Blood and Brains – can vampires survive a zombie apocalypse?

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The scenario is familiar to us all – Some sort of disease begins in a small town or large city, it spreads rapidly, infecting everyone in its wake, the infected become mindless, murderous creatures, hellbent on consuming or converting everyone they encounter, the walking dead. Finally, through some heroic effort, the survivors either turn back the tide or find a stronghold from which the human race can be rebuilt. It is the Zombie Apocalypse.

cautionHollywood is full of hype and heroic exploits. Of simple people overcoming tremendous odds, of triumph in the face of certain destruction. But how well would we really fare in a zombie apocalypse? Fortunately, Munz et al. (2009) have done the math for us, and the outcome does not look good. These are, of course, the shambling, slow-witted classical zombies, hungry for your flesh, not the sleek, mean zombies of whimsy.They propose 5 scenarios – basic outbreak (no quarantine, no cure, no coordinated response), an outbreak with a latency period, an outbreak with quarantine, an outbreak with a cure, and an outbreak with coordinated attacks. For all but the last two, the zombies make short work of the human race, with the only variation being in time and number of zombies produced. In the cure scenario, a small population of humans survives (10% the zombie population), and in the attack model, frequent, increasingly aggressive attacks eventually eradicate the zombies.

Listen to an interview with the lead author here.

The future does not look good for the human race during a zombie apocalypse. But what about our other undead brethren? Vampires are dependent on us for survival, both as a food source and a template for reproduction. As the human population declines, what happens to the vampire population? Can vampires survive a zombie apocalypse?

Several studies of vampire population dynamics and predator/prey relationships have been conducted over the years. In “The Transylvanian Problem of Renewable Resources” and its follow-up “Cycles of Fear: Periodic Bloodsucking Rates for Vampires”, Hartl et al. attempted to  solve the optimal conditions for vampire feeding strategies and equate it with periodic empirically observed vampire appearances. Physicists Efthimiou and Gandhi attempted to prove the impossibility of vampires through an exponential growth curve. Basically, if insatiable vampires produced a new vampire every month, beginning in 1600, the whole human race would be vampire before the end of 1602.

vampire-power-1Mathematician Dino Sejdinovic has something to say about that. Exponential growth is a sub-optimal condition. Building on the pioneering work of Hartl et al, Sejdinovic did something no previous vampire ecologist had done before, he added variables to account for a vampire death rate – unfortunate encounters with stakes, garlic, holy water, Southern Fried Scientists, and the occasional slayer. Brian Thomas, a graduate student in ecology at Stanford University, put together a nifty little treatise, using a fictional California town as a model. In short, a town of 36,000 can support about 18 vampires. Extrapolating out to the whole world (and this is a suspect figure at best) that gives us a standing vampire population of about 3.25 million.

But all these models rely on one important assumption – that vampires are the top predators. What happens when we pit the undead against the undead?

First, a few assumptions:

  1. Vampires need to feed on humans. Although technically immortal, starving vampires are weak and easily killed.
  2. Vampires cannot feed on zombies. Most recent cases of zombie outbreaks are the result of a blood-born vector, so zombie blood is tainted.
  3. Vampires cannot become zombies. That just gives me the willies.
  4. Vampires are strong, but not invincible. The Zombie Survival Guide estimates that an average human can fend of 8 to 9 zombies. Assuming vampires are at least 10 and at most 50 times stronger than humans, then a single vampire could fight off between 80 to 450 zombies.
  5. Vampire victims, if not turned or destroyed, will eventually be infected an become zombies.
  6. Vampires are capable of feeding without killing, but it requires discipline.
  7. Although not susceptible, vampires can transmit the infection to humans. A vampire that’s bitten an infected – but not yet zombified – human can spread the disease to new hosts.
  8. Zombies eat anything with a brain, undead or not.

If we start with the basic model – Humans are quickly eradicated and zombies take over, infecting everyone – then vampires obviously lose too. With their food source completely tainted, the vampires grow weaker as the zombie population reaches an asymptote around 2.5 billion. this is more than enough to handle the 3.25 million vampires, who at full strength could handle only about 1.7 billion zombies. Starving and outnumbered, the vampires would be overrun.

The same is true for the latent infection scenario. With an even greater zombie population, the vampires would fall. However, there is a twist. Because vampires would be able to sense latent infection (the blood would be undrinkable) they could screen out infected individuals and remove them. In the quarantine scenario, this means that a buffer could be built to keep out the infected. The trade-off is that human-vampire cooperation in this scenario is unfeasible. Vampires can still spread the infection, so “farming” uninfected humans would be ineffective. The time to Armageddon may be delayed, but eventually zombies would rule the earth.


There is no cure for a zombie clown (from the film Zombieland)

The cure model holds the most promise for vampires, but not necessarily humans. With a surviving human population reduced to 50 million, only 25,000 vampires could be supported. Since the initial vampire population is much higher than this, a feeding frenzy would commence, decimating the human population. Human “farming” could be an effective solution, but the vampires would be faced with a desolate future with few humans and billions of roving zombies to fend off. The human race would be reduced to livestock.

The most interesting scenario for both dead and undead alike is a coordinated attack of increasing intensity. This is the only scenario that showed promise for the human race, hit them hard and hit them often with overwhelming force. Provided vampires could be convinced that their existence depends on this tactic (perhaps that is my goal here) they could provide an extra level of overwhelming force that would allow us to drive the zombies back before the apocalypse. How the human-vampire conflict will change post-zombie-eradication is best left to the scholars.

In conclusion, Vampires can only survive if humans also survive, and the vampire population is so small as to have no effect on human survival. Vampires are helpless to alter their fate unless they join forces with their living brethren for an all out zombie-human-vampire rumble.

Both zombie and vampire population growth is directly proportional to food consumed. In both cases the food is us. Zombies represent one end of the spectrum – uncontrolled consumption with exponential growth eventually leading to a complete population collapse, while vampires represent the other extreme, controlled consumption and a stable state directly proportional to the size of the prey population.

The only question left then is “who’s managing our fisheries?”

Happy Halloween.

~Southern Fried Scientist

Munz P, Hudea I, Imad J, and Smith? RJ (2009). WHEN ZOMBIES ATTACK!: MATHEMATICAL MODELLING OF AN OUTBREAK OF ZOMBIE INFECTION Infectious Disease Modelling Research Progress, 133-150

C. J. Efthimiou, & S. Gandhi (2006). Cinema Fiction vs Physics Reality: Ghosts, Vampires and Zombies Skeptical Inquirer v. 31, issue 4 (2007), p. 27 arXiv: physics/0608059v2

D Sejdinovic (2008). Mathematics of the Human-Vampire Conflict Math Horizons

Hartl, R., Mehlmann, A., & Novak, A. (1992). Cycles of fear: Periodic bloodsucking rates for vampires Journal of Optimization Theory and Applications, 75 (3), 559-568 DOI: 10.1007/BF00940492


  1. whysharksmatter · October 30, 2009

    This cannot possibly be a real scientific paper. I don’t know any mathematical modelers who are that awesome.

    Please, please tell me that this project was funded by taxpayer money.

    Besides, everyone knows that a human doesn’t become a vampire just by being bitten. The human has to drink a little of the vampire’s blood first, which obviously can’t happen unless the vampire WANTS to turn the human.

    • Southern Fried Scientist · October 30, 2009

      I never said they would, I just assume that any dead body the vampire leaves will eventually become a zombie. Ain’t no natural death in the Zombie Apocalypse.

    • zayzayem · November 1, 2009

      Wait, what sort of zombie scenario is this?

      Any dead body becomes a zombie (including those dead before Z day – that’ll teach you for living on an Indian burial ground)
      Any body that becomes dead after Z day becomes a zombie (no matter how they die – e.g. car crash, bullets, or vampire)
      Any body that is killed by a zombie will become a zombie (zombie wounds aren’t terminal)
      Any body that is bitten/scratched/infected physically by a zombie will eventually die and become a zombie (current standard zombie trope).
      Any body within an infected area will eventually die and become a zombie (infection is airborne).

    • Southern Fried Scientist · November 1, 2009

      All dead bodies can potentially carry the disease. The model only assumes corpses formed after the apocalypse. The disease is spread through physical contact – bites, body fluids.

    • Southern Fried Scientist · October 30, 2009

      And it’s not just one paper, but at least 4.

    • zayzayem · November 1, 2009

      Let’s also not forget that dust from a killed vampire can be used a drug by humans to gain temporary vampire-like powers (and occasional bloodlust)
      [Blade TV series]

  2. Sam · October 30, 2009

    Which model of vampire is this based off of? Would that be the original (and oh-so-hardcore) Dracula, as imagined by Bram Stoker, or are we talking Twilight vampires?

    It does matter, incidentally. The Bram Stoker Dracula vampire would probably not be clever enough to figure out one of these plans until it’s too late. The Twilight vampire would probably be able to fend them all off, but wouldn’t because they’re an immortal being spending eternity in high school.

    Also, the way one is converted to vampirism varies based on the person imagining the world. Did the papers give more rules for how the vampires worked?

    • Southern Fried Scientist · October 30, 2009

      This is based primarily on the Joss Whedon model, since that is the only model with enough detail to allow for accurate population dynamics models.

  3. John Wilkins · October 30, 2009

    This is a classic Lotka-Volterra situation. Presuming that the apex predators will crash when the food population crashes, shouldn’t the prey species recover in cycles?

    • zayzayem · November 1, 2009

      But the zombie population never crashes, or at least not at a rate significant enough to rescue the prey species.

  4. jebyrnes · October 30, 2009

    This really is a classic example of apparent competition. Due to a higher lethal encounter rate and lower mortality rate (if we’re not allowing for the decomposition of undead flesh), zombies will always win (if we’re going with a Lotka-Volterra predator-prey model).

    I do wonder, though, if direct intraguild interactions could alter this, allowing for stable coexistence. Then again, this might correspond to the “pen” scenario, in which vampire cowboys (humanboys? zowboys?) keep their human herd safe from the marauding hordes of mindless shambling masses.

    • Southern Fried Scientist · October 30, 2009

      The one piece of the puzzle that makes it not a classic Lotka-Volterra scenario is that while zombie-ism appears to be predation, it’s also a disease system. Zombies eat people, but the population is maintained through infection. The vampires as apex predators will certainly crash when the humans crash, but not so for the zombies (especially considering the humans can become zombies even after their killed). Even allowing for decomposition, at what point does a decomposed zombie stop being a disease vector?

    • candiu08 · April 19, 2010

      That’s a good question? “At what point dose a decomposed zombie stop being a disease vector?” Even after the vampires have turned all the humans, or the humans became zombies, what will the two feed on from that point? Or will everything/one be completely wiped out?

  5. zayzayem · November 1, 2009

    I think a futuristic human-vampire alliance to fight a common foe was the background plot to an MUD I saw somewhere on the internets — except I think it was demons, not zombies they were fighting.

  6. Rystefn · November 8, 2009

    There’s a webcomic called Last Blood that goes into this situation: vampires realizing they have to protect humans from the zombies. It’s pretty interesting, I thought. If we’re lucky, we’ll see it on the big screen one day, as that’s the writer’s ultimate goal for it.

  7. Tony · November 18, 2009

    Question about assumptions… do zombies eventually starve to undeath? Once they have no access to any new brains, would they just wander or would they eventually die out? Wouldn’t that lead towards possible survival outcomes?

    • WhySharksMatter · November 18, 2009

      In “28 days later”, the military was keeping a zombie in captivity to see how long it would take before it died of starvation. Sadly, it escaped and killed a bunch of soldiers before we could answer your question.

    • Captain Skellett · January 5, 2010

      Au contraire. In 28 days later, at the end it skips ahead another 28 days, where the last of the infected are dying of starvation, so they would die within 28 days.

      Unfortunately, as discussed in the paper, the infected from 28 days later are not considered zombies as they move too quickly etc. So it’s a moot point. I agree with SFS below, but in terms of the river… it depends on the infectious agent. It would probably make the water around infected for a little while, but chances are decent the water would destroy a virus (like HIV) and many bacteria. Also depends how many infectious particles are needed to cause infection (water would dilute it).

    • Southern Fried Scientist · November 18, 2009

      While zombie’s wouldn’t starve to ‘death’ they do decompose, in which case they are no longer motile but remain a carrier for the virus until their bodies are completely destroyed.

      Raising an interesting question: If a zombie dies in a river, does its rotting carcass infect the entire watershed?

  8. Accidently on a Porpoise · November 18, 2009

    As long as Will Smith is converted to a vampire, we will all be safe. In all seriousness, vampires would be severly limited by sunlight and would have less of a window to operate.

  9. Annie · November 25, 2009

    If we had an all out zombie-human-vampire rumble, I think the vampires would win. They are stronger, smarter, and faster. It might be annoying to be pale white and not ever eat, but if we didn’t eat, we would save a lot of money! haha. I feel that zombies are just slow and sometimes stupid.

    • doug · November 25, 2009


  10. MissChioga · November 30, 2009

    Yes vampires could survive a zombie apocalypse. Vampires don’t just have to feed on humans. There are plenty of animals around and with the blood banks I think that they would be pretty well off.

    • Southern Fried Scientist · December 2, 2009

      You should probably read the post first.

    • whysharksmatter · December 2, 2009

      Andrew, that’s not how society works. No one reads things before they voice their opinions on them anymore. Just look at the healthcare debate. They see a title and a few buzzwords, and that’s more than enough to form an opinion that needs to be shared with everyone.

  11. Gabriel Boz · March 17, 2010

    I think that, probably,the best way to overcome a Zumbi Apocalypse will be with the help of Vampires. And that could lead us to a Human/Vampire alliance and some kind of sustainable feeding agreement between us after the zumbi extinction, but at the same time, a Zumbi infected Vampire could be almost indestructable, not dying by the tradicional ways like stakes and crosses, just with beheading, making the equation even more complex. Eventually, it will lead us to extinction, after all the brains in the planet got eaten and all the veins got sucked…

  12. Lisa Martin · March 17, 2010

    Last author on the zombie paper from Inf. Dis. Mod. Res. Prog. should actually be written “Smith? RJ”. Stands to reason that someone crazy enough to publish a genuine scientific paper on zombies would also be crazy enough to have a question mark at the end of their name!

  13. Saint Fnordius · March 17, 2010

    The problem with zombie scenarios is that longevity of the zombie is never considered, since it never matters in the story. The events often unfold within a few days, rarely more. Zombies deteriorate rather quickly, lacking nerves so they don’t protect their remaining muscle tissue from damage. They also lack any form of healing, so any damage done is permanent.

    So assume zombie infections are like Ebola: highly contagious, but burn themselves out before they can leave an isolated community. That may make the task of vampires simpler, to quarantine the infected area and then sanitise it when the plague has run its course. Since vampires in the scenarios cannot be infected, they might becomes “dragons”: protecting the community in exchange for a virgin sacrifice every now and then.

  14. Jeremy Nielsen · April 20, 2010

    I agree with a previous post. What kind of vamps or we talking here. Is it the Dracula mastermind type or the twilight sissy boy type?

    An interesting scenario though.


  15. Monisha Hawkins · May 12, 2011

    I think it would be great to then figure out how the scenario would play out if you start to factor other animals into the equations. I would guess that a zombie infection might well be able to spread to mammals and there are a number of vampire “types” that can also consume the blood of other animals and mammals. Would the extra animals delay or prevent the collapse of people, who are capable of eating plants as well? Just a thought.

  16. Greg Barron · May 13, 2011

    But wait, smeone here stated Zombies eat brains. Anything with a brain. Mainly people but Vampires have brains too. Dead they may be but they’ve got a brain, do the zombies eat those as well? what’s more, as someone suggested, since they are dead, and they’d be infected with Solanum too and therefore turn. So, vampire zombie. Inevitable. “28 days Later” zombies weren’t zombies, they had rage and could die when they starved. Nasty critters though. I forget how long it takes a zombie to beef jerky but I think it was in World War Z or the Zombie Survival Guide. (Both great literature by the way)The problem is the zombies in the ocean that don’t beef jerky. It all comes back to the sea doesn’t it…

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