Razib Khan One-stop-shopping for all of my content

April 15, 2012

Group selection survey

Filed under: Data Analysis,Group Selection — Razib Khan @ 6:43 pm

I don’t have time to do a detailed analysis of my group selection survey right now. So I’ve uploaded the raw results for anyone to play with (there is no personally identifying information obviously). You should be able to convert it into an appropriate format for R or something else pretty easily.

April 8, 2012

What do you think about group selection?

Filed under: Evolutionary Genetics,Group Selection — Razib Khan @ 8:50 pm

I just received a review copy of E. O. Wilson’s The Social Conquest of Earth. One of the reasons why this book is “hot” is that Wilson has recently been revisiting the “levels of selection” debates, and significantly downgraded kin selection in the pantheon of evolutionary dynamics (at least in his mind). There has been a lot of talk on the blogs about Wilson’s ideas, in large part because of his partisan position on the Nowak vs. most other biologists debate, in favor of Nowak.

I don’t know if I’ll have time to review the book (a reality I honestly explained already to the people working at the publisher), but, it did get me thinking: what are the opinions of biologists in relation group selection? My personal experience is that opinions actually vary by discipline and by department. It’s hard to get a real sense, because people tend to be in their own “bubble.” With that in mind, I’ve put together a small survey to assess opinions. My core audience here are people who consider themselves biologists, though I can’t prevent someone with strong opinions from participating obviously!

So, a survey on group selection. You can see the ...

January 30, 2012

Monogamous societies superior to polygamous societies

Filed under: Anthroplogy,Culture,Group Selection — Razib Khan @ 9:14 pm


The title is rather loud and non-objective.  But that seems to me to be the upshot of Henrich et al.’s The puzzle of monogamous marriage (open access). In the abstract they declare that “normative monogamy reduces crime rates, including rape, murder, assault, robbery and fraud, as well as decreasing personal abuses.” Seems superior to me. As a friend of mine once observed, “If polygamy is awesome, how come polygamous societies suck so much?” Case in point is Saudi Arabia. Everyone assumes that if it didn’t sit on a pile of hydrocarbons Saudi Arabia would be dirt poor and suck. As it is, it sucks, but with an oil subsidy. The founder of modern Saudi Arabia was a polygamist, as are many of his male descendants (out of ~2,000). The total number of children he fathered is unknown! (the major sons are accounted for, but if you look at the genealogies of these Arab noble families the number of daughters is always vague and flexible, because no one seems to have cared much)

 

So how did monogamy come to be so common? If you follow Henrich’s work you will not be surprised that he posits “cultural group selection.” That is, the advantage of monogamy can not be reduced just to the success of monogamous individuals within a society. On the contrary, males who enter into polygamous relationships likely have a higher fitness than monogamous males within a given culture. To get a sense of what they mean by group selection I recommend you read this review of the concept by David B. A major twist here though is that they are proposing that the selective process operates upon cultural, not genetic, variation (memes, not genes). Why does this matter? Because inter-cultural differences between two groups in competition can be very strong, and arise rather quickly, while inter-group genetic differences are usually weak due to the power of gene flow. To give an example of this, Christian societies in Northern Europe adopted normative monogamy, while pagans over the frontier did not (most marriages may have been monogamous, but elite males still entered into polygamous relationships). The cultural norm was partitioned (in theory) totally across the two groups, but there was almost no genetic difference.  This means that very modest selection pressures can still work on the level of groups for culture, where they would not be effective for biological differences between groups (because those differences are so small) in relation to individual selection (within group variation would remain large).

From what I gather much of the magic of gains of economic productivity and social cohesion, and therefore military prowess, of a given set of societies (e.g., Christian Europe) in this model can be attributed to the fact of the proportion of single males. By reducing the fraction constantly scrambling for status and power so that they could become polygamists in their own right the general level of conflict was reduced in these societies. Sill, the norm of monogamy worked against the interests of elite males in a relative individual sense. Yet still, one immediately recalls that elite males in normatively monogamy societies took mistresses and engaged in serial monogamy. Additionally, there is still a scramble for mates among males in monogamous societies, though for quality and not quantity. These qualifications weaken the thesis to me, though they do not eliminate its force in totality.

In the end I am not convinced of this argument about group selection, though the survey of the empirical data on the deficiencies of societies which a higher frequency of polygamy was totally unsurprising.  I recall years ago reading of a Muslim male who wondered how women would get married if men did not marry more than once. He outlined how wars mean that there will always be a deficit of males! One is curious about the arrow of causality is here; is polygamy a response to a shortage of males, or do elite polygamist make sure that there is a shortage of males? (as is the case among Mormon polygamists in the SA)

Finally, I do not think one can discount the fact that despite the long term ultimate evolutionary logic, over shorter time periods other dynamics can take advantage of proximate mechanisms. For example, humans purportedly wish to maximize fitness via our preference for sexual intercourse. But in the modern world humans have decoupled sex and reproduction, and our fitness maximizing instincts are now countervailed by our conscious preference for smaller families. Greater economic production is not swallowed up by population growth, but rather greater individual affluence. This may not persist over the long term for evolutionary reasons, but it persists long enough that it is a phenomenon worth examining. Similarly, the tendencies which make males polygamous may exist in modern monogamous males, but be channeled in other directions. One could posit that perhaps males have a preference to accumulate status. In a pre-modern society even the wealthy usually did not have many material objects. Land, livestock, and women, were clear and hard-to-fake signalers to show what a big cock you had. Therefore, polygamy was a common cultural universal evoked out of the conditions at hand. Today there are many more options on the table. My point is that one could make a group selective argument for the demographic transition, but to my knowledge that is not particularly popular. Rather, we appeal to common sense understandings of human psychology and motivation, and how they have changed over the generations.

Addendum: When I say polygamy, I mean polygyny. I would say polygyny, but then readers get confused. Also, do not confuse social preference for polygyny with lack of female power. There are two modern models of polygynous societies, the African, and the Islamic. The Islamic attitude toward women shares much with the Hindu monogamist view, while in African societies women are much more independent economic actors, albeit within a patriarchal context. The authors note that this distinction is important, because it seems monogamy (e.g., Japan) is a better predictor of social capital than gender equality as such, despite the correlation.

Citation: Joseph Henrich, Robert Boyd, and Peter J. Richerson, The puzzle of monogamous marriage, Phil. Trans. R. Soc. B March 5, 2012 367 (1589) 657-669; doi:10.1098/rstb.2011.0290

Image credit: 1, 2, 3

January 25, 2012

Born to conform

Filed under: Culture,Evolution,Group Selection — Razib Khan @ 11:52 am

There is a new paper in Nature, Social networks and cooperation in hunter-gatherers, which is very interesting. As Joe Henrich observes in his view piece the panel of figure 2 (see left) is probably the most important section.

The study focuses on the Hadza, a hunter-gatherer population of Tanzania. Their language seems to be an isolate, though there have been suggestions of a connection to Khoisan. Additionally the genetic evidences tells us that like the Bushmen and Pygmies the Hadza do descend from populations which are basal to other human lineages, and were likely resident in their homeland before the arrival of farmers. And it is critical to also note that the Hadza are probably uninterrupted hunter-gatherers in terms of the history of their lifestyle, as agriculture likely arrived in Tanzania on the order of two thousand years ago, and their genetic distinctiveness indicates a separation from groups like Bantus far deeper in time. When it comes to Paleolithic model populations the Hadza are relatively “uncontaminated.”

So how does 2a matter? It shows a sharp discontinuity in cooperation across Hadza camps, all things controlled. There have been debates about the level of analysis necessary to explain human cooperation, with reductionists focused on the individual, arguing that dynamics such as kin selection and reciprocal altruism can explain the complexity we see around us simply through extension (e.g., universalist religious ideologies and philosophies usually appeal to fictive kinship or the golden rule). These data instead given some support to models which posit that group-level cultural dynamics must also be taken into account. Remember though that these more complicated systems don’t deny the importance of kin selection and reciprocal altruism; they only posit that there are other forces which can’t easily be reduced to these two.

The peculiarity of figure 2a illustrates the difference between transmission of culture, memes, and biology, genes. The Hadza are a small population, and genetically rather homogeneous in relation to their neighbors (to my knowledge they don’t exhibit much population substructure). It is difficult for between group variance to develop between human populations with adjacent residence patterns because even small amounts of migration rapidly equilibrate gene frequencies. This is why biologists have traditionally been skeptical of selection across groups. If the two entities are nearly clonal (because the groups do not differ much) then evolution by natural selection can not operate across the groups (remember, being clonal at the scale of the group does not mean there isn’t variation within groups, so selection still operates, just at a “lower” scale). But human culture is very different. Novel groups with their own distinctive cues can emerge very rapidly, and generate horizontal networks of affinity. Sometimes, as with accents, it is rather difficult for outsiders to a group to mimic and deceive because of a biologically “critical period” of enculturation (this might also be the role that radical body modification plays in a functional sense; it’s a difficult-to-fake identity marker, often irreversible).

That’s the theory. The main problem with these group-level models is that there’s always a lot of talk (theory), but a lot less empirical data. Hopefully that will change. The paper used a lot of experimental methods, and these are probably the way to go. Obviously you can’t put people in life or death situations, but you can at least discern general and specific patterns cross-culturally. And are these canned “games” any less valid than surveys to the WEIRD set?

Citation: Social networks and cooperation in hunter-gatherers, doi:10.1038/nature10736

Image credit: Wikipedia

June 14, 2011

Band of brothers at war

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 ...

July 13, 2010

The Price of Altruism


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Sometimes in a narrative you have secondary characters who you want to revisit. What do to do after the story is complete? An convenient “work-around” to this problem is to find the story rewritten from the perspective of the secondary character. In broad strokes the picture is unchanged, but in the finer grained shadings different details come into sharper relief. Though the exterior action may be unaltered, it gains different context, and the interior motive may radically alter, as the nature of subjective perspective matters so greatly in the last instance. In many ways Oren Harman’s The Price of Altruism reads to me like a narrative rewritten from the perspective of a character who was a supporting protagonist in other stories. George Price, almost a novelty act elsewhere, now becomes the primary point of view character.

I could almost say that Harman, a historian of science, has given us a novel from a “shared universe” of stories. That universe is the real world. The other stories are the lives of great scientists, and the plot consists of the working out of their ideas. In the acknowledgments Harman alludes to the wide range of works where fragments of George Price’s life filters through. I have read many of the mentioned works, The Darwin Wars, Defenders of the Truth, and Narrow Roads of Gene Land. In all of these George Price cuts a quixotic figure, mercurial, brilliant and exceedingly eccentric. His plain biography already peculiar. Price began his career as a chemist, shifted to journalism and became what we today would term a professional “skeptic,” then entered into a period of productivity as an evolutionary theorist of some major impact, and finally spent his last years attempting to live the life of a serious Christian who followed God’s commands to the best of his abilities. He died tragically, committing suicide in his early 50s in 1975, homeless, destitute, and serious ill.

Much of what I already know comes through the memories of William Hamilton in his collections of papers, titled Narrow Roads of Gene Land. In Narrow Roads of Gene Land Hamilton admits that he did not perceive in totality the implications of Price’s eponymous equation when he first encountered it (in particular, he did not initially comprehend that the two elements within the Price equation allowed for the possibility of group selection as you move up the nested hierarchies of organization and reassign the elements to ascending levels). In The Price of Altruism Oren Harman reiterates this reality, but, importantly he emphasizes that Price felt that it was Hamilton alone in all the world who had perceived the equation’s nature upon first encountering it. The back story, which is told in Narrow Roads of Gene Land, is that George Price had difficulty in getting his papers in this area published because the referees simply did not see the implications. Hamilton, perceiving the importance of Price’s ideas, connived to gain publication by making his own work conditional on the acceptance of Price’s paper (which he cited). As Hamilton already had a reputation the game worked.

The necessity of these strategies makes more sense in light of Price’s unconventional background and affect.  In evolutionary biology Price was self-taught, and he entered the field in large part because he was interested in the topic, and perceived that he was going to make some difference in the world. He arrived in London in the late 1960s, impressed people at the Galton Laboratory and managed to obtain a research grant and desk, and became an important stimulator of and collaborator with both William Hamilton and John Maynard Smith, arguably Britain’s two most prominent theoretical evolutionary biologists at the time. Price’s relationship to John Maynard Smith is referenced in Hamilton’s own biography, as well as third person narratives such as The Darwin Wars and Defenders of the Truth, but The Price of Altruism fleshes out many of the details. While Price extended Hamilton’s original work on inclusive fitness, for Maynard Smith he served more as a prod and collaborator as they explored the intersection of game theory and biology which eventually led to the ideas outlined in Evolution and Theory of Games. The “hawk” and “dove” morphs made famous by Richard Dawkins in The Selfish Gene go back to Maynard Smith’s work, but the terms themselves were of Price’s invention according to Harman. If I read Harman’s chronology correctly Price was already a fervent Christian by this time, having left atheism in the same period as he launched his career as an evolutionary biologist, and there is some hint that the term “dove” may have been influenced by his particular religious leanings. This possibility seems all the more amusing in light of Dawkins’ later career as an atheist polemicist. Price’s last contribution to evolutionary biology was an explication of Fisher’s fundamental theorem of natural selection. This formalism has been the subject of so much deep analysis, such that I think Price’s interest in it prefigured his later stab at Biblical textual analysis!

The Price of Altruism is a biography of a scientist, so naturally there’s a great deal of science. The meat and heart of the work is George Price’s life trajectory, with all its travails (many) and triumphs (few, but lasting and of importance). Yet the story begins with an exploration of the lives and opinions of men who seem of a different age, Thomas Huxley and Peter Kropotkin. Huxley and Kropotkin were archetypes, who anticipated two streams of evolutionary ecology and social theory which battled it out through the 20th century. Huxley was a man who saw nature as “red in tooth and claw,” the working out of amoral competitive forces, and human virtue as having emerged out and above nature, just as he had risen up from his working class origins to eminence. Kropotkin reflected a Russian viewpoint which saw cooperation as the norm, and competition as the deviation. For him virtue emerged from our natural tendencies. Lee Alan Dugatkin covers much of the same ground in The Altruism Equation. Great men who you meet elsewhere inevitably make cameo appearances in Harman’s narrative; R. A. Fisher, the brilliant cipher, J. B. S. Haldane, the hereditarian Marxist, and Sewall Wright, the American (also see The Origins of Theoretical Population Genetics). The bright lights of Price’s generation also make prominent appearances; William Hamilton and John Maynard Smith, their characters manifesting no great surprises, but also the schizophrenic genius Robert Trivers, with whom Price perhaps shares a great deal excepting his dark ending, as well as E. O. Wilson.

All of these individuals have an interest in evolutionary biology, but biology of a behavioral sort. Though molecular evolutionists such as Richard Lewontin and Motoo Kimura are references in The Price of Altruism, they’re ancillary to the thrust of the book’s central idea (though Lewontin seems to serve as a type, the brilliant scientist who saw the import of Price’s equation too late to engage in a productive exchange with George Price himself). Evolution, like theoretical physics, spans may domains of subject, from the aggregations of millions of individual life forms, to evolution of elements within individual genomes! The Price equation’s generality is such that it does speak to the phenomena which bubble just above the level of organizations of the substrate, DNA itself. But George Price’s focus was on higher, not lower, levels of organizations, human societies. Oren Harman makes this clear, for he brings to light Price’s correspondence with Paul Samuelson, one of the greatest economists of the 20th century. Before Price left for London and began his collaboration with Hamilton and Maynard Smith on altruism, he fancied reconstructing the basis of 20th century economics. By the end of his life Price suggested that he was going to go back to this initial impulse, and attempted to renew his correspondence with Samuelson in the hopes of obtaining a research fellowship of some sort. Price also engaged with the behavioral psychologist B. F. Skinner, though as with many of his encounters it seems that the two soured on each other, in part due to Price’s impolitic tendencies.

George Price’s aim was to explain human cooperation, altruism. In short, goodness. This is the domain of angels, but his analytical bent mean that he could not let the phenomenon lay. He had to break it down, reconstruct its fundamentals, and elaborate on how and why goodness, altruism, manifested itself in the world. From the details reported in The Price of Altruism I would have to admit that Price himself was a Janus-like figure, often being in a manifestly selfish fashion, abandoning his family to follow his intellectual bliss, and yet also radically altruistic, allowing himself to be exploited by the dregs of the London underclass near the end of his life because scripture told him so (or his reading of scripture). What I had previous read did not emphasize Price’s selfishness, his need to satisfy his own wants, and place his own elective priorities ahead of the mandatory ones which decency bound him to honor (e.g., supporting his wife and daughters). Harman has a rich catalog of George Price’s selfish actions and the small vendettas which wracked his soul. No saint was he. Much of what Harmon recounts was simply not evident from other sources. Perhaps in Hamilton’s case he wished to highlight the positive aspects of a good friend who had died tragically. More plausibly I suspect that Hamilton was simply not aware of the selfish sequence of acts which led George Price to the Galton Laboratory in the late 1960s. And it was during this period that George Price became a zealous Christian and a radical altruist. Hamilton’s perceptions may simply have been colored by the slice of Price’s life to which he was privy.

Oren Harman wonders at the end of the book if George Price may have been rather far along the asperger’s spectrum. If so, combined with his fierce intelligence, one is not surprised that Price exhibited a fixation on why and how humans behaved, and why and how it came to be that humans did not seem to be rational psychopaths. Though I do not know if, and honestly do not believe, that George Price was a rational psychopath, in The Price of Altruism Oren Harman paints a picture of a man with immediate urges and impulses, earthy hedonic priorities, and a strong tendency to discount the costs which his choices may have for those close to him. George Price was not the first man to not be a good father, but he was one who perhaps wondered why there were good fathers and bad fathers, those who followed their bliss despite the consequences to their progeny, and those who sacrificed so that their children could enjoy the comforts and pleasures which they elected to forgo. The science is well elucidated in works such as Unto Others, The Origins of Virtue and The Evolution of Cooperation. The Price of Altruism is rather a case study not of the theory of altruism, but of the concrete embodied human experience which eventually gave fruit to an important slice of the theory of altruism. From the small details of his day-t0-day actions, to the arc of his life, George Price played out some of the implications of his own intellectual edifice, both through contradiction and confirmation.

Recommended Reading: The Darwin Wars, The Evolutionists, A Reason for Everything, Narrow Roads of Gene Land, Natural Selection and Social Theory, The Origins of Theoretical Population Genetics, Sewall Wright and Evolutionary Biology, R.A. Fisher: The Life of a Scientist, Defenders of the Truth, Unto Others and The Selfish Gene.

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