Gregory Cochran

Gregory Cochran is a physicist and adjunct professor of anthropology at the University of Utah who has developed some new ideas in evolutionary medicine and genetic anthropology. Cochran is known for several controversial theories.

Cochran is an occasional contributor to the genetics blog Gene Expression

Pathogen theories
Many of Cochran's theories are pathogenic theories of disease - they revolve around the idea that many common diseases are caused by pathogens instead of genetics or other environmental factors. One example is that peptic ulcers once was thought to occur because of stress by chance or because of genetic considerations. However, there is a great deal of evidence which strongly suggests that some peptic ulcers are caused by the pathogenic bacteria helicobacter pylori. As well, cervical cancer is now thought to be strongly due to the presence of the human papilloma virus.

In 2005, the American Academy of Microbiology endorsed liberalizing Koch's Postulates, which have been the basis for determining if a disease is infectious since the 19th century, along the lines Cochran and Ewald proposed.

Pathogenic theory of homosexuality
The Pathogenic theory of homosexuality (informally, the gay germ theory) is controversial speculation that, because homosexuality reduces significantly the number of resulting offspring, genetics would not have bred any genes responsible for homosexuality — which implies that the proximal cause is environmental, specifically in the form of a hypothesized pathogen (bacteria or virus).

Natural history of Ashkenazi intelligence
Cochran and co-authors Jason Hardy and Henry Harpending suggest that the widely observed high average IQ of Ashkenazi Jews may be attributed to the history of that particular subgroup of the Jewish people, including its heavy persecution and its emphasis on jobs with a high demand on intellectual capacities. Cochran et al hypothesise that this may have evolutionarily selected the very intelligent, and that this may explain the high rate of hereditary neurological disorders in this group. The paper was covered in the New York Times and the Economist, and was controversial due to its topic of race and intelligence.