Monday, 29 December 2014

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.

Saturday, 27 December 2014

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.