nd also remember where food is and where home is. For ants, workers are the most “intelligent”. Still, one lone worker is of no use. It takes the whole colony to have a properly functioning and flourishing nest. An entire colony of ants, which can be up to millions of individuals, does not even come close to matching the complexity of a single human brain. If a fungus were to develop an ability to infect and alter the behavior of humans, this would probably take a ridiculously long time to evolve. Human beings would most likely not even be around any longer. But, let’s just roll with it and say that this could happen. What would it be like and how does The Last of Us compare?
We’ll start with the mode of infection. In the video game, people seem to become infected by breathing in the spores of the mutant O. unilateralis strain. Those who wear a special breathing bask in spore filled areas do not become infected. This appears to check out. Human skin is likely to be much less susceptible to becoming invaded by spores, simply because it is so much thicker and has many more layers than insect cuticle. Other fungi are able to infect hosts via inhalation (like some molds), so it would be no different for a mutant fungus; the infection would just result in a different pathology. So getting infected by this fungus is not in question if you breathe the spores in, but you can also fall victim if there is an exchange of bodily fluids, such as from a bite. This is logical as well. If the fungus has infiltrated an infected person’s system as in ants, bodily fluids like saliva and blood may contain fungal cells. These could easily be passed on to a healthy human.
What about the behavioral and morphological alterations? In The Last of Us, any infected individual, even in the early stages, is being driven by the fungus’ gene expression and aims to spread the spores or cells to as many others as possible. There are four main stages of infection from this mutant O. unilateralis: Runners, Stalkers, Clickers, and Bloaters. All of these collectively are referred to as the Infected (noun) in the game. Individuals who have just been infected are classified as Runners. They still cling to a shred of their humanity, however small, and try to resist the fungus’ behavioral control. However, if they are startled or as the infection progresses, they will snap and attempt to attack anyone nearby who is healthy. Stalkers are fully controlled by O. unilateralis and start to show fungal growth on the face. This fungus strain attacks the eyes first, so they have poor vision and begin to exhibit primitive signs of echolocation. In Clickers, the face has been fully engulfed by fungal growth and rendered the host completely blind. These Infecteds use clicking and screeching to crudely survey their surroundings within a small radius. The growth on the head and face forms a roughly dish shaped plate that helps to direct the clicks. Bloaters are the final stage and can take 10-15 years to develop. The entire body of this Infected is now covered in fungus, some of it showing bioluminescence, and is therefore very physically hardy. Bloaters are also able to throw sacs of toxic powder both as a defense and an attack mechanism. Once the host finally dies, whatever tissue is left of the former person crumbles and is used by the parasite to complete its growth and release spores.
Now to analyze the behavior of the Infected. All stages appear to seek out specific locations and stay there, unless stimulated to pass on the infection when a healthy individual is sensed nearby. This reflects the behavior of O. unilateralis controlled ants that travel until they find the optimal conditions for the fungus’s reproduction and then fix themselves to that spot. However, infected ants will leave the colony and do not show any aggressive behavior whatsoever toward other ants. Why would the Infected exhibit such an aggressive drive to bite or kill? We actually have a disease in existence that does just this. It’s called rabies virus. If rabies can infiltrate the brains of mammal