and Cosmides proposed that disparities in subjects performance on contextualized versus non-contextualized variations of the task was a by-product of a specialized cheater-detection module, and Tooby and Cosmides later noted that whether there are evolved cognitive mechanisms for the content-blind rules of logical inference is disputed. Additionally, economist Thomas Sowell has noted that numerous studies finding disparities between the mean test scores of ethnic groups on intelligence tests have found that ethnic groups with lower mean test scores have tended to perform worst on non-verbal, non-informational, or abstract reasoning test items. Writing after the completion of the Human Genome Project in 2003, psychologist Earl B. Hunt noted in 2011 that no genes related to differences in cognitive skills across various racial and ethnic groups had ever been discovered, and in 2012, American Psychologist published a review of new findings by psychologists Richard E. Nisbett, Joshua Aronson, Clancy Blair, Diane F. Halpern, and Eric Turkheimer, economist William Dickens, and philosopher James R. Flynn that concluded that almost no single-nucleotide genetic polymorphisms that have been discovered are consistently associated with variation in IQ in the normal range. Sexual selection This model, which invokes sexual selection, is proposed by Geoffrey Miller who argues that human intelligence is unnecessarily sophisticated for the needs of hunter-gatherers to survive. He argues that the manifestations of intelligence such as language, music and art did not evolve because of their utilitarian value to the survival of ancient hominids. Rather, intelligence may have been a fitness indicator. Hominids would have been chosen for greater intelligence as an indicator of healthy genes and a Fisherian runaway positive feedback loop of sexual selection would have led to the evolution of human intelligence in a relatively short period. Philosopher Denis Dutton also argued that the human capacity for aesthetics evolved by sexual selection. Evolutionary biologist George C. Williams and evolutionary medicine researcher Randolph M. Nesse cite evolutionary psychologists John Tooby and Leda Cosmides as referring to the emotions as "Darwinian algorithms of the mind", while social psychologist David Buss has argued that the sex-specialized differences in the emotion of jealousy are adaptive strategies for detecting infidelity by a mating partner and anthropologists Donald E. Brown and Ward Goodenough have argued that marriage is a cultural universal that evolved to regulate sexual access to fertile women within a particular culture in response to male intrasexual competition and dominance. Citing cross-cultural research conducted by