In HBO’s newest zombie-apocalypse horror series, Joel (Pedro Pascal) and Ellie (Bella Ramsey) race to find a cure for The Last of Us fungus, a real-life organism called Cordyceps that takes control of its host and ultimately kills it.
In The Last of Us, the fungus spreads when an infected individual bites another. Once bitten, the victim has between 12 – 36 hours before it is completely consumed. Once the fungus has control of the host’s brain and nervous system, it uses them to spread itself to new hosts. Conceptually accurate; procedurally, dramatized for the series.
In real life, The Last of Us fungus prey only on small creatures like caterpillars and ants (who also have a symbiotic relationship with each other), and, once infected, as on the show, the host is on borrowed time. There isn’t a particularly sinister reason the fungi take the hosts’ life, but there’s no practical way to break the bond between the two once the process is complete.
An infected ant or caterpillar will see this transformation take place over weeks. As the fungus spreads through its body, it releases chemicals that direct the ant or caterpillar to behave differently, act erratically, and move non-stop. Once Cordyceps has complete control, the host climbs to the highest place it can and performs a “death bite,” where it bites as hard as it can to anchor itself in position, drops dead, and plants the fungi on the limb or leaf it dies on. This gives the fungus the ability to spread spores at a higher elevation, raising the chances it will infect more ants and caterpillars.
The Last of Us fungus works similarly, at least in the game. However, showrunners for the HBO series have said that it was difficult to make the spawning angle stick on screen, which is why the show has so far focused only on infection through contact.
The Last of Us fungus wreaks havoc on HBO, credit Warner Bros
So how did The Last of Us fungus make the jump from ant to human?
The Last of Us fungus belongs to the Eukarya domain (as do humans) but lives in the fungi kingdom. Can they infect humans? Not for now. Cordyceps relationship with ants and caterpillars goes back millions of years. These types of symbiotic relationships don’t form overnight. There are also considerations like temperature, climate, and species-specific immunities. But in The Last of Us, the fungus has managed to overcome these barriers. And it’s doing to us what it has done to ants from time immemorial.
Writers for the game and showrunners for the HBO series have hinted at current events having some impact on how the fungus managed to finally leap from insect to primate; from the distribution of a mutated version of the fungus in food to climate change (fungi can only thrive in specific types of climate) to the pandemic, but we’d love to see a Planet of the Apes type of spin where the fungus is being used as a supplement or treatment to cure a disease only to result in a new symbiotic relationship with humans that didn’t take millions of years (with Big Pharma aggressively mixing and testing elixirs along the way).
And it wouldn’t be far-fetched. Cordyceps has been used to treat illnesses and improve immunity for thousands of years.
Often hard to come by and viewed as more of a pseudoscience due to the lack of study and scrutiny in the scientific community, Cordyceps does have some known benefits, including;
- Boosting the immune system
- Helping kidneys work better
- Boosting strength and stamina
Advocates for Cordyceps have claimed there are other uses but no further research has been done.
So could we see The Last of Us fungus with origins in an American, European, or Chinese lab by the end of the series? Given our recent experiences with COVID, what are the chances The Last of Us fungus goes primetime and finds its way into a skull near you (if it’s not already in a cereal box as episode three would have us believe)?
Thankfully, little to none.
Vox had a chance to sit down with mycologist Charissa de Bekker and asked that very question: could this happen to us?
“Everything in the human body is so different from the insects that these fungi normally infect, including our physiology, our nervous tissue, and our body temperature,” Charissa said, “Even if the fungi were able to cause a small infection, the machinery that is needed for the fungus to do such a precise manipulation is simply not there.”
In other words, rest easy; The Last of Us fungus can go fung itself.