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Eric Michael Johnson has an excellent round-up of and commentary upon recent debates about “group selection” (also, a decent primer on the basics). If there is one major issue I might take with the narrative outlined, it is the idea that E. O. Wilson has made a recent about-face in regards to group selection, going from a skeptic to a believer. In Defenders of the Truth: The Sociobiology Debate Ullica Segerstrale pointed out that this was obviously not the case even in Wilson’s grand book Sociobiology. If you don’t accept this, David Sloan Wilson seems to implicitly confirm Segerstrale’s position in his semi-autobiographical book Evolution for Everyone. Finally, I’ve heard it from acquaintances at Harvard that it was an open secret that E. O. Wilson was skeptical of the “Hamiltonian orthodoxy” ascendant in evolutionary biology and ecology. The controversy over the notorious paper, The evolution of eusociality, was years in the making. From what I gather many of Wilson’s colleagues at Harvard were skeptical that he comprehended the depths of the mathematics which he promoted to support his more intuitive empirically informed skepticism of the power of inclusive fitness. It isn’t an unheard of sin for an eminent empiricist to go shopping for a theoretician to add some luster to his logic, but it does frame the reason that some of Wilson’s colleagues seem so irritable about the whole affair.

I think this is at the heart of the acidity in Richard Dawkins’ review of Wilson’s latest book, The Social Conquest of Earth. If I, a nobody, could hear through the grapevine that Wilson is lending his name to ideas which he doesn’t have a deep understanding of in terms of the mathematical superstructure, then Dawkins surely knows as well. This is what I believe is at the heart of this section of Dawkins’ review: “But one can make a good case that the 2010 paper would never have been published in Nature had it been submitted anonymously and subjected to ordinary peer-review, bereft of the massively authoritative name of Edward O Wilson. If it was authority that got the paper published, there is poetic justice in deploying authority in reply.” Wilson has a great deal of authority as an entomologist and a synthetic thinker, but not as a formal theoretician. Obviously there are many great partnerships between theoreticians and empiricists in science, but it strikes me that many feel that the relationship between Wilson and his two mathematically oriented co-workers was too convenient by a half. In his gut Wilson long knew that inclusive fitness was not all there was, and here were these biologically naive mathematicians willing to stand by his side. It makes fascinating sociology of science.

Finally, you should also check out Steven Pinker in Edge, The False Allure of Group Selection. Pinker’s essay is fine as far as it goes, but the responses are also excellent. As it happens I agree with the group selection skeptics that the framework is often incoherent, muddled, and lacking in robust empirical illustration. On the other hand, do read the responses of Joe Heinrich, Robert Boyd, and Peter Richerson. They make cogent defenses of the multi-level framework, but to be frank I think that E. O. Wilson has kind of lost it at this point. He claims too much for multi-level selection, and I do wonder if his fellow travelers are starting to wonder if he’s a liability. On the other hand I do think that Pinker sells group level dynamics short for human cultural modeling. I will be frank, I think inclusive fitness and reciprocal altruism are not sufficient to explain human cultural complexity. This does not mean that I accept inter-group selection as “the answer.” But even if it’s a difficult and dodgy framework, it is an alternative.

One last thing. My personal experience is that this is an issue where discipline and “who you know” matters in terms of what you think as to the science. I’ve encountered eminent behavioral ecologists who think Wilson is in the right. On the other hand, there are many others, especially in genetics, who are absolutely skeptical. Overall I suspect that the apologists for multi-level selection, especially in terms of biological process, are in the minority. But probably not a tiny minority.

Addendum: Readers may be curious that W. D. Hamilton reported that his paper, Innate Social Aptitudes of Man: An Approach from Evolutionary Genetics, which Eric Michael Johnson references as evidence of Hamilton’s rapprochement with group selection, was referred to as the ‘fascist paper.’ For more in that vein see Narrow Roads of Gene Land: The Collected Papers of W. D. Hamilton Volume 1: Evolution of Social Behaviour.

(Republished from Discover/GNXP by permission of author or representative)
• Category: Science • Tags: Evolution, Social Evolution 
🔊 Listen RSS In reading The cultural niche: Why social learning is essential for human adaptation in PNAS I couldn’t help but think back to a conversation I had with a few old friends in Evanston in 2003. They were graduate students in mathematics at Northwestern, and at one point one of them expressed some serious frustration at the fact that so many of the science and business students in his introductory calculus courses simply wanted to “learn” a disparate set of techniques, rather than understand calculus. The reality of course is that the vast majority of people who ever encounter calculus aim to learn it for reasons of utility, not so that they can grok the fundamental theorem of calculus. With the proliferation of tools such as Mathematica and powerful portable calculators fewer and fewer people are getting their hands dirty with calculus in an analytic sense, and more often see it as simply a “requirement” which they have to pass.

Calculus, and mathematics generally, is a clean and crisp human invention. In the late 17th century Isaac Newton and Gottfried Leibniz originated calculus as we understand it. Later thinkers extended their work. But for the vast majority of humans who have ever learned calculus it is simply a “black box” set of techniques which work rather magically. They did not contribute anything new to the body of knowledge which they drew upon. Mathematics is part of our cultural patrimony, we implicitly stand upon the shoulders of giants without apology. Such is to be human.

In a The cultural niche Robert Boyd, Peter J. Richerson, and Joseph Henrich sketch out the broad thesis about the nature of human culture which is explored in more depth in works such as Not by Genes Alone and The Origin and Evolution of Cultures. Though the subject which they tackle is vast, the powers of precise description and crisp inference can sometimes lead to surprising conclusions:

In the last 60,000 y humans have expanded across the globe and now occupy a wider range than any other terrestrial species. Our ability to successfully adapt to such a diverse range of habitats is often explained in terms of our cognitive ability. Humans have relatively bigger brains and more computing power than other animals, and this allows us to figure out how to live in a wide range of environments. Here we argue that humans may be smarter than other creatures, but none of us is nearly smart enough to acquire all of the information necessary to survive in any single habitat. In even the simplest foraging societies, people depend on a vast array of tools, detailed bodies of local knowledge, and complex social arrangements and often do not understand why these tools, beliefs, and behaviors are adaptive. We owe our success to our uniquely developed ability to learn from others. This capacity enables humans to gradually accumulate information across generations and develop well-adapted tools, beliefs, and practices that are too complex for any single individual to invent during their lifetime.

The authors use examples of foraging societies which have “lost” knowledge through population crashes to illustrate the collective nature of human knowledge. It is reputedly an African proverb that “when an old man dies a library burns.” This was certainly the case when a particular group of Greenland Inuit experienced a population collapse which impacted their older cohorts to the point where they all expired before passing on their knowledge and skills. The community forgot the techniques of hunting caribou or making kayaks! The younger individuals who survived understood that these were possibilities, but none of them had the suite of skills necessary to replicate the abilities of past generations.

Let’s use a more contemporary example. Imagine you had hand 200 business students who had completed a term of differential calculus. Now give them a year to infer what they would have learned in integral calculus. I’m not sure even with a knowledge of differential calculus that a random set of 200 business students would be able to derive much of integral calculus. Part of the issue here is that often students who must take mathematics, but are not of a mathematical bent themselves, have no “big picture” grasp, but master a set of discrete techniques. They solve problems of a specific form, but are not able to improvise anew from first principles, because they’re rarely asked to do such things.

As humans we always take for granted an enormous store of cultural knowledge, which we absorb both implicitly and explicitly. We are adapted to be cultural creatures. This is why the authors posit the “cultural niche” rather than “cognitive niche” hypothesis in terms of the transmission of sets of ideas. The cognitive niche hypothesis emphasizes the individual competencies of humans. We have relatively advanced general intelligence aptitudes, and we are master imitators. Therefore, once an innovation occurs, instead of reinventing the wheel, humans replicate. This is far cheaper than the act of invention. A sequential and synergistic set of imitations can then lead to a ratchet effect of cultural evolution, as beneficial memes sweep through populations.

But there is a problem with this thesis: imitation can be viewed as a “free rider” strategy. Why think for yourself when you can let others do the heavy lifting for you! Don’t worry about the large menu, just have what “he’s having.” The problem is that this cheap and effective strategy is liable to spread, and over time more and more imitators anchor on upon a few keystone innovators. These hard working de facto altruists though eventually become not keystones, but weak links. If one of them is gifted not with prudence and intellect, but arrogance and blindness, then a whole population can find itself hurtling over the cliff. Imitation is the root of irrational herds and chaotic mass social behavior.

What’s the solution to this? Naturally it is not a fixation upon a given strategy, but a facultative flexibility in learning from others. We don’t just imitate anyone, we imitate prestigious and successful individuals. Ergo, endorsements by sporting figures of seemingly unrelated products. And the nature of the environment impacts how liable we are to imitate or innovate. In a world subject to stasis the cost of individual innovation has few upsides. Best to simply do as “the ancestors did.” Collective cultural memory plays a critical role in passing down “best practices.” But sometimes this can become maladaptive when circumstances change. European peasants resisted the attempts by their rulers to promote the cultivation of potato for centuries because of its resemblance to nightshade. There was a deep-seated custom, which resulted in generations of suspicion which had to be overcome. Today the potato is a “customary” and “traditional” crop in many of these societies. Conservatism had its costs, as another food crop may have buffered famines in France and Russia.

An implication of this broader dynamic might be that environments which change more will have less pressure to enforce imitative conformity. I suspect that the protean social and technological milieu of the developed world does fit this description. “Doing your own thing” makes good sense when traditions and customs can never take hold because the background conditions of your environment are always in flux. Instead of vertical transmission of collective memory over time you see horizontal sweeps of fads and fashions across sets of peers, with each set of norms being overturned in rapid succession by that of the next cohort.

But let’s go back to the beginning: what does culture have to do with human evolution? The figure to the left was generated by Luke Jostins using hominin data sets. By this, I mean individuals who are not anatomically or behaviorally modern humans before ~200,000 years before the present at the outer limit. The story told above leans heavily on the “standard model” of recent human evolution, whereby modern humans arose ~50,000 years ago in Africa, and swept like wildfire around the world. The reason that modern humans conquered all before them is laid out explicitly in the paper: we are an incredibly flexible cultural creature. And because of the demands of culture you see a rapid encephalization of cranial capacities over the last “500,000″ years. From Luke’s data it looks like actually it was more the last ~250,000 years, before which there was a more gentle ascent upwards. In any case, we may also be living through a revision of the old model of recent human origins. The details are yet to be written, but it looks like the story is going to be a little more complex and multi-layered that one East African tribe of African Eve exploding outward from its ancestral territory .

But the way I see it that only makes the idea of human adaptation to a cultural environment more plausible. Instead of a singular mutation ~50,000 years ago conferring the ability to speak, as Richard Klein would have it, it may have been a co-evolutionary process where the brain and culture operated in tandem, ratcheting toward modernity step by step. Still, one would have to revise the thesis that this is the hallmark of a sui generis behaviorally modern human lineage. Neandertals, for example, seem to have been subject to the same long term dynamics of encephalization….

Citation: Robert Boyd, Peter J. Richerson, & Joseph Henrich (2011). The cultural niche: Why social learning is essential for human adaptation PNAS : 10.1073/pnas.1100290108

(Republished from Discover/GNXP by permission of author or representative)
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The fruits of human cooperation

ResearchBlogging.orgThe Pith: Human societies can solve the free rider problem, and generate social structure and complexity at a higher level than that of the band. That implies that much of human prehistory may have been characterized by supra-brand structures.

Why cooperation? Why social complexity? Why the ‘problem’ of altruism? These are issues which bubble up at the intersection of ethology and evolution. They also preoccupy thinkers in the social sciences who address fundamental questions. There are perhaps two major dimensions of the parameter space which are useful to consider here: the nature of the relationship between the cooperators, and the scale of the cooperation. An inclusive fitness framework tracks the relation between altruism and genetic relatedness. Reciprocal altruism and tit-for-tat don’t necessarily focus on the genetic relationship between the agents who exchange in mutually beneficial actions. But, in classical models they do tend to focus on dyadic relationships at a small scale.* That is, they’re methodologically individualistic at heart. So all complexity can be reduced to lower orders of organization. In economics a rational choice model of behavior is individualistic, as are the critiques out of behavioral economics.

There are other models which break out of this individualistic box, insofar as they make analogies between organisms at the individual scale to social entities which are aggregations of individuals (e.g., a colony or ethnic group). The society as an organism has an old intellectual pedigree, and was elaborated in great detail by Émile Durkheim. More recently David Sloan Wilson has attempted to resurrect this framework in an explicitly evolutionary sense. Wilson has also been the most vocal proponent of multi-level selection, which posits that the unit of selection can be above the level of the gene or individual. For example, selection operating upon distinctive ‘demes.’ Roughly, a breeding social unit.

There are major theoretical and practical issues with evaluating social units as ‘organisms.’ I will set those aside for now, and shift the focus to humans. I do so because some of those theoretical and practical issues abate when you put the spotlight on higher order cultural structure and variation. In a more technical sense it seems rather obvious that humans have the ability to throw up a large amount of between group ‘memetic’ variance, and maintain that variance, long enough that selection may be able to operate across the two different phenotypes which are homogeneous within group and utterly disjoint across group.

But even if such ‘cultural group selection’ is possible, that does not negate the power of kin, as well as other ‘lower level’ dynamics which may operate at cross-purposes with organismic social units. The biggest problem which comes to mind is the ‘free rider,’ the individual who takes from the benefits accrued to group harmony, but does not put anything into the system and so incur a cost. Over the long term evaluated on the individual scale the free rider is the fit, and therefore the group will become far less effective as its phenotype and genotype wax. This powerful logic is why individualist dynamics are so much more attractive. By simply optimizing fitness through invariant individual behavior you don’t have to confront the specter of the long term futility of the group strategy in the face of self-interested personal tactics.

Yet if you think about it the same problem confronts conventional biological organisms at the scale of the individual. We’re a coalition of disparate cells, some of which even retain their own distinctive genetic lineage (mitochondria). How is the problem of cooperation at this scale solved? If you want a book-length treatment, get Mark Ridely’s The Cooperative Gene: How Mendel’s Demon Explains the Evolution of Complex Beings. But we do have a variety of tactics to stall the ourselves from self-destructing via intra-organismic competition, though in many cases those tactics are futile by the end of your life. I’m referring here to the high probability that you’ll develop cancers, which are basically individual cells whose selfish replicative propensities destroy the useful equilibrium of tissues which help to maintain the integrity of the individual. Over the short to medium term cancerous lines of cells are highly fit, as they spread throughout your body. But over the long term they are self-defeating, insofar as the organism which they parasitize as free riders eventually comes crashing down due to the weight of the stresses which the selfish cells impose on the complex cooperative edifice that is the individual.

Many of these same dynamics have social applicability. In fact the metaphors at the level of cell and tissue derive from older social concepts. So let’s move back to humans. One extreme model of social complexity posits that all the baroque richness of human societies we see today are ad hoc extrapolations and reconfigurations of impulses and instincts which were shaped in an environment of evolutionary adaptedness (EEA) of the hunter-gatherer band. As an example, the idea of meta-ethnic spiritual brotherhood which is common to many ‘higher religions’ is simply an elaboration on our cognitive disposition to think in terms of kinship due to the evolutionary effect of inclusive fitness. Many individual selectionists, most radically George C. Williams, but also Richard Dawkins, seem to posit that human nature is at base positively evil in its selfish intent. Despite Dawkins’ atheism and anti-Christianity I have wondered on occasion if he didn’t have some similarities to a particular sort of reactionary Roman Catholic who took St. Augustine’s theories of original sin too much to heart. Be as that may be, these sorts of individual models generally either imply that social order and complexity are incidental, if valuable, byproducts of proximate instincts, or, social constructions emerge out of phenomena operating at cross-purposes with the stream of evolution (e.g., a complex ideological system constructed from our general intelligence).

This is of course one end of the spectrum. At the other end are a range of broad families of ideas which are group selectionist, or posit a more complex and nested array of dynamics and forces. Williams and his admirers were certainly right to point out the inchoate and woolly nature of much of the ‘survival of the species’ talk which was in the air in the mid-20th century. And, I think talking of taxon level biological selection is something we should do very cautiously if at all. In other words, I accept the general scale independence of evolution. But I do not believe that the 50,000 year experiment of human beings with social complexity is one long extended spandrel. Assuming infinite time for the human experiment to work itself out I can accept that social complexity is due to collapse because of its internal contradictions, but I am but a man alloted a mere few score years, and tend to assent to the proposition that phenomena which span millennia have some right to be accorded the due respect given to the ‘permanent things.’

A new paper in PNAS looks at a society of people who operate in the gray land between ‘small-scale hunter-gatherer bands’ and national entities with all the institutional accoutrements which that entails. The focus of the study are he Turkana. They are a group of Nilotic pastoralists who number between 500,000 and 1 million. They are subdivided into smaller patrilineal units, as well as territorial sections. But the major organizing force among the Turkana in terms of collective action seems to be ‘age group’ cohorts. Basically these are groups of men who come up together as peers. It seems that the Turkana lack institutional religion or formal hereditary leadership. So no kings or warlords of the Turkana who pass their charisma on to the next generation. And the Turkana fight. Or more precisely they raid. As pastoralists they raid for cattle, and they raid for vengeance. Finally, it seems that they do not as a rule raid each other, but rather direct their martial energies outward upon other ethnic groups.

Here’s the abstract, Punishment sustains large-scale cooperation in prestate warfare:

Understanding cooperation and punishment in small-scale societies is crucial for explaining the origins of human cooperation. We studied warfare among the Turkana, a politically uncentralized, egalitarian, nomadic pastoral society in East Africa. Based on a representative sample of 88 recent raids, we show that the Turkana sustain costly cooperation in combat at a remarkably large scale, at least in part, through punishment of free-riders. Raiding parties comprised several hundred warriors and participants are not kin or day-to-day interactants. Warriors incur substantial risk of death and produce collective benefits. Cowardice and desertions occur, and are punished by community-imposed sanctions, including collective corporal punishment and fines. Furthermore, Turkana norms governing warfare benefit the ethnolinguistic group, a population of a half-million people, at the expense of smaller social groupings. These results challenge current views that punishment is unimportant in small-scale societies and that human cooperation evolved in small groups of kin and familiar individuals. Instead, these results suggest that cooperation at the larger scale of ethnolinguistic units enforced by third-party sanctions could have a deep evolutionary history in the human species.

The raw numbers killed proportionally are rather high, but not atypical for many pre-state societies. There are two types of raids. Offensive mass attacks, which seem to be the closest the Turkana and their rivals come to “pitched battle,” and stealth raids with smaller complements of men. I couldn’t but help think of the Cattle Raid of Cooley. Material benefits are real and tangible in many cases, 3 cows per man if victory is theirs. But the costs are real too, the mortality rate is on the order of ~1% per raid. This explains how nearly ~20% of men are dying in their prime years due to violence. Assuming independent probabilities of death you only need 20 raids to have an expected outcome of survival of 0.80. Also, it must be noted that some raids are purely retaliatory and don’t entail any loot, or benefit, to the fighter. These raids of vengeance maintain the honor of the Turkana, and serve as deterrents to future attacks from their enemies. Mass action “tit-for-tat” if you will.

With all the costs and benefits as they are there is naturally free riding. Men beg off on fighting because they can’t find someone to watch their herds, or they’re ill. This might be especially tempting on vengeance raids, where the benefit is a public good which isn’t privately dispersed. Some men avoid being at the tip of the offensive spear during the conflict, and let others take risks so they might live another day. And of course there are stragglers who deviously catch the fleeing cattle first, and secure the best or only portions. If you’ve tread epic myths you know all the varieties of cowardly trickster behavior which might manifest when you are faced with temptations. These raiding parties are numerous, on the order of 250-300 men. They don’t consist of men who are closely related and from the same kin group, but rather a heterogeneous local lot of Turkana, albeit clustered by age group. It seems that the median number of age groups, settlements, and territorial sections, represented in these war parties are around 5 for all of these variables. These war parties are above Dunbar’s number, are not part of some unified group aside from ethnicity and local proximity.

Theory predicts that when you have a diverse lot that diverse interests are going to result in temptation to cheat and let those with whom you’re not close take the fall. How is the problem solved? I’ll quote:

Informally enforced norms allow the Turkana to partially solve the collective action problem in warfare. In 47% of the force raids in which desertions were reported, at least one of the deserters was sanctioned, and in 67% of the force raids in which cowardice was reported, at least one of the cowards was sanctioned (Fig. 7). There are two levels of sanctions. When a warrior’s behavior in a raid deviates from that of his comrades, he is subjected to informal verbal sanctions by his age-mates, women, and seniors. If there is consensus in the community that the act merits more serious sanctions, corporal punishment is initiated. Corporal punishment is severe: the coward or deserter is tied to a tree and beaten by his age-mates. One participant had scars on his torso from being whipped by his age group more than a decade earlier.

This is rather straightforward. In early modern European armies which were involved in set-piece battles there were dragoons stationed at the rear whose role was discourage desertion and retreat through intimidation and force. Obviously the incentive structure here was somewhat different, as defeat in war for a nation-state can have drastic consequences and punishment after the fact may be rendered moot. In the case of these raids documented in this paper it does not seem that the Turkana were involved in existential genocidal conflicts. This may be a function in part of modern norms and the constraining effect of African nation-states in which they’re embedded. Battles between regional warlords in late medieval Europe still occurred, and the monopoly of force accrued to the central government and the monarchy only over time. I would not be surprised if Turkana norms have shifted concomitantly, and non-capital punishment after the raid is an adjustment to the lack of existential urgency in this conflicts.

We know all of the results in this paper in the general verbal sense. How do you fix a free rider problem? You punish them! But the devil is in the details. Here the authors show quantitatively and descriptively that group level dynamics can manifest in a pre-state society above the level of the family band. In fact the unit of organization, the ethno-tribal group, scales up to 500,000 individuals or more! So the social norms were enforced across and beyond kinship groups. Rather it seems that among the Turkana the age groups have a particular power below the level of ethnicity. Presumably what in other contexts might be termed ‘fictive brothers.’ Interestingly these raiding parties were organized and led in an ad hoc and “crowd-sourced” fashion. They illustrate the power of spontaneous dynamics of structured order coming out of a less elaborated and simple social context. And importantly, the violence was directed outward. The rates of murder amongst the Turkana is rather low. Rather, the high risk of death is due to inter-group conflict.

But it seems that the authors are not presenting a simple inter-demic group selection argument. Much of the “action” here operates underneath the level of the group, insofar as group action and cohesiveness is mediated through the regulation of norms of collections of individuals and sub-group entities. This is why I personally find the “group” vs. “individual” dichotomy less than useful. Where do we draw the line from highly elaborated cultural structures built upon atomic units of individual human action to quasi-organismic societies? To a greater extent it seems a matter of taste and convenience, not substance.

One study on the Turkana proves nothing. It may just be part of the bigger puzzle though. For a generation evolutionary psychologists have focused on the model of the hunter-gatherer band during the Pleistocene. Anthropologists working within this tradition have attempted to show that successful hunters and warriors are fecund hunters and warriors. Individual level dynamics then would be validated, as social status is converted into biological currency. From what I have read in the literature (and mind you, I began one theoretically high committed to this hypothesis) the results have been somewhat mixed. This tells us perhaps that one dynamic to explain it all is not going to do the job.

Most of the world’s societies were and are not patrilineal pastoralists. But the Turkana are human, and so they give us a window into the intersection of human psychology and social context, and what that may produce. The intersection is multi-layered, and the product is difficult to distill down to a few broad characterizations. Human social complexity’s raw variety defies broadness of characterization with any economy. But it exists, and it needs explaining, bit by bit.

Citation: Sarah Mathew, & Robert Boyd (2011). Punishment sustains large-scale cooperation in prestate warfare PNAS : 10.1073/pnas.1105604108

* In theory inclusive fitness can obviously be generalized very broadly

Image credit: Wikimedia

(Republished from Discover/GNXP by permission of author or representative)
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