From the Walking Dead to Pride, Prejudice, and Zombies, pop-culture has been obsessed with the idea of the zombie apocalypse. Many people have looked at the social implications of the “end of the world.” Explanations range from the economy and pessimism to hope and the need for cooperation to overcome all obstacles. But what about the science behind the brain-eating corpses?
One novel that took this into consideration was M.R. Carrey’s The Girl with All the Gifts. The book starts out with Melanie, a brilliant little girl who is in lock-down with several other children about twenty years after a mysterious fungal disease wiped out most of humanity. Those who were infected turned into “hungries,” basically the “fast type zombies” that will attack anything and everything that moves. But the actual fungus cited in the book is not at all fiction.
Ophiocordyceps unilateralis is a fungus that infects ants, more specifically, Camponotus castaneus and Camponotus americanusIt, two carpenter ant species. It is known as the “zombie ant” fungus. When foraging, the ants pick up the spores. Once established, O. unilateralis will take control of the central nervous system of the ant. The ant will abandon its colony and climb to a high purchase where it will bite the underside of a leaf until it dies of starvation or the fruiting body of the fungus bursts out of the back of its head. Perfect zombie material, right?
But it is unlikely that O. unilateralis would ever actually make the jump from carpenter ants to humans. A study done by evolutionary biologists at Pennsylvania State University show that the fungus and its host species have co-evolved. In order to take over the ant’s behavior, the fungus produces a wide array of chemicals, specific to the ant’s biochemistry. When the scientists injected the fungus into non-host ant species, it could not produce the correct drug cocktail to control the behavior. The ants died, but no change in behavior or fruiting body was observed. Continued experiments showed that O. unilateralis actually adjusts the chemicals it releases to match the ant it infects, implying that the fungus recognizes the ant’s brain or chemical makeup. However, since the fungus cannot even make the jump between different ant species, we’re safe for now.
M.R. Carry wasn’t the only author to use fungus as a means to humanity’s end. Joe Hill in his book The Fireman also took inspiration from the natural world. In his introduction, he wrote that most of the aspects of his fictional fungal disease occur in nature and mentioned the zombie ant fungus in an interview. However, instead of turning the infected into brainless puppets, Hill’s fungus makes the person spontaneously combust. He combined the effects of CNS infections with the fact that spores can travel great distances by fire and cause intense burning sensations (ie athlete’s foot).
Luckily both of these diseases in humans are fictional, but recently there has been an increase in fungal infections that affect the central nervous system. With the rise of HIV, prolonged ventilation, oncological therapies, organ transplants, and the extensive use of antibiotics, fungal infections have become more common. These infections drastically increase the morbidity and mortality of a patient if not treated, so early detection is paramount as the antifungal drugs are still an effective treatment.
If these books don’t satisfy, there is also Station 11 by Emily St. John Mandel. This novel does not contain a parasitic fungus but instead a devastatingly virulent flu, nicknamed the Georgia Flu. The book focuses on the human aspect of the disease, weaving an extremely well-crafted narrative that connects the characters both before and after the epidemic.
Overall, the quality of biological reasoning behind re-animated corpses has improved, but as fiction dives deeper into the science, the end of the world seems one step closer.