Everyone wants to believe they'd survive a zombie apocalypse – that they could scavenge supplies, find a safe house, load a rifle and outrun the shambling hordes. Real world survival, let alone zombie survival, is harder than it sounds... and that's before you factor in a zombie apocalypse spread by airborne fungal spores. The Last of Us released in 2013 by Naughty Dog and launched a critically acclaimed franchise about the parent-child bond between two survivors... and the desperate lengths they go through to survive the swarms of fungus-infested zombies. The upcoming Last of Us Part II continues the story of Joel and Ellie while also furthering Naughty Dog's unique, disturbing take on the "zombie apocalypse" genre, featuring a fictional plague that's actually based on a real (and just as disturbing) fungal parasite.

First, the fiction: The Last of Us Part I depicts a humanity on the brink of slow extinction. North America has been overrun by the "Cordyceps", a fungal parasite that spread through clouds of spores, burrowing into human hosts and steering them around to attack the uninfected. The zombies in question are eerily grotesque, ridden with fungal growths that explode from their skulls. Their bites spread the infection... but so will breathing in their airborne spores without gas mask protection.

Related: The Last Of Us 2 Reportedly Comes On Two Discs Because It's So Big

The few remaining quarantine zones are ruled by military juntas, and the survivors are cynical, hardened, with little hope for the future of their species. In The Last of Us Part I, Joel, one of those hardened survivors, and Ellie, a savvy yet optimistic teenager, embark on a trek across the country, searching for a cure to the Cordyceps contagion while dodging infected swarms and pillaging bandits. The Last of Us Part II focuses on a grown-up Ellie, who embarks on a quest for revenge against the gang of survivors that wronged her, while contending with Infected more dangerous and grotesque than ever.

The Real-Life Inspiration for The Last of Us' Infected

Now, the reality: there's a fungal parasite called Ophiocordyceps unilateraliswhich primarily infects Carpenter Ants in the forests of Brazil and Thailand. Spores burrow beneath the exoskeleton of an unlucky Ant, eating them from the inside and hijacking their nervous system. The Ant is compelled to walk away from a hive, climb a plant and bite the underside of a leaf with their mandibles. There, the fungus consumes their host entirely, and a fleshy fruiting body sprouts from the Ant's skull and bursts, raining down a fresh cloud of spores to infect more ants. For Carpenter Ants,  Ophiocordyceps is a very real zombie apocalypse that can wipe out entire ant colonies without certain counter-measures (expelling ants with signs of infection from the hive, cultivating beneficial fungus that devours  Ophiocordyceps, etc.).

The odds of this fungal parasite spreading from Ants to Humans is very low but the most devastating plagues started out in animals before making the jump to humans. This, among other things, is what makes the fictional "Cordyceps" of The Last of Us so vividly plausible. Other fictional zombie contagions (flesh-reanimating viruses, comet radiation, brain slugs, etc.) lack real-world precedent... but Ophiocordyceps unilateralis already mimics many of the characteristics of the classic zombie apocalypse, needing only a few key mutations to start turning humans into Runners, Stalkers and the blind, mushroom-faced Clickers. And that doesn't factor into account the ruthless potential of human beings, capable of all sort of cruelties when their back's against the wall...

Naughty Dogs has promised many new features for The Last of Us Part II - improved gameplay, expanded stealth and survival mechanics, smarter, deadlier enemies and a gripping narrative about the cost of vengeance. Hopefully, they won't try to make their fictional zombie apocalypse more plausible than before. It's freaky enough as it is.

Next: The Last Of Us Part 2 Will Contain Nudity & Sexual Content