The Last Of Us is the HBO TV show released in 2023, based on the popular video game of the same name published by Sony in 2013. It tells the story of a lethal infection that kills humans, indicating a form of cordyceps fungus is responsible for the apocalypse. One of the first questions people had was if really a fungus infection could happen in real life and cause the “zombie” effects we see in The Last of Us. Science has provided an answer, partially covered by the prologue: let’s discover it.
You can find the official trailer for The Last of Us here on Youtube.
The Cordyceps fungus infection in The Last of Us: can it happen in real life?
According to the plot in The Last of Us (both the video game and the HBO TV show), if a fungus manages to evolve enough to become capable of attacking humans, it will turn every human being into a zombie who attacks other men to spread, and there will be no cure for it. The fungus responsible for the zombie apocalypse in The Last of Us is referred to as Cordyceps.
The Cordyceps fungus exists in real life. It was discovered in the early 1800s, and it counts about 600 different species in nature. One of those, in particular, the Ophiocordyceps unilateralis, is really considered a fungus capable of turning living beings into zombies.
As this old article from National Geographic explains, some years ago (after the video game The Last of Us was out but before the popularity of the TV show), scientists observed this Cordyceps fungus infect a colony of ants. Their behavior reflects the explanation you can see in the TV Series prologue: the fungus enters the insect body and starts invading it, “eating” the host’s body and replacing it with the fungus itself. Its final goal is to spread as much as possible on other individuals, so he manages to “control” the host’s behavior, manipulating it. “Like a puppeteer with a marionette,” as the scientist in the series explains. And that also includes the development of toxic spores that bloom out of the ant’s head.
Cleverly enough, the fungus avoids infecting the insect’s brain: it controls their behavior through their nervous and muscular system. Even if the brain is not acting as infected, the ultimate result is that the ants move and behave according to the fungus’ goal, which is relatable to the zombie stereotype: finding other living beings and attacking them. In the case of the Ophiocordyceps unilateralis, the infected “zombie” ant targets a plant and really bites it. As the Wikipedia page explains, “the ant climbs up the stem of a plant and uses its mandibles with abnormal force to secure itself to a leaf vein, leaving dumbbell-shaped marks on it.”
So we have a fungus that provokes a lethal infection, manipulates the host’s behavior, and forces him to bite another living being to spread, like zombies in popular culture. But can it apply to humans? Let’s find out.
Are humans exposed to a fungus infection?
As this research on the National Library of Medicine explains, four basic conditions are necessary for a fungus to infect humans:
- High temperature tolerance
- Ability to invade the human host
- Lysis and absorption of human tissue
- Resistance to the human immune system
The main argument provided by the scientist in The Last of Us Episode 1 is related to the first condition, temperature, and it’s actually true: most fungi (including the Cordyceps) need a temperature between 20° and 30° Celsius (68° to 86°Fahrenheit), while the human body reaches temperatures higher to 37° C (98-100° F). A fungus wouldn’t survive at the temperature of the human body.
But even in the remote possibility that a fungus evolves so much that it would be able to survive with temperatures so different from the ideal ones, a transformation into zombies is really unlikely. For two main reasons: humans have a much stronger immune system than an insect due to thousands of years of evolution. Simply, we have many more weapons than an insect to fight and kill a fungus. And human biology is so complex that it’s pretty impossible for a fungus to come up with a way to control human behavior: our brain is incredibly complicated if compared to the simplicity of a fungus, and also, our nervous and muscular systems run through so many different organs and body parts that no fungus would be able to take control. On the other side, insects like ants are much simpler living beings and live at the right temperature for a fungus.
In conclusion, a fungus can’t kill humans, turning them into zombies, as in The Last of Us. But some species of Cordyceps fungi indeed work that way, and their manipulative behavior has been observed in nature. The idea behind the video game and TV series is inspired by nature and real life, just adding an advanced step of evolution to turn it into a horror, sci-fi story.