If vampires were real — and I say "if" because, for all we know, they might be very real — how long do you think it would take for them to wipe out humanity? Shockingly, there have been several academic studies conducted to answer this question.
In 1982, Austrian mathematicians Richard Hartl and Alexander Mehlmann published "The Transylvanian Problem Of Renewable Resources." In this paper, they explored "optimal bloodsucking strategies for dynamic continuous vampires," to see how long real-life vampires could feed on humans.
As it turns out, vampires wouldn't take too long to suck their way through humankind. Hartl and Mehlmann concluded the vampires would face "a typical consumption-resource trade off." They feed on humans, turning them into vampires, which would create more vampires needing more food...and fewer humans, which act as the food.
The researchers wrote this as a way of showing how vampires could best feed without running out of resources...namely, us. This is a smart move to keep vampires from destroying us too quickly. That said, the researchers knew how ridiculous this all was, and even wrote in their paper, "The authors are well-aware that belief in vampires seems highly irrational to a scientist."
So exactly how long did they conclude it would take for vampires to drain humanity to extinction? Looking at population stats and using the extremely conservative estimate of vampires only needing to feed once a month, the researchers predicted vampires would eliminate humans within three years.
Oxford statistics professor Dino Sejdinović took offense to Efthimiou and Gandhi's vampire paper — as Oxford statistics professors are wont to do — and in 2008 wrote his own paper refuting their findings, "Mathematics of the Human-Vampire Conflict." In it, he points out their glaring omissions.
Sejdinović points out that "vampires are presented exclusively as greedy consumers: a rational strategy of managing their human resources is not considered." Nor do they account for the death rate of vampires due to vampire-hunting humans. Omitting these facts completely destroys the credibility of their entire paper.