odie_q writes "It has long been known that the Toxoplasma gondii parasite alters its host's behavior, but now it seems the way it alters it depends on the sex of the host. From the article: 'A common parasite can increase a women's attractiveness to the opposite sex but also make men more stupid, an Australian researcher says ... Infected men have lower IQs, achieve a lower level of education and have shorter attention spans. They are also more likely to break rules and take risks, be more independent, more anti-social, suspicious, jealous and morose, and are deemed less attractive to women. On the other hand, infected women tend to be more outgoing, friendly, more promiscuous, and are considered more attractive to men compared with non-infected controls.'"