Kin Selection, Genetic selection, and Information-dependent Strategies 

This article is a critique of Phillippe Rushton’s article of “Genetic similarity theory.” This article sets out to address the problems with his theoretical framework on three main points. 1) The failure to fully understand the theory of kin selection 2) failure to distinguish the operation of kin selection as a selection pressure from the operation of adaptations that evolved in response to kin selection 3) failure to distinguish circumstances reliably present during human evolutionary history that we can have evolved adaptations to, from recently emerged circumstances that we cannot have evolved adaptations to (ex. Encounters with those of other races).

Kin selection is defined as how natural selection shapes genetically inherited traits that simultaneously impact the reproduction of the carrier of the trait and the reproduction of individuals who share genes underlying that trait. Rushton adds to this the concept of “genetic similarity” which is between individuals is substituted for relatedness. This concept illustrates that selection operates on a genetic level and therefore kin selection and inclusive fitness should be addressed on the genetic level instead if the individual level. Thus, Rushton sees kin selection as a strategy of reproductive trade-off between carrier and recipient that will emerge in the genetic code relative to the strategy needed for that particular environment. However, flaws are pointed out here on the concept of “genetic similarity.” The major flaw is that at the genetic level there is no similarity, genetics are either are identical, nonidentical or information indicating that a replica of a gene will be duplicated. Thus, genes will replicate regardless of what individuals they are in and in relation to the environment. Rushton’s theory raises two distinct questions about the significance of “genetic similarity theory” and whether or not traits with social consequences which develop out of many different locations are in fact related to genetic relationships that arise out of common ancestry. These two questions are 1) does genetic similarity operate as an evolutionary principle independent of common ancestry 2) can and does a phenotype matching process that samples heritable phenotypic markers (in order to create altruism and/or mating) operate in humans?

The answer to the first question shows that “genetic similarity” does not arise independently from relatedness because of the amount of possible gene combinations created during sex. Thus, the likelihood that someone not of common ancestry in the Pleistocene era who was genetically similar to oneself would be virtually impossible due to the countless combinations of sex. Also, if it did happen there would be no way to really know if a non-related stranger contained a genetically similar trait. Thus, the concept of altruism shared between related kin is lost in this theory due to the fact that we are altruistic toward our own kin and not someone who might have a similar trait as oneself. The answer to the second question is “yes,” adaptations for assessing relatedness between kin must arise as a mechanism so one will be able to regulate kin relevant strategies such as altruism and mating. This genetic similarity thus arises out of a shared common ancestry. Furthermore, it is possible that using information of heredity markers could help in constructing patterns of kinship as it helps influence mating, friendship, and altruism in humans.

Rushton then goes on to explain the concept of blood group data, which deals with the concept of race, and how we as people tend to travel with those of one’s race due to the fact that we share more common genes with those of our own race. This concept can be seen as both true and false. Thus, we notice throughout history people of different races tend to live and associate among their own kind. This can be seen in that people tend to marry and befriend individuals similar to one’s own race. However, this idea ends here, as the concept of blood groups does not explain the evolution of kin-selection mechanisms. Especially, since a non-relative of one’s own race are only slightly different from individuals of a different race. Hence, such problems as war, race conflict, and other problems not experienced during the Pleistocene are not adaptations to modern circumstances but evolutionary adaptations misfiring in modern settings. Competition could only come from neighboring groups, which would have reflected cooperation with nearer kin against more distant kin. Thus, this competition evolving out of the Pleistocene would help in the development of inclusive fitness effects on such concepts as coalitions and altruism. This is what thus promotes the evolution of mechanisms governing human coalitions, and not the notions of group selection that Rushton favors.

In conclusion the concept of genetic phenotype markers as a way to form human coalitions is limited since they would only provide information for the formation of inclusive fitness strategy. Markers do not seem useful though in tracing close kinship links as the more distant the relationship tracked the more useless the markers would serve as source of information. In sum Rushton's empirical results have a sound basis but the concept of “genetic similarity” distorts the main idea of inclusive fitness and how altruism and coalitions form based on kin ties.

Kin Selection, Genetic Selection, and Information-dependent Strategies


I.                    Flaws found in Phillippe Rushton’s article


A.     Comprehension of theory of kin selection

B.     Failure to distinguish difference between operations of kin selection caused by selection pressure and operation of kin selection caused by evolved adaptations

C.     Failure to establish evidence that evolutionary adaptations took place


II.                 Kin selection & Genetic Similarity


A.     Kin selection- the way in which natural selection shapes genetically inherited traits and simultaneously impacts the reproduction of the individual with the trait and the reproduction of individuals who share genes underlying that trait.

B.     Genetic similarity- instead of operating on an individual level as in kin selection, people to help to perpetuate people with the same genetic makeup even if they are not related to them

C.     Does genetic similarity follow evolutionary theory even though it is independent of common ancestry?

D.     Does altruism occur just because someone looks like us?


III.               Validity of genetic similarity

A.     Endless amounts of gene combinations

B.     Is it possible to “know” that an individual who is not related to you carries the same genes?

C.     Mechanisms for assessing relatedness as a means for altruism