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Tipping the balance towards humanity in World War Z

Could a dire new infection sweep the world in a matter of weeks? Might the disease be so strange that it alters the behaviour of people beyond recognition, making them predatory and fearless? Could a great…

The Brad Pitt zombie action thriller World War Z has a strong enough premise to give us pause to think. Image from

Could a dire new infection sweep the world in a matter of weeks? Might the disease be so strange that it alters the behaviour of people beyond recognition, making them predatory and fearless? Could a great city like Philadelphia be overrun in a matter of hours?

World War Z, the latest Brad Pitt action thriller, is premised on these disturbing possibilities, and there’s a seed of science in each of them. The film is loosely based on a book by Max Brooks, history major and son of film director Mel Brooks, who has said that although his book is called “World War Z: an oral history of the Zombie Wars”, it should really be called “World War Z: insert real plague here”.

The terror of a zombie plague is deftly realised in this film, with a lot of tense action and surprisingly little gore. And Pitt’s character is immensely likeable – believably a family man, surprisingly gentle under strain, practical and swiftly resourceful in the face of sudden threat.

The plot centres around seemingly inexorable logic: infection deletes personalities and creates zombies, infected individuals infect others faster than they can be killed, and the infected have lost all self-preservation intent, so can’t be awed or reasoned into stopping their destruction of humanity.

World War Z: insert real plague here. Sergey Galyonkin

The chilling idea that a single bite can transform loved individuals into automata intent only on transmitting the infection, is reflected in some real illnesses, some of which we can’t always cure. Rabies may be transferred by a bite, and cause mania, violence, brain damage and death; and can be transferred from animals to humans.

The toxoplasma virus in mice causes them to become fearless, get in the vicinity of cats and get eaten, where the virus completes its life-cycle in the cat’s gut. Other diseases that attack human brain tissue and can change behaviour and apparent personality include neurosyphilis and CJD (Creutzfeldt–Jakob disease) - the human form of Mad Cow Disease.

Zombie-modelling literature?

Director Marc Forster has created a film that juxtaposes the personal scale with that of cataclysms of nature - lead character Gerry Lane (Pitt) reluctantly leaves his family, using all the skill and judgement that he learnt as a former UN operative, to combat a threat that is biological but mindless. And again in scenes of zombies running and flowing up and over a giant wall like a river of ants, indifferent to their personal survival, using each other’s fallen bodies as a self-growing ladder.

These two themes: critical personal choices by individuals, versus mass behaviour, are reflected in the existing mathematical literature modelling zombie attack - yes such literature does exist!

The paper, “When Zombies Attack!: mathematical modelling of an outbreak of zombie infection” by an Ottawa-based Australian mathematician and his students defined the genre when they applied standard mathematical disease-modelling techniques to a hypothetical zombie plague.

In that model, infected and non-infected persons contact and infect each other at random, at a rate which, in context, determines the demise or survival of the human race. A follow-up book, due to be published next year, includes articles by a range of academics including myself, and explores different scenarios via mathematical modelling techniques that take into account human agency, skill and choices, leading to different outcomes.

Researchers use mathematical disease-modelling techniques to analyse a hypothetical zombie plague. Image from

Both mathematics and films allow us to explore possibility-space: the world of what might be. The power of the human imagination, supported by the insights provided by mathematics and computer simulation, allows us to plan and prepare for the future, including major threats.

Mathematical modelling is routinely used to estimate the effectiveness of different plans for vaccination, medication, education programs, in extreme cases quarantine, and other strategies used to try to control deadly diseases such as SARS (severe acute respiratory syndrome) and TB (tuberculosis).

The latter matters more than one might expect in Australia, since the incidence of multi-drug resistant TB is high and rising in Papua New Guinea. This affects incidence a short canoe ride away in Australian territories in the Torres Strait.

When resources are limited and decisions need to be made about whom to treat and when, modelling helps decide what choices may profoundly affect the outcome. In regard to the Torres Strait, mathematics shows us that Australian treatment of PNG nationals helps keep TB-infection in Australia lower than it would be without that intervention.

Zombie scenarios from mathematics

The maths of zombies turns out to be not so different to that arising in the analysis of any infectious disease, with three main possible outcomes. There’s the chance that the disease infects every member of the population: in World War Z this is the zombies-win-and-humanity-is-destroyed outcome.

There’s the chance that the disease itself dies out due to death or cure of the hosts: in World War Z, this is the humans-win-and-zombies-are-destroyed outcome. And the third possibility is that rates of transmission and death or cure balance in just such a way that the disease persists in the population without overwhelming it.

In reality, a single hero is unlikely to bring us the insight we need to survive. Grmisiti

The original Zombies Attack paper showed how the chances of the survival of humanity vary based on whether interventions such as quarantine, treatment or impulsive eradication are available.

In the film, we follow Pitt’s character through each heart-racing moment as he seeks the origin and cause of the outbreak, in the hope that he’ll find an insight that can be utilised to lead out of the scenario in which humanity is destroyed, and into one of survival.

In a real plague, could we rely on a hero emerging to bring us the insight we would need to survive? Understanding is seldom achieved quickly: it is more often built up slowly by many people working on the same problem from different points of view.

Might we be better placed to invest now in understanding all the vagaries of nature including our own human nature? World War Z is a rip-roaring good action film, with a strong enough premise behind it to give us pause to think.

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22 Comments sorted by

  1. Mat Hardy

    Lecturer in Middle East Studies at Deakin University

    I'm sure it all works out mathematically. But the issues with all these zombie type plague stories is generally the speed with which the disease takes over the body (often in seconds) and then the hive mind type co-operation that ensues. Rabies takes weeks or months to develop. Toxo just makes individual mice do silly things, not band together and attack the cat.

    1. Jim Howe

      Neurologist at Neuropalliative rehabilitation

      In reply to Sean Lamb

      There is epidemiological evidence that's toxoplasma may affect human behaviour, as well as causing eye & brain damage. Don't have the reference on this handheld machine. But the suggestion is that in countries/places with more pet cats there is more neurotic anxiety. Correlation not causation, of course.

  2. robert roeder
    robert roeder is a Friend of The Conversation.


    Sci fi has a disturbing way of predicting the future. A video game " The last of us " has just been released. The plot starts with a pandemic caused by cordyceps fungal spores which have adapted to affect humans. David Attenborough did a doco showing how these spores infect insects brains which leads to growth formation. While these are not zombies they appear almost identical. Anyway I will continue on saving whats left of humanity while muttering the well worn gamer adage " shoot them in the head.

  3. Deirdre Whitford


    Thanks so much, Judy-Anne, for such a fascinating discussion around Pitt's latest offering.
    I only started reading because I had heard elsewhere that the film might be one to consider buying when it's released on DVD. What you've written about your own and your fellow maths modellers' work is so very unexpected and so absolutely intriguing that I may find myself making a (for me very rare) trip to a cinema this weekend.
    Wish now that I had focused more on what my year 11 maths teacher was actually saying and less on how cute his beard was. Obviously you were concentrating on the former - perhaps you had a closer grip on reality as a very young woman than I did at 16.
    It's always just great to hear from women in maths/science/tech/engineering from all over. On you, sister!

    1. Judy-anne Osborn

      logged in via LinkedIn

      In reply to Deirdre Whitford

      Thanks Deirdre!!

      Yes I am constantly amazed, too, at how some systems of equations or rules expressed mathematically can often capture the essential behaviour of a real-world phenomena, and that we can see possible futures as a result. I do find that surprising, given that the actual world seems so much more intricate than the mathematics representing it. In particular I find the work on TB by my UoN colleague Roslyn Hickson and her colleagues at ANU fascinating and important.

      Another neat…

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  4. Ron Chinchen
    Ron Chinchen is a Friend of The Conversation.

    Retired (ex Probation and Parole Officer)

    Methinks Judy-Anne that you enjoy a good SciFi like I do and in our imagination creating potential worlds and circumstances that in reality just dont happen in real life. I have no doubt that a viral condition could wipe out a large percentage of the human population and I suspect overpopulation will eventually cause this unless we address population levels ourselves or find some alternative world to live on, whether it be natural or man made

    Somehow though, and despite the fact that the movie…

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    1. Dianna Arthur


      In reply to Ron Chinchen

      "Perhaps you dont need a disease to create the mayhem of this film. Just desperation for something to eat. "

      And, thus, it begins....

    2. Deirdre Whitford


      In reply to Ron Chinchen

      What a great comment to make, Ron.

      Also very pertinent to the current business plans of corporate fossil fuel giants, which mandate digging up every last gram of coal/oil/gas there is and combusting it all, so as to (1) enrich their shareholders; and (2) ensure that there is so much carbon in the atmosphere that the other seven billion of us may well be desperate for something to eat, as you put it Ron, and generally experiencing lots of other unwelcome discomfort some time quite soon.


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  5. Greg Wood

    Energy Consultant

    It's already happening. The global banking industry has generated a global syndrome whereby we are infected at multiple levels of perception, via multiple modes of persistent transmission, to commit ourselves to intractable debt. We then predate upon others and the planet in our uni-lateral efforts support the 'growth', and our own relative position within that 'growth', necessary to repay that interest. In most cases our successful repayment of interest enables us to further indulge the constantly…

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  6. Deirdre Whitford


    @ Greg Wood

    Thank very very much for your post, especially for its clarity, concision and accuracy.

    It doesn't surprise me one bit that there are lots of extremely negative references to usury in the Christian Bible, or that practice of charging interest also gets an explicit and definite veto from the author of the Koran.

    Like lots of others, I'm re-reading The Great Gatsby at the moment before seeing the Baz flick. There is a whole lot going on in that slim Penguin, but one thing that Fitzerald seems to be shouting from almost every page is, roughly : "LOOK! This is what material wealth is. And this is what it does."

    1. Greg Wood

      Energy Consultant

      In reply to Deirdre Whitford

      It is likely that many dystopian story lines, such as the one expressed in this film, serve to expurgate the negative feelings we accumulate from our routine pursuit of fatally perverse behaviour.

      Oddly enough a comic strip most aptly sums up the overall situation that now binds us - "we have seen the enemy, and it is us".

    2. Greg Wood

      Energy Consultant

      In reply to Greg Wood

      Apologies, that quote should be, "we have met the enemy... and he is us".

    3. Deirdre Whitford


      In reply to Greg Wood

      Yes, Greg.
      Your comic strip strip quote reminds me of the "Doppelganger myth", that often seems to get a bit of a run (or at least an oblique reference) in fiction I've come across (I'm thinking maybe H. Hesse, H Fallada, T Mann, maybe doubt someone better read could perhaps cite others).
      In my limited experience these writers all seem to be Germans, and I only mention that I've noticed that fact, which I cannot explain, in case you or anyone else would care to try to enlighten me as…

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  7. Christina Birdsall-Jones


    We ought also to consider the appropriate international response to a Zombie plague. Brooks does this to some extent in his excellent World War Z, but a more focused discussion of this issue can be found in Daniel Drezner's International Politics and Zombies. Drezner places the Zombie issue in the context of competing and conflicting political systems. It's a fun read if you're a Zombie nerd. Yes, I confess. I am a closet Zombie nerd.

  8. Alex Njoo

    Architect/academic (ret.)

    Judging by their last editorial, I think the "dire virus infection" has gone viral in te editorial offices of The AGE. Between Murdoch's right-wing propaganda and Fairfax's zombie journalism, what chance do we have for a sober discussion on anything, including Brad Pitts latest extravaganza?

    1. Deirdre Whitford


      In reply to Alex Njoo

      Absolutely, Alex, I completely get where you're coming from there.
      As you say, sober discussion is impossible because our Titanic seems to be into its post-iceberg phase by now.
      My own coping stategy is to acknowledge and accept that we're going down, and to fill the time that remains with as much groovy and neato deckchair re-arrangement planning as I can.

  9. Louise O'Brien

    Marketer.Communicator. Observer

    My guess, without even seeing this movie, is that it involves the world being saved by an America!

    So this time it's a disease instead of aliens or some strange natural disaster which has engulfed the world!

    American Brad Pitt instead of American Bruce Willis saving us from bad guys or something bad.

    When are the Chinese going to wake up to the benefits of doing these types of movies to sell themselves around the world?

    I think I'll skip this movie.

    1. Alan John Hunter


      In reply to Louise O'Brien

      Exactly, we are saturated with this American Imperialism, and now every time the shit hits the fan we expect a Yank in a big white cowboy hat to SAVE THE WORLD, when all they really want to is sell arms, blow shit up and get reelected.
      Its about time we grew up and realised is all bullshit, the Yanks are not saving anything or anybody. They invariably make things worse, and they are only there for their own ends,
      which rarely if ever coincide with the locals needs and wishes.

  10. Alan John Hunter


    Oh dear.My comment is Oh dear, but I have to have more than 10 words which is pretty stupid as I can express my contempt for dreay as Oh dear.