Friday, 31 October 2014

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.

Sunday, 19 October 2014

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.

Saturday, 18 October 2014

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.

Friday, 17 October 2014

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.

Sunday, 12 October 2014

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:

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.

Friday, 3 October 2014

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:

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.