History
A 2013 study found tentative support for some aspects of the theory, specifically the correlative relationships between IQ and parental investment along with fertility rates. However, the authors noted that, after accounting for the proportion of black residents among counties, no association was observed between IQ and either life-history variable. Some researchers have also tried to combine differential ''K'' theory with Terrie Moffitt's developmental theory of crime to create what they call a "unified crime theory".Reception
As Andrew Winston summarizes, "Rushton's work was heavily criticized by psychologists, evolutionary biologists, anthropologists, and geneticists for severe scientific inadequacies, fundamental errors, inappropriate conceptualization of race, inappropriate statistical comparisons, misuse of sources, and serious logical errors and flaws." Differential K theory in particular was described in a 2020 statement by Rushton's former department at Western Ontario University as "thoroughly debunked." Weizmann et al. argued that Rushton attempted to validate this hypothesis by use of "selective citation and misrepresentation of the research literature and by the use of unreliable sources" and that Rushton's methodology "indicates a lack of familiarity with ecological thinking and scientific method in general." A 2014 study found differences in the General Factor of Personality across races that were not compatible with differential ''K'' theory. Additional criticism of the theory has come from Edward M. Miller, who has argued that contrary to the theory, unpredictable environments select for ''K'', not ''r'' characteristics.References
Psychological theories Race and intelligence controversy {{Psychology-stub