Overthinking: March 2011 Archives


March 5, 2011

As I've mentioned before, a world with a lot of vampires is a world with a blood supply problem. I recently watched Daybreakers, which takes this seriously; nearly everyone in the world is a vampire and the vampires farm most of the remaining humans for blood while sending out undeath squads to round up the rest. Obviously, this isn't a scalable proposition and sure enough the vampires are frantically trying to develop some kind of substitute for human blood before supplies run out.

In a world where synthetic blood isn't possible, there's some maximum stable fraction of vampires, dictated by the maximum amount of blood that a non-vampire can produce divided by the amount of blood that a vampire needs to survive. According to Wikipedia blood donations are typically around 500ml and you can donate every two months or so. This works out to about 3 liters of blood per donor per year. Presumably, if you didn't mind doing some harm to the donors (e.g., if it's involuntary), you could get a bit more, but this still gives us a back of the envelope estimate. I have no idea what vampires need, but if it's say a liter a day, then this tells you that any more than about 1% of the population being vampires is unstable. This is of course a classic externality problem, since being a vampire is cool, but not everyone can be a vampire. If we wish to avoid over-bleeding, they will need some sort of system to avoid creating new vampires.

Luckily, this is a relatively well understood economics problem with a well-known solution: we simply set a hard limit on the number of vampires and then auction off the rights (cap-and-trade won't work well unless we have some way of turning vampires back into ordinary humans). I'd expect this to raise a lot of money which we can then plow into synthetic research to hasten the day when everyone can be a vampire; either that or research into better farming methods the better to hasten the red revolution.