A parasite could dictate the leader of a wolf pack
Two wolves from the Druid Peak pack are playing in Yellowstone National Park.
Wolves infected with a common parasite have a much higher chance of s& #x27;impose as leaders of their pack, according to a study which suggests that the intruder, which colonizes the brain, encourages its host to take risks.
< em>Toxoplasma gondii, a single-celled parasite, breeds only in cats and felines, but can infect any warm-blooded animal.
It is estimated that between 30 % and 50% of the human population is infected with the parasite, whose immune system usually prevents the appearance of any symptoms.
Studies have established a relationship between its presence in the human brain and an increase in risky behavior and aggression. Others have disputed the existence of such a link.
The study published Thursday in the journal Communications Biology is based on 26 years of observing gray wolves in Yellowstone National Park, United States.
Wolves from the Druid Peak pack in the American national park of Yellowstone.
Researchers at the Yellowstone Wolf Project analyzed blood samples from 230 wolves and 62 cougars. The latter are known to spread the parasite in their interactions with wolves.
Their research established that an infected wolf is 11 times more likely than a wolf uninfected to leave their pack, which is characteristic of a greater propensity to take risks.
And an infected wolf is 46 times more likely to become pack leader, according to the study, which reminds us that this role normally falls to the most aggressive and adventurous individual.
These three findings provide rare evidence of a parasitic infection influencing behavior in a wild population of mammals, according to the study.
Being more fearless is not in itself a bad thing, but it can shorten the existence of animals, because their decisions can more often put them in danger, explained to AFP Kira Cassidy, co-ordinator. -author of the study.
Another study published last year concluded that more aggressive behavior, induced by the parasite, in young hyenas in Kenya made them more likely to approach lions and be bitten.
The same scenario would be at work in rodents infected with the parasite: they lose all instinctive fear of their first predator, the cat, which is the host of choice for Toxoplasma gondii .
While praising the findings of the wolf study, William Sullivan, professor of pharmacology and toxicology at Indiana University, warns that it does not prove a causal relationship.
A wolf with a risk-taking nature might simply be more inclined to venture into cougar territory, and contract toxoplasmosis there (caused by the parasite in question), remarks to from AFP the professor, who has studied the parasite for more than 25 years.
But if the results prove to be correct, they suggest that we are under- estimate the impact of Toxoplasma on ecosystems, he adds.
In humans, the parasite primarily affects immunocompromised people, and causes toxoplasmosis, a disease that can damage the brain and eyes. Infection usually occurs through the absorption of too raw meat, or through the care given to his cat, in particular by cleaning his litter.
Ajai Vyas, specialist in parasite at Nanyang University in Singapore, doubts that such an infection in humans could lead him to risky behavior. Human behavior is very different from that of other animals, he points out.