Science fiction and real science are much more intertwined than we believe. It's not just about the famous image of the "mad scientist" that Hollywood sold us; we find it in every corner of our lives, even in the kitchen when we seek the perfect recipe for simple buttered noodles.
Many fiction plots are built on scientific concepts: superhuman metabolisms, individuals who acquire extraordinary abilities after an accident, microorganisms capable of wiping out entire civilizations, or inspiration taken from a simple animal to create fascinating worlds—fiction nourishes itself from science, making us see that everything that is unreal can become real.
The creators of The Last of Us did not fall behind when it came to combining science with entertainment. The famous video game, later adapted into a series, revolves around a real fungus: Ophiocordyceps unilateralis. Yes, quite challenging to pronounce!
In the story, a strain mutated by global warming causes an infection that wipes out thousands of humans, making them behave erratically and uncontrollably. In Hollywood, they call them "zombies."
Thus, many questions, doubts, and uncertainties come to light, prompting us to ask where fiction ends and science begins—a thin line that sometimes disappears.
After 2020, society is on alert for any threat. The premiere of the second season of "The Last of Us" reignited fears about pandemic civilizations and apocalyptic scenarios. As the episodes progressed, that anxiety became increasingly persistent: Could something like this really happen to humans?
The need to answer the big question led to formulating a clear hypothesis: “This could happen to our species.” With that starting point, research advanced, sources were analyzed, and data were collected, allowing for conclusions worth sharing.
These kinds of stories teach us that intrigue is fundamental: holding attention, sparking curiosity, and leaving the reader wanting more, as if they were binge-watching the series.
O. unilateralis, or the so-called "zombie fungus" among friends, is an entomopathogenic fungus, meaning it can infect and kill insects, acting as a natural biological control for pests. In this case, it specifically attacks and "zombifies" carpenter ants (Camponotus leonardi), which inhabit the trees of tropical forests.
The infection and development process consists of three key phases: adhesion, penetration, and replication within the host.
The fungus produces a kind of anchoring structure or base, allowing it to spread its spores (reproductive cells that allow the fungus to multiply and disperse in a suitable environment, like “seeds”). Once released, the spores spread with the help of wind, rain, or animals until they reach their host. There, they adhere to the cuticle (the outer layer that acts as an exoskeleton) through the recognition of specific receptors. This concludes the adhesion stage, similar to ticks, and the penetration phase begins. It is here that the fungus employs two simultaneous mechanisms:
A physical one, based on the mechanical pressure exerted by the fungal structure on the surface of the insect, and a chemical process: the release of hydrolytic enzymes capable of breaking links, such as proteases, lipases, and chitinases. In this way, the host's tissue degrades, facilitating the entry of the fungus into the organism.
Once inside the organism, the fungus begins to grow and spread throughout the insides of the ant. Now established in the hemolymph (the “blood” of invertebrates), it initiates the most fascinating and disturbing part of the infection process: the moment when the host, the ant, begins to change its behavior.
The fungus produces and releases chemical substances within the host, similar to neurotransmitters, which affect the nervous system and muscular activity, controlling its behavior patterns and making the ant lose all will over its movements. The infected ant leaves its colony, falls from the tree, and heads to the forest floor, a moist area conducive to fungal growth. There, the “Zombie Ant” performs the famous death bite: it firmly attaches itself to a leaf or branch before dying.
But this does not end here; the fungus will continue to grow and feed inside the carcass until it finally emerges from the insect's body through the head. From there, it will release new spores, which will wait for more victims, thus repeating the cycle.
As research advances, the question becomes more pressing: In the real world, could this happen to humans? It sounds like a movie plot... but it's entirely real in ants.
It may sound disappointing, spoiler alert! The result strays from fiction; the hypothesis is negative. The likelihood of something like this occurring in humans is highly improbable. The physiology of these fungi is adapted to an extremely specific relationship developed over millions of years of evolution. It has survived catastrophes and climate changes, yet that connection between the fungus and its host remains intact. Over time, it has become more efficient and selective. Ophiocordyceps unilateralis is designed to live in such organisms, but fortunately for us, humans are spared—at least for now.
In the case of humans, there are three factors that prevent the development of an infection like that which occurs in insects:
-Body temperature does not allow the fungus to develop.
-Physical barriers like skin.
-The immune system would quickly attack it upon detection.
These are insurmountable obstacles for O. unilateralis.
In fact, we have coexisted with it since the origin of our species; far from being a threat, it is currently being studied, especially in the field of Eastern medicine. There is still much to discover and questions to answer. Therefore, the invitation is to do science from your living room: first through the series, then in books.
Ask, research, and re-ask—don't settle for the first answer. This applies in all areas, not just in science. Because an educated, informed, and curious society is the best weapon we can have, even more powerful than any that appears in fiction.
As Miguel Angel Noceda would say, "An uninformed society is a manipulable society."
Author: Guadalupe Yantani, a student of Biotechnology at UADE
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