If a real-life zombie apocalypse broke out, would you prepared to take on the undead? Most of us know at this point that zombies are a work of fiction, but scientists wanted to determine if humans could actually fight off the creatures in a worst-case scenario.

A study published in the University of Leicester’s Journal of Physics Special Topics now looks at how long it would take zombies to take over the world. The researchers estimated that each zombie would have a 90 percent success rate at finding and infecting one human per day. This would make the zombie virus twice as contagious as the Black Death (or plague) of the 1300s.

The researchers also determined that each zombie could live up to 20 days without brains. A noticeable impact would likely take approximately 20 days to be seen as well. Without geographic isolation, the human population would drop to about 273 people (from about 7.5 billion) by Day No. 100.

To arrive at their conclusions, the researchers used the SIR model, which is typically used to determine the spread of disease. “S” represents the number of susceptible individuals, and “I” is the number of infected individuals. “R” represents the number of recovered individuals.

In this case, the researchers examined the S (the susceptible population), Z (the zombie population) and D (the dead population), and suggested that the average life-cycle of a zombie would be S to Z to D.

However, these numbers shouldn’t be strongly relied for a few reasons, aside from the fact that it regards fictional zombies. The study did not take natural birth and death rates into account. The researchers also did not take mankind’s ability to fight back.

Real-Life Zombies?

In terms of “real-life” zombies, a certain tetrodotoxin can create a zombie-like sensation in humans. When an individual is poisoned, he or she may appear to be dead. When the poison wears off and the individual rises from the grave, it creates a “zombie-like” situation.

When too much of the tetrodotoxin is taken, an individual can die. However, it remains a critical part of some cultures in the Caribbean today. Those who practice religions, such as Santeria and voodoo, believe in magic and witchcraft – some of which involve the undead.

Sources

Radford, Benjamin. “Zombies: The Real Story of the Undead.” LiveScience. Published Oct. 10, 2012.

Pappas, Stephanie. “Zombies Would Wipe Out Humans in Less than 100 Days.” LiveScience. Published Jan. 6, 2017.

“Zombie apocalypse would wipe out humankind in just 100 days, students calculate.” University of Leicester. Published Jan. 5, 2017.

Smith, David. Moore, Lang. “The SIR Model for Spread of Disease – The Differential Equation Model.” Mathematical Association of America. Retrieved Jan. 10, 2017.