More fallout from the 2010 Nowak, Tarnita and Wilson kin selection meltdown

Fallout from the 2010 Nowak, Tarnita and Wilson kin selection meltdown continues to rain down. Earlier this year we had this (from Wilson and Nowak):

Inadequacy of Inclusive Fitness and Beyond

The evolution of social insects often is presented as a testing ground for inclusive fitness theory. It has been claimed that inclusive fitness can explain sex allocation, worker policing, conflict resolution, and evolution of eusociality (14), but precise calculations of inclusive fitness do not exist for any of these phenomena. Relatedness-based arguments, such as the monogamy window hypothesis, are not necessarily wrong but rarely provide a complete picture; moreover, one cannot rely on inclusive fitness to determine when they are correct. The failure of inclusive fitness theory to provide exact calculations is not surprising, because a mathematically meaningful approach to inclusive fitness (72) cannot be performed for the majority of evolutionary processes (5), and the linear regression method (73⇓–75) does not provide meaningful insights and cannot make empirical predictions (76). In general it is not possible to study social evolution from the perspective of an individual by evoking the virtual quantity of inclusive fitness. Instead we should focus on how natural selection acts on alleles that modify social behavior. On the level of genes or alleles, there is no inclusive fitness: Mathematical descriptions of the evolutionary dynamics of genetic mutations do not require a partition of fitness effects (which usually is impossible anyway) or any other aspect of inclusive fitness theory.

These folk have a bee in their bonnett. I - and many other scientists - think it is a stupid one. For homework, I think these authors should write an article explaining - at undergraduate level - why kin selection has been as successful as it has been - including when and why it is useful. At the moment, it doesn't look as though they are clear on these topics. The Price equation can't be used to make empirical predictions? It might be funny if it wasn't so silly and sad. If you don't have a sympathetic understanding of a topic, you are often in a poor position to criticise it. You wind up attacking straw men of your own making.

IMO, probably the main lesson here for other scientists is the value of humility in science. If you are overconfident, nail your flag to the mast and then dig in then it is easy to wind up making a fool out of yourself.

Kin or group selection: which is more confusing

The last decade has seen a bit of a shake out in the domain of kin selection and group selection.

Until recently it was possible to argue that the group selection advocates were consistently more confused about social evolution than users of kin selection. However as group selection advocates learned more about their topic some of them gradually started making sense - and some of them now hold fairly reasonable positions.

Also, it has become clear that some of the opponents of group selection are very confused about the whole topic. Steven Pinker wrote a fairly embarrassing article on the topic in 2012 - and some of that article's commentators made similarly embarrassing follow-ups.

Popular blogger Jerry Coyne has written a string of articles about group selection. He doesn't seem to have made much effort to understand what advocates of group selection are saying - and so produces mostly straw man attacks.

Richard Dawkins isn't exactly helping either. For example, he writes:

Is a group a replicator? No. We do not have a 'group pool', a metapopulation in which some groups are more successful than others at making replicas of themselves, replicas that persist through geological time.

This seems like classic replicator rot to me. Try talking about copying and heredity instead, and we do indeed have collections of groups, some of which are better at making copies of themselves than others. Maybe none of them are especially brilliant at making copies of themselves: but so what?

The broad equivalence between kin and group selection makes the issue of which framework causes more confusion into a significant issue. One of the main problems with group selection historically has not been that it's wrong, but that it is confusing and easy to mis-apply.

The confusion by the group selection opponents is unfortunate. It doesn't help to make the case that kin selection is less confusing and less subject to abuse.

However, I think it is still dwarfed by the confusion related to group selection. Martin Nowak and E.O. Wilson are perhaps the most prominent examples - but it seems to me that they represent only the tip of a pretty substantial iceberg.

Kin selection and its critics

Here's an interesting new paper: Kin Selection and Its Critics - Jonathan Birch and Samir Okasha.

Samir Okasha wrote a rather flawed book on group selection some years ago. However, this article shows that he is doing a good job of keeping up with developments in the field - and it isn't so easy to find significant mistakes in this large recent article.

I think one problem is that it takes the work of Nowak and Wilson a bit too seriously.

In one place the authors argue against equivalence, saying:

In one respect, the kin selection approach is arguably more general than the multilevel approach, because the latter requires that individuals be nested into nonoverlapping groups, as in figure 4; this is necessary for the decomposition technique in box 2 to apply (Hamilton 1975, Okasha 2006, Frank 2013). Groups of this sort exist in some taxa (e.g., the colonies of many social insect species). But in other cases, individuals engage in social interactions with their conspecifics, but there are no well-defined, discrete groups. The kin selection approach can handle such cases easily; indicative of this is that in deriving equation 4 above (box 1), we did not make use of the fact that the individuals were nested into nonoverlapping groups. Therfore, the claim that kin and multilevel selection are formally equivalent requires at least this qualification.

This doesn't seem like too much of a stumbling block to me. The modern "group selection" approaches depend critically on defining a "group" to include any collection of organisms - no matter how fleeting or ephemeral. You have to buy into this conception of a "group" for the approach to be worth considering in the first place.

The authors say:

The widespread preference for kin selection may be partly due to multilevel selection's association with the flawed good-of-the-group tradition of the 1950s and 1960s and the associated superorganism concept, of which many biologists remain suspicious. It is undeniable that the careless appeal to group-level advantage as a way of explaining a trait's evolution led to serious errors in the past, so biologists’ wariness of this mode of explanation is understandable.

That's about the size of it. However, this paints group selection's problems as being in the past. I think that this is inaccurate. A fairly cursory look at the evolutionary social sciences shows that misapplication of group selection is still widespread.

The essay closes with a plea for "causal aptness": use kin selection when you have relatives, use group selection when you have interacting groups. This proposal sounds reasonable - but I think it would do little to stem the existing misuse of group selection. The problem is that people see differential group reproduction, reach for group selection, and produce just-so stories about how group traits are the product of differential group extinction or reproduction. This is a systematically bad methodology that use of group selection directly encourages. Using "causal aptness" would probably boost usage of group selection. That seems as though it is likely to cause a range of negative outcomes associated with the misuse of group selection - and so I regard the proposal as suspect.

"Causal aptness" is one proposal. A big health warning relating to the misuses of group selection is another. I think that, if you adopt the first proposal, you should also adopt the second one.

Disagree with Steve Frank

I read Steve Frank's paper A new theory of cooperation recently. Steve Frank is an expert, but I thought that this paper was mostly wrong. The theme of the paper is that suppression of competition within groups represents a new theory of cooperation - that beyond kin selection and reciprocity. He credits the development of the idea to Richard Alexander - in The Biology of Moral Systems.

Many of the examples of suppression of competition within groups Steve gives are due to kin selection. Steve disagrees with this, writing:

[...] the main weakness of the theory was also apparent. Extensive cooperation occurs between nonrelatives. Different genes in genomes are functionally integrated but not related. Larger human societies often have many highly cooperative but distantly related individuals. Some of this cooperation between nonkin can be explained by extensions of reciprocity to a general notion of mutual benefit for interacting partners (West Eberhard 1975).

In the early 1980s, kin selection plus these extended notions of reciprocity were the main conceptual tools. Those limited conceptual tools led to blind spots about unsolved problems. Only rather forced theories of mutualism could work for the nearly complete integration of genes into cooperative genomes. Only a very enthusiastic belief in the scope of reciprocity could explain the broad social integration in larger groups of weakly related human

However, cooperation between groups of "unrelated humans" that is not due to reciprocity has turned out to be largely associated with cultural kin selection. This is kin selection applied to memes - not genes. Many of Steve Frank's examples fit onto the familiar kin selection / group selection axis - though he apparently doesn't fully realise this.

There is indeed another force that produces cooperation besides reciprocity and kin selection - and that is "manipulation". Manipulation is where agents impose their wills on other agents. Teams sometimes cooperate because they are cooerced into doing so by supervisor figures. Manipulation helps to explain suppression of competition in cooperative genomes. The efforts of individual genes to bypass meiosis is thwarted by the "parliament of genes" in the genome. Manipulation isn't the same as kin selection or reciprocity - so Steve Frank's paper is partly correct.

However, I think that there's a good reason to call this "manipulation" and not "suppression of competition". "Suppression of competition" is just another way of saying "cooperation". Explaining cooperation in terms of "suppression of competition" seems pretty circular to me.

Manipulation is responsible for the symbiont hypothesis of eusociality. This was proposed in 1934. The "parliament of genes" phrase comes from Leigh (1971). Since manipulation is such an obvious and well-known phenomenon, there may well be earlier examples of it being involved to explain cooperative behaviour. As a theory of cooperation, the idea is not exactly new - and I'm pretty sure that Richard Alexander wasn't responsible for it.

In The Biology of Moral Systems, Richard Alexander wrote:

It is a common error to suppose that something additional to nepotism and reciprocity is required to account for the structure of society. (p.153)

Here it sounds as though he repudiates this particular revolution.

West and Gardner on kin vs group selection

West and Gardner have not been shy about pointing out the virtues of kin selection over group selection. Here they are with a summary in 2013:

The most frequently used methods are neighbour-modulated and inclusive fitness. In particular, modern neighbour-modulated fitness methods allow the modeller to go from the underlying biology to an expression or fitness, in a way that facilitates the development of relatively general models [8,27,28,35,37]. In contrast, the group selection approach is used relatively little for modelling specific traits partly because as soon as one moves away from the simplest, most abstract models, and wants to add in real world biology, it often becomes analytically intractable — for example, when populations are structured into different classes of individual, according to sex, age, caste or ploidy [38–40].

I know these folk also have plenty of other objections to group selection. Here, forced to pick one, they went for analytic tractablility. It seems like an odd choice to me. As a veteran computer modeller, analytic tractablility comes relatively low on my list of virtues. I would probably list group selection's association with junk science as my number one complaint.

Identity by descent: a confusing concept

There's a lot of discussion of kin selection using the term "identical by descent" and "identical by state". The idea of "identical by descent" is that genes are shared as a result of direct descent from a common ancestor - without recombination or mutation. "Identical by state" just means that the DNA sequence is shared. It is said that 50% of their genes with their daughters "IBD".

I think the "identical by descent" terminology is confusing and not useful. In biology, if genes are identical, they are practically always identical through being copied from one (or more) shared ancestors. Mothers share more than 50% of their genes with their daughters - due to genes that have reached fixation, inbreeding and so on. However they still share these gene sequences due to descent from shared ancestors. As to a gene mutating into another form and then mutating back again. If you do the sums, for a gene of any reasonable size this rapidly becomes ridiculously unlikely. There's too much scope for neutral mutations elsewhere. In practice, when genes are identical, the odds are enormously in favour of this being due to shared ancestry. The idea that recombination with an identical gene makes genes not "identical by descent" is an awful one. They are still "identical by descent" - just descent from various different ancestors.

You can't say that mothers share 50% of their genes with their daughters "IBD". It is confusing and mistaken. If you want to use the 50% figure, you have to find another reason for doing so.

Analysis of "group selection and inclusive fitness are not equivalent"

I briefly analyzed the paper:

Group selection and inclusive fitness are not equivalent; the Price equation vs. models and statistics by Matthijs van Veelen, Julian Garcia, Maurice W. Sabelis, Martijn Egas.

This is one of the papers mentioned on my equivalence naysayers page.

The paper claims that group selection and kin selection are not equivalent. It argues that inclusive fitness requires fitnesses to be "additive". Additive fitness is a common assumption when deriving Hamilton's rule - and is indeed associated with inclusive fitness. However, inclusive fitness is a simplified model of kin selection. Kin selection enthusiasts are not too impressed with such critiques - the limitations of inclusive fitness are well known. The paper uses "kin selection" and "inclusive fitness" as though these concepts are interchangeable. I think this is not all that useful an approach.

Kin selection doesn't depend on fitness being additive. That idea is associated with inclusive fitness and Hamilton's rule. These are concepts associated with simplified models of kin selection.

Hamilton advocated using "inclusive fitness" instead of "kin selection". Hamilton (1975) "Innate social aptitudes of man" says:

The usefulness of the ‘inclusive fitness’ approach to social behaviour (i.e. an approach using criteria like (b K-k) > 0) is more general than the ‘group selection’, ‘kin selection’, or ‘reciprocal altruism’ approaches.

However, I think the pendulum has swung away from "inclusive fitness" and back towards "kin selection" as the term of choice. That's what Gardner and West use tend to use, for example. I'm with them.

Steven Frank on why kin selection beats group selection

Here's Steven Frank writing fairly recently - on why kin selection is better than group selection:

In more complicated biological problems, it often becomes difficult to express all of the selective forces in terms of relative variances among groups. The problem is that patterns of interaction may differ with respect to different processes, such as mating, competition between certain individuals such as males, and competition between other individuals such as females. In that sort of realistic scenario, it is far easier to trace pathways of causation through a series of partial correlations that can be interpreted as an extended form of kin selection analysis (Frank, 1986, 1998). In practice, it is rarely sensible to express such multiple pathways of causation by expressions of relative amounts of variance among groups, although such expressions may be possible mathematically. For that reason, kin selection often becomes a more natural form of analysis for realistic biological problems, leading to a generalized path analysis framework.

I think this is part of it. The idea of a "trait group" represents an attempt to overcome this issue. However there are other reasons too:

• Kin selection is more quantification-friendly - with its r, b and c;
• In practice, use of group selection often seems to lead to naive group selection;
• Group selection avoids problems where kin selection is obviously responsible;

These problems have also led to issues associated with scientific status. Group selection is promoted by scientific rebels who try and pick holes in established views. That appeals to some - while repulsing others.

Confusion about the topic in the popular press

The popular presentation of the kin selection vs group selection affair still seems to be very confused. For example, consider the coverage of a recent study by some group selection advocates: "Elusive Form of Evolution Seen in Spiders". The article says:

According to one model, known as kin selection, highly related organisms such as bees and ants can develop altruistic behavior — for example, many females forgo reproduction in order to raise the queen’s brood — because they will still pass down their genes indirectly, through the queen. But despite its altruistic appearance, kin selection is selfish — it helps an individual’s genes to survive. Can natural selection promote truly unselfish traits, behaviors that are good for the group, but not necessarily to the benefit of individuals (or their immediate kin)? Some evolutionary models predict that it can [...]

The rest of the article is all about group selection. Can kin selection be selfish while group selection is altruistic? Not according to the modern scientific consensus on the topic - that has kin selection and group selection being different accounting methods that attempt to account for the way in which genes propagate in viscous populations. Modern versions of these theories make the same predictions.

Originally, group selection was widely imagined as taking place between demes. However Williams, Maynard Smith, Dawkins and many others pointed out that this sort of "group selection" didn't work very well - individual-level adaptations swamped the group-level ones. Much later, the "groups" of group selection were re-imagined as involving any kind of social cohesion, including - critically - family groups consisting of mothers and their offspring - or groups of siblings. Individuals are then modeled as being part of an enormous number of partly-overlapping groups - including, critically, close family groups. With this radical readjustment, this new form of group selection - if properly applied - reproduces the predictions of kin selection exactly.

Most group selection advocates have now (finally) come on board with the scientific consensus on kin selection that was established in the 1970s. They recognize they these two theories - if properly applied - produce the same predictions and results. However, you wouldn't guess at this from this popular article. It's promoting the idea of group selection as a novel, revolutionary theory. This conception of group selection is not scientifically accurate.

Another article promoting the study has a different take on it: group selection vs gene selection. Their champions of "gene selection" are Pinker and Dawkins. It should really be group selection vs kin selection. Genes (in the broad sense of heritable information) underlie both.

More coverage:

• Is 'group selection' a thing? Spiders support an evolutionary, revolutionary idea - Jim Algar
• The Silken Reef: Social Spiders and Evolution by Group Selection - Michael Schultheiss

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Update 2014-10-29: Goodnight has weighed in on his spider study on his blog. Kin selection and equivalence are apparently unmentionable topics. To me this seems like a parallel universe.

Cultural group selection - bibliography

I have previously posted bibliographies of cultural kin selection and the closely-related topic of tag-based cooperation. However some academics have been studying the same topic under a different name and using different models and approaches.

Most bibliographies of cultural group selection seem to be in pre-internet document formats: devoid of links. Here's an HTML linkified one:

• Andre, J.B. and Morin, O. (2011) Questioning the cultural evolution of altruism.
• Bell, Adrianm Richerson, Peter J. and McElreath, Richard (2009) Culture rather than genes provides greater scope for the evolution of large-scale human prosociality.
• Boyd, R. and Richerson, Peter J. (2010) Transmission coupling mechanisms: cultural group selection.
• Boyd, R., Richerson, Peter J. (2002) Group beneficial norms can spread rapidly in a structured population.
• Boyd, R., Richerson, Peter J. (2009) Culture and the evolution of human cooperation.
• Boyd, R. & Richerson, Peter J. (1985) Culture and the Evolutionary Process.
• Cullen, Ben R. S. (1995) On Cultural Group Selection.
• De Smedt, Johan and De Cruz, Helen (2012) Human Artistic Behaviour: Adaptation, Byproduct, or Cultural Group Selection?
• Efferson, Charles, Rafael Lalive, and Ernst Fehr (2008) The coevolution of cultural groups and ingroup favoritism.
• Henrich, Joseph (2004) Cultural group selection, coevolutionary processes and large-scale cooperation (preprint).
• Henrich, Joseph and Boyd, R. (1998) The Evolution of Conformist Transmission and the Emergence of Between-Group Differences
• Molleman, L., Quinones, A.E. & Weissing, F.J. (2013) Cultural evolution of cooperation: the interplay between forms of social learning and group selection
• Richerson, Peter J. & Boyd, R. (1990) Group selection among alternative evolutionarily stable strategies.
• Richerson, Peter J. & Boyd, R. (1999) The evolutionary dynamics of a crude super organism.
• Richerson, Peter J. & Boyd, R. (2008) Solving the Puzzle of Human Cooperation
• Soltis, J., Boyd, R., Richerson, Peter J. (1995) Can group-functional behaviors evolve by cultural group selection? An empirical test.
• Steele, D. R. Hayek's Theory of Cultural Group Selection.
• Zimmerman, Matt, McElreath, Richard and Richerson, Peter J. (2012) Evolution of Cooperation.

Group selection is surprisingly popular

Some statistics follow:

Google trends:

Google NGRAM:

Google scholar:

• "group selection": 66,000;
• "kin selection": 29,300;
• "inclusive fitness": 21,500;

Even if you add together the "kin selection" and "inclusive fitness" volumes, "group selection" often comes out on top.

Group selection doesn't look particularly down-trodden - from this data.

How kin selection pushed group selection into the scientific fringes

Group selection lost out to kin selection in the 1960s and 1970s as an explanation for cooperative behaviour. Group selection went on to lead an underground existence - in which a few remaining proponents sought out ways to find things which group selection explained which kin selection did not.

We now know that modern versions of these theories make the same predictions. So there isn't really anything that group selection can explain that kin selection cannot. However this didn't stop the group selection proponents from trying to find these types of phenomena. Indeed, if they had succeeded, fame and glory would have awaited them.

This quest took group selection to the borderlands of science. Kin selection was uncontroversially used to explain obvious adaptations - such as breast feeding, parental care and nepotism. Group selection picked more controversial targets - senescence, the maintenance of sexual recombination and cultural evolution. The theme of these topics seems to have been avoiding rapid refutation of: "kin selection explains that without invoking group selection".

This quest now seems to be mostly over. Most of the group selection enthusiasts have publicly given up their original quest - and have accepted the equivalence between kin selection and group selection.

However the topics group selection is invoked to explain still seem to be skewed away from those that kin selection is used to explain. As a result, group selection is generally offered as an explanation in areas where the theory doesn't function well. This seems like a hangover which group selection is still recovering from.

The "multi-level" terminology

This article will claim that "multi-level selection" and "group selection" should not be understood as being synonyms.

It does appear that "multi-level selection" is terminology that was invented to give group selection a face lift - and allow it to escape from an unglamorous past.

However, group selection is not more or less "multi-level" than kin selection is. The concepts of "relatedness" and "kin selection" can be applied at multiple levels too. One can meaningfully discuss the relatednes between cells in an ant, the relatedness between an ant and its sisters and the relatedness between entire colonies of ants. This has been understood since the 1970s and it can be seen as a result of the generality of the Price equation.

These days, group selection enthusiasts often prefer to use the "multi-level selection" terminology. This article is my explanation of why I rarely follow them - and why I think it is a confusing gambit. Kin selection is "multi-level" too. Using the term "multi-level selection" fails to distinguish between kin selection and group selection. It is true that kin selection and group selection are equivalent - in the sense that modern versions of these theories make the same predictions. However that doesn't mean that proponents use the same methodologies. These are still topics that are worth distinguishing between. The best way of doing that is, I think to use the terms "kin selection" and "group selection".

Group selection enthusiasm still rampant in the social sciences

Most evolutionary biologists got over group selection back in the 1970s. However, there's one area of biology where it is particularly prominent: the social social sciences. There's particular enthusiasm for cultural group selection - as though cultural evolution plays by different rules in this area.

Cultural kin selection represents an alternative perspective which makes little mention of selection acting on groups. Instead of humans being part of innumerable overlapping groups, their genes and memes are modeled as being related to the genes and memes of others. This perspective has been much more enlightening in the organic realm, and I think it will prove to be much more enlightening in the cultural realm as well. The largely-fictional groups of group selection are just a clumsy and awkward way of viewing the situation - most of the time. The perspective has a long history of producing dud science.

In most of evolutionary biology, 90% of scientists are using kin selection and 10% are using group selection. In the social sciences, it's the other way around. I think that this fairly clearly indicates the existence of a problem.

Why is group selection still so popular among social scientists? For a long time many of them held out hope that it would prove to be a new theory of social behaviour. These hopes now appear to have been crushed by the failure of the theory to make different predictions from the long-established orthodoxy of kin selection.

Social scientists have a long history of not understanding how evolutionary biology applied to their subject areas. As a result there's a large scientific lag afflicting the study of cultural evolution. Group selection enthusiasm seems to be clearly one aspect of that: the numerous social scientists involved are stuck back in the 1960s somewhere, where the virtues of the kin selection perspective were not yet widely appreciated.

Lastly, group selection in the social sciences seems to have found extensive funding from the John Templeton Foundation. In a surreal twist to the final battle between science and religion, group selection enthusiasm has been funded to the tune of millions of dollars. That kind of marketing budget can buy a considerable quantity of confusion.

Obvious types of kin selection

If you ask a student of kin selection about the most obvious aspects of the human phenotype that have been influenced by kin selection and are coded for in human DNA, I think you would generally get back a list looking something like this:

• Genitals;
• Breasts;
• Placenta;
• Umbilical cord;
• Female body fat;
• Maternal love;

If you ask a group selection proponent the corresponding question (what are the most obvious aspects of the human phenotype that have been influenced by group selection and are coded for in human DNA), I think you would get back a very different list. The group selection proponent might be more likely to mention multi-cellularity - but I think they would be highly likely to back a very different list.

What's up here? Kin selection and group selection are basically the same thing.

I don't pretend to have a complete explanation for this - but I think the group selection enthusiasts were led astray by the urge to distinguish themselves from kin selection enthusiasts. If discussing family groups, it was obvious that kin selection applied to it - and explained it. The group selection advocates therefore focused their attention elsewhere - where it seemed as though there was more chance to explain new phenomena that kin selection failed to cover. This hypothesis explains the migration of group selection enthusiasts to cultural evolution - since that is obviously not down to shared DNA.

Eventually, there was nowhere else to run, and the group selection advocates mostly gave up their claims that group selection was something new and different. Now the rhetoric in the area has mostly shifted to other issues.

Goodnight on kin selection rampage

Charles Goodnight has been explaining why he doesn't like kin selection recently, in a string of articles - most notably Why I Don’t like Kin Selection.

However, this article seems littered with misunderstandings to me. Goodnight claims kin selection can only focus on altruism. That is a mistake - kin selection has also been applied to spiteful behaviour. Goodnight claims that kin selection can't handle cultural relatedness. That's wrong - cultural kin selection handles cultural relatedness just fine. Goodnight claims that kin selection is ¨an optimality approach¨. In fact, evolution is a gigantic optimization process. All adaptations are the result of optimizations. The accusation that that kin selection is an optimality approach just seems totally confused to me. Goodnight claims that multi-level selection models in which selection on different levels acts in the same direction can't be studied using kin selection models. That seems ridiculous to me - of course they can. In fact, neither group-selection nor kin selection models spend much time on this case. For group selection, this is because proponents are still struggling to find evidence for their effects - and this case typically doesn't help do that.

Goodnight winds up publicly explaining where he doesn't understand kin selection. That's fine - but readers should not be persuaded by an article with so many mistakes.

The article closes with:

However, like optimal foraging theory, it appears to mainly be useful in making broad stroke qualitative predictions that can be used in the introduction, or in a laudatory paragraph about how wonderful Hamilton is at the end of a paper. If you want to make quantitative statements about selection in real world populations that will contribute to our understanding of social evolution multilevel selection might be a better choice.

Ironically, this is almost the exact reverse of what kin selection enthusiasts often say about group selection. Kin selection features the coefficient of relatedness - whereas group selection is rarely concerned with the level of relatedness within or between groups. So: kin selection is typically quantitative, while group selection is much more concerned about identifying the level at which a feature is adaptive - which is a more qualitative issue.

Inclusive fitness applies to genes too

Recently Martin Nowak - in one of his attacks on the concept of inclusive fitness claimed that:

On the level of genes there is no inclusive fitness

I think this is a fairly straightforwardly mistaken idea. The basic logic of Hamilton's 1964 paper applies to genes too. Hamilton claimed that organisms are not just be driven by self interest, and concern for their offspring, but can be expected be interested in the welfare of their other relatives too (brothers, cousins, parents, etc). Similarly, genes aren't just out for themselves. They also act as though they are concerned about their relatives.

With genes the situation is simpler to analyze. To a first approximation, most other genes are related to them by either being identical clones - or by being completely unrelated. These situations correspond to r=1 and r=0 - in the standard inclusive fitness mathematical formalism. If you plug these numbers into Hamilton's rule, you get sensible results. Genes often act as though they do care about the welfare of identical copies of themselves.

The inclusive fitness of a gene can be calculated in the same way as the inclusive fitness of an organism - by adding and subtracting fitness components due to self and relatives - as described by Hamilton.

West, Gardner and I are all in agreement on this issue. In 2013, they said:

Even at the level of the gene, we would still want to know what the maximand is, and the answer is ‘the inclusive fitness of the gene’

So: what was Martin Nowak thinking about? Perhaps he meant to write that inclusive fitness was not a necessary concept at the level of the gene. For example, if you think of genes as being informational, then it is conventional to refer to all the copies of a particular physical nucleotide sequence as representing the same "gene" (or "allele", as some people prefer to say). In which case, talk of "inclusive fitness" is unnecessary.

However, the concept of inclusive fitness is applicable on the level of the genes. I think to claim otherwise is just to invite confusion and misunderstanding.

Why the kin vs group selection arguments persist

There have been a few attempts to explain the persistence of the clash between kin selection and group selection enthusiasts, beyond the recognition of the broad equivalence of the approaches.

D. S. Wilson wrote Clash of Paradigms: Why Proponents of Multilevel Selection Theory and Inclusive Fitness Theory Sometimes (But Not Always) Misunderstand Each Other.

Recently Herbert Gintis has offered his perspective in a review of the book Evolutionary Restraints: The Contentious History of Group Selection.

It seems to me that much of the apparent disagreement comes from those on the outskirts of the debate, who don't properly understand it. The last couple of years has seen a number of confused articles - from Steven Pinker, Edward Wilson, Martin Nowak and others - who just don't know what they are talking about.

Part of the disagreement comes from inertia. People get taught one technique and then get attached to it - and are reluctant to use the other 'unnecessary' approach.

I also think this is partly a conservative vs revolutionary issue. Kin selection is the establishment, group selection is the rebel. Kin selection is tried and trusted, group selection is new and disruptive. Theories with these traits appear to different personality types.

There's also the issue of 'selfishness'. Group selection pictures groups that nurture cooperation flourishing at the expense of groups of selfish individuals. Kin selection seems to be promoting a picture of gene level selfishness. This picture is factually false (the reality doesn't change depending on how you look at it) but the connotations are there. Some like to publicly signal their unselfishness via their beliefs. To others, such cheap signalling seems more like tasteless self-promotion.

Lastly there's confusion over cultural evolution. Most of the group selection enthusiasts come from the social sciences. I've repeatedly heard them argue that kin selection only applies to genetic relatives, and that human cooperation extends beyond blood kin - so there must be something else going on. This argument ignores the important topic of cultural kin selection. The "something else" that is going on turns out to be kin selection after all.

Since kin vs group selection seems closely tied to political and moral issues, perhaps we won't see much more agreement on the topic anytime soon.

Kin selection's 50th birthday

There were prior murmurings, but 1964 marked kin selection's initial publication in a number of respects. Now it's 2014 - it's kin selection's 50th birthday.

Academics have noticed this and are celebrating. One of the celebrations is the Philosophical Transactions of The Royal Society B's theme issue:

‘Inclusive fitness: 50 years on’ compiled and edited by Andy Gardner and Stuart A. West

The introduction says:

In order to better assess the health of inclusive fitness theory on its 50th anniversary, here we showcase research showing the research programme in action, from the extremely pure, mathematical realm, through basic empirical science, to bold applications in a variety of disciplines.

I disapprove of the Claidière / Scott-Phillips / Sperber contribution. They doubt the applicability of kin selection to cultural variation, writing:

Darwinian selection leads to the maximization of inclusive fitness, and this explains the appearance of design in the natural world. Is there an analogous result for cultural attraction? As selection is a special case of attraction, design is possible and in some cases explicable in standard Darwinian terms. Having said that, such explanations will not apply generally, and may not even apply commonly.

From my perspective, this seems like ignorant nonsense. Kin selection is about as applicable and useful to cultural evolution as it is to understanding organic evolution.

Nowak nominates inclusive fitness for retirement

The 2014 annual question at The Edge is: What scientific idea is ready for retirement?

Martin Nowak nominated inclusive fitness. He writes:

Contrary to what is often claimed there exists no empirical test of inclusive fitness theory; nobody has ever performed an actual inclusive fitness calculation for a real population. Inclusive fitness was originally understood as a crude heuristic that can guide intuition in some cases, but not in general. It is only in recent years that inclusive fitness has been elevated—mostly by mediocre theoreticians — to a religious belief, which is universal, unconstrained and always true. Understanding the limitations of inclusive fitness gives us now the opportunity to develop mathematical descriptions of key phenomena in social evolution. It is time to abandon inclusive fitness and focus on a meaningful interaction between theory and experiment in sociobiology.

This seems like unsubstantiated scientific FUD to me.

Nowak claims that the:

dominant and unfortunate impact has been the suppression of meaningful mathematical theories in wide areas of sociobiology.

He means group selection? I think this is unreferenced and unsupported nonsense.

From the 1970s onwards we actually understood that evolution does not permit a single quantity that is always maximized. This fact still has to sink in with many in the inclusive fitness community.

I think that the first sentence here is technically mistaken. You can in fact, model the evolution of any dynamical system using the concept of maximisation of a utility function. Take, for example, the utility function that assigns world events that happen utility 1 and world events that do not happen utility 0. In this case, the evolution of the system can be modeled by "a single quantity that is always maximized". This is the fact of the matter. Nowak's proposed 'fact' is a simple falsehood. We didn't understand this 'from the 1970s onward' - it is simply not true in the first place.

Nowak writes:

On the level of genes there is no inclusive fitness.

Really? Most pairs of genes are either copies of each other (r=1) or not (r=0). Plug these numbers into Hamilton's rule and it works fine. This illustrates the meaning of "The Selfish Gene": genes only care about themselves - or copies of themselves. Nowak doesn't explain what the perceived problem is.

More relating to Nowak's article:

• Marczyk, Jesse (2014) Which Ideas Are Ready to Go to Florida?

• Reuell, Peter (2014) Harvard Gazette press release