# Zombies Could Wipe Us Out In 100 Days, Research Says

Unless we get smart and fight back.

Life with zombies wouldn’t last long. A new study concludes that ravening zombie hordes would reduce Earth’s population to no more than 200 survivors within 100 days.

The research, published in the University of Leicester’s peer-reviewed Journal of Physics Special Topics, is a tongue-in-cheek analysis by physics students of a mathematical model that predicts the spread of disease. But in the model, zombies serve a deadly serious function: to simulate how quickly a virus could wipe out the planet.

The model divides the population into three categories: those susceptible to the infection, those infected, and those who have either died or recovered. The model then considers the rates at which infections spread as individuals in the population come into contact with each other.

An initial study assumed that each zombie would have a life span of 20 days and 90 percent success at finding and infecting one human per day — which would make the zombie virus twice as contagious as the Black Death pathogen. Within 20 days, a single zombie could trigger a pandemic. A population of 7.5 billion people could be reduced within 100 days to just 100 to 200 survivors, with 190 million zombies still roaming around.

Relax, that’s the worst-case scenario. It assumes that humans would continue to be easy for zombies to find. In fact, humans would become more difficult to find because there would be fewer of them, and they would learn how to avoid the zombies. Also, humans would fight back.

A more optimistic scenario found better odds for humanity, even while increasing the zombie’s expected life span to a year. In the more positive mathematical model analyzed by the physics students in another paper, taking into account human reproduction and a 10 percent chance that each human could kill one zombie a day, the human population still fell to a few hundred. But the zombies all died off after 1,000 days, and humanity began to recover after 10,000 days (a little over 27 years).

The new parameters, such as “people having children within the nightmare scenario … made human survival more feasible,” a statement from the British university noted.