Imagine if a zombie apocalypse really happened. Could humans survive it? The Walking Dead makes it seem like grit and a love for fascism might give you a chance, but could our species make it as some of us turn into brainless, shuffling husks of meat, compelled to kill and eat the living?
No, says the University of Leicester in England, where a group of students ran the numbers and conceded that after just 100 days, fewer than 300 people would be left alive on the planet.
The paper was published in a peer-reviewed student journal designed to let students practice publication, which is why a paper about hypothetical zombie survival was accepted for publication at all. Not that that necessarily make its scientific method any less rigorous.
The students used the SIR model to predict the spread of the disease, which is a standard model in epidemiology, used to predict the rates at which infections spread, and how those infections die off. Using this method, the students plugged in their zombie "data." The data assumes that a zombie can find one person each day and that it has a 90% chance of infecting that person. The model shows that, after 100 days, the non-zombie population would stand at just 273, who would be outnumbered a million-to-one by zombies.
The first study discarded natural birth and death rates among humans, as the time period of just 100 days seemed to make it irrelevant, but the students ran a second study that included these, as well as a new parameter—the rate at which zombies themselves are killed. The results were much more optimistic. "We find that adding such parameters makes it far more feasible for a given simulated population to survive a zombie epidemic," says the paper.
And in fact, in this model, the human race can pull through. After hunting humans to near extinction, the zombies' food source is gone, and they eventually die off too. Zombies aren't much good at, say, farming new humans in order to feed themselves after all. Meanwhile, if the spunky human survivors manage to keep themselves alive for long enough, they will outlive the zombie epidemic and start to rebuild the population.
It turns out, then, that according to science, all those zombie movies had it dead right after all.