Parasite gives wolves what it takes to be pack leaders
This came in on my Nature News Feed:
Parasite gives wolves what it takes to be pack leaders
Subtitle:
It's probably open sourced, but if not, some excerpts:
The parasite, Toxoplasma gondii, makes its hosts bold — a mechanism that increases its survival. To reproduce sexually, T. gondii must reach the body of a cat, usually when its host is eaten by one. That becomes much more likely if the parasite alters the host’s behaviour, making it foolhardy. Research results are mixed, but in rodents, infection generally correlates with decreased fear of cats and increased exploratory behaviour. Physical and behavioural changes have also been found in people: testosterone and dopamine production is increased and more risks are taken.
Warm-blooded mammals can catch the parasite by eating an infected animal or ingesting forms of T. gondii shed in the faeces of infected cats. After a period of acute infection, semi-dormant cysts form in muscle and brain tissue, and persist for the rest of the host’s life. Up to one-third of humans might be chronically infected.
Unique data set
T. gondii is known to infect wildlife, but few studies have examined its behavioural effects. In one work, infected hyenas in Kenya became more likely to be eaten by lions2. Connor Meyer and Kira Cassidy, wildlife ecologists at the University of Montana in Missoula, thought of a rare opportunity to link infection with behaviour in wild wolves: data on grey wolves (Canis lupus) collected intensively in Yellowstone National Park, Wyoming, over nearly 27 years. Some wolves in Yellowstone live near, and sometimes steal prey from, cougars (Puma concolor), which are known to carry the parasite. Wolves could become infected by eating the cats — or their faeces.
The team looked at 256 blood samples from 229 wolves, which had been carefully watched throughout their lives, and had their life histories and social status recorded. Meyer and Cassidy found that infected wolves were 11 times more likely than uninfected ones to leave their birth family to start a new pack, and 46 times more likely to become pack leaders — often the only wolves in the pack that breed...
...Wolves are known for killing cougars, however, so even bold, risk-taking wolves infected with the parasite are not likely to end up as lunch for the cats, Meyer says. He speculates that in the past, infected wolves could have been more likely to be preyed on by American lions (Panthera atrox), massive feline predators weighing around 200 kilograms, which prowled North America until they went extinct over 11,000 years ago.
The full original article is definitely open sourced:
Meyer, C.J., Cassidy, K.A., Stahler, E.E. et al. Parasitic infection increases risk-taking in a social, intermediate host carnivore. Commun Biol 5, 1180 (2022).
Note that this behavior is slightly different than in American politics. In 2016, a minority of American citizens managed to promote a parasite into a de facto leader, with the result that the country was almost eaten by wolves.
A little different, I think.
I hope you're enjoying the holiday break.
= new reply since forum marked as read
Interesting article on brain regions most commonly affected:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5549945/
Magat amygdalas are generally more hyperactive:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3092984/
"Apart from the anterior cingulate cortex, other brain structures may also show patterns of neural activity that reflect political attitudes. Conservatives respond to threatening situations with more aggression than do liberals [1] and are more sensitive to threatening facial expressions [5]. This heightened sensitivity to emotional faces suggests that individuals with conservative orientation might exhibit differences in brain structures associated with emotional processing such as the amygdala. Indeed, voting behavior is reflected in amygdala responses across cultures [6]. We therefore further investigated our structural MRI data to evaluate whether there was any relationship between gray matter volume of the amygdala and political attitudes. We found that increased gray matter volume in the right amygdala was significantly associated with conservatism (Figure 1B) (R = 0.23, T(88) = ?2.22, p < 0.029 corrected). No significant correlation was found in the left amygdala (R = 0.15, T(88) = ?1.43, p = 0.15 corrected; see Figure S1 available online for the individual gray matter volumes of the ACC and amygdala)."
Thx for sharing! 
