The findings add to a growing body of evidence that Toxoplasma gondii, a single-celled parasite, pulls on the puppet strings of its hosts, goading them into pursuing risky behaviors."We identified a substantial increase in the odds of dispersal and of becoming a pack leader, both risky behaviors," in wolves that showed signs of T. gondii infection in their blood, the authors wrote in the study, published online Nov. 24 in the journal Communications Biology (opens in new tab)."These two life history behaviors represent some of the most important decisions a wolf can make in its lifetime and may have dramatic impacts on gray wolf fitness, distribution" and the overall rate of births and deaths within a population, the scientists reported.They discovered that infected wolves were more likely than uninfected wolves to engage in risky behaviors, such as abandoning their families to start new packs, and were twice as likely to assert themselves as pack leaders, which often entailed picking perilous fights with other would-be top dogs.The study authors also raised the possibility that infected wolves put the entire pack at risk by fearlessly leading fellow wolves into cougar territory where they too may become infected."