The Last of Us ‘zombie’ mushroom, explained

The Last of Us ‘zombie’ mushroom, explained

The Last of Us ‘zombie’ mushroom, explained

The scariest shows and movies are often the ones grounded in reality — about psychopathic serial killers, late-night home invasions, and AI robot dolls. Zombie apocalypses generally don’t count.

But a new show on HBO, titled the last of yous, presents a compelling case that there might be such a thing as a lifelike zombie. Or realistic. And it’s definitely scary.

The show’s premise, which is based on the popular video game of the same name, isn’t all that different from your typical post-apocalyptic horror story: American cities are collapsing, there are enraged humans everywhere and a manly man must protect a young girl as she travels across the country.

Zombies, however, are truly inspired. Specifically, they are inspired by nature – by real zombies that live on Earth.

Pedro Pascal, of The Mandalorian and NarcosHBO stars The last of us as Joel Miller, the main protagonist.
Liane Hentscher/HBO

In the show, which premiered last Sunday, it’s not a virus that turns people into mindless automatons, but a kind of fungus called Cordyceps. The fungus takes hold of their minds and bodies and makes them want to spread the fungus to uninfected people.

This mushroom is real.

In tropical, subtropical, and even temperate forests around the world, there are many species of fungi of the genera Cordyceps and Ophiocordyceps (these fungi were once called only Cordyceps) that infect insects like ants and other invertebrates. And they basically turn them into zombies. The mushrooms take over their minds and bodies, causing them to behave in ways that spread spores to others of their kind.

Mushrooms were popularized in 2016 by the show Earth, which captured an Ophiocordyceps parasitizing a bullet ant. And it’s actually the clip below – in which the fungus makes the ant climb up a branch, before killing it and sprouting a spore-producing fungus from the ant’s head – that inspired the creator of the game, Neil Druckmann.

So the fungus is real and it can turn insects into zombies. It’s pretty awesome. But is it a threat to us?

A comforting fact is that people have been eating Cordyceps for centuries without getting rabid. It is a traditional Chinese medicine, used to treat kidney disease and other ailments. Even wellness brands are now marketing it.

But to be sure – because you really can’t be sure enough, can you? “I contacted Charissa de Bekker, a mycologist who does research on Ophiocordyceps. A professor of biology at Utrecht University in the Netherlands, de Bekker has not seen the show but is familiar with the game. Our conversation has been edited for length and clarity.

To be clear, the mushroom in the show The last of us is real, right?

Yes. Cordyceps and Ophiocordyceps fungi are real and infect insects in nature. There are many different species.

Many!? How much?

Researchers have described at least 30 species of Ophiocordyceps that parasitize ants, but we know there are many more because each species of infected ant has its own specialized Ophiocordyceps species.

There are also Ophiocordyceps and Cordyceps fungi that infect other insects like wasps and flies. We also see this going beyond insects to arthropods like spiders. Then there’s a whole other group of fungi, in the order Entomophthorales, that also do some manipulation – and those species look nothing like Ophiocordyceps.

Manipulation has evolved many times throughout the mushroom kingdom. The biodiversity of these fungi is probably very high, we just haven’t discovered them all yet.

A type of Cordyceps fungus growing on a bullet ant near Puerto Viejo de Sarapiqui, Costa Rica.
Kevin Wells/Getty Images

Another type of ‘zombie’ fungus grows from a dead winged insect in a rainforest in Vietnam.
Quang Nguyen Vinh/Getty Images

How do these fungi manipulate their hosts in nature?

What we see, especially with ants, is that they pick up spores [which are kind of like seeds for fungus] when they go out to look for food. The spore infects the ant and fungal cells begin to grow inside its body.

At first, this ant might act normally. But eventually, it ceases to participate in the colony’s foraging efforts. He no longer communicates well with his nest mates.

And then this ant begins to become hyperactive and no longer has the same daily rhythms as the other ants. Most carpenter ants, for example, feed at night, but the infected ant essentially becomes active all the time.

A ‘zombie’ fungus sprouts a fruiting body (fungus) from an ant in Indonesia.
Reza Saputra/Getty Images

At some point, the infected ant moves away from the colony to find a place in the forest to climb and bite [down on the twig or vine]. This is where the fungus will quickly begin to consume everything inside, which will kill the host. The fungus uses this energy to germinate a stock with a fruiting body – the fungus, if you will – which has spores that will fly out and infect more ants.

By climbing higher in the forest, the ant essentially helps the fungus spread its spores. The specific place it chooses to climb may actually aid in the development of the fungus.

This whole process can take days, weeks, or even months. What you often see in zombie movies, or The last of us, things happen much faster. In nature, things take time.

Do Ophiocordyceps actually control the minds of ants?

We believe that this fungus secretes certain chemicals that can bind or interact with receptors or other types of proteins that are related to the nervous system, and normally result in different behaviors. For example, it could be receptors that normally bind to dopamine or serotonin, which could then trigger a certain type of behavior. We are still trying to figure this out.

We certainly think it’s more than this fungus eating away at certain brain tissue because the behavior is so specific.

A zombie is glued to the wall by the Cordyceps fungus in episode 1 of The last of us.
Liane Hentscher/HBO

Do you call these infected hosts “zombies”? Is it scientifically correct?

If you compare it one-to-one with pop culture zombies, it’s not entirely accurate. These insects are very much alive, whereas in fiction films, zombies are often undead. These ants infected with Ophiocordyceps are not dead and are walking around.

What makes real hosts similar to fictional zombies is that they behave in ways that benefit the parasite, not the host.

Is there any reason to believe that a fungus like this could infect a human body and turn us into zombies?

The very short answer is: No.

Everything in the human body is so different from the insects these fungi normally infect, including our physiology, nerve tissue, and body temperature. Even though the fungi may have caused a small infection, the machinery necessary for the fungus to perform such precise manipulation is simply not there.

These fungi have evolved strategies to manipulate specific insect hosts over millions and millions of years. They are not generalists. Each species only knows how to deal with one particular insect.

We don’t see fungal scientists jumping from one species of ant to another, much less from one species of ant to another insect. Spreading from ant to human is such a big leap.

In the show, a fictional epidemiologist suggests that climate change could make harmful fungi more tolerant of warmer temperatures. As a result, they could more easily jump on warm-blooded humans. Is this a real concern?

This is actually a real concern of medical mycologists [about harmful fungi like Candida auris, not Cordyceps]even if it’s not my area of ​​expertise.

Most fungal infections are skin infections – or if, for example, you’re an immunocompromised patient, some normally benign spores can land in your lungs and cause a problem. But most mushrooms don’t grow at our body temperature. Most of them actually prefer lower temperatures.

Some experiments show that fungi might be able to adapt to higher temperatures, as they adapt to a warming world. You can imagine that if their optimum temperature gets closer to our body temperature, fungal infections could become more of a problem.

In the show, the fungus is spread by bites, not spores. That’s not how it would work if those fungus-infected zombies were real, is it?

If you play the game, you will see that the spores play a role in spreading the infection. But no, the fungus wouldn’t be spread by biting. Generally, throughout the fungal kingdom, the passage from one place to another, or from one host to another, is done by the spores.

I’m a huge mushroom fan. They break down plants, they can be psychedelic. They are also delicious. Is it unfair that Cordyceps is the villain of the series?

It’s great that mushrooms are finally in fashion and happening. I hope the show sparks some interest in fungi in general, as they are incredibly fascinating organisms. They are more important than people think.

A Cordyceps fungus grows from a wingless insect on a leaf in Ecuador.
Luis Espin/Getty Images

They really are the bad guys on the show, and that’s usually how we think of parasites, because they make us sick. But in nature, they are actually super important and just as important as all other organisms.

They control everything. If ants, for example, weren’t harassed by certain pests – not just Ophiocordyceps but anything that makes them sick – then their numbers could spiral out of control. You might have an overpopulation of certain species. Eliminating a parasite like this fungus could be like eliminating a predator from the ecosystem, and it could lead to a decline in biodiversity.

I’m a little afraid to ask, but how common is fungus, in general?

Not to scare you, but in every breath of air you take there will be fungal spores. Most of them aren’t harmful to us – most of the spores you’re inhaling right now are benign or fungi that don’t know how to deal with our bodies, so you’ll never even notice them. But they are everywhere.

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