A study of 26 years' worth of wolf behavioral data, and an analysis of the blood of 229 wolves, has shown that infection with the parasite Toxoplasma gondii makes wolves 46 times more likely to become a pack leader.

They found that wolves with a lot of territory overlap with cougars were more likely to be infected with T.

Infected wolves were 11 times more likely to disperse from their pack, into new territory.

Infected males had a 50 percent probability of leaving their pack within six months, compared with a more typical 21 months for the uninfected.

Similarly, infected females had 25 percent chance of leaving their pack within 30 months, compared with 48 months for those who weren't infected.

Infected wolves were also way more likely to become pack leaders.

gondii and show behavioral changes … this may create a dynamic whereby behavior, triggered by the parasite in one wolf, influences the rest of the wolves in the pack.".

If, for example, the pack leader seeks out the scent of cougar pee as they boldly push into new territory, they could face greater exposure to the parasite, thus a greater rate of T.