Take a look!
You’ve certainly heard of The Last Of Us, the exciting HBO series. Perhaps you’re already watching it (’cause that’s what we’re doing here at The Blob Lab).
In this series adapted from Naughty Dog’s video game, a fungus called Cordyceps infects humanity, turning humans into zombies and precipitating the fall of civilization. A terrifying premise that begs the question of whether such a phenomenon could really happen.
On the other hand, the appearance of most of the mushrooms featured on screen seems familiar to the most discerning viewers: could the blob have finally led mankind to its doom?
While the plot of the series takes some liberties with biological accuracy, it is nonetheless based on very real facts known to scientists. I promise, this article is spoiler-free!
There will be spores
One of the most striking images in the series is the spectacular arborescent growth of the mushrooms, which made a lasting impression on the audience right from the opening credits. These are fungal webs whose appearance is very reminiscent of the blob.
Yet the blob is not a fungus, but an amoebozoan (“Amoebozoa” in the diagram below). Although they both reproduce by spores, fungi and blobs come from completely different kingdoms.
Phylogenetic tree of eukaryotes: The blob in the Conosa “supergroup” is not the only one to be confused with a fungus. The other dotted supergroups also include species that have been misclassified as fungi.
Pssst …. looking for where humans are? Find the fish! Like all animals, humans belong to the Metazoa (📸 Tricholome)
An usurper on the family portrait
To depict the main threat, the series’ set designers and graphic artists (and those of the video game before them) drew inspiration from nature, while adding an artistic vision and freeing themselves from biological species boundaries. On screen, the famous “Cordyceps” is a veritable fungal bouquet, made up of no less than 5 different species, one of which is not even related to the mushroom kingdom.
© HBO
© HBO
With Samir from La Nature et ses Secrets (Nature and its Secrets) (1), we’ve put together this gallery of authentic fungal and myxomyceal portraits.
Sometimes, several species of the same genus could be used to illustrate the inspirations of The Last Of Us concept artists. We’ve chosen the most iconic of them all.
Fungi…
(1) Ischnoderma benzoinum
📸 Henk Monster
(2) Bulgaria inquinans
📸 AnemoneProjectors
(3) Cordyceps militaris
📸 Andreas Kunze
(4) Scleroderma citrinum
📸 Hans Hillewaert
(5) The blob (Physarum polycephalum)
© Le Labo Du Blob
… and a myxomycete
(5) The blob (Physarum polycephalum)
© Le Labo Du Blob
Who’s the culprit?
None of these species is a parasite for humans. Their simultaneous presence in fiction makes for a macabre spectacle of varied colors and shapes, but which is in fact completely harmless. So there’s no risk of one of them infecting you or turning your neighbors into cannibalistic monsters.
So where does this zombie story come from? Actually, I haven’t told you everything…
One species among these portraits is indeed deadly! Have you figured out which one?
Cordyceps and the zombie ant
📸 João P. M. Araújo
Certain species of ant, including Brazilian leafcutters, can be parasitized by several genera of fungi with flowery names: Ophiocordyceps unilateralis, Cordyceps kniphofioides, Cordyceps cucumispora… This is where the famous “Cordyceps” that inspired the creators of The Last Of Us comes from.
The real Cordyceps grows mainly in tropical forests, particularly in Amazonia. To reproduce, the fungus manipulates an ant like a puppeteer: it invades its body and takes control of its behavior. Not by directing it from the brain, as the researchers first thought, but by taking direct peripheral control of its muscles (2).
The parasitized ant will then, under duress, leave its nest and climb up a plant. It stops its ascent at a height of around 25 cm (0.39 inch), where the temperature and humidity are perfectly suited to the development of the fungus. Still under its influence, the ant uses its mandibles to bite the plant, anchoring itself firmly in position. It then dies, while a long, strange tube begins to grow from the back of its head. This is the Cordyceps, which, now visible, completes its life cycle by releasing spores into the surrounding air. Their goal: to reach other members of the colony.
🏆 Hunting chart
Ants are not the only victims of Cordyceps: locusts, spiders, stick insects and other small beasts are not spared. There are literally thousands of species of Cordyceps and Ophiocordyceps fungi, but each specializes in a specific prey. The Cordyceps militaris featured in the portrait gallery, for example, parasitizes butterfly larvae and pupae.
🔪 A methodical killer
Although the ant brain is not invaded by Cordyceps, a 2019 study noted that infected ants undergo neurological alterations and significant stress. However, the same researchers also noted the presence of ergothioneine, a compound from the fungus that is known to protect neuronal cells.
This discovery suggests that the fungus, despite its indirect negative impact on the brain, is at the same time trying to preserve it. What a courtesy! It’s probably not in the Cordyceps’s best interests to destroy the ant’s entire cognition too quickly.(3)
Fungal panic
The first episode of the series opens with a 1968 talk show in which Dr. Neuman, a fictional scientist, explains the dangerousness of numerous species of fungi. Clearly ahead of his time, Dr. Neuman is already anticipating that global warming may enable certain fungi to adapt and colonize new prey with higher body temperatures than insects, namely humans.
However, this hypothesis is largely nuanced by American researcher John Perfect and his team, real-life scientists and experts in infectious diseases. In a 2014 study (4), they explain that of the millions of fungal species present on Earth, only a small fraction possess the four characteristics needed to infect humans: tolerance to high temperatures, the ability to invade a human organism, the capacity to absorb our tissues, and resistance to our immune system.
Even if fungi can evolve to increase their number of potential targets, the scientific community believes that a large-scale scenario such as The Last Of Us remains fiction.
They put it into perspective, however, pointing out that every year around 1.3 million people die from fungal diseases.
For its part, the blob is totally harmless. But its strange appearance and natural ability to form fabulous tree-like networks make it the perfect inspiration for a spectacular disaster scenario. After all, its name “blob” came from a sci-fi movie!
🍽 Little beasts don't eat big ones
A bunch of Cordyceps sinensis
Not only has Cordyceps never attacked a human, it’s quite the opposite: certain species of caterpillars parasitized by Cordyceps sinensis are traditionally consumed as a tonic in Chinese medicine. Would you like some more zombified caterpillars?
📚 References
- (1) Samir from the channel “La nature et ses secrets” (Nature and its secrets) A (brilliant) channel to discover all the anecdotes about the mushrooms of our forests. Find Samir on: Tiktok Instagram
- (2) Hughes DP. et al., Three-dimensional visualization and a deep-learning model reveal complex fungal parasite networks in behaviorally manipulated ants. Proceedings of the National Academy of Sciences, 2017. doi:10.1073/pnas.1711673114 https://pubmed.ncbi.nlm.nih.gov/29114054/
- (3) Loreto RG, Hughes DP., The metabolic alteration and apparent preservation of the zombie ant brain. J Insect Physiol. 2019. doi: 10.1016/j.jinsphys.2019.103918. https://www.sciencedirect.com/science/article/abs/pii/S0022191019301404
- (4) Köhler JR, Casadevall A, Perfect J., The spectrum of fungi that infects humans. Cold Spring Harb Perspect Med. 2014. doi: 10.1101/cshperspect.a019273. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4292074/
0 Comments