Monday, 28 December 2015

Answers for Doug Hoxworth

Doug Hoxworth had some questions which he aired in public recently:

  • If transmission only happens based on the “selfish” gene theory, how do behavioral or personality traits that are advantageous for the group but disadvantageous for the individuals within the group ever get transmitted to the next generation and become dominant/ubiquitous? If it is heritable, how can this phenomenon be explained?

    • Kin selection. For example, worker sterility is disadvantageous to the worker as an individual, but beneficial to the group they are part of. The reason for this is because the worker and the reproductives (queens and drones) share genes. It is possible to explain this in terms of group selection as well. However group selection explanations often turn into simplistic group-level functionalism - whereas kin selection quantifies relatedness (using 'r') and so is a better tool for making quantitative predictions with - in those cases where relatedness is less than 1.

  • How can altruism to non-relatives be explained?

    • For humans, the most significant mechanisms are probably cultural kin selection, virtue signaling, manipulation, over-generalization and environmental mismatch - in roughly that order.

  • If it is through enculturation and imitation, how are these behaviors so ubiquitous at a very young age, if not at birth (even applicable to animals/organisms other than humans that presumably do not emit pheromones indicating that they are unambiguously related, e.g., ants)?

    • Cultural transmission is often advantageous to individuals. Using socially-transmitted information from others can give a short-cut to learning - if maladaptive traditions can be avoided. There are various ways of avoiding maladaptive traditions.

Doug's article contrasts group selection with the selfish gene. In fact these ideas are compatible. The selfish gene is compatible with kin selection and it is compatible with group selection. Richard Dawkins might not agree - but we don't need to heed him here. The disagreement in this area mostly lies elsewhere.

The problem with group selection is not so much that it's wrong, but that it causes confusion among its practitioners. For decades group selection advocates held out hope that their theory would make novel predictions. In the last decade, this hope has mostly collapsed and most now recognize that group selection and kin selection are broadly equivalent. It is a matter of different accounting techniques, so to speak.

The main problem is that we know that kin selection is strongest between close relatives. Group selection advocates often want to apply the theories to whole tribes and to warfare. This sort of group selection isn't equivalent to kin selection - and, for the most part, it doesn't actually work.

What is left of this whole debate? Not too much. There's some noise surrounding Hamilton's inclusive fitness concept, but this is mostly coming from Martin Nowak and friends - and his papers have been met with ridicule. At this stage, most of the facts seem to be in and the group selection controversy resembles a mopping up operation.

Sunday, 23 August 2015

Prospective kin

Organisms treat their mates better than average conspecifics - even before they have had any offspring with them.

It isn't hard to think of reasons for this, but many of of those reasons invoke the idea of prospective kin - unborn children.

Most children have a probability of becoming an ancestor - and it is possible to extend this idea to children that haven't been born - and to children that haven't been even conceived.

Pretty standard kin selection models can thus be applied to courtship behaviour, bower construction, nuptual gifts - and so forth. These are cases where cooperative behaviour without relatedness occurs. In fact, there is relatedness - relatedness to unborn children.

Saturday, 28 March 2015

David Queller on the evolution of eusociality

Liao, Rong and Queller just weighed in on the Nowak/Tarnita/Wilson 2010 model of the evolution of eusociality.

That paper was mostly smacked down by critics because of its delusional depiction of kin selection, but few bothered to criticize its model of the evolution of eusociality. Now, David Queller's gone through the model, and the results are not too pretty.

They had a modeling strategy that should work and should be fine, but they weren’t careful enough when they made claims about their models’ novel results
...David Queller is quoted as saying.

From the abstract of the article:

The claim of these authors was bolstered by a new model of the evolution of eusociality with novel conclusions that appeared to overturn some major results from inclusive fitness. Here we report an expanded examination of this kind of model for the evolution of eusociality and show that all three of its apparently novel conclusions are essentially false. Contrary to their claims, genetic relatedness is important and causal, workers are agents that can evolve to be in conflict with the queen, and eusociality is not so difficult to evolve. The misleading conclusions all resulted not from incorrect math but from overgeneralizing from narrow assumptions or parameter values. For example, all of their models implicitly assumed high relatedness, but modifying the model to allow lower relatedness shows that relatedness is essential and causal in the evolution of eusociality. Their modeling strategy, properly applied, actually confirms major insights of inclusive fitness studies of kin selection. This broad agreement of different models shows that social evolution theory, rather than being in turmoil, is supported by multiple theoretical approaches. It also suggests that extensive prior work using inclusive fitness, from microbial interactions to human evolution, should be considered robust unless shown otherwise.
Queller's paper certainly makes entertaining reading. However I can't help thinking that it takes the Nowak/Tarnita/Wilson paper too seriously. The most obvious response to that paper is, I think, ridicule. Jon Wilkins hit roughly the right note with Important Harvard Scientists Attack Kin Selection.

News coverage:

Update 2015-05-09:

Nowak and Allen reply in Inclusive Fitness Theorizing Invokes Phenomena That Are Not Relevant for the Evolution of Eusociality

Liao, Rong and Queller reply: Some Agreement on Kin Selection and Eusociality?

Nowak's papers on the topic are here.

Sunday, 1 March 2015

Popular internet dictionary parrots kin selection FUD

I visited the entry for inclusive fitness today and was surprised to see the following F.U.D.:

Inclusive fitness turns out to be a phantom measure that cannot be obtained.

Inclusive fitness theory is neither useful nor necessary to explain the evolution of eusociality or other phenomena.
Further, the second quote was mirrored by Google at the top of its search results for "inclusive fitness" - as though it was a definition of the term! You might still be able to see this for yourself here.

Low levels of machine intelligence can cause this sort of problem, it seems.

Friday, 6 February 2015

David Sloane Wilson has doubts; asks for help

People have been trying for decades to find something that group selection predicts that kin selection does not. Now the results are in. The most coherent forms of group selection make no new predictions. They are an alternative accounting technique that makes the same set of predictions that kin selection makes. This is fairly widely acknowledged by most of the parties involved these days. Of course, kin selection has been part of the standard orthodoxy in biology for decades.

However, it seems that David Sloane Wilson still has doubts about this. He doesn't see how to apply kin selection in some cases - and he's publicly asking for help. As far as I can see, David has nothing. One of his three examples is cultural group selection. I replied here.

I'm not sure how much help David will get from other kin selection enthusiasts. Most have been unimpressed with David's attempts to rechristen and take credit for a well-established existing theory. Group selection has a long association with junk science. Kin selection depends on close relatedness to produce adaptations. If you emphasize group membership instead of close relatedness - you include a bunch of cases where there's no close relatedness, and adaptations are not produced. Group selection was pushed by kin selection into the scientific fringes - where it focused on cases not obviously explicable by kin selection - which were mostly cases where the theory didn't actually work. In short, group selection is kin selection's evil twin.

David engages in a bit of a straw man attack on kin selection in his article. He focuses on Hamilton's rule. Hamilton's rule is one of the findings by kin selection theorists - but it isn't the same thing as kin selection. Here's how Hamilton explained the topic:

The existence of altruism in nature can be explained by thinking about the replication of genes. We need to descend to the level of the gene, rather than the individual, in order to see that the gene exists surrounded by copies of identical genes that exist in all its relatives - in particular in its close relatives, its siblings, who have a half chance of carrying a copy of that particular gene, its offspring, which also have a half chance, parents: a half-chance, cousins: one eighth, etc. Seeing this swarm of genes that exists around a particular one, we can then ask what is the behavior caused by this gene that is most likely to cause the propagation of this set of copies in the relatives around it.
That is more like kin selection in a nutshell. Of course, these days, we have to clarify that it's the evolutionary gene that we mean here. Hamilton's rule is the product of kin selection and a bunch of assumptions.

Sunday, 4 January 2015

Herbert Gintis vs inclusive fitness theory

Herbert Gintis has an elaborate attack on inclusive fitness theory on his web site. It's titled: Inclusive Fitness and the Sociobiology of the Genome. It says, among other things:

The general point is that if there is a conflict among loci concerning fitness maximization, and if the frequency of alleles at one locus affect the fitness costs and payoffs at other loci, then it is logically impossible that the allele at each locus maximize its inclusive fitness. Rather, the proper setting is evolutionary game theory [...]

I think this is a case of expecting too much from the concept of maximization. The idea of maximization does not imply that all parties reach the maximum they are seeking. It doesn't even imply that they increase the value they are trying to maximize. A hill-climber might be climbing a hill on a mountain that is sinking into the sea. Their elevation may decrease until it reaches zero and they die. This is quite consistent with the idea of maximization.

Gintis apparently claims that frequency-dependence invalidates the idea of maximization of inclusive fitness:

If the genome’s success is based on a pattern of cooperation, promotion, and suppression across loci, which will occur, for instance, if the production of a protein, RNA sequence, or social behavior requires the collaborative activity of many genes (Noble 2011), or if there are frequency dependent social interactions among individuals in a social species (Maynard Smith 1982), then neither genes nor individuals can be characterized as maximizing inclusive fitness. The conditions under which a population genetics model of gene flow implies fitness maximization at the gene or individual level has been carefully explored (Grafen 1999, 2002, 2006; Metz et al. 2008; Gardner and Wild 2011; Gardner West and Wild 2011). With frequency independence, they affirm the maximization hypothesis. With frequency dependence, the hypothesis it is in general false, and no careful researcher has ever claimed otherwise.

Frequency dependence typically means that genes are spending time in environments that differ from the average of the environments they evolved in. It's a case of adaptive lag - where organisms are adapted not to their current environment, but to a weighted average of ancestral environments. This is a classic case where organisms sometimes behave sub-optimally in ways that don't further their own interests.

In such cases, organisms don't always act to maximize their inclusive fitness - but rather act to maximize their inclusive fitness under the hypothesis that they are in an environment that is like the one that their ancestors evolved in. Of course, that hypothesis might be mistaken.

In fact, sufficiently sophisticated creatures might be able to evolve a superior strategy - where they sample the frequency involved and change their behaviour adaptively, based on the observed frequency. So, what frequency dependence often boils down to is that organisms can sometimes fail to maximise their inclusive fitness - because they have cognitive limitations and make mistakes.

In this case, I feel that Gintis is expecting too much from inclusive fitness theory. It doesn't claim that all creatures maximize inclusive fitness perfectly. Creatures have all kinds of imperfections and limitations that prevent them from acting as perfect maximizers.