Zombie outbreak: Humans don't stand a chance, new study suggests

Zombies from TV show The Walking Dead (AMC)
Zombies from TV show The Walking Dead (AMC)

A zombie epidemic would take little over six months to obliterate humanity, new research has found.

Starting with a single zombie, in 100 days there would only between 100 and 200 non-infected humans left alive, struggling against 190 million zombies - all the while surrounded by the corpses of more than 7 billion dead.

Three months later, there'd be no one left.

Students at the University of Leicester used a mathematical model to come up with the apocalyptic scenario. It's normally used to determine how quickly diseases can spread, but they adapted it to an outbreak of conscious deficit hypoactivity disorder - the semi-scientific term for being a zombie.

They assumed that each zombie would have a 90 percent chance of infecting a person each day, "roughly twice as contagious as the Black Death"; each zombie would last about 20 days "before starvation and thirst renders it effectively dead"; and zombies will only move on from an area once the population reached a critical threshold (like humans, zombies also need their space it would seem).

"With only one person infected at day 0, it takes 20 days for the infection to spread to a noticeable fraction of the population," the paper, published in the Journal of Physics Special Topics, reads.

"From this point, the remaining population is quickly wiped out. By day 100 we find that there are 181 survivors and 190 million zombies."

A graph showing the timeline of a zombie epidemic (supplied)
Two models of how the epidemic may play out. On the left, if the population was evenly distributed; on the right, with geographic isolation taken into account. Blue = uninfected, green = infected, red = dead (supplied)

The students admit their model doesn't take into account the fact most humans don't want to be zombies, and - as illustrated in movies like Shaun of the Dead - will likely fight back.

A scene from Shaun of the Dead (Universal Pictures)
A scene from Shaun of the Dead (Universal Pictures)

"We also assumed that a zombie will turn one person into a zombie each day with a 90 percent probability, meaning that each zombie is able to find a person every day. As the zombie to human ratio increases, this becomes less realistic."

It also doesn't explain how zombies are able to board planes or ships and infect populations on different continents - or far-flung islands like New Zealand.

A competing model last year predicted it would take 60 days for 2 million to be infected - that one assumed people would fight back.