The Last of Us begins decades ago, on a television talk show in the 1960s. A panel of experts discusses the threat posed by novel viruses that could cause a global pandemic. (The parallels to our own world and time are hard to miss.) One of the experts says he is not worried about a pandemic, at least from a virus. Such viruses, he explains, have been around since the dawn of time and new ones appear on occasion. And why they may result in significant illness and death, mankind’s natural immunity eventually adapts, and the pandemic ends.
What keeps this particular expert awake at night are fungi.
Although they seem harmless to mankind — and some fungi are quite beneficial to humanity — some strains of fungus can be quite dangerous and even parasitic. They latch on to a host and can replace its tissue and even assume control of the host organism. Such fungi do not attack people because they cannot survive in temperatures as high as the human body. But, the talk-show guest warns, if the planet were to warm slightly, and these fungi evolved to match a warmer planet, that could change. And if that happened, there would be no treatment for such a fungal infection, or even a chance of a cure.
In 2003 (at least within the fictional world of The Last of Us) that is exactly what happens. A mutated Cordyceps fungi begins infecting people around the world. Once infected, the sufferers basically turn into bloodthirsty zombies, hungering for human flesh and chasing after anyone who isn’t infected to satisfy their monstrous appetites. 20 years after that, the main story of the HBO series, based on the popular PlayStation video games, begins.
Obviously, the Cordyceps infection zombies are fabricated, but the fungus itself is real, and it can infect insects in a way not entirely dissimilar to the way it infects people on the show. In fact a specific variety of Cordyceps called Ophiocordyceps unilateralis has the ability to create what are known as “zombie ants”:
In carpenter ants, the fungus snakes its way through the body, taking control of their muscles. Then, shortly before its demise, the ant will leave the colony at sunset, find a high-hanging leaf or branch, and clutch it in its jaws. There, the ant hangs motionless until it dies and the fungus emits spores that rain down upon unsuspecting victims. That process has earned it the nickname “zombie fungus.”
But what about zombie humans? It’s highly unlikely, but not entirely out of the realm of scientific possibility.
David Hughes, an entomologist and biologist (and an advisor on The Last of Us games), has said “people get fungal diseases all the time” particularly if they are immunocompromised. The question, he argued, is not whether a fungus might infect someone, it’s whether a fungus might have the ability to control someone’s behavior. And he pointed to historical examples where people have been given “convulsive deliriums” by eating rye tainted by fungus. (Mr. Hughes seems like a really fun guy.)
The last case was in 1954, thereabouts, in France when somebody intentionally sold a load of grain to a small French town containing the fungus. Everybody went mad and some 12-year-old girl tried to kill her mother with a kitchen knife… so yes, consuming the fungus will drive you crazy, and getting infected is possible. But it jumping from ants to humans and then onward [to other people] … that probably requires too many [improbable] circumstances to happen.
In other words, it’s not 100 percent impossible, but it’s not particularly likely.
That said, Cordyceps zombies are not exclusive to The Last of Us. One year after the original Last of Us game was released, the novel The Girl With all the Gifts used a nearly identical premise to explain its zombie infection: Someone became infected with Ophiocordyceps unilateralis, and it sparked a global infection and the breakdown of society. Like The Last of Us, The Girl With All the Gifts — which was adapted to a little-seen but very effective film in 2016 — is largely set decades later, when humanity’s few survivors are trying to find a cure for the fungal infection within a little girl who is infected but immune to its mind-controlling side effects.
Essentially, Cordyceps zombies are good science-fiction: They’re not real, but they’re built on enough real scientific principles and phenomena to make them plausible — and thus scary.
New episodes of The Last of Us premiere weekly on Sundays on HBO and HBO Max.
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