Science of Games: Zombies, part 1

Science of Games is a twice-monthly column that digs deep into the coolest science fiction elements of videogame universes, and tries to separate fact from fiction. Whenever possible, we’ll even bring in scientists, scholars, and experts to help us get at the truth of what’s really going on. Got a game you want to see investigated? Let us know in the comments!

We thought we’d launch our new column with a somewhat timely topic. Naughty Dog recently announced their new project, The Last of Us, which prominently features a humanoid creature that appears, at first blush, to be quite zombie-like. One of the most intriguing parts of Naughty Dog’s announcement of The Last of Us is that it has posted videos of so-called “zombie ants” from the Thailand rainforest on the game’s official website. These videos could simply be creepy ambience to prime gamers for a discussion about the zombie apocalypse, or they could hint at a plot point in the upcoming game. We’ll playfully assume the latter.

The Zombie Ants
Since being introduced to the world via BBC documentaries, the carpenter ants under the effects of a type of fungus called Cordyceps have become superstars of the geek world, and are now the flavor-of-the-month theory for many zombie predictions. Basically, once infected, these ants start to exhibit zombie-like behavior. This isn’t some crackpot theory. This is well-documented biology. 

The most incredible part about this as a zombie-theory is that theoretical zombie parasites act in much the same way. The infection is on a mission to spread itself as far as possible. In this case, it does that by marching the host body onto the underside of a leaf around high noon in preparation to explode spores onto the jungle floor below (as opposed to a classic zombie, which marches its body into populated areas). Researchers note that it does this around noon (yes, it really does pick a specific time) so that the fungus will have plenty of time to grow out of the ant’s head during the cooler nighttime.

Where many go wrong is in assuming this fungus could mutate in order to affect humans in a similar way. Suffice to say that the human nervous system is quite a bit more complex than that of an ant. Moreover, evolution of these sorts of abilities takes tens of millions of years. Thinking that one day this fungus will suddenly have the staggering complexity to control a human nervous system in a very specific way is just as absurd as thinking one day a fish was born with legs and waltzed onto dry land.

That said, there are already parasites that have been honing this ability for millions of years in humans, and are surprisingly adept at it.

Toxoplasma Gondii
In no way does Toxoplasma Gondii create human zombies that are in any way similar to the infamous zombie ants. However, you may be surprised at how widespread and influential these brain parasites actually are.

Researchers have said that this parasite is present in 20-60 percent of the population of most countries, depending on factors like hygiene standards and cooking practices (it’s most commonly spread through poorly cooked meat and contact with feces). The parasite tends to come from the intestines of cats, and is usually fairly harmless in human beings. However, research has shown that people infected with Toxoplasma Gondii are diagnosed with schizophrenia at a higher rate, generally have slower reaction times, and are six times more likely to be involved in traffic accidents.

But that’s not all. While benign in most adults (remember that it’s already in at least 20 percent of us, so if it was really bad, you’d know about it) it can actually be fatal to infants and fetuses. Which, fun fact, is the reason why pregnant women are supposed to stay away from cat litter. Because, as previously mentioned, the parasite is common in the digestive systems of cats.

If the parasite develops into a full-blown disease, the infected person first experiences flu-like symptoms, and afterward may (in uncommon cases) develop symptoms like depression. If that doesn’t sound like the beginning of a zombie movie, we’re not sure what does. So if a friend or loved one has the flu, be careful: they could be Patient Zero.

At this year’s San Diego Comic-Con, the publisher of Dead Island put together an awesome panel called “The Science of Zombies: How Possible is a Zombie Virus?” (I had the incredible pleasure of speaking on it. /brag.) On the panel were distinguished scholars, including a Harvard professor of medicine and two neuroscientists. One of these people, Dr. Bradley Voytek, has studied the zombie brain in detail. He’s even gone so far as to work with colleagues to create a mock-MRI of what the zombie brain would look like in real life. 

We talked with him for this article, and discussed his research along with a number of credible zombie theories. Voytek’s mock-up of the zombie brain shows a mind with massively reduced activity along with some over-activity in the sectors of the brain that control aggression. However, what we were curious about is whether this mangled zombie brain could actually still support its own body. “In very extreme cases, huge swathes of the brain have been damaged and--although the person may have certain cognitive or behavioral deficits--they're very much alive,” said Voytek.

What’s interesting is the way in which that brain damage might be caused. Almost all varieties of zombie feature a moment of death and a resurrection. But even if a virus was able to retake control over the body that it kills, the body would still undergo damage during the time it was dead. A lack of oxygen and nutrients flowing to the brain and other organs causes what is called ischemic damage.

The brain quickly accumulates damage that is often irreversible. “Certain brain regions, such as the hippocampus (which is required for memory formation) can be damaged with only a few minutes without oxygen,” said Voytek. “The hippocampus, and other parts of the limbic system of which it's a part, make up a big part of what we think is damaged in the zombie brain.” 

The best part about this theory is that it can account for different types of zombies. A virus or parasite that resurrects its host quickly could create more intelligent zombies as it would only have hosts with some brain damage. If the host stayed dead for longer, they’d be dumber but also less sensitive to pain. 


  • BladedFalcon - January 13, 2012 4:33 p.m.

    Hah, cool! And i like the premise and idea behind this column! ^^ I HAVE to ask though... Is this going to replace High horse? I liked High Horse... Why can't we have both?? XD
  • BladedFalcon - January 13, 2012 4:45 p.m.

    Actually... Scratch what i said. Says in the beginning that this will be bi-monthly, so chances are High force won't be affected. That's what i get for commenting before properly reading ^^; And well, this is seriously cool and interesting. I knew and had watched the videos of the fungus that controls ant's brains ages ago. But while I knew certain details of the toxoplasma parasite, I didn't knew it could cause damage such as schizophrenia and causing people to crash. Same with the ischemia. I was a aware that the brain suffered irreparable damage after a few minutes without oxygen. But didn't know that the areas it damaged first would be parallel of what a zombie brain would be like... Oh man, I really hope this won't cause people to try and asphyxiate people for long periods of time to try and create zombies XD
  • Andrew Groen - January 15, 2012 2:53 p.m.

    Thanks for the props! And not to worry, High Horse is completely unaffected by this new column.
  • BladedFalcon - January 15, 2012 6:48 p.m.

    Yeah, I kinda figured that soon after I saw that this was a bi-monthly column, and that the High Horse article was posted just a few minutes after XD Honestly, min was pretty much a silly "react first, read properly later" reaction ^^;
  • Cyberninja - January 13, 2012 4:45 p.m.

    this is pretty interesting
  • gamingfreak - January 13, 2012 4:56 p.m.

    This was really interesting. Keep up the good work GR!
  • codystovall - January 13, 2012 5:18 p.m.

    My research shows that zombies are a cheap excuse for AI. But yes interesting article.
  • Jedipimp0712 - January 13, 2012 5:24 p.m.

    next you should do something like laser guns or warp tech, or invisibility (obviously from the sci-fi side of games) very interesting though, a really good read is "The Zombie Survival Guide" by Max Brooks. cleverly written to be an awesome satire on survival techniques. i cant wait to see what part II has in store (and maybe even a part III! :D )
  • blazikenrocker - January 13, 2012 6:31 p.m.

    I would just like to mention that Toxoplasma Gondii just like Cordyceps is not designed to work on the human body. Toxoplasma Gondii is normally found in Cats and Rats/Mice it begins it's lifecycle in the cat but is eventually spread to other organisms through dead skin, sheading faeces, etc. Once it reaches the Rat host it hijacks the brains fear centres and removes a fear of cats and instead causes a sexual atraction. This does not affect any other part of the brain as the Toxoplasma needs to be eaten by a cat in order to complete it's lifecycle. The makeup of the fear centre in our brain is not like rats so the Toxoplasma cannot complete it's very specific task, as humans are rather unlikely to be eaten by cats. This means that Toxoplasma Gondii can never evolve into a Zombie disease as it simply dies of old age in humans, because like I mentioned earlier they can only reproduce in cats and evolution comes from a mutation in the genes which is past on to it's offspring meaning any mutant Toxoplasma with a better ability to control US will simply die in that human and never complete it's lifecycle. I also think latest research showed Toxoplasma was in 75% of Humans, but not so sure about that one.
  • waitingforCharlietosnap - January 13, 2012 7:47 p.m.

    Nice article, Mr. Groen, I look forward to the next part of zombie science, as well as the other topics you will eventually explore.
  • Andrew Groen - January 15, 2012 2:57 p.m.

    Thanks! Hope to see you back in the comments for the next one. (Seriously, comment like crazy so Gary and Mikel let me keep doing this forever ;-) I'll be covering Haitian zombies, rage zombies, and neurotoxins.
  • BladedFalcon - January 15, 2012 6:51 p.m.

    Wait... so you mean that the more comments you have, the likelier this will remain going? I'll be sure to comment whenever I can then! honestly Mr. Groen, your articles and the ones in High horse are easily my new favorite features of this site. Your articles are both informative, and entertaining, and very interesting. So keep up the good job!
  • BladedFalcon - January 13, 2012 8:59 p.m.

    Okay, I've now also though of a couple things that I think could be cool to know the science behind them: -Chargeable energy/Plasma guns such as the mega/X-buster from the Megaman series, or the plasma pistols from Halo. Basically, how plausible could it be in real life to have a gun that can store a high quantity of energy and release it as a blast, yet still be able to fire quicker, but less charged bursts of energy? -Plasmids as the ones seen in the Bioshock games. It's obvious that they will never be as drastic or as cool as the ones we see in those games. But the concept of integrating plasmids of ADN and splicing them into our own ADN is something that doesn't sound entirely impossible, considering that bacteria pretty much do that. -The functionality behind the ARS (Augmented Reaction Suit) used in Vanquish. Okay, i realize this one's far more obscure, but it might also be the most plausible one. basically, the idea behind the suit is that it would, during intense battle scenarios, inject a surge of drugs that would allow the brain and body to react much faster for short periods of time to basically allow the user to get out of seemingly impossible situations. I already know that in real life there's drugs that can enhance brain speed processing and reflexes, (Meth comes to mind.) but would it be possible to refine them to such a degree that it could make it seem that time is slowed down? even if it's just for a few seconds?
  • dog360spider - January 13, 2012 9:38 p.m.

    About your last point, stim packs in starcraft 2 comes to mind
  • Andrew Groen - January 15, 2012 2:57 p.m.

    I loves me some StarCraft 2. Might have to do something on Stim Packs.
  • Andrew Groen - January 15, 2012 2:59 p.m.

    Those are good suggestions. I'll definitely keep this on file when I'm planning future installments. Also it'll give me an excuse to finally play Vanquish while rationalizing that "it's for work..."
  • BladedFalcon - January 15, 2012 6:54 p.m.

    *Laughs* It would really be awesome if it got you to play Vanquish! I mean, that's one of those games that deserves to be played by a lot of people. In my eyes, it truly refined and kinda perfected the cover based third person shooters in a way that makes Gears of War look sluggishly boring, easy and slow... Additionally, the ARS isn't the only science-y thing that you could find in the game, a lot of the weapons have very cool "what if we can actually make this IRL?" concepts as well.
  • CJB95 - January 14, 2012 1:49 a.m.

    the way I see it, since that guy recently just modified the bird flu to be human compatible, I can see someone down the road taking that Zombie ant or that new Zombie bee parasite and modifying it so that humans will be there next targets.
  • Sinosaur - January 14, 2012 8:23 a.m.

    The difference between birds and humans is a lot smaller than the difference between insects and humans. Bacteria is also different from fungi, which just ups the Bacon score.
  • Pwnz0r3d - January 14, 2012 9:47 a.m.

    Zombies will never exist. There are way too many issues with the logical aspects of a rotting, walking, biting, moaning abomination whose brain (which is the most complex in the world) was supposed to have decayed along with its body, thus making its very existence a logical impossibility. Coupled with the fact that they have no way of determining living from dead flesh (they're dead, their sense of smell must be impaired right?), the infection will solve itself very quickly. True zombies will never exist, however, living infected who exhibit zombie like qualities due to a highly mutated rabies virus could, in theory, exist. But again, not for that long.

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