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Buffy The Vampire Slayer

Math proves that the Buffy universe harbors no more than 512 vampires

Friday 23 March 2007, by Webmaster

One of the most totally fun areas of publishing in recent years has been the emergence of books that probe the scientific bases of fictional universes — like The Physics of Star Tre or The Science of Star Wars. Thus I was tickled to discover a paper called "Ghosts, Vampires and Goblins: Cinema Fiction vs. Physics Reality", authored by Costas Efthimiou and Sohang Gandi (PDF here). Among their conclusions? Vampires can’t exist.

Why? Because they’d quickly depopulate the earth. To prove it, the scientists do some calculations by picking a random year in history — 1600, specifically — and imagining what would happen if one person suddenly appeared on earth. They assume, for the sake of argument, that a vampire needs to feed "only once a month", and that in the course of feeding, the vampire turns its victim into another vampire. They note that the global population of humans was 536,870,911 in the year 1600.

Then the calculations begin. If a single vampire fed on a single human in the first month, this would create two vampires — and decrease the human population by one, leaving it at 536,870,911 - 1 = 536,870,910. In the second month, those two vampires would each feed, transforming two people into vampires — so you get four vampires and a human population of 536,870,911 - 3 = 536,870,908. So you can see where this is headed. The vampire population is increasing in a geometric progression, and the population of humans is similarly decreasing — and at that rate, the authors calculate, the entire human population would be transformed into vampires in only 30 months. QED!

Sure, humans could increase their numbers by having children — but the birth rate could never keep pace. Thus, the authors’ implacable logic leads them to only one conclusion:

We conclude that vampires cannot exist, since their existence contradicts the existence of human beings. Incidently, thelogical proof that we just presented is of a type known as reductio ad absurdum, that is, reduction to the absurd. Another philosophical principal related to our argument is the truism given the elaborate title, the anthropic principle. This states that if something is necessary for human existence, then it must be true since we do exist. In the present case, the nonexistence of vampires is necessary for human existence. Apparently, whomever devised the vampire legend had failed his college algebra and philosophy courses.

It’s worth checking out the full paper, if only to see a bigger version of the their spreadsheet (excerpted above) showing how the vampire-vs-human population evolves, month-by-month.

This would seem to strike a horrible blow to the whole concept of Buffy the Vampire Slayer, eh? And indeed, when this study came out last year, Buffy fans worldwide wept hot, bitter tears.

But wait! The whole point behind the Buffy universe is that there’s a slayer out there killing vampires and keeping their population down. This is something the authors didn’t consider in their paper. So couldn’t a vampire killer simply slaughter vampires as fast as they’re created?

Sure — except then the math gets even more interesting.

Because the thing about the Buffy universe is that the population of vampires is reasonably stable. There are a fair number of vampires around, but not enough to overwhelm the earth. But as it turns out, if you look at that chart above, there’s a very narrow vampire-population window at which equilibrium can be kept.

That’s because powers of two increase slowly at first, then at a hellacious rate. Think of it this way: According to the numbers calculated by the academics, at month five in the year 1600, there are only 16 vampires. That’s such a paltry number than any self-respecting slayer could quickly dispatch them in a few evenings, and the vampire menace would permanently be extinguished. But at month 12 — only a few months later — the number of vampires, unchecked, rises to 2,048. That’s probably too many vampires for a slayer to squelch in a single month.

So the really sweet spot seems to be months eight to ten — when the vampire population would range from 128 to 512, respectively. Those seem like realistic numbers of vampires for a slayer to kill in a single month, assuming she kills 2 to 8 per night. With that kill-ratio, a slayer each month could kill enough vampires to knock the population back a month or two. This would keep the vampire menace sustainable — neither fully depleting it nor letting it race out of control.

So there you go. I’ve calculated the precise number of vampires that probably exist in a Buffy universe: No more than 512. Granted, this number could change depending on one’s assumptions of how many vampires a single slayer can kill in a month, or how many slayers exist at any one point in time, or how many other people might be killing vampires in addition to the slayer(s). I’m not actually a Buffy fan, so I’d be interested to hear what other assumptions that more-informed fans might make — and calculations would ensue.


6 Forum messages

  • Interesting article, but in the Buffyverse, every victim of a vampire does not turn. New vampires are chosen by their sires and not created at random. That number (512) does sound about right though as I don’t think Buffy could handle much more than that. Although now that there are hundreds (thousands?) of Slayers, things aren’t looking good for the vampire population.
  • the biggest problem with this is in most vampire mythos vampires mostly kill when they feed not actually turn because that process is considered sacred and not just anyone is to be turned.Also some lore suggests that vampires do not need to completely drain a person to feed and therefore may keep someone chained up alive to feed of off for a very long time before they feel their food becomes stale and finally finishes it off.
  • Yeah - Interesting article. Except this isn’t how the vampire/human relationship actually works.

    If you look at Angelus/Angel. in 250 years as a Vampire - how many new vampires did he sire. what maybe 10. That breaks down to about 1 every 25 years. Now think about how many people he killed in his original reign of terror (1st 145 years or so). Even if you figure 1 person per month - then that was close to 2,000 people. Possible more likely 10s of thousands.

    A truer measure of the number of vampires in the Buffy/Angel verse. Since most people only know vampires as movie monsters or legends. This suggest they’ve always been fairly rare. Maybe no more than 1 vampire per 1,000,000 people. This is rare enough for most people to know about the myth or legend - but few to actually believe they exist (because they never seen them).

    So in present day - with over 6 billion Humans on the planet, the vampire population is likely around 6,000 at most. In 1600, there may have only about 500 vampires. About 2000 years ago - there may have only been between 200-300 vampires in the world.

    Also consider that Slayers & vampire hunters act to help keep the vampire population in check. A slayer, like Buffy (who’s consider exceptional by slayer standards) may actually take out up 500 vampires per year. And a Vampire Hunter, like Holtz(that’s on a mission) may take out as many as 50-100 vampires per year. so that means would need a 10-20% growth just to maintain there present populations.

    Now if you also factor in (that offically there’s up to 1800 slayers in the world), but only about 500 actively slaying(according to BtVS: season 8 comic). Even if the active slayers only killed 1 vampire per month (average), they would slay 6,000 vampires in a single year. Which means just to maintain their present population - each vampire need to sire at least 1 vampire per year.

    Now that’s the real Btvs/Angel ’verse post "Chosen".

  • That’s an interesting article to say the least, but as it was mentioned before it’s way to abscure to assume a vamp would sire one a month, as some never do. More to the point though, The slayer isn’t the only one that kills vamps. Remember Holtz? There are numberous viliganties, (and if you really wanna get into it: Wolfram and Hart - they use vamps as tools and thus don’t let them feed or sire, as well as the whole pig’s blood thing) and even other demons (not to mention rival vamps) that take each other out as well. Also, according to the laws of the Whedonverse, humans are fine in daylight, and vamps can’t break in during the night; so how are humans really in danger of extinction? (Doppelganger land, anyone?) It’s a neat thought, but there are -way- too many unaccounted variables in that. lol, maybe I just took that way too seriously. ;P
  • I agree that the people doing this article are going by a vampire model that’s not at all familair to Buffy or even Anee Rice fans for that matter. Apart from the most glaring mis-assumption (i.e that vampires turn whoever they feed off of which as those above have stated just isn’t true in any of the reigning pop-culture vamp stories. In fact, I think Salem’s Lot is the only well known Vamp story that displayed anyone bitten by a vamp appeared to have become one as well - but although I’m a huge Buffy fan and used to be a pretty major Anne Rice fan, I do freely admit to not being into Vamps to the point I read every author’s take on them, so perhaps there are more examples. But yes, in Buffy or The Vampire Chronicles, a Vampire ONLY turns someone into another vamp with a very specific procedure to do so (i.e. drink their blood to almost the point of death - then have the victim feed on the Vampires blood).

    For Issue #2 - one victim a month? These must be Vamps on a strict diet. Most of the stories I’ve read show Vamps quite easily would kill (or at the very least, feed) at least one person per night, sometimes more (And of course, sometimes less, but certainly more than one a month!). Of course in Anne Rice’s Vamp Chronicles younger vamps may kill several a night (or it seems most of the latter books had vamps who were highly concientous and only performed the "Little Drink" where they take so little blood that the victim is scarcely aware of it, while older Vamps - really old ones - don’t seem to need blood very often at all. There were also plenty examples of Vamps on Buffy that did not kill - even ones you might suspect would (i.e. those Vamps like Angel who waited on the blood bank shipments to the hospital, the vamps in the Vamp House that fed on willing humans who would actually pay for the experience (i.e. as in Riley’s big weird doings) as it’s apparently very pleasurable (and the Vamp Chron. also describe the biting and taking of blood as something that causes an extremely blissful swoon). And then (as mentioned above) you don’t have any shortage of Vamps who will kill one another without a second’s delay. And I’m not just talking about brain-chipped Spike and good boy Angel- plenty Vamps would punish vamps by killing them for failure (the Master and the 3 among others), on Angel we saw a lot of this, and even whilst fighting over various resources. So a fair number of Vamps get dusted by far more than just a Slayer (humans like Wood and the Watchers, other vamps, other demons, or as Anne Rice ;likes to show - by self sacrifice. So despite the number of vamps being "made" their calculations appear to simply assume once made a vamp, you are indestructable which most certainly is NOT the case. By leaving this important data out, one wonders just how much thought and research they put into this.

    So despite the fact they left out valid data points, the very base assumptions they are working from are erroneous. Thus this study has little intrinsic value, if any at all.

    And despite the seemingly serious tone I’ve written this in, I (and I hope they) did it mainly in jest. :-) But the points I make are truly important ones! :-)

  • Someone’s probably already pointed this out, but in the Buffyverse it’s not the case that every vamp victim becomes a vamp. Most of ’em just get drained. The vic has to drink the vamp’s blood in turn before he/she turns vamp.