From human race to zombie planet in less than 100 days

If left unchecked, a zombie apocalypse could wipe out humanity in 100 days or less - so says a new tongue-in-cheek mathematical model [1]. Appearing in the University of Leicester's Journal of Physics Special Topics, a peer-reviewed student journal reported that the zombie hordes would take Earth's population down to a mere 200-ish survivors in 100 days. The report is based on the SIR model, used in epidemiology to simulate how diseases spread. In 2015, the Lancet published a tongue-in-cheek paper titled "Zombie infections: epidemiology, treatment, and prevention." Similarly, a zombie outbreak was used as a metaphor for actual publich health challenges in  a blog posted from the US  Centers for Disease Control and Prevention. The blog, which 'went viral' urged readers to consider zombie-apocalypse preparations as a metaphor for real-life disaster preparedness.

In the present analysis, the model assumed that each zombie would have 90% chance of finding and infecting at least one human per day. There is no saying whether this reflects infection rates expected from hit television shows like 'The Walking Dead' or 'Fear the Walking Dead'. However, it would make the zombie virus twice as contagious as the Black Death. The authors further refined their model by predicting that each zombie could live for around 20 days with having a brain-meal. With a staring world population of 7.5 billion people it would take around 20 days for a single infected person to create a substantial epidemic - assuming that the infection didnt initiate in a geographically isolated region - thus slowing the spread.

Unlike your traditional zombie movie, the model doesnt included the possibility for the humans to kill the zombies. When you add complexities such as the possibility of humans killing zombies, human reproduction and zombie starvation (and a reduced opportunity for killing) hope begins to emerge for the human race. In this instance the human population rapidly drops off but the zombies die off after 1,000 days and the human population starts to recover 10,000 days after the beginning of the epidemic. Good luck.

[1] A Zombie Epidemic. Devies et al., 2016

 

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