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In video game and HBO show The last of us, humans struggle to survive after an infectious fungus turns ordinary people into zombies. The franchise’s creators didn’t look far for inspiration – the series is based on an actual mushroom species that exerts a kind of “mind control” over its insect hosts.
Ophiocordyceps unilateralis, otherwise known as cordyceps or zombie-ant fungus, infects insects such as ants or spiders. Like other parasites, cordyceps completely drains its host of nutrients before filling its body with spores that will allow the fungus to reproduce. It then causes the insect to seek height and stay there before expelling these spores, thus infecting other insects nearby.
Bryn Dentinger, professor of biology at the University of Utah and curator of mycology at the Utah Museum of Natural History, told NPR that the fungus is one of the most well-known types of organisms and probably the most commonly encountered with this mind control ability.
And he said scientists aren’t entirely sure how cordyceps is able to have the effect it has on insects, although there are theories.
“There seems to be a combination of physical manipulation of muscle fibers, for example, possibly growth in the brain itself, which may impact its behavior,” he said. “But there’s also most likely some sort of chemical attack on the host, either small molecules or proteins or other things, that end up manipulating brain behavior.”
Dentinger, who is also a fan of the HBO adaptation of The last of us, stated that there are major differences between how the mushroom is depicted on the show and in real life. Cordyceps does not usually infect other hosts through the mouth, for example, and infected people are not connected to each other via a network.
And, perhaps most importantly: the fungus cannot infect humans.
“Our body temperature is high enough that most organisms, their proteins denature at this temperature and therefore cannot survive in our body,” he said.
But there are species of fungi that are able to withstand higher temperatures, and therefore can infect humans. Climate change, as Dentinger explains, gives some fungi the ability to withstand higher temperatures.
And it’s possible that a fungus with similar mind control abilities could, at some point, be able to withstand a human’s body temperature.
“That may be one of the reasons we’re seeing more fungal infections in humans, but again, to date, none of them are cordyceps,” he said. he declares. “However, that may happen in the future, but, at the moment, it’s not a possibility.”
And, like Dentinger, there are already species of mushrooms that alter a human’s mental processing, such as psilocybin, otherwise known as “magic mushrooms.” Meanwhile, other types of fungi are already ubiquitous in human life. Take yeast, for example, which is found in bread and in the human intestine.
And while the prospect that fungi can manipulate human behavior isn’t impossible, it’s not likely, according to Dentinger. The characteristics of the fungus that allow it to attack an insect host are very specific to that insect and are not easily transferable to another species.
“It’s unlikely that they could go from, say, an ant to a human, because we’re so different,” he said.