The ‘Science’ Behind The Last of Us

At a recent hands-on session with upcoming Sony exclusive, The Last of Us, the press were treated to a short talk from the game’s scientific advisor: a Penn State University Professor who’s also the advisor for upcoming zombie flick, World War Z. He took to the stage to explain how he was drafted in to help lend authenticity to the science behind the – BBC documentary-inspired –  Cordyceps infection that forms the crux of the game’s narrative.

We were shown footage of the fungus, Ophiocordyceps unilateralis, which a member of the Naughty Dog team saw on the aforementioned Planet Earth documentary. We saw how the fungus interacts with the indigenous ant species in the tropical climes where the corruption grows. Once an ant ingests the spores from the fungus, it alters the way the ant behaves, forcing it to fall from its home in the trees and climb onto the stem of a nearby plant.

Upon climbing the plant, the ant clamps its mandibles together on a leaf and stays there until death. The affliction then sprouts from the ant’s head, after consuming any living tissue, and releases its spores for the purposes of spreading even further. The scourge is so dangerous that it can wipe out entire colonies of ants, erasing them from the face of the Earth.

The ants have become so used to this cycle that, when they notice a member of the colony is riddled with the substance, a healthy ant will drag its comrade away from the colony, preventing the exposure of spores to the rest of the dominion.

The professor then went on to show us how this isn’t isolated to fungus alone.

Another instance that we were shown of a parasite controlling its host, was with the Nematomorpha, a parasitic worm that infects a variety of insects. Once the spindly sycophant has had its fill, it controls the nervous system of its host and leads the insect to water, where it can exit its victim and begin the cycle anew.

After the videos had finished, the professor took to the stage to go into a bit more detail about making the game as plausible as possible for a modern audience.

“Hollywood and the gaming industry are very focused on this dystopian angle, like the film [28 Days Later] which shows a deserted London. It’s something that’s rather spectacular, because we never think of cities being deserted.”

And he’s not wrong. Whether it’s Fallout or Resident Evil, gaming is saturated with this type of scenario. So it makes sense for the studio to at least make the situation as believable as possible, especially with the – much touted – focus on building believable characters.

“For example, in this modern scenario, in the whole human population, more than half of us live in cities in these terribly dense situations. In a city like London, this has always been the case and we’ll always have large population centres.”

Part of our morbid fascination with post-apocalyptic fantasies is also the chance to explore an area that’s usually bustling, only… when it’s deserted. Obviously, in real life it wouldn’t be much fun to be in this situation, but gaming is a way to escape to a fantasy world, however morbid the fantasy.

The thing is, we’re not as safe as you may think, and the people around you can do you harm, regardless of intention.

“Large population centres are breeding grounds for parasites and diseases, and this is really fuelling a lot of this sort of dystopian view that’s become part of popular culture. We’re all primed to think about the next pandemic, mainly because basically we’re all scared to shit of the next pandemic.”

Look back at the impact Swine Flu had in the UK in 2009, and it’s easy to see that even something comparatively tame – compared to zombies and mushroom monsters, at least – can wreak havoc with our normal way of life.

“Even though London has cleaned up its act over the last few hundred years, since the major plagues, such as the bubonic plague, we’re still getting into incredibly crowded conditions. And it doesn’t take much for one of those individuals to be infected having got off a flight from Hong Kong, for example, then spreading that infection to vast numbers of people.”

Which again, did actually happen back in 2003. An outbreak of the SARS coronavirus in Asia led to the deaths of many across the globe. The virus highlighted how woefully underprepared for an outbreak of this scale, with air travel playing a huge part in the spreading of the infection. In the end, over 700 people died as a direct result of the pandemic.

Seven hundred people, dead.

“So, what’s interesting about the Naughty Dog scenario is, they’ve taken this dystopian view, but they’ve gone twenty years in the future and you see that the cities have been encroached upon by nature. And one interesting thing is there has been a particularly unusual phenomenon, which is a zoonotic jump, which is the jump of a disease which is in an animal to being inside  of a human.”

Again, this is something that happens outside of the realms of fiction with a variety of documented cases of diseases mutating and infecting different species altogether. We have seen this in the aforementioned Swine Flu epidemic, there was also the Avian Flu – or Bird Flu – outbreak, and the jump can also be transferred from a bite in some cases, like with Rabies.

“So the developers of the game saw the fungal infection of the ants, that we saw in the video, and they said, well, let’s imagine if that happened to humans. It’s Cordyceps Militaris, which importantly, is not a zombie. A lot of zombies are viral in origin – I’m also the consultant on the Brad Pitt movie, which is coming out next month and there I was giving some insights into collective behaviours.”

The science behind the game is interesting, for sure, and hopefully it’s expanded on more in the game itself, fleshing out the backstory. One thing’s for sure, Naughty Dog are putting everything into this title to make it a believable and, hopefully, powerful experience.

I’ll leave you with some words of wisdom from our professor.

“What I like about the Naughty Dog thing is it’s a lot of really cool biology.”

Indeed it is, Professor… Indeed it is.