From a video game to a TV show to … real life? HBO’s The Last of Us has taken social media by storm ever since its first episode aired on January 15 of this year. The show takes place in a post-apocalyptic world after humans were invaded by a pathogenic fungus. Said fungus would take over their host’s nervous system and cause them to become violent and eager to spread to other hosts. While it may seem implausible for this zombie-like invasion to occur in real life, recent scientific research has suggested that fungi may be evolving more quickly than we would like to see.
Earlier this month, researchers at the Institute of Science and Technology Austria, led by professor Sylvia Cremer, conducted an interesting study with ants and six pathogenic fungi strains. The ants were infected with these strains and then observed over several generations, for ten different trials. During each trial, the scientists noted that not one of the fungi would become more notably prevalent than the others. Rather, each strain tried to win out the others but did not succeed. However, something interesting happened when the researchers compared how many infectious spores the fungi were producing versus the ants’ response.
Ants are social creatures and, much like humans, try to combat pathogens with social immunity measures. The main tactic the ants used against the fungi involved “grooming off infectious spores from exposed individuals.” Grooming for ants is similar to how humans use hand sanitizer to prevent illnesses. As the ants discovered the spores on their peers, they would work to get rid of them. Expectedly, the fungi produced more spores to try and mitigate the defense mechanism of the ants. However, instead of working harder and faster to destroy these spores, the researchers observed the ants showing less of a response towards those rapidly-generating spores. Cremer explained, “This suggests, that the spores have become more difficult to detect by the ants.”
After more investigating, the team concluded that the fungi intentionally reduced their chemical fungi signals to protect their spores from being detected by the ants. Specifically, they decreased their production of ergosterol, “a key fungal membrane component.” As production of that component was reduced, the ants would not groom as much as they previously did, showing that they did not know the spores were among them. Yuko Ulrich, an evolutionary biologist not involved with this study, suggested the fungi’s adaptation “could allow the fungi to hide out from the grooming ants while they evolve new ways to fight back—a strategy not previously seen.”
It is interesting to consider how “intelligent” the fungi behaved in response to the behavioral changes of the ants. While this research was done on ants, its results can highlight greater implications and challenges humans may face in the future as we are also social creatures. Given ample time, what is stopping any pathogenic strain of fungus from evolving in such a way that humans are unable to quickly detect their presence? We never expected a pandemic like the one we are still currently recovering from, so what makes a dangerous fungus unable to unpleasantly surprise us in the near future?
