Sunday, 27 April 2014

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.

Wednesday, 9 April 2014

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.

Tuesday, 1 April 2014

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.