Respectful Insolence

Now here’s some perfect reading for a lazy stay-at-home vacation day. It’s even pretty science-y. Well, math-y, at least. It may even be the best scientific paper ever. The title says it all:

When Zombies Attack: Mathematical Modeling of an Outbreak of Zombie Infection

The long version is at the link above.

The short version is that, if this ever happens, we’re screwed.

The intermediate version is at Night of the Living Model.

Comments

  1. #1 Gregory Gadow
    August 18, 2009

    This paper is about mathematically modeling the spread of a highly contageous disease through the population. The actual disease agent is irrelevant; it could just as easily have been H1N1, Ebola or a virulent strain of the rhinovirus. That the authors chose to model the spread of zombieism was a stroke of marketing genius. How many other scientists can take a dry topic and make it the buzz of blogs around the world?

    I think it is particularly amusing that Max Brooks (“The Zombie Survival Guide”, “World War Z – An Oral History of the Zombie War”), George Romero (Night of the Living Dead) and Danny Boyle (28 Days Later), among others of the genre, are listed in the references.

  2. #2 JD
    August 18, 2009

    I’ve always been a staunch anti-zombie vaccine advocate.

  3. #3 Andrew Dodds
    August 18, 2009

    Actually, I did once consider the basic physical principals behind zombies as a thought experiment.

    The central problem with an infective-agent model of zombies is that respiration is still required; so a virus cannot work. Zombies do not need to breathe, they have little or no blood flow, etc – oxygen based resparation as we know it cannot be going on.

    So the infectious agent must be sufficiently complex to create what is effectively an entirely new creature. It is clearly capable of using the senses of the original, but at a biochemical level must function differently.

    Clearly this is some sort of nanotech device – capable of self replication (so carbon-based nanotech) from a variety of source materials, and also capable of using chemical energy in any form from it’s environment. The breakdown of proteins in the human body should provide some energy, even anaerobically, and some oxygen would presumably enter by simple diffusion (presumably nanotech devices of sufficient complexity could construct micro-channels to the surface from within the body); this would be beyond the capability of any virus but within that of a theoretical nanotech machine. In any case the energy available to the zombie is restricted – as witnessed by their slow motion – although since they require no thermal homeostatis this is less of an issue than it may appear.

    The actual driving of the corpse requires further work; two areas of difficulty remain. First is the actual driving of the muscles which is observed. This must be a two phase process – in the infective stage, devices within the muscles are able to detect contractions and create networks of their own to simulate the effect in the reanimated corpse. Second is the control phase – clearly the main focus of infection in the brain is able to integrate information from outlying areas during the infective phase to establish how the muscles are used to achieve locomotion, and quite possibly build it’s own balancing structures. The destruction of significant amounts of brain tissue to achieve this is witnessed by the increasing disorientation of the infected.

    The ‘learning/infection’ phase must also include this putative network of nanotech devices being able to interpret signals arriving in the brain from the sensory apparatus, so that the reanimated corpse will be able to ‘see’; again these devices will have to grow along nerve fibres to create the appropriate signal pathways, although the optical structures of the eyes would still be of use.

    Clearly this is a complicated machine.

    This interpretation suggests several possible experiments -

    - Zombies should gradually lose mass over time as tissue is converted into carbon dioxide, methane, sulphur dioxide, ammonia, and water – low energy end materials. After some time in a zero-oxygen environment movement should be significantly slowed.

    - If an infected individual is sedated and restrained from the moment of infection, the resultant zombie should be uncoordinated and unable to walk.

    - In a similar manner, an individual blindfolded from the moment of infection would end up unable to ‘see’ as a zombie. In a similar vein, earplugs on an unfortunate bitee would result in a ‘deaf’ zombie.

    It is hard to avoid speculating on the source of such an agent; although clearly it appears to be an extremely effective biological weapon, combining a maximum of both physical and psychological effectiveness.

  4. #4 LovleAnjel
    August 18, 2009

    Awesome! I have forwarded this to my colleagues who teach public health & epidemiology.

  5. #5 Scott
    August 18, 2009

    This paper is about mathematically modeling the spread of a highly contageous disease through the population. The actual disease agent is irrelevant; it could just as easily have been H1N1, Ebola or a virulent strain of the rhinovirus. That the authors chose to model the spread of zombieism was a stroke of marketing genius. How many other scientists can take a dry topic and make it the buzz of blogs around the world?

    Actually, their model has a very unique feature that renders it quite distinct from any normal infection. Resurrection! The fact that the dead can rise as zombies and then proceed to infect others is rather unique.

    The point, based on my reading of the paper, was to demonstrate that these modeling techniques can be applied successfully even to infections with exceedingly exotic features.

  6. #6 Zombie Joe
    August 18, 2009

    Did you know that zombies are people? Ya. Individuals who can see energy see what looks like a zombie when they look at some human beings.

    How can I explain this in a way you can understand? Hmmm….

    I tell you what. I give it to you straight and see if you can handle it. You say you are scientists so you should have the brainpower.

    The human body generates forces. The kinds of forces described by the science of Physics. The sum of all of those forces form a duplicate of the physical human body, mostly because the forces are generated and contained within the physical body.

    The force body should be exactly centered and aligned on the physical body in a healthy person.

    A zombie is a human being whose force body has moved away from the physical body in any direction in any way, or whose force body has been distorted by processes such as shrinking.

    When the force body moves away from the physical body, the physical body will change. In cases of large movements of the force body, the physical body will change so much that it can easily be seen with the naked eye.

    People who say they can see “the energy” of another human being can see more subtle physical changes of the human body caused by the shifting of the force body. An untrained person cannot see these subtle changes but a trained person or a person with a natural ability can.

    Zombies are regular human beings like you, me, or the guy walking down the sidewalk, whose force body has shifted away from the physical body. That movement of the force body changed the physical body in ways that zombies are typically shown to look like in movies.

    Artists are usually artists because they can see the energy of other human beings. I can show you some pictures of Zombies made up for a movie by special effects artists. The way that the Zombies are made up exactly matches the way that the bodies of the actors of naturally changed as a result of the movement of their force body.

    The artists did not mentally think up some zombie look for the actors and applied it to their faces. The artists looked at the actors, saw the zombie changes that were naturally in their faces, then used the special effects makeup to highlight the natural zombie look the actors always display to anyone who can see what is frequently referred to as the energy of another human being.

    Zombies are not some imaginary creation that popped out of someone’s head. Zombies are a label that describes certain human beings walking around in every human society on the planet earth right this very second.

    It is easy to point them out to you. But you have to be careful what you ask for. What if you are a zombie? Do you really want someone to tell you? Then you have to live with the knowledge you look like a zombie, or you have to spend the rest of your life doing physical therapy to correct the misalignment of your force and physical bodies that caused the zombie changes in the first place.

  7. #7 JMG
    August 18, 2009

    I’ve been scooped! Years of precious research into zombie epidemiology…for nothing! I demand recognition!

    (NOTE: This not not completely sarcastic. Mostly sarcastic, yes.)

  8. #8 Ranson
    August 18, 2009

    Zombie Joe is Happeh, right? Last paragraph gives it away, I think, though the writing is generally better than Happeh’s.

  9. #9 Orac
    August 18, 2009

    Good call. The IP address matches some of Happeh’s old comments.

    Goodbye, Happeh. Again.

  10. #10 trrll
    August 18, 2009

    I think that Stephen King, in “Salem’s Lot” was the first to point out that the model of vampirism presented in the Dracula movies, in which every victim arises as a vampire, predicts an explosive epidemic of vampirism. Subsequent authors of vampire fiction have generally included some mechanism to prevent vampirism from exponentially spreading to the entire population–either the vampires intentionally do something to prevent their victims from rising again, or else some special procedure, such as ingestion of vampire blood, is required to create a new vampire.

  11. #11 Robert S.
    August 18, 2009

    The most original bit of this paper seems to be that the zombies can be resurrected after being destroyed. All of the zombie lore I knew said that the living can become zombies, and that the dead could become zombies, but that zombies couldn’t, well, become zombies. Can anyone establish where this idea came from? If zombies were able to reassemble and reanimate after getting hit by a nuke, of course they would be unstoppable.

  12. #12 Eric
    August 18, 2009

    “The most original bit of this paper seems to be that the zombies can be resurrected after being destroyed. All of the zombie lore I knew said that the living can become zombies, and that the dead could become zombies, but that zombies couldn’t, well, become zombies. Can anyone establish where this idea came from? If zombies were able to reassemble and reanimate after getting hit by a nuke, of course they would be unstoppable.”

    I’m not an expert on zombies, but my suspicion is this stems from the old “restless/improperly buried dead” legends that brought us the Voodoo-type zombie, and the Vampire (before they got sexy-fied). Zombies aren’t actually an independent entity, they just need to be properly put down.

  13. #13 Karl Withakay
    August 18, 2009

    If only someone had invented a zombie infection simulator…

    http://kevan.org/proce55ing/zombies/

    @Andrew Dodds

    Actually, the concept of zombies works best w/o breaking the laws of physics if you throw the whole undead thing out the window and just go with “The Infected” ala 28 Days Later. (Still living and breathing with pumping hearts) They are vulnerable to gunshots, but less so than normal people because pain doesn’t slow them down; you have to wait for them to loose consciousness from blood loss if you don’t take a head shot, etc.

  14. #14 D. C. Sessions
    August 18, 2009

    Now why can’t I get papers like this published?

    Just taking a wild guess, but could it have anything to do with the fact that you haven’t written any?

  15. #15 Shawn Smith
    August 18, 2009

    Robert S,

    Yeah, I noticed that too. The authors decided to use the conceptions of zombies from a couple zombie stories (e.g. Night of the Living Dead) but not use all the rules. One of those rules being that once a zombie was burned or took a head shot, they were permadead instead of undead. Their model basically made zombies undestroyable, and it could have been corrected by having another R (removed) state. Call it RZ, which would be a way to take zombies out of the picture. It seems the math was just a way of obfuscating that simple assumption. I’m surprised the advisor didn’t question them on this and ask them to fix their model.

  16. #16 antipodean
    August 18, 2009

    Orac

    You publish in Blood, which may make you a vampire?

    Why not some sort of joke paper on the vampiric spread of an imaginary breast cancer oncovirus? Christmas BMJ contender?

  17. #17 Rogue Epidemiologist
    August 18, 2009

    That paper is all kinds of AWESOME. I just sent the link and a short blurb to my journal club email list at work.

    /needs to add ‘Shaun of the Dead’ to the Netflix queue again.

  18. #18 GAZZA
    August 18, 2009

    As others have pointed out, this paper is “fatally” flawed with its totally unjustified assumption that dead zombies can reanimate. The primary source is Night of the Living Dead (and, we may assume, the rest of Romero’s Dead movies); a head shot to a human is canonically demonstrated as a way to prevent that human ever zombifying, let alone such a shot to a zombie. Thus, they would need to revise their work to include the category of, say, “Non-Susceptibles” that is a distinctly different group from R (“Removed”).

    It was also a bit disappointing to see that they never really played around with their variables. In particular, some variants (Resident Evil, the “new” Dawn of the Dead movie) have the situation such that the only way to become a zombie is to get bitten by one and not die of any other cause – there is no actual resurrection of uninfected individuals (to use their terminology, nobody ever moves from R to Z). I’m not nearly clever enough to work out what that changes – perhaps nothing – but it did strike me as an oversight in that they are apparently implicitly assuming all their constants are > 0.

  19. #19 Andrew Dodds
    August 19, 2009

    Karl -

    Yes.. but that sort of takes away the original Zombie concept…

    As far as epidemiology goes, I think we need several categories of human:

    - UI: Uninformed/Inexperienced. Do not know about Zombies, and do not know that an outbreak is in progress.
    - II Informed/Inexperienced. Do know about Zombies, but do not know that an outbreak is in progress.
    - UE: Uninformed/Experienced. Do not know about Zombies, have encountered zombies and survived.
    - IE: Informed/Experienced. Do know about Zombies, have encountered zombies and survived.

    So those in the UI category are far more likely to be killed or infected when they encounter a Zombie; wheras when an IE encounters a Zombie, they are far more likely to destroy the Zombie. So the model really should include the makeup of the population changing to become less and less vunerable over time, and more likely to actually stop the infection.

    This should work with other diseases where behavior changes in response to the disease.

  20. #20 Amph
    August 19, 2009

    Why the last author of the paper has a question mark after his name? It is reiterated in the acknowledgments (‘RJS?’) but not in the references to his own work and neither in his e-mail address.
    Intriguing, but admittedly, totally irrelevant.

  21. #21 jordan 6 rings
    August 19, 2009

    I’m surprised the advisor didn’t question them on this and ask them to fix their model.

  22. #22 Lucas McCarty
    August 19, 2009

    When the zombie apocalypse co-op game Left4Dead was released last November, a serious discussion actually started on the forums regarding an in-game graffiti comment sprayed on a wall:

    “We are the real monsters”

    Followed by, “No that would be the zombies” and “I hope you die”.

    Very few people took the side of the original comment, but a hard-core of Romero fans did. In the Night of The Living Dead the only survivor is a black man who is then(SPOILER) shot at the end at a distance because the authorities just assumed him to be a zombie. At the end of a later sequel, a female zombie is hung from a tree and used for target practice while she struggles.

    The films were social commentaries in the style of Lord of The Flies. Social commentary is now part of the zombie genre and the reason why the cause of the outbreak is never a focus.

    I haven’t read this study but I’m presuming it takes absolutely no account of the human cost in terms of what our reaction will do to us because it seems to advocate unrestrained, explosive violence against the infected and says looking for a cure should not be a priority.

    Take the zombie apocalypse seriously will you?

  23. #23 DLC
    August 19, 2009

    I’m hungry.
    I need some braaaaaains…

  24. #24 Marcus Wilson
    August 19, 2009

    Am I allowed to say something at all serious? From a mathematical and physical modelling point of view, it is pretty basic stuff – all very standard methods – they just happen to have picked on a rather non-standard problem. In this regard, as opposed to its application, I’m surprised that it has been published. In short, it’s not the best science paper ever.

    OK – back to the non-serious stuff – I now know where to focus my next funding proposal.

  25. #25 Melody
    August 21, 2009

    “I think that Stephen King, in “Salem’s Lot” was the first to point out that the model of vampirism presented in the Dracula movies, in which every victim arises as a vampire, predicts an explosive epidemic of vampirism. ”

    Yes, many of my dreams as a kid/teenager followed an infection storyline where everyone I knew would quickly get the dreaded “thing” – of course, rather than actual diseases it’s usually vampires or zombies or being turned into goo at someone’s touch or something. Even if the fear of vampires and such left me in the light of day, there’s still a bit of an irrational contamination fear that has persisted, but is fortunately slight. Good thing that, while there are numerous diseases, we do not have to contend with vampires too!

  26. #26 MetaEd
    August 25, 2009

    Nobody has commented on the clever dig in the paper, drawing an analogy between zombie infection and allegiance to political parties.

    What if the Stupid turns out to be as virulent and hard to put down as a zombie outbreak?

    Imagine a doomsday scenario in which every human is either (i) dead, or (ii) a shambling right winger searching for brains.

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