Last August I wrote about a new paper in Nature by three Harvard biologists, Martin Nowak, Corina Tarnita, and Edward O. Wilson. Their paper was, as I called it, a “misguided attack on kin selection,” referring to the form of selection in which the reproductive success of a gene (usually a gene that affects behavior) is influenced not only by its effects on its carrier, but also by its effects on related individuals (kin) carrying the same gene. This idea, introduced to evolutionary biology by George Price and W. D. Hamilton, has been enormously productive, explaining all sorts of things from parental care and parent-offspring conflict to sex ratios in animals and, perhaps most important, the evolution of “altruism.” Nowak et al.’s paper attacked the idea that this form of selection—based on a gene’s “inclusive fitness”—was important in explaining anything; indeed, they didn’t even see kin selection as a form of natural selection. My original post details most of my objections to their paper.
Now, seven months later, Nature has published a spate of objections to the Nowak et al paper: there are five critiques and a response to them by Nowak et al. Here are the papers and links:
“Inclusive fitness theory and eusociality” by Patrick Abbot et al. I am an author on this paper, along with one hundred and thirty six other authors. The list of authors and their institutions, which occupies two pages of the three-page letter, reads like a Who’s Who of social evolution. It’s telling that nearly every major figure in the field lined up against Nowak et al.
“Only full-sibling families evolved eusociality” by Jacobus J. Boomsma et al.
“Kin selection and eusociality” by Joan E. Strassmann, Robert E. Page, Jr., Gene E. Robinson and Thomas D. Seeley, four big names in social insect evolution
“Inclusive fitness in evolution” by Regis Ferriere and Richard E. Michod
“In defence of inclusive fitness theory” by Edward Allen Herre and William T. Wcislo
and the reply, called simply
I won’t go through the critiques, but their main points are these:
- Nowak et al.’s insistence that there’s a difference between inclusive fitness theory and “standard natural selection” theory is simply wrong. The former is just a special case of the latter taking into account the effects of a gene in one body on the effects of other bodies also carrying that gene. As Ferriere and Michod note:
“In fact, there is only one paradigm: natural selection driven by interactions, interactions of all kinds and at all levels. Inclusive fitness has been a powerful force in the development of this paradigm and is likely to have a continued role in the evolutionary theory of behaviour interactions.”
- Nowak et al.’s insistence that kin selection theory requires a number of restrictive assumptions that makes it largely invalid is also wrong.
- Nowak et al.’s insistence that the idea of kin selection has been of no value in in understanding nature is wrong. Our own paper gives many examples in which kin selection theory has clarified or advanced our understanding of phenomena like eusociality in insects (the phenomenon of an insect colony that contains a cast of nonreproductive individuals), sex ratio, altruism spite, alarm-calling, and so on. Further, the idea of kin selection has led to testable predictions—predictions that have been verified.
- Nowak et al.’s own “new” theory for explaining eusociality becomes a disguised form of kin selection when it tries to explain eusociality.
Curiously, in their very short reply, Nowak et al. don’t really address the criticisms, but merely reiterate what they said in their original article. They resort instead to legalisms, explaining away the success of kin selection theory by saying this:
Abbot et al.claim that inclusive fitness theory has been tested in a large number of biological contexts, but in our opinion this is not the case. We do not know of a single study where an exact inclusive fitness calculation was performed for an animal population and where the results of this calculation were empirically evaluated.
This is a misunderstanding of how kin selection theory—indeed, all of evolutionary theory—is used. You don’t have to perform an “exact inclusive fitness calculation” to make predictions. (It’s nearly impossible anyway to “exactly” measure fitness in nature under any form of selection!) In sex ratio theory, for example, one can predict that if a female wasp is the only individual parasitizing a fly pupa, and all offspring wasps mate within the pupa, then you need produce only enough males to fertilize all your daughters, producing a female-biased sex ratio. But if more than one unrelated wasp parasitizes that pupa, you must invest in more sons to compete with the other wasps’ sons in fertilizing females, and so your relative production of males should increase. That prediction has been amply verified without “exact” fitness calculations. (Indeed, insofar as quantitative predictions can be made, they’ve fit the data remarkably well.)
In his piece on the kerfuffle, Carl Zimmer also noticed the non-responsive nature of Nowak et al.:
Nowak et al respond to all the criticism and don’t budge in their own stand. They claim that their critics have misinterpreted their own argument. And they claim that sex allocation does not require inclusive fitness. Oddly, though, they never explain why it doesn’t, despite the thousands of papers that have been published on inclusive fitness and sex allocation. They don’t even cite a paper that explains why.
If the Nowak et al. paper is so bad, why was it published? That’s obvious, and is an object lesson in the sociology of science. If Joe Schmo et al. from Buggerall State University had submitted such a misguided paper to Nature, it would have been rejected within an hour (yes, Nature sometimes does that with online submissions!). The only reason this paper was published is because it has two big-name authors, Nowak and Wilson, hailing from Mother Harvard. That, and the fact that such a contrarian paper, flying in the face of accepted evolutionary theory, was bound to cause controversy. Well, Nature got its controversy but lost its intellectual integrity, becoming something of a scientific National Enquirer. Oh, and boo to the Templeton Foundation, who funded the whole Nowak et al. mess and highlighted the paper on their website.
The lesson: if you’re a famous biologist you can get away with publishing dreck. So much for our objective search for truth—a search that’s not supposed to depend on authors’ fame and authority. I feel sorry for co-author Corina Tarita, a young scientist with splendid qualifications, for this paper will always cast a shadow over her career.