Vampires - a mathematical impossibility

A physics proffesor at the University of Central Florida came up with this one:

Legend has it that vampires feed on human blood and once bitten a person turns into a vampire and starts feasting on the blood of others.

Efthimiou's debunking logic: On 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. (Live Science)

There you go. There's no such things as vampires.