of Life and Society? Cliodynamics 2: 208–214.

Go to the Journal

January 2011

Warfare and the Evolution of Social Complexity: A Multilevel-Selection Approach published in Structure and Dynamics

Multilevel selection is a powerful theoretical framework for understanding how complex hierarchical systems evolve by iteratively adding control levels. Here I apply this framework to a major transition in human social evolution, from small-scale egalitarian groups to large-scale hierarchical societies such as states and empires. A major mathematical result in multilevel selection, the Price equation, specifies the conditions concerning the structure of cultural variation and selective pressures that promote evolution of larger-scale societies. Specifically, large states should arise in regions where culturally very different people are in contact, and where interpolity competition – warfare – is particularly intense. For the period of human history from the Axial Age to the Age of Discovery (c.500 BCE–1500 CE), conditions particularly favorable for the rise of large empires obtained on steppe frontiers, contact regions between nomadic pastoralists and settled agriculturalists. An empirical investigation of warfare lethality, focusing on the fates of populations of conquered cities, indicates that genocide was an order of magnitude more frequent in steppe-frontier wars than in wars between culturally similar groups. An overall empirical test of the theory’s predictions shows that over ninety percent of largest historical empires arose in world regions classified as steppe frontiers. PDF here

January 2011

Review of Secular cycles by Salvatore Babones in Journal of World-Systems Research

The main shortcoming of this book is its lack of sociological grounding. ... That said the intellectual content of the book is staggeringly impressive. It is hard to quarrel with Turchin and Nefedov's careful analyses, and their data sources are extensively documented. For anyone interested in applying social theory to historical data on pre-modern Europe, Secular Cycles will be a treasure trove of data from obscure sources; the authors have certainly done their homework. Turchin and Nefedov's demographic-structural model also has the potential to spark several Ph.D. theses applying it to societies other than the four studied here. In short, this is a solid and persuasive work, a true scientific monograph. It is certainly not easy going, but highly-motivated scholars will find it extraordinarily rewarding reading. Read the whole review

November 2010

Cliodynamics: The Journal of Theoretical and Mathematical History is launched! Go to the Journal

Volume 1, Issue 1 contents:

Turchin, Peter. 2010. Editor's Column: Launching the Journal. Cliodynamics 1: 1–2.

Collins, Randall. 2010. A Dynamic Theory of Battle Victory and Defeat. Cliodynamics 1: 3–25.

Thompson, William R. 2010. Synthesizing Secular, Demographic-Structural, Climate, and Leadership Long Cycles: Moving Toward Explaining Domestic and World Politics in the Last Millennium. Cliodynamics 1: 26–57.

Gavrilets, Sergey, David G. Anderson, and Peter Turchin. 2010. Cycling in the Complexity of Early Societies. Cliodynamics 1: 58–80.

Turner, Edward A. L. 2010. Why Has the Number of International Non-Governmental Organizations Exploded since 1960? Cliodynamics 1: 81–91.

Goldstone, Jack A. 2010. New Patterns in Global History: A Review Essay on Strange Parallels by Victor Lieberman. Cliodynamics 1: 92–102.

Hall, Thomas D. 2010. The Silk Road: A Review Essay on Empires of the Silk Road by Christopher I. Beckwith. Cliodynamics 1: 103–115.

Currie, Thomas E. 2010. Tests of Time: A Review of Natural Experiments of History , edited by Jared Diamond and James A. Robinson. Cliodynamics 1: 116–121.

Tsirel, Sergey V. 2010. Accumulation of Knowledge in Theoretical History:A Review Essay on Historical Macrosociology by Nikolai S. Rozov. Cliodynamics 1: 122–133.

Zeng, An and Betrand Roehner. 2010. Regularities in Human Actions: A Review of Bursts by Albert-László Barabási. Cliodynamics 1: 134–137.

November 2010

Cycling in the Complexity of Early Societies by Sergey Gavrilets, David G. Anderson, and Peter Turchin. Cliodynamics 1: 58-80.

Warfare is commonly viewed as a driving force of the process of aggregation of initially independent villages into larger and more complex political units that started several thousand years ago and quickly lead to the appearance of chiefdoms, states, and empires. Here we build on extensions and generalizations of Carneiro’s (1970) argument to develop a spatially explicit agent-based model of the emergence of early complex societies via warfare. Reprint (PDF)

DailyScience: Mathematical Model Explains How Complex Societies Emerge, Collapse

November 2010

My research visit to NIMBioS (National Institute for Mathematical and Biological Synthesis, Knoxville, TN)

NIMBioS Press Release (includes a short video interview with me ) is here

November 2010

My book review essay in JWSR (forthcoming) Strange Parallels: Patterns In Eurasian Social Evolution

Most professional historians have abandoned the search for general patterns and laws of history, but not Victor Lieberman. Strange Parallels II ( SP II ), following on SP I , proposes that similar mechanisms governed state building in such different, and distant, regions as Southeast Asia, China, Western Europe, and Russia. During the period covered by Lieberman (c.800–1830) the general trend within these regions of Eurasia was towards increasing political and cultural integration. This overall trend was not monotonic; it was periodically interrupted by interregna – periods of state breakdown and territorial fragmentation. However, as time unfolded the interregna became shorter and less disruptive. Remarkably, during the second millennium cycles of political integration and disintegration became increasingly correlated between the widely separated Eurasian regions. Lieberman's bold thesis is combined with truly encyclopedic scholarship and a breathtaking scope. SP II is a major achievement in comparative world history that will take future researchers years to fully digest. This review essay aims to make a first step in this direction.

Preprint in PDF

September 2010

Review of Secular cycles by Brian J. L. Berry in The American Journal of Sociology: here

August 2010

Three reviews of Secular Cycles

Kristian Skrede Gleditsch writes in Journal of Peace Research: "Although I am generally sceptical of many variants of Malthusian arguments and claims about regular cycles in political dynamics, it is hard not to be impressed by this book. The authors provide a rigorously developed theoretical model and evaluate this by an impressive wealth of historical data for the cases studies, including innovative sources such as coin hoards as a proxy for internal warfare and instability. The book provides a strong case for parsimonious theories and quantitative historical analysis. However, I missed a discussion of the theory’s wider implications, in particular whether it only applies to agrarian-based empires or whether demographic-structural trends may tell us something about future prospects for conflict and stability." PDF here (Commentary: working on it....)

Jan de Vries concludes in Population Studies: "In a crowded field of Malthus-inspired historical analysis, their book stands out for its careful specifications and candid discussions of the limitations of the findings. I can recommend it to demographers with an interest in big-picture societal evolution." Earlier he writes: "Yet, I would be more comfortable with their synthetic theory or secular cycles if it incorporated non-agrarian economic life." PDF here (Commentary: well, Rome was not built in a single day... I am working on extending the theory to industrializing and industrialized societies right now)

Jeremy F. Walton writes in Insight Turkey: "Peter Turchin and Sergey Nefedov’s book focusing on recent theoretical analysis of economic and sociological history, is a text of limitless ambition. In its scope and certitude, this ambition itself is anachronistic, more characteristic of an earlier era of social science in which grand-unified, universal models of history, economy, society and culture were the order of the day. Both the appeal and the fundamental difficulties of Secular Cycles stem from this outdated aspiration to a trans-historical and transsocietal model of social, political and economic change. In an intellectual and scholastic context in which the subject of the researcher herself is far too often a more interesting object of theorization than phenomena in the social world, Secular Cycles evinces a refreshing willingness to cross both disciplinary boundaries and historical eras. Unfortunately, however, this daringness is not complimented by an acute, reflexive awareness of the very critiques of social science that have made such universal arguments largely passé." PDF here (Commentary: actually the review is not as scathing as I would expect from a postmodernist, given our diametrically opposed worldviews)

May 2010

Processes affecting medium-term dynamics of political instability in the USA, 2010-2020 (in Russian) by Peter Turchin

This article for a Russian journal Economic Strategies describes my project on applying the demographic-structural theory to the history of the United States. It provides the supporting data for the Nature letter '2020 visions': Political instability may be a contributor in the coming decade (see below). PDF

April 2010

The Historic Duty to Persevere (in Russian: — ) by Peter Turchin. «» 16-17 (702)

A cliodynamical analysis of the Great Fatherland War, 1941-45: "Russo-Japanese War lead to the Revolution of 1905, World War I to the Revolution of 1917, and the Soviet Union collapsed after USSR-Afganistan war. Why, then, did not the USSR collapse in 1941-42, when it was stressed to an unmeasurably greater degree? (- 1905 , — , . 1941–1942 , , ?) PDF

February 2010

'2020 visions': Political instability may be a contributor in the coming decade Nature 463: 608

This is a letter that Nature invited me to write in response to their decadal research predictions, published in January.

Text (PDF)

December 2009

A review of Secular Cycles on EH.net by Harry Kitsikopoulos

"In the end, notwithstanding the noted shortcomings, I am fascinated by this book, particularly by the theoretical framework which is laid out in the introductory and concluding chapters. Economic historians, particularly those dealing with the Middle Ages where my expertise lies, have tended to advance explanations of historical dynamics based on a fairly dogmatic adherence to particular models and downplay the merits of competing explanations. In contrast, Turchin and Nefedov stress the need of coming up with “a synthetic theory that encompasses both demographic mechanisms (with the associated economic consequences) and power relations (surplus-extraction mechanisms). In the dynamical systems framework, it does not make sense to speak of one or the other as ‘the primary factor’. The two factors interact dynamically, each affecting and being affected by the other” (p. 4).

But the main strength of the book lies in its scope, reminiscent of the broad perspectives of classical economists. It is the type of scholarship which proves that historical narrative can be fascinating."

See the full text of the review on EH.net

November 2009

Historical Dynamics (in Russian: ) by Valery Tyrnov

An article about cliodynamics in the Russian popular science journal Science and Technology. PDF

October 2009

Our PNAS Article on Roman Censuses and Coin Hoards in the Popular Press

Several major world newspapers discussed our results: New York Times (USA), Spiegel (Germany), Die Presse (Austria), Standaard (Belgium), and Folha de S. Paulo (Brazil). Other media that discussed it include N-TV (the German TV channel for financial news), ORF (Austrian Public TV), and Echo Moskvy (a Russian radio station). The article in Science includes a rejoinder from a proponent of the high count hypothesis (which we reject in our paper). The story was featured in the science sections of Yahoo, Yahoo-UK, Lenta and Infox (Russia), and EuropaPress (Spain). Other web-based sources that covered the story are Wired, EurekAlert, and NSF News (the latter includes a video interview). The story also appeared in a variety of popular science magazines and web sites, too many to list here (see Cliodynamics in Popular Media). Last, but not least, is our own UConn Today, which perhaps lacks the wide readership of New York Times or Spiegel, but was the only publication that managed not to garble any aspects of the story.

October 2009

Coin Hoards Speak of Population Declines in Ancient Rome by Peter Turchin and Walter Scheidel. PNAS 106: 17276-17279.

Abstract. In times of violence, people tend to hide their valuables, which are later recovered unless the owners had been killed or driven away. Thus, the temporal distribution of unrecovered coin hoards is an excellent proxy for the intensity of internal warfare. We use this relationship to resolve a long-standing controversy in Roman history. Depending on who was counted in the early Imperial censuses (adult males or the entire citizenry including women and minors), the Roman citizen population of Italy either declined, or more than doubled, during the first century BCE. This period was characterized by a series of civil wars, and historical evidence indicates that high levels of sociopolitical instability are associated with demographic contractions. We fitted a simple model quantifying the effect of instability (proxied by hoard frequency) on population dynamics to the data before 100 BCE. The model predicts declining population after 100 BCE. This suggests that the
vigorous growth scenario is highly implausible.

Reprint (PDF): here. Online Supporting Information: here

October 2009

Analyzing Genetic Connections between Languages by Matching Consonant Classes by Peter Turchin, Ilia Peiros, and Murray Gell-Mann

The idea that the Turkic, Mongolian, Tungusic, Korean, and Japanese languages are genetically related (the “Altaic hypothesis”) remains controversial within the linguistic community. In an effort to resolve such controversies, we propose a simple approach to analyzing genetic connections between languages. The Consonant Class Matching (CCM) method uses strict phonological identification and permits no changes in meanings. This allows us to estimate the probability that the observed similarities between a pair (or more) of languages occurred by chance alone. The CCM procedure yields reliable statistical inferences about historical connections between languages: it classifies languages correctly for well-known families (Indo-European and Semitic) and does not appear to yield false positives. The quantitative patterns of similarity that we document for languages within the Altaic family are similar to those in the non-controversial Indo-European family. Thus, if the Indo-European family is accepted as real, the same conclusion should also apply to the Altaic family.

Manuscript: PDF Supporting Information: MS Excel file

August 2009

Warfare and the Evolution of Social Complexity: A Multilevel-Selection Approach

Multilevel selection is a powerful theoretical framework for understanding how complex hierarchical systems evolve by iteratively adding control levels. Here I apply this framework to a major transition in human social evolution, from small-scale egalitarian groups to large-scale hierarchical societies such as states and empires. A major mathematical result in multilevel selection, the Price equation, specifies the conditions concerning the structure of cultural variation and selective pressures that promote evolution of larger-scale societies. Specifically, large states should arise in regions where culturally very different people are in contact, and where interpolity competition – warfare – is particularly intense. For the period of human history between the Axial Age and the Industrial Revolution, conditions particularly favorable for the rise of large empires obtained on steppe frontiers, regions where nomadic pastoralists and settled agriculturalists lived in close proximity. An empirical investigation of warfare lethality, focusing on the fates of populations of conquered cities, indicates that genocide was an order of magnitude more frequent in steppe-frontier wars than in wars between culturally similar groups. An overall empirical test of the theory’s predictions shows that over ninety percent of largest historical empires arose in world regions classified as steppe frontiers.

A manuscript, comments are welcome: PDF

Mathematical History and Cliodynamics: Theories, Models, Data

First Announcement and Call for Papers: go here
Conference dates: December 21-23, 2009
Conference location: Ekaterinburg, Russia

July 2009

Long-Term Oscillations in Population Numbers of Human Societies (in Russian: ). This is a reworked and expanded translation of my 2009 review for the Russian popular science website Elements.ru. Go here.

The Causes of the Revolutionary Crisis in Russia, 1905-1917: A Comment on the Debate between B.N. Mironov and S.A. Nefedov (in Russian: 1905–1917 . . . . . ) Preprint here.

May 2009

Evolution of Complex Hierarchical Societies by Peter Turchin and Sergey Gavrilets

One of the greatest puzzles of human evolutionary history concerns the how and why of the transition from small-scale, “simple” societies to large-scale, hierarchically complex ones. This paper reviews theoretical approaches to resolving this puzzle. Our discussion integrates ideas and concepts from evolutionary biology, anthropology, and political science. The evolutionary framework of multilevel selection suggests that complex hierarchies can arise in response to selection imposed by intergroup conflict (warfare). The logical coherency of this theory has been investigated with mathematical models, and its predictions were tested empirically by constructing a database of largest territorial states in the world (with the focus on the preindustrial era). PDF preprint here

Toward Cliodynamics – an Analytical, Predictive Science of History by Peter Turchin (to appear as part of a volume edited by David Krakauer, John Gaddis, and Ken Pomerantz)

History is not “just one damn thing after another.” Strong empirical patterns arise because the dynamics of historical societies reflect the action of general social mechanisms. There are laws of history (in the broad sense of the word). Furthermore, successful case studies of scientific prediction, reviewed in this article, show that we are well on the way to identifying some of these laws. PDF preprint here

February 2009

Warfare and the Evolution of Social Complexity a talk by Peter Turchin presented at the Evolution of Human Aggression conference, Salt Lake City, 26 February 2009. Conference Program Slides of my talk (sans bulky images) here


A Theory for Formation of Large Empires. Journal of Global History 4:191-207.

Between 3000 BCE and 1800 CE there were more than sixty ‘mega-empires’ that, at the peak, controlled an area of at least one million square kilometres. What were the forces that kept together such huge pre-industrial states? I propose a model for one route to mega-empire, motivated by imperial dynamics in eastern Asia, the world region with the highest concentration of mega-empires. This ‘mirror-empires’ model proposes that antagonistic interactions between nomadic pastoralists and settled agriculturalists result in an autocatalytic process, which pressures both nomadic and farming polities to scale up polity size, and thus military power. The model suggests that location near a steppe frontier should correlate with the frequency of imperiogenesis. A worldwide survey supports this prediction: over 90% of megaempires arose within or next to the Old World’s arid belt, running from the Sahara desert to the Gobi desert. Specific case studies are also plausibly explained by this model. There are, however, other possible mechanisms for generating empires, of which a few are discussed at the end of the article.

This is an expanded version of the Working Paper 08-05-024 in the SFI series (May 2008). I added a lot more empirical material and now review empire formation in the following world regions: (1) East Asia, (2) Ancient Egypt, (3) Maghrib, (4) South Asia, (5) the Middle East during the Axial Age, (6) Eastern Europe, and (7) the Great Plains of North America.

The electronic reprint is here.

January 2009

Demography and Political Crises: the Historical Aspect ( . ). An on-line interview with Peter Turchin on the web site of the journal "Science and Life". The text of the interview (in Russian) is here.

November 2008

Long-term population cycles in human societies. In The Year in Ecology and Conservation Biology 2009 (R. S. Ostfeld and W. H. Schlesinger, eds). PDF

' ' (On the Threshold of Great Discoveries) My interview for Science & Technology in the Russian Federation (in Russian). To read click here

October 2008

A Science of History? My talk at the conference Beyond Belief: Candles in the Dark. The video of the talk can be watched here

' ' (On the Eve of a Great Revolution) My interview in the Expert magazine (in Russian). To read the interview click here

September 2008

The Russian Cliodynamics Community Launches Its Website

Go here - but it's in Russian!

August 2008

Cliodynamics in the Blogosphere

"Cliodynamics, a science of history?" a blog by Massimo Pigliucci, with my responses

"Cliodynamics, the rise & fall of empires and asabiya" a blog on Gene Expression.

July 2008

My Nature Essay: Arise 'cliodynamics'

"If we are to learn how to develop a healthy society, we must transform history into an analytical, predictive science, argues Peter Turchin. He has identified intriguing patterns across vastly different times and places."

To read the Essay click here

Editor's Summary (Nature, 3 July 2008)
The future of history: Why it needs to become a science

"For much of human history we have plenty of facts. The job of historians is to select and arrange those facts to support a range of subjective interpretations. Peter Turchin thinks that at that rate, we are doomed to repeat our mistakes. Instead, he says, we need unifying theories. We should use the data to construct general explanations, and test them on all the data, not a subset chosen to make a point. To learn from history, first we must make it science."

Can History Become a Real Science? A report on my Nature essay by Alexander Markov at the popular science site The Elements (in Russian) To read, click here

Clio with a Calculator a news piece by Yury Drize in Poisk, the popular science newspaper of the Russian Academy of Sciences (in Russian) To read, click here

30 June - 6 july 2008

Cliodynamics: Philosophical Foundations and Mathematical Modeling of Macrohistorical Processes. A scientific conference in Elikmanar, Altay Mountains, Russia. To read the report on the conference(in Russian) click here

June 2008

Building nations after conflict: my review of Ghani and Lockhart, Fixing Failed States text here

May 2008

A Theory for the Formation of Large Agrarian Empires by Peter Turchin

Between 3000 BCE and 1800 CE there were at least 60 agrarian “megaempires” that controlled at the peak an area equal to or greater than one million of squared kilometers. What were the social forces that kept together such huge agrarian states? A clue is provided by the empirical observation that over 90 percent of megaempires originated at steppe frontiers—zones of interaction between nomadic pastorialists and settled agriculturalists. I propose a model for one route to megaempire. The model is motivated by the imperial dynamics in East Asia (more specifically, the interface between the settled farmers of East Asia and the nomads of Central Asia). It attempts to synthesize recent developments from theories of cultural evolution with insights from previous work by anthropologists on nomad/farmer interactions.

Posted as Working Paper 08-05-024 in the SFI series here

April 2008

Empirical regularities in historical dynamics: secular cycles by Peter Turchin (in Russian)

Article in press in the next issue of the almanac History and Mathematics.

The text is here

March 2008

Can History Become an Analytical, Predictive Science?

This is the paper that I presented at the meeting History, Big History, and Metahistory: An Approach through the Sciences of Complexity organized by the Santa Fe Institute in Honolulu, March 17-19, 2008

The text of the paper is here

December 2007

From Dec. 1, 2007 to May 31, 2008 I will be based at the Santa Fe Institute

This is my sabbatical year and I am spending six months of it at the Santa Fe Institute as Visiting Professor.

November 2007

My talk before general audience at Binghamton University on The Rise and Fall of Empires

There is a striking macrohistorical pattern: largest empires tend to arise at interfaces between settled and nomadic societies. An example of this pattern is the recurrent state formation in East Asia: China has been unified ~14 times throughout its history, and on all but one occasion the unification proceeded from North (and most frequently, Northwest). Simultaneously, a series of nomadic imperial confederations arose on the steppe side of the Inner Asian nomad/settled frontier. I will discuss one explanation for this empirical pattern. The basic idea is that the military power of mounted archers puts farming communities under selective pressure to unite to better resist the predation from the steppe. In turn, the nomads are forced to unite to be able to overcome the defenses of the emerging agrarian states. The scale of states on both sides of the steppe frontier increases in an autocatalytic fashion, until this runaway process is stopped by logistic and/or space limitations.

You can dowload the slides of the presentation (it's a big one - 40 MB!) here

October 2007

II International Conference Mathematical Modeling of Historical Processes: October 29-31, 2007; Institute of Applied Mathematics (Moscow)

Information on the conference (in Russian): here

The first degree in cliodynamics conferred: On October 10, 2008, at the Institute of History and Archaeology in Ekaterinburg Sergey Nefedov defended the D.Sc. (...) thesis, entitled "Demographic-structural theory and its application to the study of socio-econoic history of Russia".

June 2007

A roundtable on History and Mathematics

On 25 June 2007 a group of 16 scholars, who included historians, anthropologists, philosophers, biologists, and mathematicians, gathered at the pansionat "Podlipki" near Moscow. For two days we brainstormed on the theme, is a science of history possible? And what needs to be done to accomplish it? As a result of this discussion, we formed the Cliodynamics Research Network that will coordinate our efforts in establishing and promoting theoretical and mathematical history. Our next planned activity is a general conference that will take place in late October at the Institute of Applied Mathematics in Moscow.

March 2007

Can history become a real science?

A talk presented on March 12 at the Santa Fe Institute. The slides in PowerPoint are here (13 MB)

Most historians and many philosophers believe that a science of history is impossible because history is too complex and historical processes are too different from physical or biological ones. Unlike molecules, for example, people have free wills. I will argue that, on the contrary, it is possible to employ regular scientific approaches in history. Certainly we can study large-scale dynamical processes in history, those that involve large collectives of people and unfold on the time scale of decades and centuries. We can build mathematical models for these processes and, more importantly, test model predictions with data. With just a little creativity it is possible to obtain quantitative time-series data on a wide variety of economic, social, and political aspects of historical systems. Furthermore, experience so far suggests that history is not simply a "mess," "one damn thing after another." There are strong patterns in time-series data. These recurring empirical regularities hint at the operation of some kind of laws of history (in the general sense of the term).

February 2007

The paperback version of War and Peace and War is out! See it at Amazon.com

Mathematics and history – my interview on Radio Liberty (in Russian)

Imperiów wzloty i upadki – czyli wojna, pokój i znów wojna a review by Piotr Tryjanowski in the Polish magazine "Nauka" (Science) read the text

January 2007

Commentary on my work in the American Conservative

Steve Sailer argues that multiculturalism doesn’t make vibrant communities but defensive ones. Go to the article

Review of Historical Dynamics in the Journal of Peace Research Read the review

November 2006

Two chapters came out in Hornborg, A (ed). World System History and Global Environmental Change (2007. Columbia University Press)

Hall TD, Turchin P. 2007. Lessons from population ecology for world-systems analyses of long-distance synchrony

Chase-Dunn C, Hall TD, Turchin P. 2007. World-systems in the biogeosphere: urbanization, state formation and climate change since the Iron Age

October 2006

Rat i Mir i Rat by Peter Turchin

A Serbo-Croatian translation of War and Peace and War has been published!

September 2006

Secular Cycles by Peter Turchin and Sergey Nefedov

Chapter 5 on the first early modern secular cycle in France is posted (go to the Secular Cycles page). Comments and critique are welcome.

July 2006

A review of Historical Dynamics in American Journal of Sociology by Dingxin Zhao

"... The book is well organized and clearly argued. ... unlike some simple-minded mathematical modelers, Turchin is very familiar with the relevant literature and has made a genuine effort to incorporate historical data into his models. I have learned a great deal from this work, and I strongly recommend it to scholars who are interested in historical sociology and mathematical modeling in social sciences. This said, however, I would like to point out some of the problems with this book..."

June 2006

The New Scientist on Overconfidence in War, with my comments

Roxanne Khamsi reports on the recent study by Dominic Johnson (Princeton University) and colleagues go to the article (if not available on NewScientist.com, click here)

April 2006

Evolution of Cooperative Strategies from First Principles by Mikhail Burtsev and Peter Turchin published in the 20 April 2006 issue of Nature see the article in PDF

The commentary on our article on the German Radio (here)

March 2006

Secular Cycles by Peter Turchin and Sergey Nefedov

Chapters 2, 3, 6, 7, and 8 on secular cycles in England and Rome are posted (go to the Secular Cycles page). Comments and critique are welcome.

Commentary on my article in Structure and Dynamics

A comment by Andrey Korotayev

A critique by Natalia Komarova, and my response

Commentary on my work in the Russian magazine Politichesky Klass (The Political Class)

Nikolai Rozov discusses the implications of asabiya for modern Russian politics (see the text in Russian)

February 2006

A very nice review of cliodynamics in the French popular science magazine Sciences et Avenir. The PDF of the article (2.6 MB!) is here.

December 2005

A review of War and Peace and War in The Times Higher Education Supplement by Gordon Johnson

"History has had a long, and on the whole fruitful, relationship with adjacent subjects such as archaeology and anthropology, and is just emerging from a testing (and largely negative) cohabitation with literary and cultural theory. Turchin's view of our subject from the perspective of an evolutionary biologist, versed in the hard language of mathematics, promises a great deal. He may not have invented a new science or rewritten the history of the world, but he might encourage others in the history profession to think differently and to consider whether they should take down their disciplinary scaffolding from time to time to share their ideas more effectively with a popular readership."

Gordon Johnson is president of Wolfson College, Cambridge, and general editor, The New Cambridge History of India. full text of the review

November 2005

Evolution of Cooperative Strategies from First Principles by Mikhail Burtsev and Peter Turchin. To be published by Nature in early 2006

One of the greatest challenges in the modern biological and social sciences has been to understand the evolution of cooperative behavior. The main conceptual tool used in probing the logical coherence of proposed explanations has been game theory, including both analytical models and agent-based simulations. The game-theoretic approach yields clear-cut results, but assumes, as a rule, a simple structure of payoffs and a small set of possible strategies. We propose a more stringent test of the theory by developing a computer model with a significantly extended spectrum of possible strategies. In our model agents are endowed with a limited set of receptors, a set of elementary actions, and a neural net in between. Behavioral strategies are not predetermined; instead, the process of evolution constructs and reconstructs them from elementary actions. Two novel strategies of cooperative attack and defense emerged in simulations, as well as the well-known dove, hawk, and bourgeois strategies. Our results indicate that cooperative strategies can evolve even under such minimalist assumptions, provided that agents are capable of perceiving heritable external markers of other agents.

October 2005

A review of War and Peace and War in The New Scientist by Mark Buchanan

"Are there 'laws of history', patterns or regularities that would let us make predictions? Karl Marx thought he saw a steady progression in history, leading inevitably to a future of world government by the workers. British historian Arnold Toynbee saw cyclic patterns in the rise and fall of civilisations. But most historians today think that Marx and Toynbee were deluded, and that the pursuit of historical laws is, in general, a fool's errand. Refreshingly, Peter Turchin doesn't agree."

Mark Buchanan's latest book is Small World full text of the review

Another review of WPW in Library Journal text here

September 2005

Two articles published

Dynamical Feedbacks between Population Growth and Sociopolitical Instability in Agrarian States has been published by Structure and Dynamics go to the article

The most interesting result in this paper is that historical process can be studied with standard quantitative methods of natural sciences, such as time-series analysis, regression, and cross-validation. The statistical analysis reveals strong and repeatable patterns in the data on population numbers and the intensity of internal war. And history of science suggests that strong empirical regularities are usually associated with the action of fundamental laws...

A companion paper to Dynamical Feedbacks, A Primer on Statistical Analysis of Dynamical Systems in Historical Social Sciences (with a Particular Emphasis on Secular Cycles) was published in the same issue of Structure and Dynamics go to the article

Publicity associated with War and Peace and War: in TO BHMA (Greece), and Haaretz (Israel).

August 2005

Advance publicity for War and Peace and War

War and Peace and War is not yet out but is already getting press: in the August 25 issue of the Guardian, Empire of the Sums by Philip Ball. The article was also reprinted by the Sydney Morning Herald, which gave it a rather sensationalist title: The US Collapses: A Scenario. There is also a quick review in the Publishers Weekly (here it is).

May 2005

A review of Historical Dynamics in Contemporary Sociology by Philip A. Schrodt

"When an individual from the natural sciences takes on a complex issue in the social sciences, the result can be either an exercise in naIve determinism bordering on the absurd, or a set of provocative insights bringing new perspectives to classical problems. In the latest volume in Princeton's 'Studies in Complexity' series, biologist Peter Turchin has accomplished the latter..." see the whole review

Another review of Historical Dynamics in Theory and History by Noël Bonneuil

"...what he [Turchin] perceives to be insights gained by mathematical modeling could as easily be seen as misconceptions aided and abetted by mathematical dust in the eyes." see the whole review

December 2004

A review of Historical Dynamics in Economics of Transition by Paul Seabright

"This fascinating and ambitious book presents a number of attempts to quantify and test theories of the growth and decline of political organizations over a time-span of many centuries. The author’s ambition is to show that a rigourous quantitative theory of historical dynamics is possible—he calls it ‘cliodynamics’. This involves expressing the underlying relationships in the form of differential equations and testing predictions against various kinds of historical data. Though the underlying philosophy is a little less novel than the author recognizes—quantitative macroeconomics with political and institutional variables is becoming increasingly fashionable—the book is rich in applications of the approach and full of illuminating historical material..." see the whole review

A news article about Historical Dynamics in UConn Advance here

November 2004

East-West Orientation of Historical Empires by P. Turchin, J. M. Adams, and T. D. Hall

Does environment affect the ability of states to project power? If state expansion is more easily accomplished by staying within the same ecological zone, then state territories should be oriented in the east-west direction, mirroring the orientation of major ecological zones of the world. Our analysis of 62 largest empires in history supports this conjecture.

PDF of the article here

October 2004

Emergence of Cooperative Strategies from Elementary Actions in Agents with Neural Nets by Mikhail Burtsev and Peter Turchin

This article has now (October 2005) been accepted for publication by Nature (see above; the title has been changed to Evolution of Cooperative Strategies from First Principles)

PDF of the article here

May 2004

Dynamic maps of evolution of the state system and metaethnic frontiers in Europe during the two millenia CE

These slides complement the material in Chapter 5 of my book on Historical Dynamics, where I empirically test the predictions of the metaethnic frontier theory. The basic matrix is the snapshots of political landscape of Europe and Mediterranean taken at 100 year intervals from 0 to 1800 BCE. On top of the matrix I overlayed metaethnic frontiers. For European material see Appendix B of Historical Dynamics. Locations of Near Eastern frontiers are still in process of being worked out, and will probably be revised in future.

These PowerPoint slides were presented at the Santa Fe Institute working group on Analyzing Complex Macrosystems. PowerPoint presentation here (22 MB)

April 2004

Dynamical feedbacks between population growth and sociopolitical instability in agrarian states

Most preindustrial states experienced recurrent waves of political collapse and internal warfare. One possible explanation of this pattern, the demographic-structural theory, suggests that population growth leads to state instability and breakdown, which in turn causes population decline. Mathematical models incorporating this mechanism predict sustained oscillations in demographic and political dynamics. Here I test these theoretical predictions with time-series data on population dynamics and sociopolitical instability in early modern England, the Han and Tang China, and the Roman Empire. Results suggest that population and instability are dynamically interrelated as predicted by the theory.

A PDF of the article is here

This manuscript (rejected by Science last Fall) was the basis of my presentation at the Santa Fe Institute working group on Analyzing Complex Macrosystems.

Note added March 2005: the manuscript is now in press in Structure and Dynamics

February 2004

A review of Historical Dynamics in Nature by Joseph Tainter: here

"Social theory is a minefield, even for those experienced in it. The quantification of historical patterns is useful and important, and should have a place in historical research. But sophisticated mathematics will not improve naive social theories."

December 2003

Population Dynamics and Internal Warfare: a Reconsideration
by Peter Turchin and Andrey Korotayev

The hypothesis that population pressure causes increased warfare has been recently criticized on the empirical grounds. Both studies focusing on specific historical societies and analyses of cross-cultural data fail to find positive correlation between population density and incidence of warfare. In this paper we argue that such negative results do not falsify the population-warfare hypothesis. Population and warfare are dynamical variables, and if their interaction causes sustained oscillations, then we do not in general expect to find strong correlation between the two variables measured at the same time (that is, unlagged). We explore mathematically what the dynamical patterns of interaction between population and warfare (focusing on internal warfare) might be in both stateless and state societies. Next, we test the model predictions in several empirical case studies: early modern England, Han and Tang China, and the Roman Empire. . .

Article in press to appear in Social Evolution and History 5:2 (2006).
A PDF of the article is here
Supplementary Material (some details on data, analytical procedures) here

December 2003

Scientific Prediction in Historical Sociology: Ibn Khaldun meets Al Saud

One of the hallmarks of a mature discipline is its ability to make predictions that can be used to test scientific theories. Scientific predictions do not necessarily have to be concerned with future events; they can be made about what occurred in the past. I illustrate such retrospective prediction with a case study of conversion to Christianity in the Roman Empire. The bulk of the paper deals with the logic and methodology of setting up a scientific prediction in macrosociology. The specific case study I develop is the possible state collapse in Saudi Arabia. . .

A manuscript submitted to the American Journal of Sociology.
A PDF of the article is here The accompanying Excel spreadsheet: here
See it posted on QuanHist.Reccurrent Archive

Other publications:

Hall, Thomas D. and Peter Turchin. 2006. Lessons from Population Ecology for World-Systems Analyses of Long-Distance Synchrony. Chapter in: Hornborg, A (ed). World System History and Global Environmental Change. Columbia University Press, New York. PDF

Chase-Dunn, Christopher, Thomas D. Hall, and Peter Turchin. 2006. World-systems in the biogeosphere: urbanization, state formation and climate change since the Iron Age. Chapter in: Hornborg, A (ed). World System History and Global Environmental Change. Columbia University Press, New York.

Turchin, Peter and Thomas D. Hall. 2003. Spatial Synchrony among and within World-Systems: Insights from Theoretical Ecology. Journal of World-Systems Research 9:37-66. http://jwsr.ucr.edu/archive/vol9/number1/pdf/jwsr-v9n1-turchinhall.pdf

Turchin, P. 2003. Secular waves in historical demography (in Russian). Priroda 6: 3-12.


Arise 'cliodynamics'

History needs to become an analytical, predictive science

See my Nature Essay

Cliodynamics: The Journal of Theoretical and Mathematical History

Go to the Journal Web Page

War, Peace, and the Evolution of Social Complexity click here

Buried Coins May Help Solve Mystery of Ancient Roman Population click here

Also featured on ScienceNow and WorldScience.net

Secular Cycles in bookstores (August 1, 2009) see it at Amazon

Read sample chapters




ESSAY: Why do we need mathematical history? click here

Co-authors, colleagues, and other like-minded scientists:

The Russian Cliodynamics Network

The Institute for Research on World-Systems (Christopher Chase-Dunn)

Networks and Ethno-Sociology (Douglas White)

Spatial Dynamics of Human Populations: Some Basic Models (Robert Hanneman)

World History, Demographic Cycles (Sergey Nefedov)

Econophysics, Analytical History (Bertrand Roehner)

Historical Linguistics, Regularities in Human History (Murray Gell-Mann)

Evolutionary Religious Studies (David Sloan Wilson)

Evolution and Politics (Dominic Johnson)

Roman Demography (Walter Scheidel)

Historical Macrosociology (Nikolai Rozov)

Cliodynamics, Cross-Cultural Studies (Andrey Korotayev)

Center for Social Complexity (Claudio Cioffi-Revilla)

World-Systems Analysis (Thomas Hall)

Quantitative analysis and simulation of prehistoric societies (Tim Kohler)