Wolves: Want to lead your pack? Get a parasite!

A lot has been written about the toxoplasma gondii parasite.  You might have read that it's a protozoan parasite whose life cycle involves getting ingested by cats, reproducing inside cats, getting pooped out of cats, and starting all over again.

How does it get ingested by cats?  The theory is that rodents come in contact with the infected cat poop, and then the parasite infects and alters the rodents' brains to make them actually them less risk-averse generally, and less afraid of cats specifically.  That bold behavior increases the chance that a cat will catch and eat the rodent, starting the circle again.

That's crazy enough. But some have even theorized that when humans come in contact with the parasite, their brains can become infected and transformed in the same way intended for rodents, and they can become permanently less fearful and more aggressive.

If you haven't heard of this, I recommend this mind-blowing Atlantic article that introduced this theory.

This parasite-induced behavioral change may be more common throughout the animal world than we knew.

A new study of wolves in Yellowstone National Park shows that some are infected with toxoplasma gondii, possibly because they share their range with cougars, and those that are have certain behavioral/personality traits, according to Connor Meyer, a field biologist at the University of Montana in Missoula. From a Science News article:

"The team screened the wolf blood for antibodies against T. gondii parasites, which reveal an infection. The researchers also noted which wolves left their pack — usually a family unit consisting of a breeding pair and their offspring — or became a pack leader. 

"Both are high-stakes moves for a wolf, Meyer says. 

"Infected wolves were 11 times as likely as noninfected wolves to disperse from their pack, the team found, and about 46 times as likely to eventually become leaders. The findings fit in with T. gondii's apparent ability to boost boldness across a wide range of warm-blooded life."

Study co-author Kira Cassidy is not convinced that the high-risk behaviors caused by the parasite are necessarily advantageous, and believes that more study is needed.  There may be some survival-bias in the study because we're only studying the wolves who survived the infection, and who survived the aggressive, risky behaviors that it may have caused.