In 2005, Costas Efthimiou, a physics professor from University of Central Florida whose work attempt to debunk pseudoscientific ideas, such as vampires and zombies, made the headline by claiming that vampires are a mathematical impossibility.

To reach such a conclusion, he used the following assumptions: in Jan 1, 1600, the human population was 536,870,911. If the first vampire came into existence that day and bit one person a month, there would have been two vampires by Feb. 1, 1600.  A month later there would have been four, and so on. In just two-and-a-half years the original human population would all have become vampires with nobody left to feed on.

If mortality rates were taken into consideration, the population would disappear much faster. Even an unrealistically high reproduction rate couldn't counteract this effect.

"In the long run, humans cannot survive under these conditions, even if our population were doubling each month," Efthimiou said. "And doubling is clearly way beyond the human capacity of reproduction."

However, not all vampire legends support the belief that vampire victims become vampires and there is no further evidence that such a law would follow a geometric progression. Last but not least, there are many other ways for vampires to survive without proliferating ....

Let’s look at the theories in presence ...