EVOLUTION, ALTRUISM AND GENETIC SIMILARITY THEORY by J. PHILIPPE RUSHTON
The reason people give preferential treatment to genetically similar others is both simple and profound: they thereby replicate their genes more effectively. Altruism is a very interesting phenomenon, even recognized by Darwin as an anomaly for his theory. How could it evolve through his hypothesized "survival of the fittest" individual when such behavior would appear to diminish personal fitness? If the most altruistic members of a group sacrificed themselves for others, they ran the risk of leaving fewer offspring to carry forward their genes for altruistic behavior? Hence altruism would be selected out, and indeed, selfishness would be selected in. Altruistic behaviors, however, occur in many animal species, some to the point of self-sacrifice (Wilson, 1975). For example, honey bees die when they sting in the process of protecting their nests.
Darwin proposed the competition of "tribe with tribe" to explain altruism (1871, p. 179). Thus, a tribe of people willing to cooperate and, if necessary, sacrifice themselves for the common good would be victorious over tribes made up of those less willing or able. Subsequently Herbert Spencer (1892/93) extended this, suggesting that the operation of a 'code of amity' towards the members of their own group, and a 'code of enmity' toward those of out-groups prevailed in successful groups. In non-elaborated forms, some version of "group-selection" was held by most evolutionists for several decades.
A degree of polarization followed [Wynne-Edwards' advocacy of group selection] As D. S. Wilson put it, "For the next decade, group selection rivaled Lamarkianism as the most thoroughly repudiated idea in evolutionary theory" Essentially, there did not seem to exist a mechanism by which altruistic individuals would leave more genes than individuals who cheated. The solution to this paradox is one of the triumphs that led to the new synthesis of sociobiology. Following Hamilton (1964) the answer proposed was that individuals behave so as to maximize their "inclusive fitness" rather than only their individual fitness by increasing the production of successful offspring by both themselves and their relatives, a process that has become known as kin selection. This formulation provided a conceptual breakthrough, redirecting the unit of analysis from the individual organism to his or her genes, for it is these which survive and are passed on. Some of the same genes will be found in siblings, nephews and nieces, grandchildren, cousins, etc., as well as offspring. If an animal sacrifices its life for its siblings' offspring, it ensures the survival of shared genes for, by common descent, it shares 50% of its genes with each sibling and 25% with each siblings' offspring.
…the makeup of a gene pool causally affects the probability of any particular ideology being adopted, which subsequently affects relative gene frequencies. Religious, political, and other ideological battles may become as heated as they do because they have implications for genetic fitness; genotypes will thrive more in some cultures than others. … Obviously causation is complex, and it is not intended to reduce relationships between ethnic groups to a single cause. Fellow ethnics will not always stick together, nor is conflict inevitable between groups any more than it is between genetically distinct individuals. Behavioral outcomes are always mediated by multiple causes.
J. Philippe Rushton