As I wrote in yesterday’s blog, Robert Bellah’s Religion in Human Evolution is a complex book that addresses many roles of religion in human social evolution. One theme that I was particularly interested in was the influence of religious developments on the evolution of human egalitarianism, especially during the Axial Age. The starting point for approaching this question is what is sometimes called as the ‘U-shaped curve of despotism’ in human evolution. We know that our closest relatives, the chimps and gorillas, live in fairly ‘despotic’ or inegalitarian societies. The chimps, for example, establish linear dominance hierarchies, in which alpha males get better food and greater access to females. We don’t know for sure whether human ancestors also lived in similarly inegalitarian societies, but it seems likely.
In contrast, as was argued by Christopher Boehm in Hierarchy in the Forest: The Evolution of Egalitarian Behavior, human hunter-gatherers, who lived in small-scale societies before agriculture, were fiercely egalitarian. High degree of equality does not simply happen because hunter-gatherers are poor and cannot accumulate much wealth (chimps also cannot accumulate wealth). No, equality requires active maintenance. People living in small-scale societies possess numerous norms and institutions designed to control ‘upstarts’ – those who attempt to set themselves as alpha-males so that they can gain control of an unfair share of resources (including females). The sanctions deployed against upstarts range from gossip and ridicule to ostracism and, ultimately, assassination.
Thus, until c.10,000 years ago, before agriculture was invented, the human evolutionary trend was that of increasing egalitarianism. The adoption of agriculture, however, enabled the rise of large-scale societies organized as states and empires with highly unequal distributions of power, wealth, and social status. In other words, the trend to greater equality reversed itself. What accounts for this U-turn? Why did humans allow inequality to develop?
The answer apparently is that the U-turn was a side effect of the transition from small-scale to large-scale societies. Small-scale societies of hunter-gatherers were integrated by face-to-face sociality. Such a diffuse, non-centralized social organization was well-suited to maintaining egalitarian ethos. However, once the size of cooperating group increases beyond 100–200 people, even gigantic human brains are overwhelmed by the demands of face-to-face sociality (this is the argument made by Robin Dunbar). Shifting from diffuse, uncentralized social organization to hierarchical organization (as chains of command) allowed evolution to break through the upper limit on society size imposed by face-to-face sociality. A member of a hierarchically organized group needs to have face-to-face interactions with only a few individuals: a superior and several subordinates. Such links can connect everybody in a group of arbitrarily large size. The group size grows by adding additional hierarchical levels.
So far so good, but the great downside of hierarchical organization is that it inevitably leads to inequality. Once you allow a leader to order everybody around, he will use the power to feather his nest. This is sometimes known as the iron law of oligarchy.
I have argued elsewhere that conditions of endemic warfare between human groups create enormous selection pressures for larger group size (“God is on the side of big battalions”) and for effective (which means centralized) military organizations. Under such conditions, emergence of centralized military hierarchies becomes virtually inevitable. The result is the rise of increasingly complex centralized societies – chiefdoms, complex chiefdoms, and archaic states.
As Bellah notes, archaic states were characterized by enormous fusion of power in the person of the ruler. Almost invariably the rulers of such states were ‘divinized’, that is, considered to be gods as well as kings. They had literally the power of life and death over their subjects. One frequent characteristic of early centralized societies was the practice of massive human sacrifice. This naked pursuit of power and voracious appetite for consuming resources is reflected in such characterizations of rulers as a land shark who ‘eats’ island (in Hawaii), or a big rat that gobbles people’s millet (in archaic China).
Thus, although highly effective on the battlefield, a centralized military hierarchy has several drawbacks as a general way of organizing societies. A society cannot really be held together by force alone. Worse, great inequities resulting from rapacious military chiefs and their retinues alienate large segments of the population. As a result, early despotic chiefdoms and archaic states were very fragile and frequently did not outlast their founders.
The tension between the human preference for equitable outcomes and the need for centralized hierarchy brought about the “legitimation crisis of the early state” (this idea was borrowed by Bellah from Jürgen Habermas). The tension became particularly acute during the Axial Age (c.800–200 BCE), for reasons discussed in my review of Bellah’s book and other publications. One central argument in Bellah’s book is that the new world religions and philosophies that arose during the Axial Age began the long job of building more equitable societies. A large part of this evolution was imposing limits on the power of rulers and replacing power based on naked force with legitimate authority.
This is a very interesting idea. Further, whatever the explanation, it seems clear to me that empirically the post-axial period saw a general trend of human evolution away from the peak of despotism, which was achieved in archaic and early-axial states and empires. In particular, such extreme forms of inequality as human sacrifice, slavery, and distinction in legal status (such as that between nobles and commoners) have been gradually disappearing over the last 2.5 thousand years. God-kings have gone out of fashion, and what royalty are left have been relegated to an entirely ceremonial function. The spread of democracy in the last couple of centuries have imposed more effective restraints on the rulers. The only exception to this overall trend towards greater egalitarianism is that economic inequality remains as large as ever (and, in fact, has been growing over the last three decades in, for example, the US). Still, overall it appears that the peak of despotism (massive concentration of power within the hands of the ruler and the ruling clique) took place in archaic states.
If this is correct, and I believe it is, then the implication is that the evolution of egalitarianism in humans was not just a U-shaped curve, but a more complex trajectory. After ‘zigging’ to greater inequity during the pre-axial period, the trajectory than ‘zagged’ back to greater equity in the last 2.5 thousand years. I propose that we call this evolutionary pattern the Z-curve of human egalitarianism.
I just finished writing a commentary on Robert Bellah’s Religion in Human Evolution. Bellah’s ideas are highly stimulating and I want to discuss one central issue of the book, that of evolution of egalitarianism in the next blog. But first a few words about the book itself.
Bellah wrote Religion in Human Evolution over the period of 13 years. This reminds me of the first book that I wrote (on the analysis of animal movements), which took just over 10 years to complete. In the process I went from a postdoc position to a job with the US Forest Service, then to an academic job I presently hold, I got tenure, I switched publishers… By the time I was working on the second half of the book, the first one was becoming obsolete (because the field was moving rapidly). Basically I did everything to make the process of writing as stressful as possible (aspiring authors, take note!). I learned my lesson. Now when I want to write a book I first clear the decks, and then work on it until I finish it, ignoring everything else. Naturally, the reality intrudes on this ideal scheme, but it pays to approach the ideal as much as possible.
It appears that Robert Bellah had to struggle with similar problems while writing Religion in Human Evolution. As he relates towards the end of the book, after writing the first draft of all but the last chapter, he discovered a new theme, the importance of animal play for our understanding of the evolution of rituals in human cultures. This prompted him to completely rewrite Chapters 2 (Religion and Evolution) and 10 (Conclusion), while leaving the intervening chapters intact – because “having being at work for thirteen years” he couldn’t “imagine rewriting the whole book to give adequate attention to play” (p. 567). This bit of personal history explains the complex structure of the book, but as a reader I wish Bellah had done us all a favor and saved the play theme for another monograph. Had I not agreed to write a commentary, I would have probably given up somewhere in the middle of the book. One report I have from another reader suggests similar exasperation with the book. A reviewer for New York Times puts it bluntly, “A shorter book would have been a better book.”
So I suspect that most readers (especially those who had not agreed ahead of time to write a review) would not get very far with it. This would be a great pity, because the book offers many rewards to those who persevere. One theme that I found particularly productive for my own research was the evolution of human egalitarianism. I will address this issue in the next blog.
I am an avid consumer of science fiction and fantasy novels. The most interesting aspect of such fiction to me is how authors construct social structures within which their heroes operate. Whether this happens in some alternate world where magic is possible, or “a long time ago in a galaxy far, far away” the authors need to create an internally consistent social reality. Some novels are so bad at this, that I stop reading them in disgust. But a surprising number of authors do quite a good job, probably because they have read enough history to internalize general mechanisms underlying the functioning of historical societies (cliodynamics), even if these authors would be unable to explicitly formulate these rules.
One example is Dune by Frank Herbert. I don’t know whether Herbert read Ibn Khaldun, but much of his cliodynamics, especially the aspects dealing with Arrakis and Fremen, could come directly from Ibn Khaldun. As a result, he creates a highly believable world (well, this is a science fiction novel), both ecologically and sociologically. This must have been an important reason why this novel was so successful.
There is one law of historical dynamics that Herbert discusses explicitly. This general rule may be formulated as follows: Harsh environmental conditions create a selective regime under which only the best survive, producing cultures with tough and capable warriors. This is the reason why the Emperor recruits his best shock troops, the Sardaukar, from the prison planet Salusa Secundus. Only the Fremen, evolving under equally harsh conditions of Arrakis, can match the ferocity and fighting ability of the Sardaukar.
What is particularly interesting about this hypothesis is that it is explicitly evolutionary. Nevertheless, I believe it is wrong. The problem is that it focuses on individual fighting ability, which is much less important than collective fighting ability. To give a single historical example, an average Roman legionary would most likely lose in a single combat against an average Celtic warrior. A Roman legion, on the other hand, would easily defeat an equal number of Gauls. Cooperation, discipline, ability to work as a team, willingness to sacrifice for the common good (in short, asabiya of Ibn Khaldun) is what wins battles and wars, not ferocity of individual warriors.
The selective regime that breeds militarily capable cultures is not harsh physical environment, but living in a ‘tough neighborhood.’ In other words, it is between-group selection, not individual selection, that creates aggressive expansionist cultures.
This post was prompted by a recent discussion with colleagues about whether people living in poor environments (those capable of supporting lower population densities) are more likely to go to war. The logic here is that people living under such conditions have greater incentive for attacking neighbors, than people living in rich environments. I think that in predicting incidence of warfare, incentives are less important than capabilities. So people living in relatively poor environments that are also characterized by intense between-group selection (e.g., Ibn Khaldunian Bedouins) would be expected to be quite troublesome for their neighbors. On the other hand, people living in poor environments with weak between-group selection (e.g., boreal forests) should be relatively peaceful.
I would be interested in hearing alternative views. And, ultimately it would be interesting to test the ‘Dune Hypothesis’ empirically.
When I first met Sam Bowles (it must have been in the early 2000s) I was already a committed proponent of multilevel selection. My recollection of our interactions at the time was that while he was not a strong critic of the idea, neither was he a strong supporter. I was reminded of our early conversations as I was reading the new book co-authored by Bowles and Herb Gintis, A Cooperative Species: Human Reciprocity and Its Evolution.
A central concept of the book, and more generally of Bowles and Gintis research, is strong reciprocity. I really dislike this term (I prefer cooperation), and I suspect that Bowles and Gintis use it because it reflects their personal evolution on the way to accepting multilevel selection. As many other economists, they are very well versed in game theory. Game theory played an extremely important role in defining the central puzzle of cooperation: how can it evolve despite its vulnerability to free-riders? This problem was starkly delineated in the canonic Prisoner’s Dilemma (PD) game, in which the only rational decision is to ‘defect,’ that is, to withdraw cooperation.
This insight has been with us for a long time and its implications for cooperation have been rather gloomy. During the 1970s and 1980s, an apparent solution was found. It turned out that if the PD game is played repeatedly (the so-called Iterated PD) then a cooperative strategy becomes possible. Such a strategy is conditional: cooperate if the other player does so, defect otherwise. Anatol Rapoport called this strategy “tit for tat,” and Robert Trivers referred to it as “reciprocal altruism” (by the way, another misnomer, since it has nothing to do with altruism; as Bowles and Gintis note on p. 52). Unfortunately, the reciprocal altruism breakthrough turned out to be illusory in the larger quest for the understanding of why humans are such a cooperative species. The problem is that it really works best for tiny groups of two, or very few people. Once the group becomes larger than 5–10, reciprocal altruism starts to break down, and it is certainly not the answer for lasting cooperation for any realistic group sizes, even in small-scale human societies (hundreds, or a few thousands of individuals).
Although David Hume did not know game theory, he clearly saw the problem with reciprocal altruism in larger groups: “Two neighbors agree to drain a meadow, which they possess in common; because ’tis easy for them to know each other’s mind; and each must perceive, that the immediate consequence of his failing in his part is abandoning of the whole project. But ’tis very difficult and indeed impossible, that a thousand persons shou’d agree in any such action; it being difficult for them to concert so complicated a design, and still more difficult for them to execute; while each seeks a pretext to free himself of the trouble and expense, and wou’d lay the whole burden on others.”
In fact, of course, it is quite possible for a thousand and more people to cooperate in performing highly complex tasks (think of a Roman legion building a fortified camp – something legionaries excelled at). The reason is that people are not rational actors. People can sacrifice their own payoffs in order to promote cooperative ventures, and punish free-riders, even at a cost to themselves.
Bowles and Gintis call such behaviors “strong reciprocity,” but I don’t think that simply tacking the adjective ‘strong’ on ‘reciprocity’ results in good terminology. Why not use ‘cooperation’ or ‘pro-sociality’ instead? One might object that no harm is done, because they clearly define the term (on p. 20 of their book) and so there is no confusion, as long as the reader carefully reads the book. The problem with this approach is that the science of cooperation is a highly multidisciplinary field, in which diverse disciplines are involved – from modeling and evolutionary biology to economics, sociology, psychology, neurobiology, anthropology, and even history (although according to the NSF classification history is not a science but humanity). Additionally, and even more importantly, the science of cooperation is (or, perhaps, should be) of high relevance to the general public and the world of social policy. So it is better to use words carefully and choose such terms that would be readily understood by different kinds of scientists, humanists, and non-scientists without a need for technical definitions.
Now that I’ve ‘vented my spleen’ about strong reciprocity, I wish to make a confession. I actually liked A Cooperative Species a lot. This is a book that I’ve been hoping (for years!) that someone would write. Bowles and Gintis do a great job describing the current state of theory in the highly dynamic field of social evolution.
They review dozens of models on diverse topics such as altruistic punishment, coordinated punishment, reputation and indirect reciprocity, signaling, parochial altruism, gene-culture coevolution, coevolution of institutions and preferences, evolution of shame and other pro-social emotions, and many more. It’s the best handbook of social evolutionary theory I’ve read so far. And I found the use of explicit math to be just about optimal: key formulae and equations in the text, the rest in the appendices and in references.
The book is also much more than a simple compendium of models. Bowles and Gintis have thought long and hard about how insights from different models interlock together to create a holistic canvas of our understanding how human cooperation may have evolved. The field is mature enough so that several general lessons have been gained.
One such general insight is that all successful models of altruistic behaviors share one feature – positive assortment of altruists (p. 48). Group selection works if altruists are more likely to find themselves in the same group. Kin selection works if relatives preferentially interact with each other. Even reciprocal altruism shares this feature (because of the iterated manner of the interaction: positive assortment in time, rather than space). Although those steeped in the modeling literature have known about this general result for some time, now there is an excellent reference to direct non-modeling colleagues to.
So despite my terminological problems, my recommendation is: buy the book, read it, and keep it handy as a reference.
A week ago I was interviewed by a BBC person who is working on a TV series about the role of geography in history. The questions were prompted (of course!) by Jared Diamond’s magisterial Guns, Germs, and Steel. I love the book, even though I disagree with many of Jared’s views. (There is no contradiction here, in science it is much more important to be interesting than right.)
Today I’d like to discuss one of Diamond’s ideas that I find very productive. In the chapter entitled “Spacious Skies and Tilted Axes” Diamond pointed out that ecological zones (the technical terms is ‘biomes’) tend to be stretched from east to west, because climates, soils, etc. are more similar as one travels east or west, compared to north/south. As a result, crops and domestic animals can spread more easily along the lines of latitude (in the East-West direction). The Eurasian landmass is oriented along an East-West axis; it is also huge. Different plants and animals, domesticated in different parts of Eurasia, spread East or West quite readily. The end result was that each particular region could profit not only from crops and animals domesticated within it, but also from many other species domestcated in distant, but ecologically similar regions. As an example, peach was domesticated in China but it spread to Europe already in the Antiquity. Earlier, cereals, such as wheat and rye, readily spread from the Fertile Crescent west into the Mediterranean Europe. But it took millennia longer to spread north into Russia, although the distance that needed to be traveled was actually shorter.
An argument can be made that it should be easier for many other things to spread along the East-West axis – not only cultivars, but also human genes, artifacts, ideas, and even political power. As an example of the latter, think of the Roman empire. The Roman state evolved within the Mediterranean biome. Once it expanded beyond Italy, it rapidly spread West and East to other regions with the same ecology, from Spain to the Levant. Pushing beyond the Mediterranean ecological zone, however, proved to be much harder. The Roman push into the forests of northern Europe ended in the disaster of the battle of Teutoburg Forest in 9 C.E., in which 20,000 legionaries led by Publius Quinctilius Varus were wiped out by an alliance of Germanic tribes. Being used to the Mediterranean shrubland/woodland habitat, the Romans had a lot of trouble with conducting military operations in northern forests, where “the trees grew close together and very high” (in the words of the Greek historian Cassius Dio). In the end, the Romans decided that conquering the Germans was more trouble than it’s worth.
In the east, the Roman expansion was stopped by the Syrian and Arabian deserts. The famous Roman defeat there was the battle of Carrhae (53 B.C.E), in which the invasion force of 35,000 legionaries plus supporting troops led by Marcus Licinius Crassus was virtually obliterated by Parthian cavalry.
Although deserts can be a serious barrier to people who are not used to them, for others, like the Arabs, they were essentially highways of expansion. After the Prophet Muhammad died, his successors expanded the Islamic Caliphate West into North Africa and East into Persia and Central Asia. Again, as in the Roman case, the shape of the resulting empire was stretched in the East-West direction. However, the biome at its core was not the Mediterranean, but the hot subtropical desert. Yet another example is the Mongol Empire, which stretched from Ukraine to Korea, with the Great Eurasian Steppe at its core.
I can multiply examples, but this wouldn’t be science. What needs to be done is to test the idea empirically – collecting data and doing statistics. In short, we need to do some cliodynamics. Incidentally, this is one of the criticisms that I have for Guns, Germs, and Steel – it is long on ideas, but short on testing them in a systematic fashion.
A few years ago we decided to do a proper scientific test of the hypothesis that extending state power should be easier East-West than North-South (this was research co-authored with Jonathan Adams and Tom Hall). We compiled a list of all large historical empires with territories exceeding a million square kilometers, and calculated the ‘latitudinal index,’ which measures the extent to which territories are stretched along the East-West axis. The details are here:
Our results indicated that the physical and biological environment had a very strong effect on the shapes of historic states. As you can see from the graph below, the great majority of historical empires have a positive Latitude Index (meaning they are stretched in the East-West direction).
The two empires with a strong north-south orientation were in areas where ecological zones were stretched in the North-South direction. The New Kingdom of Egypt had at its core the valley of a major river oriented North-South, the Nile. The Inca empire was located on the west coast of South America where ecological zones are stretched North-South due to the Andean mountain chain. In other words, these exceptions to the East-West rule conformed to the more fundamental rule that projection of military and political power was easier within the same ecological zone.
So Diamond’s argument is supported by data. More importantly, it turned to be a productive idea, because it prompted us to collect data to test empirically a particular extension of the argument. I know of at least one other article (by David Laitin and co-workers), currently under review, that applies Diamond’s hypothesis to the shapes of modern nations.
To reiterate what I said above, the best of science is not to be right (one can be right in obvious, boring ways), but to put forth productive ideas; ideas that lead to further research. In this Jared Diamond succeeded very well.
About a month ago I participated in a public debate, which followed the workshop in Knoxville on social evolution theory. Together with Jerry Sabloff I argued that warfare was a creative force in social evolution – it transformed humans from living in villages to living in huge states, building cities and civilizations, and ultimately made our lives more peaceful. Our esteemed colleagues Sander van der Leeuw and Tim Kohler argued against this thesis. At the end of the debate the audience voted, and our side was soundly trounced (I think there were perhaps five percent voting for the thesis). Fair enough, but I had a distinct feeling that the audience was not only swayed by the arguments of our opponents, excellent as they were, but that many simply voted “against war.”
More recently, I have been reading Evolutionary and Interpretive Archaeologies: A Dialogue edited by Ethan Cochrane and Andrew Gardner. It’s a fascinating book in many ways, but to me the most interesting article was by Simon James, on violence and warfare. “Most would agree that rejecting beating of children and spouses, abolishing capital punishment and condemning militarism represents a general advance in human values,” James writes. In the last several decades, the level of violence experienced by most Westerners has declined strongly, and it became easier to view violence as an aberration from the norm. Discussing violence has become uncomfortable and, as James provocatively suggests, this topic has become a cultural taboo, just as sex was in Victorian England.
Laudable as such attitudes may be, they make it difficult for social scientists to study war. Scientists are part of the broader society and are affected by shifts in the public mood. As war became to be morally condemned, its scientific study fell out of fashion. Within anthropology and archaeology there arose a tendency to sweep under the rug any empirical evidence of war and violence. Although a high proportion of skeletons studied by archaeologists show damage diagnostic of violence, this evidence was simply not seen, and if seen, not reported. It became fashionable to explain away massive fortifications, for example, as symbolic statements of civic pride, or imperial grandeur. Lawrence Keeley in his 1996 book War Before Civilization calls this tendency “the pacification of the past.”
In history, similarly, the study of warfare fell out of fashion and military history almost became extinct as a discipline. Fortunately, recently there has been a bit of a revival, both of military history and of anthropology of warfare. But I wonder, whether it will be sustained. If you study war, does it mean that you excuse it, or even worse, glorify it?
Warfare is a difficult subject to study, because it is so emotionally fraught. War brings out both the worst and the best sides of human nature. It is difficult to approach analytically and dispassionately. Furthermore, war has diverse effects on societies, some of them bad, and some good. I have been developing an argument (this is what I talked about during the debate) that warfare is the direct cause of the evolution of large-scale complex societies, and the chief selection force that held such societies together. This creative role of warfare has been explored by other colleagues, such as the economist Sam Bowles, anthropologist Peter Richerson, and historian Ian Morris. If this view is correct, then we should be careful about how we go about abolishing warfare. Clearly the great majority of people on Earth, including myself, want warfare to cease. But suppose we abolish warfare and the result is fragmenting societies and failed states. Then a new spiral of warfare will inevitably follow, so all our work will be in vain. History is full of well-intentioned interventions with pretty awful unintended consequences.
A discussion of this uncomfortable topic would be incomplete without addressing the disconnect between moral condemnation of war and the actual practice of it by our own society. The USA spends nearly as much on what is called ‘defense’ as the rest of the world put together. And, as Madeleine Albright famously put it, what’s the point of having all these goodies if you don’t use them? So it should not come as a surprise that most current wars are either fought with US troops, or by various kinds of proxies.
This potent mixture of moral condemnation coexisting with energetic pursuit of war and the emotionally charged nature of the subject create a veritable mine field for social scientists brave enough (or foolish enough) to study war. But this subject is too important to be left entirely to politicians and other nonscientists.
When we launched the Social Evolution Forum a few months ago, one of our declared goals was to advertise future conferences and workshops and publish reports on completed ones. Today we begin to deliver on this promise with a report on the investigative workshop on social evolution theory that took place at NIMBioS last month. Comments are welcome from both participants and other interested parties.
NIMBioS Investigative Workshop
Towards a formal theory for the evolution of human social complexity
February 6-8, 2012; Knoxville, TN
Peter Turchin, Univ. of Connecticut
Laura Fortunato, Santa Fe Institute
Sergey Gavrilets, Univ. of Tennessee
Background. The great majority of humans today live in complex societies, which can exist only on a basis of extensive cooperation among large numbers of individuals. Ultrasociality, the ability of humans to cooperate in large groups of genetically unrelated individuals, presents a puzzle to both evolutionary and social theory. Its emergence likely involved the evolution of cooperation in small groups, characterized by an egalitarian social structure, followed by a reversal of this trend starting around 5–10 kya, with the rise of the first nonegalitarian complex societies. Theories to explain how complex societies evolved span the biological, social, and historical sciences, but they largely rely on verbal reasoning: until recently, formal models have focused on the evolution of cooperation in small groups, while the transition from small- to large-scale societies has been mostly neglected.
Objectives. The aim of this workshop was to bring together a diverse group of modelers with anthropologists, archaeologists, and other social scientists to (i) synthesize the state of knowledge in formal models of the evolution of social complexity, (ii) identify unresolved issues, and (iii) set an agenda for future collaborative work. The workshop was organized around the following general themes: What theories and data are available? What are the empirical patterns that cannot be explained by the existing theories and data? How can we adapt existing models to make full use of the available data? What kinds of data are needed to better inform the models? What new modeling techniques and methods need to be developed?
SUMMARY OF THE WORKSHOP
The workshop started with a brief discussion of general goals and some conceptual issues, followed by five half-day sessions, each dealing with one of the general themes specified in the proposal.
Session 1 focused on general patterns in the transition from small- to large-scale societies. Specific topics addressed were (i) the growth in the information-processing capacity of human beings, both individually and in groups, and how that could drive the evolution of social complexity; (ii) the driving forces and constraints in the evolution of archaic states with an emphasis on “pristine” states; and (iii) effects of population growth after the Neolithic transition on the evolution of hierarchic leadership and increasing scale of public goods provision.
The discussion focused on general patterns associated with growing social complexity: increasing population density and size of sociopolitical groups; emergence of permanent leaders; evidence for public goods; and increasing formalization of social institutions. Other patterns and process discussed were: cross-generation transmission of wealth; the scale of “emotive participatory rituals” (measured by the area of public spaces where they could take place); spatial scale and magnitude of taxation; differentiation of functions within a society; trends in the welfare of nonelites. Key issues involved in the transition to complex societies are: How is trust maintained and how does this interact with scale? How is social alignment and coordination achieved? What are the effects of variability in production and distribution (inicluding role of climates at various temporal scales)? What are the rate constraints in these processes? What is the balance of scales (levels) of selection (in a multilevel set-up)? What are the mechanisms of cultural groups selection – conflict with “outside” groups? Attrition by “voting with feet”?
Session 2 dealt with general theories of growth of social complexity. Presentations (i) reviewed the state of theory starting from the nineteenth century evolutionists, (ii) discussed the roles of warfare, bureaucracy, and the applicability of population ecology methods, and (iii) examined theoretical explanations of cyclicity in the evolution of societies.
The discussion continued with a focus on general patterns associated with state emergence, but also began to engage with mechanisms that could explain these patterns. Specific issues included: continuity versus discontinuity in the emergence of states (including the possibility of multiple dynamic equilibria and transitional phases); unicentric versus polycentric systems (also ideological versus political unity). There was an intense discussion of issues involved in cultural group selection, including differences between biological and cultural modes (and coevolution of these modes); transition from initial sociality (small-scale, “simple”) to complexity; dynamic roles of boundaries. Other questions discussed were: How does bureaucracy get larger and change? What is the role of variations in bureaucratic strategies? Resistance against bureaucratic control? Do we need different models for the emergence of “pristine” (primary) and secondary states?
Session 3 summarized a variety of mathematical modeling techniques used for studying the evolution of social complexity. It also included several presentations with novel modeling developments focusing on the emergence of leadership, evolution of languages, cooperation and warfare.
The discussion centered on what mechanisms and processes need to be modeled. Proposals included: dynamics of polity size and complexity; ethnic markers and cultural boundaries; social stratification; cultural evolution and learning; and cooperation, altruism, group selection, kinship. General processes included: yielding autonomy for gains in group/polity size/power; creating norms and institutions that alter individual (or subgroup) payoffs to favor increasing complexity. There was a substantial degree of consensus on the most important modeling goals: articulating spatial models into a coherent theory that can span a range of social systems; identifying institutions and mechanisms involved in each move “up” the scale (e.g., from chiefdoms to complex chiefdoms, then to archaic states, etc); linking social evolution to evolved (human) psychology; determining how material constraints shape evolution of social complexity.
Session 4 focused on the data available to inform theoretical models of the emergence of human social complexity and test their predictions. Two of the presentations related to available cross-cultural archaeological, historical, and ethnographic data; the other three related to data from field-based projects with small-scale populations in Bolivia, Kenya, and India.
The session concluded with a general discussion of issues raised by the presentations. Topics addressed during the discussion session include:
Session 5 discussed possible approaches to integrating theories, models, statistical methods, and data. Talks focused on linking dynamic models to data; evolution of capacity for social complexity in deep human history, and the role of phylogenetic methods. The last talk summarized the state of knowledge in the field of multilevel evolution.
The discussion focused on activities after the workshop. The group discussed specific initiatives by workshop participants to develop models and databases; how our efforts can be better integrated; how graduate students could be involved; and plans for future working groups (at NIMBioS and elsewhere).
Public Session. After the conclusion of the workshop several participants took part in a public debate on the role of warfare in the evolution of early social complexity, which generated a lot of interest on campus, drawing on the order of 100 participants.
Background: In the last 10,000 years, human societies have evolved from highly egalitarian bands of a few dozen people to the huge societies of today with great economic and social divisions, thousands of professions, and elaborate governing structures. How this transition occurred is one of the greatest puzzles in science. To throw some light on this fascinating topic, NIMBioS hosted a debate, focusing on the role of warfare in explaining the transition from simple to complex societies.
Thesis: Warfare has transformed us from living in villages to living in huge states, building cities and civilizations, and ultimately making our lives more peaceful.
Antithesis: Warfare is an unfortunate side-effect of the evolution of social complexity, but it was other evolutionary mechanisms that resulted in highly complex human societies.
For the thesis: Peter Turchin (University of Connecticut), Jeremy Sabloff (Santa Fe Institute)
For the antithesis: Sander van der Leeuw (Arizona State University), Tim Kohler (Washington State University)
Laura Fortunato (Santa Fe Institute), Sergey Gavrilets (NIMBioS)
To find out more about the debate and a link to view it, click here.
When I was in graduate school at Duke University in the early 1980s I remember a young professor visiting from Michigan State who gave a talk about group selection. The professor was of course David Sloan Wilson, because at the time he was the only academic willing to stick his neck out for group selection. I thought his ideas were eminently sensible and was surprised to learn that none of the other graduate students agreed with me. Group selection was not particularly close to my research interests then (I was working on population movements of insects), but I kept following it. What I heard during the 1980s and 1990s was a relentless drumbeat against group selection. As a result of books by such luminaries as G. C. Williams and Richard Dawkins, evolutionary biology at the time thoroughly repudiated this idea.
Later, during the 1990s I became interested in scientific study of history (so much that I eventually switched from biology to historical social science) and discovered that the theory of group selection, which by then became the theory of multilevel selection, could provide a very productive conceptual framework for the study of the evolution of complex societies. It turned out that multilevel selection yielded predictions that could actually be tested with historical data. What was particularly exciting was that theoretical predictions, time and again, yielded novel insights that were, amazingly enough, supported empirically (when I started working on historical dynamics I did not realize how much data there are to test different theories).
Meanwhile, there was a glacial, but also tectonic shift (sorry about mixing metaphors) in social evolution, especially in human social evolution. Gradually an increasing number of researchers came over to the view that cultural and genetic group selection provides a very viable theoretical framework for the study of evolution of human sociality. Colleagues like Pete Richerson and Rob Boyd, Sam Bowles and Herb Gintis, Elliott Sober, Joe Henrich, and many others became seriously engaged with models and empirical analyses framed within the multilevel selection paradigm.
The signal event in this tectonic shift was the “defection” of E. O. Wilson to the group selection side in 2007. The two Wilsons co-authored a Quarterly Review in which they proposed the dictum, “Selfishness beats altruism within groups. Altruistic groups beat selfish groups. Everything else is commentary.”
A month ago we ran a workshop at NIMBioS (the National Institute for Mathematical and Biological Synthesis; I will be reporting on it later this week). The workshop was attended by a truly multidisciplinary group of more than 40 scientists. What was really surprising was that the idea of multilevel selection was something all of us could agree upon.
I believe that we are in a Kuhnian paradigm shift, and I fully expect that multilevel selection will become the reigning paradigm in the next 5-10 years. But the transition is not going to happen without pain.
This paradigm shift is associated with a remarkable degree of acrimony (although I did not experience at first hand other paradigm shifts, so perhaps they all are similar in this respect). The case in hand is the exchange over the weekend between David Wilson and Jerry Coyne. It started with a post by Wilson When Richard Dawkins is not an Evolutionist. Coyne shot back with David Sloan Wilson loses it again, and Wilson blasted away with Pugilistic Science.
In the process, Wilson intimated that Dawkins is not really a scientist, while Coyne suggested that “Wilson is totally over the waterfall.” At the end of his post, Coyne added: “I recently did a podcast interview for the Evolution: This View of Life site. Had I known that the biology part of the site was run by Wilson, and is used largely to promote his own views about religion and group selection, I would not have done it.” Now I don’t want to paint Jerry as a blackguard, all parties of this debate have transgressed over the norms of polite discourse, and in a different age this could easily lead to a dawn encounter with matched weapons.
But let’s return to the substantive issue, that of group, or better multilevel selection. Specifically, not whether it is prevalent in the animal world, but its role in the human social evolution. I am of course a partisan in this debate, but I don’t understand the extreme position taken by Richard Dawkins and Jerry Coyne, who deny any role for multilevel selection. If we want to understand the evolution of large-scale complex societies, what is the alternative? How could human ultrasociality, our ability to cooperate in huge groups of genetically unrelated individuals, evolve? The two theories discussed in The Selfish Gene, reciprocity and kin selection, fail utterly on both conceptual and empirical grounds, as has been abundantly demonstrated by the likes of Richerson and Boyd.
To make this question even more specific, we know that humans are capable of sacrificing their lives for the sake of huge groups consisting of unrelated strangers. As an example, think of the Southerners and Northerners volunteering for the Confederate and Union armies during the American Civil War. It is a particularly well-documented case, because those volunteers were literate, and they left behind thousands of letters explaining their motivations. Hundreds of thousands of them died on the Civil War battlefields. So how can you possibly explain such remarkable properties of human sociality, other than with a group selectionist model?
This is not a rhetorical question – I genuinely would like to see what theoretical alternatives there are, so that we can start figuring out how to test them empirically. So let’s hear them.
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