Recently two economists, Quamrul Ashraf and Oded Galor, published an article in a prominent economics journal comparing genetic diversity in various countries with economic development (ungated version here).  They found the following relationship: high and low genetic diversity is associated with low economic performance.  High economic performance is associated with moderate levels of genetic diversity.  Below is the take-home “hump-shaped” graph comparing genetic diversity to per capital income for a slew of countries (lower numbers on the x-axis represent higher genetic diversity).

Critique 1: If any finding is consistent with an hypothesis, finding something is not very good support for the hypothesis.

Ashraf and Galors’s hypothesis, as quoted above, predicts that genetic diversity should have both a positive and a negative effect on economic productivity. The great thing about this sort of hypothesis is that it can explain any observed pattern in the data.

For example, in the stylized charts below, the top chart reflects the findings of Ashraf and Galor, highlighting the positive and negative effects of genetic diversity creating a “hump-shaped” curve.  The bottom chart reflects the exact opposite findings: a “trough-shaped curve.”  Notice that this curve is also consistent with Ashraf and Galor’s hypothesis – showing regions of “negative effects” and regions of “positive” effects.  Even a flat line would be consistent with their hypothesis (the effects cancel out!).  If any empirical pattern is consistent with an hypothesis, finding a specific empirical pattern that is consistent with the hypothesis is not too surprising.

Critique 2: Genetic Difference Only Matters on (Very) Small Scales

There is a large body of work in evolutionary biology on the scale at which genetic differences should matter in cooperation. The consistent finding is that genetic differences only matter for very close relatives, for animals like humans who have fairly limited number of offspring (unlike social insects), the scale at which genetic differences might matter is something under a dozen individuals.  Any more than that and genetic relatedness is just too diluted to make a difference. 

Countries are much bigger than a dozen individuals. Within a country, people might be more cooperative with their immediate relatives, but any genetic diversity beyond that shouldn’t matter.
  
When they hypothesize that genetic differences cause “miscoordination and distrust arising from genetic differences across members of society” this sounds a lot like kin recognition.  Basically, individuals act differently towards others based on observed genetic similarities and differences. In the classic paper by François Rousset and Denis Roze, they find that even under the most ideal conditions, kin recognition only works in extremely small groups [summary here].

Critique 3: Genetic Diversity Cannot Explain (much) Cognitive Diversity

Political scientist Scott Page has two books summarizing research into diversity from a variety of academic disciplines. One of the books’ key points is that are that the important type of diversity in group decision-making and innovation is “cognitive diversity,”  defined as “differences in how people see, categorize, understand, and go about improving the world.”

For example, economists see and understand the world differently than population geneticists. This implies that a study about population genetics and economics would be better if conducted by a mixed group of economists and population geneticists, than by a group of only economists or a group of only population geneticists (see what I did there).

What are the sources of cognitive diversity? Are they likely to be genetic? The answer is no.  The basic argument is that in any given group there is much more cognitive diversity than genetic diversity. Therefore, genetic diversity cannot explain very much cognitive diversity. Most cognitive diversity seems to result from differences in training and experience.

(Update: After posting this, I saw that Jason Collins posted today on the claimed relationship between genetic diversity and innovation.)

Conclusion: Reasons to Be Skeptical

 
I am skeptical of the conclusions of this study for three basic reasons. (1) The hypothesis is consistent with any observed pattern in the data, (2) the hypothesized negative effects of genetic diversity are unlikely to matter on the scale of countries, (3) the hypothesized positive effects of diversity are unlikely to be a result of genetic diversity.

I subscribe to various biology and political science journals. When scanning tables of contents, I always have an easier time deciding what biology papers to read than what political science papers to read. At first, I assumed this was because I knew more biology than political science. However, this never really changed as I learned more political science.

Today, I noticed a big difference in the way biologists and political scientists title papers. Biologists generally use their main result as a paper’s title and political scientists generally write titles that are more broad in scope.

For example, here are the most recent tables of contents from the American Political Science Review (a top political science journal) and Proceedings of the Royal Society B (a top biology journal). 

I have helpfully underlined articles titles that are also the authors’ key findings. These tend to be papers titled with a complete declarative sentence. In this sample, eight out of twelve (67%) of Proc B articles and zero out of twelve (0%) APSR articles follow this convention.

For someone interested in norms and institutions, this is an interesting puzzle.  My first instinct is to call this a somewhat arbitrary self-reenforcing norm.  In ecology, these titles might better meet the expectations of readers, reviewers and journal editors.  From the “journal article checklist” in Karban and Huntzinger’s How to Do Ecology book:

Is there a similar expectation in political science-style titles?

Or maybe there is something about political science and biology as disciplines that make them more prone to these conventions?  Perhaps biology articles are more focused on specific questions than political science which tend to be more broad?  Certainly political science articles are longer on average. Or are political scientists more cautious about sounding like they are trying to have the final word on a subject than biologists?

There seems to be advantages to each.  I likely read more political science paper abstracts than I would if they were titled more like biology papers. So in the end, I am more broadly exposed to political science than biology. However, when pressed for time I am probably more likely to read a paper selected from a biology journal since, because I can be more discriminating, my expected returns are higher.

Do political scientists rely more heavily on authors’ reputations when deciding what to read?  For example, since I know Branislav Slantchev, (who wrote one of the above APSR articles) is a game theorist working in international relations, I am pretty likely to read his paper.

Any thoughts?

PS – I originally titled this post something like “Article titling conventions in biology and political science.”

At the end of this article about human cooperation, West, El Mouden and Gardner (WEG), ask “Are Humans Special?”  The authors specifically consider two questions:

1) Do humans have especially high levels of altruism?

2)  Are humans special because cooperation occurs between non-relatives?

After reviewing the literature, they answer both of these questions in the negative, suggesting that human cooperation is not so special after all.  However, their argument misleads because they answer two questions separately that really should be answered together:  The special thing about cooperation in humans is that we have especially high levels of altruism that occurs between non-relatives.

Allow me to illustrate with a Venn diagram:

The left circle in the diagram represents altruistic cooperation.  This is normally defined as cooperation where an individual pays a cost and confers a benefit on another individual. In evolutionary biology, these are normally considered as reproductive costs and benefits at the level of the individual (some like to do the accounting at the level of the gene, but that is outside the scope of this post).  WEG give examples of non-altruistic cooperation:

…a number of organisms have higher levels of altruism than humans, ranging from social amoebae and bacteria to ants and cooperative breeding vertebrates… An extreme example at the altruistic end of the continuum is the long tailed tit, where helpers never reproduce and so
cooperation has been favoured purely by indirect fitness benefits.

Something to notice is that in each example (social amoeba, ants, and long-tailed tits) altruistic behavior occurs between close genetic relatives. For example, in most ant colonies workers are all the offspring of a single queen or multiple closely-related queens. And on top of that most ants are haplodiploid which makes workers even more genetically related. Because altruism promotes the fitness of similar genes in close relatives, this allows for large-scale altruistic cooperation in ants.  This is what WEG means by “purely indirect fitness benefits.”

In contrast, the right circle represents cooperation in non-kin. WEG write:

…cooperation between nonrelatives occurs in a range of organisms. Many forms of cooperation occur between nonrelatives in birds and mammals (Clutton-Brock, 2002). In cooperative breeding vertebrates, there are several examples where non-relatives cooperate, the indirect fitness benefits of cooperation appear to be negligible and it is thought that cooperation is driven by direct fitness benefits…

They do not give specific examples but this review by zoologist Tim Clutton-Brock describes cooperation between meerkats, pied babblers, and African wild dogs.  Something to notice about these examples is that cooperation is not altruistic. Instead, it is what is called mutualistic cooperation, which occurs where an individual’s behavior provides reproductive benefits to both itself and another individual. This is what WEG mean by “direct fitness benefits.”

For example, if an African wild dog goes hunting by itself, it can capture food which will help it reproduce. If more dogs join in the hunt, the expected return to the hunt increases with the number of dogs. If the returns to the hunt are only shared by participants, there is no reproductive cost to cooperation and, thus, cooperation is not altruistic (more about this in my encyclopedia article.)

But don’t take my word for it.  Here is WEG earlier in their paper:

Cooperation is defined as a behaviour which provides a benefit to another individual (recipient) and which is selected for because of its beneficial effect on the recipient (West et al., 2007b). This definition of cooperation therefore includes all altruistic (–/+) and some mutually
beneficial (+/+) behaviours.

If you were paying close attention to the Venn diagram you will notice that there is only one animal that is enclosed in both circles – humans – and this is the only animal described by WEG as being a member of both. This seemingly unique position is what makes human cooperation special – our willingness (or even eagerness) to cooperate altruistically with very distant genetic relatives. You see this type of cooperation all around us and we mostly take it for granted. There are extreme examples, like the willingness to sacrifice oneself for unrelated comrades in war, but also everyday examples like throwing trash in a can instead of on the street. Economic experiments have long established that individuals will often behave altruistically even when their behavior is completely anonymous and one-shot.

So why do humans cooperate altruistically with non-relatives? I am of the school that thinks this is a result of the unique properties of human social learning (i.e., human culture) – a topic I will discuss in a Part II of this post.

For obvious reasons, my RSS feed is full of blog posts about the (ir)rationality of voting in presidential elections. The skinny of the matter is that voting takes non-trivial effort, but the likelihood that one’s vote will matter (i.e., be the pivotal vote that decides the election) is very small. The arguments for voting are that, the likelihood of casting the pivotal vote isn’t really all that small compared to the rewards, if no one else voted then one’s vote would be pivotal, people get internal satisfaction from voting, and that people vote to signal how good they are to other people.

First I should say that I am skeptical of the last one because, well, a lot of people who vote spend at least some effort deciding who to vote for and, if they were just after the “I Voted” sticker, that would be wasted effort. Second, explaining voting by saying that it gives people internal satisfaction begs the question of why it people should get internal satisfaction from voting.

Some commentators focus on the material benefits of presidential elections in the cost-benefit analysis of voting. But let’s get away from the presidential election and its obvious benefits and ask a harder question (from a cost-benefit perspective).  Why do large numbers of people vote in the Eurovision Song Contest? Compared to the “benefits” side of the presidential election, they are basically voting to have a slightly larger number appear next to the name of a wind-swept Swedish pop singer instead of an adorable gaggle of Russian babushkas. Any theory explaining votes in presidential elections, should also apply to this harder case.

From here we can move on to a better understanding of why people yell at their television sets during professional (both American and rest-of-the-world) football games.

Awhile ago I caught myself writing the following sentence in a research proposal:

The proliferation of weapons is similar, in many respects, to what biologists call an evolutionary ‘arms race.’

There has to be a term for this sort of thing.

A few weeks ago, I was invited write a commentary for a Social Evolution Forum article by D.S. Wilson called “Human Cultures are Primarily Adaptive at the Group Level.” My commentary,”Should the Consensus be Essentialist and Adaptationist?” was just posted.

While I agreed with what I felt was the spirit of Wilson’s article, I had two caveats:

1) It is problematic to call human groups “cultures” in terms of multi-level selection models. The reason is that there is important variation in cultural traits within groups, and thinking of them as monolithic cultures encourages researchers to ignore this variation and instead focus on traits that are commonly held. For those of us interested in testing models of cultural evolution, this is a big problem with most ethnographic data  because ethnographers (anthropologists who study culture) have tended to ignore within-group variation and, instead, describe traits that generally define their particular study group. In my commentary, I refer to this thinking as a type of essentialism.

2) I am not ready to focus on adaptation. In evolutionary biology, adaptations are traits that appear to be designed for some purpose, but that exist because of the processes of natural selection. Some evolutionists focus on adaptations and some see explaining adaptations as the primary goal of evolutionary biology. Others, including me, are less interested in adaptation itself and more interested in explaining the distribution of traits in a population which may have resulted from different evolutionary mechanisms, including drift, mutation, migration, selection at different levels of analysis, and frequency-dependent selection. In terms of cultural inheritance, there are also different learning biases (more on these in a future post) that have to be taken into account. Focusing on adaptations may encourage researchers to ignore mechanisms other than selection and non-adaptive traits. This type of thinking is called adaptationsim.

In short, when looking at the fitness landscape, adaptationists tend to focus on the peaks, but I am more interested in explaining how traits are actually distributed across the whole landscape.

The modern science of cultural evolution and gene-culture coevolution began, by some accounts, in the 1960s with the work of psychologist Donald T. Campbell and further developed by Cavalli-Sforza and Feldman in the 1970s and Boyd and Richerson in the 1980s to the present.  This all seems rather late.  Why didn’t an evolutionary science of cultural change get started earlier?

All the pieces were there.  For example, Darwin’s “inherited habits” in The Descent of Man can be as easily (if not more easily) interpreted as descriptions of cultural transmission than genetic transmission. (Remember, Darwin did not know anything about genes).  When population geneticists started integrate Darwinian evolution with Mendelian genetics in the 1920s and 1930s using mathematical models,* why were there not evolutionary social scientists, in concert or in parallel, using mathematical models to describe cultural inheritance and or develop models of gene-cultural coevolution?

A couple years ago, from a brief mention in Lippman’s Public Opinion, I came across a 1921 book by political scientist Graham Wallas called Our Social Heritage. Although there were no mathematical models, Wallas had the basic premises for what I would consider relatively modern ideas concerning cultural inheritance.

First, Wallace specifies the difference between what he calls “biological” inheritance and “social” inheritance. Today we distinguish between “genetic” and “cultural” inheritance (since both systems are inherently biological). He also discusses things in terms of the nature/nurture divide which seems antiquated today.  But given that the population genetics was only three years old and it was still 30 years before Lewis and Crick published the structure of DNA, his description seems remarkably modern.

Our nature consists of those facts of structure and instinct which are inherited by the biological process of begetting and birth. We inherit biologically, for instance, the viscera by which we digest certain kinds of food, and the instincts which make us desire them; a skin which resists bacterial infection, and an instinct to brush away a fly before he pierces our skin; a highly complex nervous system and an instinctive impulse to think.

He also distinguishes between what we call individual and social learning.

Our nurture may be divided into two parts. The first part consists of that which each one of us acquires for himself, without learning it from other human beings. The second part consists of the knowledge and expedients and habits which were originally the personal acquisition of individuals, but which have been afterwards handed down from one generation to another by the social process of teaching and learning. It is this second part of our nurture which I shall call our “social heritage.”

Humans rely more on social learning than other animals.

Men differ widely from all other animals by the extent of their social heritage and the degree of their dependence on it. Those insects among whom one generation dies out before another is born can obviously have no social heritage at all; nor can fishes, or any other species among whom parents do not associate with their offspring. A certain amount of social heritage apparently exists in some species of birds…

He actually goes on about social heritage in birds at some length.  This is interesting because birds are thought to be the only other taxa, besides possibly chimpanzees, that show clear signs of “cumulative cultural evolution.”  From a 1995 Boyd and Richerson paper, “cumulative cultural evolution resulting in behaviors that no individual could invent on their own is limited to humans, song birds, and perhaps chimpanzees.”  The sign of cumulative cultural evolution is when cultural traits are complicated enough that individuals organisms could not figure them out on their own.  For an extreme example, no one could, starting from scratch, invent an automobile or an mp3 player. In birds, cumulative cultural evolution is associated with bird songs.

In one of my favorite passages from the book, Graham Wallas makes an implicit distinction between normal social learning and cumulative culture evolution with a rather long science-fiction type story where (1) a comet strikes the earth, (2) somehow deletes all of our cultural inheritance, which (3) eventually kills everyone in Europe and North America. I think someone should pitch this as a premise for a new NBC television drama.

The process of social inheritance is, as far as I know, not necessary for the existence of any wild non-human or variety. The swallows or the London rats might if they forgot all that they had learnt from their parents, sink for a few generations to one half or one quarter of their present numbers. But the most important and progressive varieties of the human race would probably, if social inheritance were in their case interrupted, die out altogether. If the earth were struck by one of Mr Wells’s comets and if, in consequence, every human being now alive were to lose all the knowledge and habits which he had acquired from preceding generations, though retaining unchanged all his own powers of invention and memory and habituation, nine tenths of the inhabitants of London or New York would be dead in a month and 99 per cent of the remaining tenth would be dead in six months. They would have no language to express their thoughts and no thoughts but vague reverie. They could not read notices or drive motors or horses. They would wander about, led by the inarticulate cries of a few naturally dominant individuals, drowning themselves, as thirst came on, in hundreds at the riverside landing places, looting those shops where the smell of decaying food attracted them and, perhaps at the end stumbling on the expedient of cannibalism. Even in the country districts, men could not invent, in time to preserve their lives, methods of growing food, or taming animals, or making fire, or so clothing themselves as to endure a northern winter. An attack of constipation or measles would be invariably fatal. After a few years mankind would almost certainly disappear from the northern and temperate zones…

He also writes about what we would now call “gene-culture coevolution,” hypothesizing that cultural traits should influence genetic ones and comparing our genes to a parasitic barnacle. 

Man has been increasingly dependent on his social heritage since the beginning of conventional language and of the art of flint-chipping, that is to say, for perhaps half a million years. This fact has brought about important modifications in our biologically inherited nature. We have become biologically more fitted to live with the help of our social heritage and biologically less fitted to live without it. We have become, one may say, biologically parasitic upon our social heritage. Just as the parasitic crustacean sacculina, after living for unnumbered thousands of generations upon the body-juices of the crab, has evolved special organs and a special body of instincts which fit it to obtain that food and unfit it to live without that food; so man has evolved and is still evolving certain modifications of structure and instinct, which, while they increase his power of acquiring and using social heritage also increase his dependence on it.

Since these ideas were in the ether, why didn’t some enterprising researcher take them on and independently, or in concert with population geneticists at the time, develop a more complete Darwinian synthesis.  Perhaps Wallas could have inspired this effort.  As one of the founders of the London School of Economics, he was no slouch.  However, he wrote this book towards the end of his career and, perhaps, did not promote these ideas with the persistence of one establishing a career.

Although I would like to picture an alternate history where Fisher or some analogous person tackled cultural evolution with the drive of the early population geneticists, perhaps the history of science is just a road routed by the whims of path dependence.

But it is nice to have so much work ahead.

PS – In the later chapters of the book, Wallas applies his ideas about social inheritance to furthering cooperation and preventing conflict both within and between states.  Since this is a focus of my research, I find his ideas her interesting – at least from an historic perspective, but will save them for a later post.

* – Before population genetics, Darwinians and Medellians had considered themselves members of rival camps.

This month the University of California Press published the Encyclopedia of Theoretical Ecology.  I have an article in it, written with Richard McElreath and Pete Richerson, on the “Evolution of Cooperation.” The article’s intended audience are undergraduate biology majors and graduate students with backgrounds in evolutionary biology or ecology, but it might also be relevant to social scientists interested in evolutionary game theory.  You can read the article, in its entirety, here.  Below is a brief summary.

In the article, we try to give an overview of work in the evolution of cooperation and also alert the reader to some common misunderstandings, listed below.  If you keep some of these ideas in your back pocket, you can pull them out at parties conferences to impress your friends colleagues! (YMMV):

1. Not all observed cooperative behavior is altruistic.  Many cooperative behaviors are mutualisms or coordination or threshold cooperation.  (The article explains what we mean by these terms with a simple model of cooperative hunting in wolves.)  Theorists and empiricists tend to focus on models of altruism, but it is important to determine what model of cooperation is most appropriate to the question being asked.  However, this is often hard to do.  (See also Tim Clutton-Brock and Brian Skyrms.)
2.  Kin-selection and group-selection are not different mechanisms of selection, they are different ways of accounting for fitness effects in models of selection.  This argument will not be new to regular readers of this blog, so I will not repeat it here.  However, I should point out that our encyclopedia article was finished in summer 2010, before the huge dust-up over Nowak, Tarnita, and Wilson’s infamous anti-kin-selection article and before the recent anti-group-selection writings of Dawkins and Pinker.  It turns out that our claim that “old debates concerning the ‘correct’ style of analysis have largely faded in biology” was, in retrospect, sadly premature.  However, in editing the page proofs, we were able to sneak in a reference to this excellent review of the debate by Lion, Jansen and Day.
3. All models where altruism evolves are based on mechanisms of positive assortment – that is mechanisms where altruists are sufficiently more likely to interact with each other than with non-altruists.  Plausible mechanisms of assortment are limited dispersal (biologists sometimes call this population structure or viscosity and social scientists sometimes call this clustering), signaling (green beards and kin recognition), and book-keeping (direct and indirect reciprocity).    
4. Tit-for-Tat is not an evolutionarily stable strategy in the iterated prisoner’s dilemma.  In fact, there are no evolutionarily stable strategies in the interated prisoner’s dilemma.  In fact, there are no evolutionarily stable strategies in any sufficiently iterated game.  This is an old result (see Boyd and Loberbaum), but many social scientists seem unaware of it.  My guess is that this is because Axelrod’s Evolution of Cooperation is still the most common introduction to cooperation in the social sciences and, while Axelrod’s book should be required reading for anyone interested in cooperation, it is particularly confusing on this point.  I will elaborate on this further in a future post
5. In humans, cultural inheritance is more likely to generate altruistic behavior in large groups than genetic inheritance.  This is because it is much easier to maintain cultural variation between groups than genetic variation in the face of migration (i.e., the children of immigrants tend to adopt the cultural norms of their new group, but they still have copies of their parents’ genes).

It occurs to me that the points in the above list will not be clear to many readers.  This is just a taste!  If you are interested in more elaboration and examples, give the actual article a try!

So I think the dust has finally settled on Steven Pinker’s Edge article on group selection.  It is followed by 20 commentaries from different perspectives (some of which I’ve already linked to on this blog) and Pinker’s reply.  Plus another series of replies (some overlapping) on The Social Evolution Forum.  There was even a post about Pinker’s article on Andrew Gelman’s statistics blog.

I have noticed that in my blog’s short history I have more posts of criticism than positive contribution.  There are many responses I generally agreed with, and I linked to them in earlier posts.  But in this one I thought I would highlight responses that I think put the debate in a larger framework.

First, I think David Queller’s response is excellent, short and pithy.  He compares kin selection modeling to English and group selection modeling to Russian – with the point that you can often say the same thing in both languages – but sometimes it is easier to say it in one language than another.  Queller’s response is particularly interesting because he is a traditional theorhetical evolutionary biologist who does primarily inclusive fitness modeling

D. S. Wilson expands on Queller’s analogy in a post at the Social Evolution Forum called the Clash of Paradigms: Why Proponents of Multilevel Selection Theory and Inclusive Fitness Theory Sometimes (But Not Always) Misunderstand Each Other.    What I like about this section is his distinction between “unilinguals”  and “bilinguals.” Some quotes:

In short, the current clash between proponents of [Multilevel Selection Theory] and [Inclusive Fitness Theory] is primarily a clash between people who are fluent in one paradigm and confused by the other paradigm, which they falsely attribute to the other paradigm in some absolute sense. This is like saying “Russian is confusing”, rather than “Russian is confusing for a non-Russian speaker such as myself.”

 It is possible to be bilingual… Many evolutionists are fluent in both MLST and IFT, a fact that is sometimes obscured by the chest-thumping rhetoric of unilinguals…

For these and many other evolutionists, toggling back and forth between MLST and IFT has become normal science, with no need for chest-thumping rhetoric. The choice of theory is simply a matter of choosing the best tool for the job.

Joe Henrich makes an analogy to an engineer deciding on a coordinate system to use for a problem in orbital mechanics.  I like this analogy because it stresses the fact that even if it is possible to solve a problem in two different ways, it is often much more easily done in one  This analogy has particular resonance for me because much of my four years of undergraduate engineering instruction seemed largely an exercise in banging my head against the wall for (doing something roughly equivalent to) trying to solve a problem in the wrong coordinate system.  For this analogy, your own mileage may vary…

A useful analogy might be the problem that an aerospace engineer faces when trying to model the trajectory of a satellite. A critical first step in solving such a problem is to select a coordinate system and a place to anchor that coordinate system in space (the origin). Among others, one can pick a spherical coordinate system (two angles and a distance) and anchor it to, say, the center of the earth; or, one can pick a Cartesian coordinate system (x, y, z orthogonal dimensions) and anchor it to a passing meteor. It is completely possible to calculate the orbit of a satellite with any number of different coordinate systems including these two, but picking the first system will allow you to easily solve the problem (analytically, using some solid assumptions) while building your intuitions about the movements of earth’s satellites. The second approach will be really hard, and provide you with no new intuitions. So, these are “equivalent” in some sense, but they are not equally useful for any particular problem. And, so it is with evolutionary accounting systems….

Rejecting group selection models is like banning spherical coordinates because you prefer to do your verbal reasoning in Cartesian coordinates.

Richard McElreath (disclosure: one of my committee members) makes a similar analogy to Bayesian vs frequentist statistics in the comments on Andrew Gelman’s blog.

I should mention that both Richard McElreath and David Queller signed the many-authored Nature paper and, from what I have heard, David Queller helped organize it.  This should cast doubt on Richard Dawkin’s implication that the signers of the paper were all against group selection.  Undoubtedly the co-signers had both bilinguals and unilinguals (and probably some nonlinguals) among them.

So, far these authors see inclusive fitness and multilevel selection as two modeling tools with varying degrees of usefulness.  Pinker does not like this line of argument.

If the two theories really are equivalent, then any advantage of group selection… would have to come from the models’ being more convenient, elegant, simple, transparent, explanatory, or mathematically tractable. Yet by stretching the meaning of “group” beyond its ordinary sense, that’s just what they fail to be. According to the old song, “We belong to a mutual admiration society, my baby and me”—the whimsy hinging on the unnaturalness of referring to a pair of individuals as a “society.” The same is true for “group.” While mathematically speaking one can identify a “group” with any arbitrary set, in practice using a single construct for a pair of siblings, a person holding a door open for a stranger, a waitress and a customer, a married couple, a street gang, a traditional band or tribe, a nation, and an empire conceals the significant psychological differences among them.

This line of reasoning is just odd to me. The theorist should define a group in a way that is useful and intuitive to the question under consideration and the model one is building.  *shrugs*  Just as you can apply inclusive fitness models to different types organisms, you can apply multilevel selection models to different types of groups.

He also does not like the fact that multilevel selection models make simplifying assumptions (comparing them to “spherical cows”).  This gives the impression that he does not realize that inclusive fitness models also make simplifying assumptions.   In fact, all models make simplifying assumptions – that is why they are models.

To be fair, I generally have a harder time following elaborate word-arguments than more precise math arguments.  I do not know if Pinker has actually ever tried his hand at mathematical modeling or has even worked through any of the models he writes about, but he does not give that impression.*  But the proof is in the pudding.

Pinker would more easy prove his point to more quantitative naysayers by, as Joe Henrich suggests, taking this MLS model by Sam Bowles and reformulating it as an inclusive fitness model.  Joe Henrich:

Of course, it may be possible! It’s also possible to calculate the position of that earth orbiting satellite using the coordinate system attached to the passing meteor. Good luck.

This would be hard enough and if Pinker hasn’t done a lot of modeling this would be a good way to learn.  But then, after all the work that task would undoubtedly take, the trick would then be to explain the math both ways to, say, advanced undergrads in evolutionary biology and see which framework is more transparent and intuitive. Good luck!

* Pinker seems, for example, unaware of the folk theorem’s application to reciprocity models – which may be a subject of a future post on this blog.