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Group Selection: Its Central Question

The inadequacy of gene selection for addressing the emergence of cooperative behavior in multi-group populations is discussed through the central question raised by group selection.

Responding to an essay by psycholinguist Steven Pinker at Edge.org rejecting the notion of group selection, biologist and anthropologist, David Sloan Wilson, points out that Pinker’s essay does not address “the central question of group selection.” That qusetion is: “How can traits that are ‘for the good of the group’ evolve when they are selectively disadvantageous within groups?” Group selection theory’s answer to this question, according to Wilson, is this: “groups of individuals who behave for the good of their group outcompete other groups, as surely as group-oriented individuals are outcompeted by by more self-oriented individuals within groups.”

Accordingly, since group selection accommodates both selfish and cooperative behavior, to show whether or not group selection (i.e. the propagation of cooperative traits) has transpired will require a case by case determination of which has been the stronger effect: the advantages conferred by a group outcompeting another group or the advantages conferred by individuals advancing self-interest within the group. If it is the former, then group selection has transpired and cooperative traits have been propagated in the total population.

The central question of group selection and the answer to it given above derives from Darwin himself, according to Wilson. Subsequently, Wilson continues, “population geneticists such as Wright, Haldane, Fisher, and Maynard Smith” translated both question and answer into equations. A “consensus” emerged in the 1960s as to what the equations told us. They were the following:

1.) Selective forces working upon groups “in a multi-group population” are “almost invariably” weaker than selective forces working upon “individuals within the groups.”

2.) Prosocial behaviors could be explained without resort to group selection because other mechanisms could do the job.

Both these conclusions, Wilson instructs us, are now known to be “mistaken.” It is possible for traits that are”selectively disadvantageous within groups” (i.e. cooperative traits) to be nonetheless propagated by selection working between groups, to therefore subsequently evolve. Further, “all evolutionary theories  of social behavior that were developed as alternatives to group selection” have failed: Without exception, all of these effectively resort to some identifiable group selection to explain the propagation of social behaviors characterized by cooperation or altruism that “are typically selectively disadvantageous [to individuals] within groups” but confer selective advantage when measured through differential group contribution “to the total population.”

Rather than addressing the central question of group selection, Pinker’s essay, Wilson points out, addresses this question: “Can a concept of group selection be formulated that is comparable to the concept of gene selection?” Pinker is therefore taking issue with a concept of group selection that is at variance with “the concept of group selection” as originally considered my Darwin, subsequently “refined by population geneticists, rejected in the 1960s, and revived today.”

Because of his mistaken conception of group selection, Pinker also mounts attacks against the notion of cultural evolution that are off-base, Wilson tells us. In Wilson’s opinion, Pinker’s misguided attacks could be remedied if he could rise above his neo-Darwinian conviction that only genes suffice as an adequate mechanism for the heredity required by natural selection. As Wilson points out, psychological and cultural mechanisms “also create a resemblance bwteen parents and offspring.”

To help Pinker on his way, Wilson advises that he go back to Darwin’s original formulation of the problem of group selection. That original formulation asked how “a phenotypic trait that benefits whole groups” be propagated in a population if it “does not maximize relative fitness [among individuals] within groups.” Since the “question is posed at the phenotypic level,” it can remain quite “agnostic about the mechanism of inheritance.” This is all to the good: “The most explicit models of cultural evolution show that group selection is an exceptionally strong force in human cultural evolution, even to the point of qualifying as a major evolutionary transition.”

Of course, the validity of group selection, as the article discussion should have made clear, does not invalidate gene selection. Group selection merely shows the inadequacy of gene selection in explaining the evolution of cooperative traits in a population since it confines itself to within-group effects, where selfishness always prevails, whereas group selection confines itself to between-group effects, where selfishness doesn’t always prevail, because in spite of such selfishness from individuals in a group, enough individuals may exhibit cooperative behavior in the group to enable the group to outcompete more selfish groups, thereby propagating selflessness in the total population.

(Reference: Wilson, David Sloan. 2012. “The Central Question of Group Selection.”

http://edge.org/conversation/the-false-allure-of-group-selection#dsw)

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