The Biology Behind The Last of Us | WIRED

some infection and HBO's The Last of Us is actually based on this very real parasitic fungus that turns certain insects into zombies growing from her head that is the fruiting body that contains the spores the creators of the game and the new show were inspired by zombie carpenter ants specifically they even gave the bugs a quick Cameo so it's a pretty cool Easter egg that's in the game the zombies in The Last of Us go through four stages of infection which have parallels in nature wired spoke to an expert on the real fungus reference in The Last of Us those are a lot of spores to compare those zombies with similar examples in nature most zombies and TV and film are depicted as reanimated corpses but not in The Last of Us viruses can make us ill but fungi can alter our very Minds one thing it does right where a lot of movies do it wrong is that the infected are still alive when they're manipulated there's lots of examples of this in nature the brains of living crickets cockroaches and even mammals can get hijacked by different types of zombie parasites that alter their behavior new research shows that gray wolves get infected with Toxoplasma by interacting with cougars and their feces which carry the parasite those that are infected are more risk-taking more bold becoming the leader of the pack the behaviors that we're seeing are rather complex and in the case of ants the cordyceps parasite spreads throughout the body as a yeast which secretes chemicals that behave similarly to neurotransmitters in the brain it looks like the fungus is avoiding the nervous tissue it's not chewing on it it's not eating it these cells might be close to the brain and then secretes molecules that manipulated in such situated behave so precisely to help this fungus spread in the first stage the infected humans don't show outward signs of their condition in the beginning the ants don't behave differently after a few days you see that the behavior of the ends definitely is changing in the video game it starts with a twitch twitching we also see this in our ants they seem to have sometimes whole body convulsions the fungus is producing a compound that is similar to eflatrim certain fungi produce this and when an animal ingests this they get stagger's syndrome so they get these Tremors then the humans in the last of us get a little hyper moving at high speed as if stimulated by chemicals excreted by the fungus a similar thing happens with the zombies in Professor to Becker's lab they're out and about all times of the day in constant Locomotion soon The Last of Us Runners lose the ability to speak so do infected ants in a sense they don't communicate so well with other Nest mates anymore ants will sniff each other out with their entity the smell of these ants definitely changed so if an end starts to smell differently because she is sick they basically will kill her and put her on a discard pile there might be a similar social immunity Dynamic at play in The Last of Us I see a pile of humans infected by this fungus and sprouting mushroom bodies definitely a pile I wouldn't want to get near you know stage two the stalker phase of the last of the zombies is characterized by obvious fungal growth the stalker definitely looks more cordyceps like so all those strings growing off of the head they very much remind me of the stocks that we see on our ants for instance it looks like the first bit of a mushroom body coming off of the left side of her head that looks pretty gnarly similarly in nature the parasitic mesopora fungus radically transforms its host's physical shape and gives it a desire to seek out new hosts to infect this cicada you'll see that it's missing a part it's behind its genitals aptly named the butt fungus because it loses its butt that's a fungal plug and the powder are the fungal spores this is how the fungus is able to release its spores and infect other cicada in the game and in the show has fungus is able to reproduce by biting other humans or by contact with spores off of other humans that have these fruiting bodies sprouting off of them misospera resembles the fungus in the game a little bit because in the last of us and in nature zombies have increased energy and they start to spread out and wander normally these ants would go forged for food with their nest mates and nicely follow and trails instead they actually just wander around aimlessly could a similar wandering Dynamic be at play with gray wolves infected with a protozoan parasite wolves infected with Toxoplasma are more likely to wander away from their former pack to find a new one and are more risk-taking more bold the Wolves studied recently in Yellowstone National Park could be drifting nearer to the source of their infection cougars because Toxoplasma reproduces only in the stomach of felines in The Last of Us during the clicker phase the fungus has really taken over in the clicker the morphologies changed entirely so it makes me think more of the fungus called chicken of the woods which is an edible fungus at this point the zombies rely on echolocation after losing their sight in real life zombie ants might also become impaired because they start randomly climbing towards light they will climb up a plant at certain light levels because they don't perceive light so well anymore and they're trying to search for it or they're getting themselves off the ground this is what we call summiting Behavior something that a lot of parasites have evolved to use as a strategy to transmit better the fungus is making the end find some sort of micro climate that helps the fungus to develop its mushroom that releases the spores but if you're higher up in the air then your spores can be more easily carried by the wind and can land on or be eaten by a new host another example of infected hosts acting in the interest of their parasite are cockroaches that get stung by Jewel wasp which inject their victims with a kind of mind control Venom along with a brood of eggs this changes the behavior of the Cockroach entirely doesn't want to fight anymore it's this very docile creature that then follows the WASP back to its burrow if he gets eaten alive by it is developing egg that eventually becomes a larva and not a situation that is beneficial to this cockroach but very beneficial to The Offspring of the WASP similarly crickets infected by the gordian worm are compelled to act self-destructively the worm needs to be in water to mate so what this worm does is it makes these crickets jump into water this Cricket has no business being in the water so basically they have committed suicide and now the worm can breed in its natural habitat the water a similar process happens with Toxoplasma in mice which breeds in the digestive system of cats rodents that get infected with toxoplasmosis actually makes these rodents attracted to cat urine it's making it more likely that this rodent will get eaten definitely behavior that is beneficial to Toxoplasma but absolutely not for the rodent in the last of this game it takes years for the fungus to cover the skin completely and turn human into slow-moving bloater but for zombie ants in real life to succumb completely takes about three weeks and the beginning of the end starts with a hyper contraction of the jaw muscles and spider Branch can't let go and die as they're eaten by the fungus within when the ant is in place the fungus quickly changes its strategy and starts to eat everything including the brain to produce a fruiting body this is when the fungus will change from being a yeast to forming a mycelium everything inside is just mycelium bursting out of the host so this is what we often call the stock you see that on that stock there's this brown bulbous thing attached that's the fooding body so that carries the spores those are all mushrooms if you will those are all fruiting bodies as the Spore gets into the air and as the air moves it can easily take it to different places so this is why we think that this summiting behavior is actually helping the fungus to spread its spores see this Spore Cloud those are a lot of spores this one would be exuding spores like crazy looks you know very similar to what we envision the spores would look like they're microscopically small so we can hardly see them but people that recorded spores coming from mushrooms that's kind of what it looks like according to a recent World Health Organization report fungal infections are estimated to kill at least 1.6 million people yearly aspergillus fumigatas can even spread to the brain of the immunocompromised other fungal pathogens are even showing resistance in settings like hospitals should we be worried most of the fungi that we know of at least they like to grow at the lower temperatures than our body temperature our bodies are just not great hosts to infect because the temperature would be too high however in climate change and the Earth getting warmer fungi need to adapt to be able to grow at higher temperatures as well their optimal temperature will become closer to our body temperature making it more likely that in the future we'll have more fungal infections yikes but there is one reason why all of humanity isn't likely to be wiped out by a mutant zombie fungus apocalypse like in The Last of Us in the game and in this show what you see is that humanity is on the brink of being extinct there and aren't that many humans left that's actually not a very smart strategy if you wipe out your host entirely then eventually there's no hosts to infect so it will stop to exist as well there's so much more going on that we don't understand quite yet we also interact with a lot of microbes and a lot of organisms that are beneficial to us our microbiome has influence on a lot of our physiology then leads to certain behaviors so who would we be without our parasites who would be being with other microbes I think it's a very interesting philosophical question

Channel: WIRED

Views: 1,869,883

Keywords: biologist, biology, cordyceps, cordyceps brain infection, cordyceps last of us, currents, last of us hbo wired, last of us infected real life, last of us video game, real life last of us, the infected hbo last of us, the last of us, the last of us hbo, the last of us wired, wired, wired biologist, wired the last of us

Id: GnEIwL_SgL0

Length: 9min 42sec (582 seconds)

Published: Fri Jan 13 2023

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[u/favorscore]

HBO is firing on all cylinders for this show. Impressive