On a show about bloodthirsty zombies and a broken, post-apocalyptic world—especially one based on a video game perhaps best known for the constant, low-grade stress it instilled in players for whom they died so many times that they considered dropping the game seems to be on the whole an almost universal experience– You wouldn’t think that flashbacks to a rosier, pre-pandemic past would make up the scariest scenes.
But they have that. In the first two episodes of HBO’s The last of us, it’s not the sprinting murderous grannies or clicker jump scares that prove most haunting. For many viewers, it has instead been the first scene of each episode, both of which dealt with the threat of the most terrifying threat: mushrooms.
OK, OK, not mushrooms per se, but mushrooms in general. The series premiere featured epidemiologists on a fictional 1960s talk show discussing pandemic dangers. One proclaims—to laughter and then to a chill as the audience understands what he is saying—that he fears neither viruses nor bacteria, but fungi, which alone could have the power to create “billions of marionettes with poisoned minds permanently fixed on one unifying goal: to spread the infection to every last human alive by any means necessary.”
“There are no treatments for this,” he continues. “No preventatives, no cures. They don’t exist. It’s not even possible to make them.”
Sunday’s episode jumped to the earliest days of the pandemic that would soon turn most people into vicious tracers. Summoned to a government facility in Jakarta to consult the corpse of one of the first infected victims, a mycology professor from the University of Indonesia (a touching cameo by Christine Hakim) slowly discovers the threat posed by the newly emerged human host ophiocordyceps fungus. She grimly advises the soldier who brought her in, “Bomb. Bomb the city.”
It turns out that these crashing jets and dark museum halls have nothing on the specter of fungus. To see The last of us is to radicalize against the humble kingdom of eukaryotes, to loathe their pilei, to fear their evil mycelia. If you take it from some viewers’ responses, many is unlikely to sample porcini ever again.
To nurse my nascent mycophobia, I turned to Jonathan Cale, an assistant professor at the University of Northern British Columbia who studies fungus-tree interactions in forests, and Matthew Kasson, an assistant professor of mycology at West Virginia University, whose work has focused on Massospora cicadina, a parasitic fungus that — gulp — infects cicadas, alters their behavior to propagate itself, and eventually seals their doom.
“It’s not far-fetched for me,” Kasson says The last of us‘s vicious mushrooms. “They are stranger than fiction.”
The virgin mushroom vs. Chad 94 degrees
The opening scene of The last of us shows the second epidemiologist trying to allay the first’s concerns about a fungal pandemic by reminding his colleague that fungi can’t survive in temperatures above 94 degrees—leaving us toasty humans safe from their spongy claws.
Alas: “That’s untrue,” says Kasson. “There are a number of fungi that can persist. In fact, we know that the limit for fungal growth is about 62 degrees Celsius”—about 143 degrees Fahrenheit and more than enough heat to cause a burn—”beyond which many or most eukaryotes, including fungi, cannot grow.”
“No Preventatives, No Cure”
The last of us makes much of the idea that because cordyceps is a fungus, it cannot be treated with medicine. That’s not true: Fungicides abound to treat common fungal conditions such as athlete’s foot, yeast infections, ringworm, and dandruff.
But the show is true that fungi are exceptionally difficult to combat, says Kasson. “Fungi are more closely related to animals than they are to plants. But it’s really hard to get rid of scales because they’re eukaryotes, and animals and fungi share a lot of similarities. It’s hard to fight them without fighting ourselves. So they have to come up with specialized types of compounds that can kill the fungi without harming the host.”
Options remain slim, even if the doctors and scientists are inside The last of us probably would not have immediately given up fighting cordyceps. Take it from microbiologist Arturo Casadevall, who told Hopkins Bloomberg Public Health magazine last year: “Because we don’t worry about the fungi, not a lot of work is done on the fungi. So we don’t have too many drugs. We don’t have fungal vaccines, and it all becomes a bit circular.”
Further nightmare fodder: Casadevall believes we’ve already seen a mushroom, White ears, adapt to the heat of the human body. “As the world gets warmer, the fungi will have to adapt,” he said. “Every hot day is a selection event.”
Smooching the Wood-Wide Web
Hear me out: What if the grossest kiss in recent TV history amounted to a randy Avatar tail touch?
Come back! The two are, for better or worse, related: Both play off of a phenomenon known as “the wood-wide web,” where fungi supposedly allow disparate trees in the same forest to communicate. As cat-people and light are motets of Avatar unite under a single fibrous connection called “Eywa”, as do the infected and their hideous vines. (Theirs may not involve a soul tree.)
In recent years, the theory has appeared as scientific fact in everything from the 2019 Pulitzer Prize winner The overstory to Ted Lasso. Recently, a number of mycologists have spoken out against the concept, which they say is exaggerated.
But mushrooms communicate in a way. “There is plenty of evidence that chemicals emitted by a fungus affect the growth and development of fungi of the same or different species. Many of these chemicals are volatile, diffusing through the air and modifying the behavior of other, separate fungi,” says Cale, who has studied the phenomenon.
IN The last of us, Joel kills an infected person in the statehouse. As the newly (re-)dead infected fall to the ground, tendrils spread over the corpse’s fingers, alerting dozens of nearby infected to the group’s location. It’s not clear whether it’s a defensive mechanism or a hunt for fresh victims, but there is real evidence for the former in some plants, Cale says.
“The types and amounts of volatile chemicals emitted by fungi change when a fungus is wounded or fed by predators (eg, soil-dwelling insects),” he says. “These modified chemical profiles can reduce or even completely deter further predation. Thus protecting the fungus from further damage.”
Cale warns that it is unknown whether the reaction can affect other fungi – but it has been seen in plants. “Chemicals emitted by plants attacked by insects or pathogens stimulate the production of defense chemicals in distant, unattacked plants.”
Cordyceps, Carpenter Ants and the zombie must chomp
On The last of us, people become infected with cordyceps if they are bitten by an already infected person. (The game also features infection via spores, although they have yet to appear in the HBO edition.)
Let’s call it creative freedom. The choice of cordyceps as the fungal enemy of the series is inspired by the real behavior of carpenter ants. A cordyceps infection will actually turn an ant into a puppet of the fungus, causing it to climb to a high place, attach itself to a leaf or twig, and die. “Once the ant is dead, the fungus will erupt violently, usually from the ant’s head,” says Kasson. “And then spores will rain down from that fruiting body onto unsuspecting ant victims below.”
But what we look at The last of us is an entirely different form of spread: active host transmission, which requires direct contact with a host to become infected. Unfortunately, this has at least some basis in reality.
Kassen specializes in the zombie cicada fungus, where cicadas infected with Massospora cicadina have the back end of their bodies gradually killed by the fungus, which also produces a psychoactive compound “that makes them hypersexual and super, super focused.”
“They continue to mate and fly around as if nothing is wrong,” says Kasson. “So that way it spreads from cicada to cicada like a sexually transmitted disease.”
… Is a destructive fungus humanity’s greatest threat?
Then we have to leave, just like the epidemiologist The last of uss premiere, lie in bed at night dreading the day a particularly nasty fungus adapts to thrive on humans?
Recent studies have documented an increase in some fungal infections believed to be the result of the COVID-19 pandemic. In particular, patients sick with COVID who receive common treatments such as steroids that can suppress immune responses, and those who suffer from the lingering effects of prolonged COVID, may be immunocompromised, opening the door to fungi they might otherwise have fended off .
“It’s not that super mushrooms are emerging,” says Kasson. “These are common fungi that live in the soil, common fungi that live in sinks, and that just take advantage of weakened immune systems that can’t mount a response against them.”
“So do I suspect that we will see higher incidences of fungi in a warming world? I think we may. But it will be some of the same fungi that we have been quietly fighting in the hospitals and clinics for a long time . It’s just that people are becoming more aware of them because maybe a larger portion of the population will be immunocompromised because of things like COVID-19 and other viruses that can predispose us to subsequent invasion by these generally pervasive fungi.”
In other words: Fear the virus and the mushroom.