Editing J. Philippe Rushton (section)

===Genetic similarity theory===
Early in his career, Rushton did research on [[altruism]]. He theorized a heritable component in altruism and developed ''Genetic Similarity Theory'', which is an extension of [[W.D. Hamilton]]'s theory of [[kin selection]]. It holds that individuals tend to be more altruistic to individuals who are genetically similar to themselves even if they are not kin, and less altruistic, and sometimes outwardly hostile, to individuals who are less genetically similar. Rushton describes "ethnic conflict and rivalry" as "one of the great themes of historical and contemporary society", and suggests that this may have its roots in the evolutionary impact on individuals from groups "giving preferential treatment to genetically similar others". According to Rushton: "the makeup of a gene pool [i.e., a human population's total reservoir of alternative genes] causally affects the probability of any particular ideology being adopted".

Articles in a 1989 issue of ''[[Behavioral and Brain Sciences]]'' criticized the theory. Judith Anderson said his work was based on statistically flawed evidence,<ref>{{cite journal | last1 = Anderson | first1 = Judith | year = 1989 | title = A methodological critique of the evidence for genetic similarity detection | journal = [[Behavioral and Brain Sciences]] | volume = 12 | issue = 3| page = 518 | doi=10.1017/s0140525x00057332| s2cid = 145652857 }}</ref> John Archer and others said that Rushton failed to understand and misapplied the theory of kin selection,<ref>{{cite journal | last1 = Archer | first1 = John | year = 1989 | title = Why help friends when you can help sisters and brothers? | journal = Behavioral and Brain Sciences | volume = 12 | issue = 3| page = 519 | doi=10.1017/s0140525x00057344| s2cid = 145551892 }}</ref><ref>{{cite journal | last1 = Daly | first1 = Martin | year = 1989 | title = On distinguishing evolved adaptation from epiphenomena | journal = Behavioral and Brain Sciences | volume = 12 | issue = 3| page = 520 | doi=10.1017/s0140525x00057356| s2cid = 144824187 }}</ref><ref>{{cite journal | last1 = Tooby | first1 = John | last2 = Cosmides | first2 = Leda | year = 1989 | title = Kin selection, genic selection, and information-dependent strategies | journal = Behavioral and Brain Sciences | volume = 12 | issue = 3| pages = 542–44 | doi=10.1017/s0140525x00057605| s2cid = 144834722 }}</ref> Judith Economos said that Rushton's analysis was speculative, that he failed to define the concept of altruistic behavior in a way that it can become manifest, and that he failed to show any plausible mechanism by which members of a species can detect the "altruism gene" in other members of the species.<ref>{{cite journal | last1 = Economos | first1 = Judith | year = 1989 | title = Altruism, nativism, chauvinism, racism, schism, and jizzum | journal = Behavioral and Brain Sciences | volume = 12 | issue = 3| pages = 521–23 | doi=10.1017/s0140525x0005737x| s2cid = 143647523 }}</ref> Steven Gangestad criticized Rushton's theory for not being compelling in terms of its attractiveness as an explanatory model.<ref>{{cite journal | last1 = Gangestad | first1 = Steven W | year = 1989 | title = Uncompelling theory, uncompelling data | journal = Behavioral and Brain Sciences | volume = 12 | issue = 3| pages = 525–26 | doi=10.1017/s0140525x00057411| s2cid = 146530234 }}</ref> C.R. Hallpike said Rushton's theory failed to take into account that many other traits, ranging from age, sex, social and political group membership, are observably more important in predicting altruistic behavior between non-kin than genetic similarity.<ref>Hallpike, C. R. 1989. "Green beard theory", ''Behavioral and Brain Sciences'' (1989) 12:3 p. 528</ref> John Hartung criticized Rushton for failing to conduct an adequate [[control group]] study and for ignoring contradictory evidence.<ref>{{cite journal | last1 = Hartung | first1 = John | year = 1989 | title = Testing genetic similarity: Out of control | journal = Behavioral and Brain Sciences | volume = 12 | issue = 3| page = 529 | doi=10.1017/s0140525x00057460| s2cid = 144642600 }}</ref>

Littlefield and Rushton (1984) examined degree of [[Grief|bereavement]] among parents after the death of a child. They found that children perceived as more physically similar to their parents were grieved for more intensely than less similar children.<ref>{{Cite journal | last1 = Littlefield | first1 = C. H. | last2 = Rushton | first2 = J. P. | doi = 10.1037/0022-3514.51.4.797 | title = When a child dies: The sociobiology of bereavement | journal = [[Journal of Personality and Social Psychology]] | volume = 51 | issue = 4 | pages = 797–802 | year = 1986 | pmid =  3783426| s2cid = 39489212 }}</ref> Russell, Wells, and Rushton (1985) reanalyzed several previous studies on similarities between spouses and concluded there is higher similarity on the more heritable characteristics.<ref>{{Cite journal | last1 = Russell | first1 = R. | last2 = Wells | first2 = P. | last3 = Rushton | first3 = J. | doi = 10.1016/0162-3095(85)90030-5 | title = Evidence for genetic similarity detection in human marriage | journal = [[Ethology and Sociobiology]] | volume = 6 | issue = 3 | pages = 183–187 | year = 1985 }}</ref> In 1988 Rushton examined [[Human blood group systems|blood group]] genes and found that sexually interacting couples had more similar blood group genes than randomly paired individuals.<ref>{{Cite journal | last1 = Rushton | first1 = J. P. | title = Genetic similarity, mate choice, and fecundity in humans | doi = 10.1016/0162-3095(88)90025-8 | journal = Ethology and Sociobiology | volume = 9 | issue = 6 | pages = 329–333 | year = 1988 }}</ref>{{primary source inline|date=March 2024}}